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Nature of ScienceSC.912.N.1.1 Scientific MethodExample OneAn osmosis investigation was conducted using chicken eggs to represent cells with semipermeable membranes. The mass of each egg was measured to determine how much water diffused into or out of the eggs. The eggs were first soaked in vinegar to dissolve the shell. Each egg was then placed in one of three different solutions for 24 hours. The table below shows the results of the investigation.Osmosis in Cells?SolutionAverage Mass of Eggs Before Soaking (grams)Average Mass of Eggs After Soaking (grams)Difference in Average Mass (grams)Percent Change in Average MassVinegar?(95% water)71.298.627.4+38.5Corn Syrup (5% water)98.664.534.1-34.6Distilled Water (100% water)64.5105.340.8+63.3??Based on this experiment, which of the following should be inferred about cells with semipermeable membranes?A. Substances other than water may also cross the cell membrane.B. Substances other than water may block pores in the cell membrane.C. Water enters the cell when placed in environments of high water concentration.D. Water leaves the cell when placed in environments with a low concentration of solutesExample TwoCarmen conducted an experiment to determine if listening to different types of music would affect a person’s pulse. Her hypothesis was that pulse rate would change with different types of music. Each person listened to seven different selections of music for 30 seconds each. Each person’s pulse was taken before the music and then after each 30-second interval of music. The pulses were taken again after the music selections were completed. Based on her experiment, Carmen concluded that a person’s pulse rate changed when the person listened to different types of music. ?Which component is missing from Carmen’s experiment? A. a question B. a hypothesis C. a control group D. a description of the experiment Example ThreeThe graph below shows atmospheric carbon dioxide levels since the year 1880.Which of the following conclusions can be drawn from this graph?A. Atmospheric carbon dioxide levels are responsible for?global temperature change.B. Atmospheric carbon dioxide levels have been rising at about the same rate?for the past century.C. Atmospheric carbon dioxide levels have remained the same over the past century.D. Atmospheric carbon dioxide levels have been rising at an increasingly higher rate as the past century has progressed. Example FourA scientist performs an experiment to see if acids have an effect on the health of a particular type of plant. Three sets of plants were treated with acidic solutions of known pH while the control set was treated with a solution of neutral pH 7.Which is the best conclusion for this experiment??A. Acid has no effect on the health of this type of plant.B. High acidity is helpful to this type of plant.C. Low acidity is harmful to this type of plant.D. High acidity is harmful to this type of plant.Example FiveA research group has discovered that damselflies, a type of dragonfly, are being infected by a particular type of aquatic protozoan. Both young and adult damselflies are not directly infected by the protozoan but contract the infection from the prey they eat. The graph shows the percentage of adult damselflies infected by protozoans during the summer and early fall.?Which of the following conclusions is supported by the graph??A. Infection in embanked ponds increased during the sampling period.B. Protozoans were more common in creek-fed ponds than embanked ponds.C. Protozoans reproduce more quickly in embanked ponds than creek-fed ponds.D. Infection in creed-fed ponds remained constant throughout the sampling period.Molecular and Cellular BiologySC.912.L.14.1 Cell TheoryExample OneCell theory was first proposed in 1838. Evidence obtained through additional scientific investigations resulted in the current cell theory. Which statement describes a component of the original cell theory that was removed because of the new scientific knowledge?A. All living things are made of cells. B. All cells come from other preexisting cells.C. Cells form through spontaneous generation.D. Cells are the basic structural and functional units of life. Example TwoWhich invention from the 17th century allowed for the development of modern cell theory? A. X-raysB. computersC. the light microscopeD. the scanning electron microscopeSC.912.L.14.3 Cell Structure Example OneThere are some similarities between prokaryotic and eukaryotic cells. Which of the following structures is found in both prokaryotic and eukaryotic cells?A. lysosomeB. mitochondrionC. nucleusD. ribosomeExample TwoGlucose is not able to pass through a semi-permeable cell membrane. If the cells need sugar to make ATP and carry out cellular processes, how does the sugar get into the cell??A. passive transport by diffusionB. active transport using ATP and carrier proteinsC. passive transport by osmosisD. phagocytosisExample ThreeWhich type(s) of cells have genetic material that is contained in a nucleus?A. bacteriaB. only animal cellsC. protistsD. both plant and animal cellsExample FourWhich characteristic do most plants have in common?A. they are unicellularB. they are prokaryoticC. they produce seedsD. they are autotrophicExample FiveWhich cell structure is correctly paired with its primary function??A. ribosome - protein synthesisB. mitochondrion - movementC. vacuole - cell divisionD. nucleus - storage of nutrientsExample SixThe diagram below represents a cell of a green plant.?Solar energy is used to produce energy-rich compounds in which structure??A. AB. BC. CD. DExample SevenA person with swollen gums rinses his mouth with warm salt water, and the swelling decreases. Which of the following has occurred?A. The swollen gums have absorbed the saltwater solution.B. The saltwater solution lowers the temperature of the water in the gums.C. The salt in the solution has moved against the concentration gradient.D. The water in the gums has moved out due to the high concentration of salt in the solution.?Example EightThe diagram below represents a cell.?Which organelle is the site where amino acids are synthesized into proteins??A. 1B. 2C. 3D. 4Example NineWhich of these best completes this concept map??A. an animal cellB. a prokaryotic cellC. a virusD. a plant cellExample TenThe cell membrane of the red blood cell will allow water, oxygen, and carbon dioxide to pass through. Because other substances are blocked from entering, this membrane is calledA. perforatedB. semi-permeableC. non-conductiveD. permeableSC.912.L.16.3 DNA Replication Example OneGenes for medically important proteins can be cloned and inserted into bacteria, as shown in the diagram below. Why can bacteria recognize a human gene and then produce a human protein?A. DNA replication in bacteria and humans is the same.B. Bacterial cells contain the same organelles as human cells. C. The basic components of DNA are the same in humans and bacteria.D. Bacterial cells and human cells contain the same kind of chromosomes. Example TwoWhich choice describes DNA after replication has taken place?A. one molecule with two original strands and one molecule with two new strandsB. two molecules, each with one original and one new strandC. two molecules, each with two new strandsD. two molecules, each with two old strandsExample ThreeAt what point in the cell cycle does DNA replication occur and why?A. before a cell divides, to provide each of the two resulting cells with a complete set of DNA instructionsB. before a cell divides, to ensure that the DNA will fit into the resulting cellsC. during cell division, to ensure that the DNA will fit into the resulting cellsD.?after a cell divides, to provide each of the two resulting cells with a complete set of DNA instructions?Example FourFour different segments of a DNA molecule are represented below.There is an error in the DNA in which molecule?A. segment 1 onlyB. segment 3 onlyC. segment 2 and 3D. segment 2 and 4Example FiveThe sequence of DNA below is part of a gene. How many amino acids are coded for by this segment??5' ATCAGCGCTGGC 3'A. 4B. 8C. 12D. 20Example SixA scientist puts nucleotide chains of UUUUUU in a test tube under conditions allowing protein synthesis. Soon the test tube is full of polypeptide chains composed only one the amino acid phenylalanine. What does this experiment indicate??A. The amino acid phenylalanine is composed of uracil.B. UUU codes for the amino acid phenylalanine.C. Protein synthesis malfunctions in test tubes.D. Most proteins contain only one type of amino acid.Example SevenWhich of the following would most likely cause a mutation?A. the placement of ribosomes on the endoplasmic reticulumB. the insertion of a nucleotide into DNAC. the movement of transfer RNA out of the nucleusD. the release of messenger RNA from DNAExample Eight?A diagram of a cellular process is shown below.?Which of the following identifies the process shown at point Z?A. TranslationB. TranslocationC. ReplicationD. TranscriptionExample NineDuring transcription the DNA base sequence is transcribed into a complimentary mRNA sequence. A codon table like the one shown below lists the amino acids coded for by particular triads of mRNA bases. A segment of DNA has undergone a mutation in which one nucleotide has been changed. The original sequence was ACG and the new sequence is ACA. Use the codon table to determine whether or not this mutation will cause a change in the phenotype of the organism.?A. yes, the phenotype of the organism would change because a new amino acid will be coded for.B. yes, the phenotype of the organism would change because any change in the DNA sequence will cause a change in phenotype.C. Even though the DNA sequence changed, the sequence still codes for the same amino acid, so no change in phenotype will occur.?D. It is impossible to determine if a change in phenotype will occur using only the DNA sequence.?Example TenWhich of the following carries amino acids to the site of protein synthesis??A. mRNAB. rRNAC. tRNAD. nRNASC.912.L.16.17 Mitosis and Meiosis Example OneMitosis and meiosis are processes involved in cellular reproduction. Which of the following describes and event that results from mitosis but NOT meiosis? A. two stages of cell divisionB. replication of cellular genetic materialC. daughter cells that are identical to the parent cellD. four daughter cells that are produced from each parent cellExample TwoHow are sexual reproduction and?asexual reproduction different from each other?A. sexual reproduction requires two parents and asexual reproduction requires only one parentB. asexual reproduction requires two parents and sexual reproduction requires only one parentC. mutation rates are lower in sexual reproduction than in asexual reproductionD. asexual reproduction occurs only in multicellular organismsExample ThreeWhich type of reproduction leads to increased genetic variation on a population? A. Parthenogenesis B. asexual reproduction C. Sexual reproduction D. Vegetative reproductionExample FourWhich of the following phrases best describes cancer?A. absence of cyclins in the DNAB. miltiple gene mutations on a chromosome of DNAC. uncontrolled cell growth caused by mutations in genes that control the cell cycleD. presence of genetic defects caused by hereditary disordersExample FiveWhich of the following phases of mitosis is represented by the diagram below?A. prophaseB. metaphaseC. anaphaseD. telophaseExample SixA scientist wants to change the DNA of a sexually reproducing organism and have the new DNA present in every cell of the organism. In order to do this after fertilization, she would change the DNA in which of the following??A. zygoteB. placentaC. testes of the fatherD. ovaries of the motherExample SevenWhich row in the chart below indicates the correct process for each event indicated??A. row 1B. row 2C. row 3D. row 4Example EightThe diagram below shows a cellular process that occurs in organisms.?What is the name of this process??A. meiosisB. mitosisC. endocytosisD. phagocytosisExample NineThe diagram below shows homologous chromosomes during prophase I of meiosis.Which of the following correctly describes the process being illustrated??A. mutation in which the DNA content of the gene is alteredB. segregation of sister chromatidsC. condensation and segregation of allelesD. crossing-over in which alleles are exchangedExample TenWhich of the following best describes meiosis??A. It is carried out in all tissues that require cell replacement.B. It occurs only in cells in the reproductive structures of organisms.?C. It happens in all tissues except the brain and spinal cord.D. It is the first stage of mitosis.?Example ElevenThe diagram below shows two strawberry plants.Plant 2 is produced asexually from Plant 1. If the leaf cells of Plant 1 have 56 chromosomes, how many chromosomes will be found in the leaf cells of Plant 2?A. 14B. 28C. 56D. 112SC.912.L.18.1 Macromolecules Example OneAs food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloride acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine?A. It becomes inactive. B. It begins to replicate. C. It's shape changes to engulf large proteins. D. It's activity increases to digest more proteins.Example TwoIn living cells, enzymes act as catalysts, which?may reduce the amount of activation energy required for a chemical reaction to occur.? In the graphs below, pathway x is a solid line representing the uncatalyzed reaction. The dotted line shows the catalyzed reaction. Which graph best illustrates the changes in a reaction when the catalyst reduces the amount of energy required? Example ThreeThe diagram below shows the general structure of an amino acid. Which type of molecule is formed?from?amino acids?A. lipidsB. proteinsC. carbohydratesD. nucleic acidsExample FourYou are analyzing a compound in the laboratory. You find that it is made up of carbon, hydrogen, and oxygen in a ratio of two hydrogen atoms for each carbon atom. How will you classify the compound?A. lipidB. proteinC. carbohydrateD. nucleic acidExample FiveFats, oils and cholesterol are all types of what?A. cell membranesB. hormonesC. lipidsD. fatty acidsExample SixRNA and DNA are which type of macromolecules??A. carbohydrateB. lipidC. nucleic acidD. proteinExample SevenWhat will most likely happen if an appropriate enzyme is added to a chemical reaction??A. The reaction rate will increase.B. The equilibrium of the reaction will be maintained.?C. The reaction rate will decrease.D. The reaction will stop.?Example EightA sugar, a phosphate group, and a nitrogen base form the building blocks of which organic compound?A. carbohydratesB. lipidsC. nucleic acidsD. proteinsExample NineThe human body maintains a temperature of around 98.6 degrees at all times. Enzymes are involved in almost every chemical reaction in the body. Which of the following describes the connection between these two statements??A. Enzymes function best at a specific temperature.B. The body needs to be warm to prevent hypothermia.C. The body is kept relatively warm to prevent too much enzyme action.?D. There is no connection between the two statements.?Example TenThe enzyme lactase will break down the sugar lactose into which of the following components??A. monosaccharidesB. nucleic acidsC. amino acidsD. phospholipidsSC.912.L.18.9 Photosynthesis and Cellular Respiration Example OneThe diagram below shows the relationship between photosynthesis and cellular respiration and the organelles in which they occur.Which statement describes how photosynthesis and cellular respiration are interrelated?A. Oxygen is produced during cellular respiration and stored during photosynthesis.B. Carbon dioxide and water released by cellular respiration are used in photosynthesis.C. Photosynthesis releases the energy that is stored during the process of cellular respiration.D. Glucose is used during cellular respiration to produce food that is broken down during photosynthesis.Example TwoWhich gas is removed from the atmosphere during photosynthesis?A. hydrogenB. oxygenC. nitrogenD. carbon dioxideExample ThreeA weightlifter is using heavy weights in short bursts for a competition. Because his muscle cells are not able to take in enough oxygen to make very much ATP the weightlifter begins to get fatigue in his muscles. Which of the following processes is most likely going on in the muscles of the weightlifter as he competes in his event??A. As the cells run out of oxygen they switch to anaerobic respiration, which allows the cell to make small amounts of ATP in the absence of oxygen.?B. As the cells run out of oxygen, they die off gradually and the weightlifter's muscles have fewer contracting muscle cells.C. The cells will never run out of oxygen if the weightlifter is breathing.D. As the cells run out of oxygen, they will continue to make the same amount of ATP, since oxygen is not required to make ATP.?Example FourWhat function does?ATP carry out in living things?A. aids in protein folding and coilingB.?used to capture and transfer energyC. identifies DNA start sequences for transcriptionD. helps maintain the fluidity of cell membranesExample FiveHow are cellular respiration and photosynthesis related, in terms of energy?A. The energy captured in photosynthesis is used to power cellular respiration.B. The energy transformed in cellular respiration is used to power photosynthesis.C. Photosynthesis and respiration perform the same task in terms of energy transformation.D. Energy is not?involved in either photosynthesis or cellular respiration.Example SixTwo different species of bacteria are examined. Scientists find that species X always produces CO2 and H2O during cellular respiration. Species Y always produces ethyl alcohol and CO2. Which conclusion can be made from these observations??A. Only species Y is aerobic.B. Only species Y is anaerobic.C. Both species X and Y are aerobic.D. Both species X and Y are anaerobic.?Example SevenIn which way are photosynthesis and cellular respiration different??A. Cellular respiration stores ATP, while photosynthesis releases ATP.B. Cellular respiration produces oxygen, while photosynthesis uses oxygen.C. Photosynthesis releases energy, while cellular respiration stores energy.D. Photosynthesis used carbon dioxide, while cellular respiration produces carbon dioxide.Example EightA diagram representing the relationship between photosynthesis and cellular respiration is shown below.The numbered boxes in the diagram represent which of the following??A. 1 - water; 2 - nitrogenB. 1 - nitrogen; 2 - oxygenC. 1 - oxygen; 2 - carbon dioxideD. 1 - carbon dioxide; 2 – waterSC.912.L.18.12 Properties of Water Example OneWater is essential for life. Its special properties make water the single most important molecule in plant life. Which of the following properties of water enables it to move from the roots to the leaves of plants?A. Water expands as it freezes.B. Water is an excellent solvent.C. Water exhibits cohesive behavior.D. Water is able to moderate temperature. Example TwoLarge bodies of water, such as lakes and oceans, do not quickly fluctuate in temperature. What is the reason for this phenomenon?A. Water is an acid.B. Water is a versatile solvent.C. Water has a high heat capacity.D. Water acts as a buffer.Example ThreeWhy does ice stay at the top of oceans instead of sinking to the bottom?A. Ice is colder than liquid water.B. Ice is less dense than liquid water.C. Ice is more dense than liquid water.D. Ice is warmer than liquid water.Example FourWater is often called the "universal solvent" because many substances can be dissolved in water. What property of water allows it to be such a versatile solvent??A. purityB. polarity and cohesionC. high heat capacityD. expansion upon freezingOrganisms, Populations, and EcosystemsSC.912.L.14.7 Plant Structure Example OneTerrestrial plants have stomata on the surface of their leaves. A single stomata is surrounded by two guard cells that change shape in response to environmental factors and open or close the stoma. Which of the following best explains how the structure of the leaf is used in processes that occur in plants??A. Water enters the plant through the surface of the leaf for transpirationB. Gases for photosynthesis are exchanged through the surface of the leaf.?C. Energy for cellular reproduction is absorbed through the surface of the leaf.?D. Carbon dioxide enters the plant through the surface of the leaf for cellular reproduction.Example TwoPlant cells that are specialized for cell division are most likely found in what part of the plant??A. root tipsB. leaf epidermisC. stem epidermisD. vascular tissueExample ThreeIf the xylem in a young tree is damaged, which process is first affected??A. performing photosynthesisB. transporting sugar to the rootsC. transporting water to the leavesD. absorbing water from the soilExample FourA plant species lives in an area with limited sunlight. Which physiological adaptation would be most useful to the plant??A. colorful flowersB. large leavesC. deep rootsD. thin cuticleExample FiveWhat is the main function of leaves??A. Leaves provide support for growth and a place to store food.B. Leaves provide a place for photosynthesis to occur.C. Leaves absorb water and minerals and transport nutrients to the stem.D. Leaves create a barrier that prevents water in the plant's tissues from evaporating.Example SixThe cambuim is a section of cells in a plant that can become either part of the xylem or phloem, depending on the growth and needs of the plant. If the cambium of a particular plant was damaged, what would be the most likely effect on the plant?A. The plant would lose its ability to carry out photosynthesis.B. the plant would have uncontrolled growth.C. The plant would not experience any change in physiology.D. The plant would not be able to transport nutrients and water.Example SevenWhich structure in the leaf controls the opening and closing of the stoma??A. cuticleB. epidermisC. guard cellD. spongy mesophyllExample EightThe diagram below shows a cross section of a plant leaf.?How does the structure marked X contribute to the survival of the plant??A. It allows the intake of gases necessary for photosynthesis.B. It allows the intake of minerals necessary for plant growth.C. It allows the intake of sunlight necessary for ATP production.D. It allows the intake of sugars necessary for plant reproduction.Example NineWhich statement describes the role of flowers in plant survival??A. Flowers can absorb carbon dioxide for sugar production.?B. Flowers produce oxygen through cellular respiration.?C. Flowers contain cells that carry out photosynthesis.D. Flowers contain cells that produce gametes.?Example TenWhat is the main purpose of seeds in plants that have them??A. To protect and distribute the zygote.B. To entice animals to eat the plant.C. To be fertilized by other plants.D. To store water for the mother plant.Example ElevenThe diagram below represents a flower, the reproductive structure of some plants. Most flowers have both male and female structures for fertilization and reproduction. ?Which structure is represented by the letter A in the diagram above??A. the stamen, a male structure which produces pollenB. the pistol, a female structure which collects pollen and passes it to the ovaryC. the sepal, a modified leaf used for protection of the flowerD. the petals, decorative structures which attract pollinatorsSC.912.L.14.26 The Brain Example OneThe illustration below shows four lobes of the human brain.?What lobe is designated by label 2?A. temporalB. parietalC. occipitalD. frontalExample TwoWhich lobe of the brain is designated by number 4?A. occipital lobeB. parietal lobeC. frontal lobeD. temporal lobeSC.912.L.14.36 Cardiovascular System Example OneThe rate at which blood flows through the human body changes in response to many factors. Which statement describes one of these factors and its effect on blood flow??A. A high viscosity of blood causes an increased resistance in the blood vessels and leads to slow blood flow.?B. A low blood pH decreases the rate of diffusion through the blood vessels and leads to slow blood flow.C. The changing of the shape of red blood cells to a crescent shape decreases resistance and lead to a faster blood flow.?D. The narrowing of blood vessels increases pressure and leads to a faster blood flow.?Example TwoWhich of the following factors would most directly affect blood flow through the circulatory system?A. blood pressureB. blood sugarC. respiratory rateD. outside temperatureExample ThreeWhat causes blood pressure??A. cholesterol in the bloodB. stress that exercise puts on heart muscleC. contraction of the ventricles in the heartD. removal of oxygen from the bloodExample FourWhich line in the graph above best illustrates an effect of the carbon dioxide level in the blood on breathing rate before, during and after a period of exercise??A. B. C. D. Example FiveWhich of the following best describes the connection between cardiovascular disease and age??A. As people age, their blood vessels become more elastic leading to less cardiovascular disease.B. As people age, the heart becomes more efficient with each pump, increasing cardiac output.C. As people age, blood pressure decreases leading to more cardiovascular disease.D. As people age, plaque builds up in the arteries increasing vessel resistance, which leads to disease.SC.912.L.14.52 Immune System Example OneThe p53 gene codes for the p53 protein that locates DNA errors for cellular repair. The diagram below shows the relationship among possible environmental influences, the p53 gene, and cancer.?Which of the following statements best describes the relationships among possible environmental influences, the p53 gene, and cancer??A. Environmental influences can lead to mutations in the p53 gene, which can cause certain cancers.B. Increased levels of p53 protein, rather than environmental influences, can cause certain cancers.C. Mutations in the p53 gene increase environmental influences that can cause certain cancers.D. Genes such as p53 are less casual than environmental influences in stimulating certain cancers.Example TwoAfter an initial infection, B-cells recognize the measles virus. How is this helpful in human immune response??A. The B-cells use this recognition to defend the body against other pathogens, such as bacteria.B. The B-cells more quickly recognize and respond to any other virus that invades the body.C. The B-cells produce antibodies more quickly if the measles virus is encountered again.D. The B-cells transfer this recognition to T-cells, which will then devour the viruses.Example ThreeWhat is the body's first line of defense against infection by foreign organisms??A. antibodiesB. lymph nodesC. white blood cellsD. the skinExample FourWhat is immunity??A. The body's ability to produce cells that inactivate foreign cells or substances.B. The body's ability to regulate homeostasis through feedback loops.?C. The body's ability to produce the "fight or flight" response.D. The body's ability to use the endocrine system to fight disease.Example FiveWhat is the term for a strong response to a harmless antigen in the environment?A. cell-mediated immunityB. an allergyC. inflammatory responseD. an autoimmune diseaseExample SixWhite blood cells are an important part of the human immune response. Two types of white blood cells, neutrophils and macrophages, act as phagocytes. Phagocytes perform which of the following functions in the human body??A. They produce antibodies.B. They bind to antigens and develop into plasma cells.C. They form a barrier against pathogens.D. They engulf and destroy bacteria.Example SevenAlthough vaccines cannot be used to treat a person who is sick, they can help to prevent infections. Vaccinations tell the body to create "memory cells", which will function later to create antibodies against certain pathogens. When a person is vaccinated, what are they injected with??A. antibodies to a disease bacteriumB. live, inactive virusesC. weakened viruses or antigens from the virusD. blood from a person who has had the diseaseExample EightAn activity that occurs in the human body is shown below.This activity helps to do which of the following??A. provide protection against pathogensB. produce antibiotics to control diseaseC. eliminate harmful gene alterationsD. regulate production of ATP by the cellExample NineWhich of the following describes a way that a person's health can be affected by heredity??A. A person with a family history of obesity is more likely to catch a common cold.B. A person with a family history of high blood pressure is more likely to have heart disease.C. A person with a family history of obesity is less likely to enroll in a weight loss plan.D. A person with a family history of cancer is less likely to be screened for cancer.Example TenMany species of bacteria have become resistant to antibiotics because antibiotics have been so widely used. Now, bacteria that used to be killed by antibiotics are more difficult to treat. What is the best way to proceed in dealing with this public health problem?A. Antibiotics should no longer be used.B. Antibiotics should be made available to anyone without a prescription.C. Antibiotics should only be prescribed to people with bacterial infections.?D. Anti-viral medications should now be used instead of antibiotics.?Example ElevenHow do human diseases caused by bacteria and diseases caused by viruses react to antibiotics??A. Neither responds to antibiotics.B. Both respond to antibiotics.C. Viral diseases respond to antibiotics; bacterial diseases do not.D. Bacterial diseases respond to antibiotics; viral diseases do not.SC.912.L.16.10 Biotechnology Example OneWhile genetic engineering has positive benefits, there are also concerns associated with widespread use of genetic engineering in agriculture. If many farmers begin to plant more genetically modified crops that have an increased tolerance to insects, which of the following may result??A. an increase in the use of pesticidesB. a decrease in genetic diversity of the cropsC. an increase in the contamination of the water supplyD. a decrease in crop productivityExample TwoStem cell research has been a controversial subject in past years. What is the reason for this??A. Cells for study are often taken from human embryos.B. Stem cell techniques will not accomplish the intended purpose.C. The cells cannot be isolated.?D. Replacement tissue will never be grown from a person's own stem cells.Example ThreeWhat kind of genetically modified crops would be most successful in?wet-tropical countries that are overcrowded??A. crops that are drought- and pest-resistantB. high-yield crops that do not need a lot of sunshineC. high-yield crops that are pest-resistantD. crops that are drought-resistant and need a lot of sunshineExample FourIn what way did gene therapy, the replacement of a faulty gene with a normal one, stimulate medical research??A. New medications had to be developed and tested.B. The effects of viral DNA had to be studied.C. The way in which DNA replicates had to be determined.D. The genes on each chromosome had to be mapped and described.Example FiveThe way that crimes are solved today was affected by which of the following technologies??A. gene therapyB. DNA fingerprintingC. genetic testingD. Genetic modificationExample SixWhich technology below would probably be the most important to a person who had diabetes and had to take insulin every day??A. testing parents for genetic disorders before they have childrenB. engineering fruits and vegetables that resist insects and other pestsC. developing ways to identify criminals through DNA fingerprintingD. using recombinant DNA to produce human hormones from bacteriaSC.912.L.16.13 Reproductive System Example OneA fertilized egg undergoes several stages before it is successfully implanted. The diagram below shows these stages as the fertilized egg travels through the female reproductive system.?In which of the following structures of the female human reproductive system is the blastocyst implanted during normal human development??A. ovaryB. uterusC. vaginaD. amniotic sacExample TwoThe drinking of alcoholic beverages by a pregnant woman is harmful to the development of her fetus. This is most damaging early in a pregnancy because during this timeA. the lungs of the fetus become functional.B. alcohol can easily enter the mouth of the fetus.C. many of the essential organs of the fetus are forming.D. the fetus cannot excrete wastes.Example ThreeSperm are created through meiosis in an area of the testes called the seminiferous tubules. Through which structure do the sperm travel to exit the testes??A. vas deferensB. seminiferous tubulesC. scrotoumD. epididymisExample FourWhich of the following is true of a zygote??A. It forms into a blastocystB. It is an unfertilized eggC. It produces haploid male gametophytesD. It is made up of only one cellExample FiveWhich of the following describes fertilization??A. cell differentiation to form a blastulaB. formation of germ layers in a deuterostomeC. a sperm joining an egg to form a zygoteD. sperm and egg productionExample SixBelow is a diagram of the male reproductive system.Which structure is represented by the letter D?A. scrotumB. testesC. prostate glandD. epididymusExample SevenAbnormalities present in the cells that line the uterus may prevent the production of offspring by directly interfering with which process??A. the development of the embryoB. the differentiation of gametes into zygotesC. the secretion of estrogen by the ovaryD. the production and release of egg cellsExample EightWhat is the human embryo called after the eighth week of development?A. a zygoteB. an infantC. a fetusD. a morulaSC.912.L.17.5 Population Size Example OneMullet are local estuarine fish that move in schools and feed on plankton and plant matter. Natural predators of the mullet include spotted sea trout, sharks, pelicans and dolphins. The graph below shows how the number of mullet in an area has changed over time.?Based on the data, one student concludes that a new predator was introduced into the area during this time period. Which of the following is a likely alternate explanation for the change in the mullet population?A. mullet prey increased in the areaB. mullet parasites decreased in the areaC. the temperature of the area increasedD. the amount of aquatic plants in the area decreasedExample TwoHow does the predator-prey relationship affect a population?A. The predators and prey are in competition with each other.B. Usually either the predator or the prey will become extinct.C. The predator species usually has exponential growth.D. The relationship controls the population size of both species.Example ThreeData on the immigration and emigration of a fish species would be most helpful in determining which of the following?A. biological magnificationB. interspecies competitionC. population of the speciesD. predator-prey relationshipsExample FourWhen an environment has reached its carrying capacity for a certain population, which of the following is true??A. Growth and immigration rate is equal to death and emigration rate.B. Growth and immigration rate is greater than death and emigration rate.C. Growth and immigration rate is less than death and emigration rate.D. Growth rate is exponential.Example FiveThe pH of the water in several lakes in Norway and Sweden had decreased to below 5.0 due to an increase in acid rain. Which of the following is most likely to happen in these lakes??A. the decline of several fish populations.B. an increase in numbers of fishC. an increase in the amount of primary producersD. increased predator-prey relationshipsExample SixWhich of the following is a limiting factor in a population of organisms.?A. reproductive replacementB. life spans of the membersC. fluctuations in atmospheric temperatureD. availability of foodExample SevenWhich of the following are abiotic factors that shape ecosystems??A. worms, plants and temperatureB. wind, precipitation, and soil typeC. niches, trees, and bacteriaD. sunlight, mushrooms, and windExample EightThe common brushtail possum is a marsupial native to Australia. This possum was introduced to New Zealand where it had no natural predators and had an abundant food supply. Which of these likely occurred a few years after the introduction of this possum to New Zealand?A. The possums became extinct.B. The possums developed shorter life spans.C. The possum population grew to a larger size.D. The possum population evolved into a different species.Example NineThe number of pythons found throughout Everglades National Park has increased in recent years. These huge snakes are not native to Florida and are believed to have been released into the wild by pet owners. Wildlife biologists have initiated attempts to capture and remove these pythons. Which statement best explains the biologists' reasons for removing these pythons from the Everglades?A. The pythons could upset the territorial boundaries of native organisms.B. The pythons could adapt to overcome diseases common to native snakes.C. The pythons could prey on native organisms and cause native population to decline.D. The pythons could begin to interbreed with native snakes and produce a more successful species.Example TenWhy are there so few aquatic plants and phytoplankton that live at the bottom zones in the ocean?A. The ocean floor contains many decomposers.B. Most sunlight is absorbed before reaching these levels.?C. Water is a limiting factor.D. The temperature in these zones is extremely low.SC.912.L.17.9 Food Webs and Energy Transfer Example OneA team of ecologists observed feeding patterns of several populations in the desert. The energy pyramid shown below depicts the feeding patterns the ecologist observed.?Which of the following best explains the difference in the amount of available energy in the trophic levels of the desert ecosystem?A. There is less energy available in the producers because their tissues are less dense than those at higher trophic levels.B. There is more energy available in the second trophic level because less energy is needed for hunting compared to the higher trophic levels.?C. There is more available energy in the birds of prey because they have greater muscle mass for storing energy than organisms in lower trophic levels have.?D. There is less available energy in the fourth trophic level because of the loss of energy through metabolism in each of the lower trophic levels.Example TwoA diagram of a food web is shown below.Which organism receives the least amount of energy from the producers?A. HawkB. RabbitC. GrasshopperD. MouseExample ThreeThe diagram below shows the cycling of nutrients in an ecosystem.?The removal of which of the following groups would cause an immediate decrease in the amount of energy flowing through the system??A. ProducersB. ConsumersC. DecomposersD. Inorganic nutrientsExample FourComplete burning of plant material returns carbon primarily to theA. herbivores.B. water.C. vegetation.D. atmosphere.Example FiveWhich of these organisms would most likely be found at the top of an energy pyramid??A. clams - a primary consumerB. sardines - a primary consumerC. sharks - a secondary consumerD. kelp - a primary producerExample SixThe diagram below shows the flow of carbon in a terrestrial ecosystem.?Which will most likely happen if the decomposers are removed from the carbon cycle??A. The amount of carbon dioxide in the atmosphere will increase.B. The amount of carbon dioxide in the atmosphere will decrease.C. The amount of carbon dioxide used by producers will increase.D. The amount of carbon dioxide needed by consumers will decrease.Example SevenIn a process called transpiration, plants get rid of excess water through pores in the leaves called stomata. This excess water is then released into the atmosphere as part of the water cycle. Which of the following terms best describes how the released water enters the atmosphere?A. condensationB. precipitationC. evaporationD. capillary action?Example EightThe framework of organic molecules essential to all organisms is composed mainly of carbon atoms. Which processes are involved in the cycling of carbon within an environment??A. photosynthesis and respirationB. evaporation and condensationC. transcription and translationD. diffusion and transpirationExample NineWhich of the following statements is true about natural systems??A. Consumers form the bottom levels of both the energy pyramid and the biomass pyramid.B. Producers are at the bottom level of both the energy pyramid and the biomass pyramid.C. Producers are at the bottom of the energy pyramid, but at the top of the biomass pyramid.D. Consumers are at the bottom of the energy pyramid, but at the top of the biomass pyramid.SC.912.L.17.20 Human Impact Example OneSalt water is an abundant resource but unusable for irrigation and drinking. As demands on freshwater sources increase, the use of desalination processes to remove salt from ocean water is increasing. A concern of desalinating water is the large amounts of recovered salts that are returned to the ocean. Which of the following describes the most likely impact of desalination on the surrounding ocean environment??A. Methane gas would pollute the ocean environment as shoreline organisms begin to die and decay.B. Alteration in ocean salt levels would cause loss of species and unbalanced populations in marine food webs.C. Nonrenewable resources in the ocean environment would become depleted and upset the ecosystem's balance.D. Increased levels of salts and minerals in the ocean would result in overpopulation of marine bivalves due to strengthened shells.Example TwoNew fuels are being produced by converting corn and grasses into compounds containing alcohols that can be broken down for energy in various engines. The purpose of this research is toA. reduce the use of nonrenewable resources.B. increase the rate of air pollution.C. reduce the rate of homeostasis in organisms.D. cause a loss of biodiversity in the rain forests.Example ThreeThe presence of wastes, such as plastic bags and motor oil, in lakes and streams miles away from developed areas suggests thatA. ecosystems are interconnected and human action can alter ecosystem equilibrium.B. recycling programs have failed to conserve biotic resources.C. natural processes can alter ecosystem stability.D. direct harvesting practices have led to irreversible destruction of ecosystems.Example FourDDT and other pesticides used over 50 years ago are still affecting the environment today. Scientists have found these substances in recent glacier runoff. Glacier runoff occurs during the summer, when precipitation that has fallen on glaciers during the winter is released. Ice layers from existing glaciers have been analyzed. The results of this analysis show that the concentrations of DDT and other pesticides were highest about 10 years after the use of these substances was banned.?This information shows thatA. DDT and other pesticides cause glacier runoff during the summer.B. it takes humans over 50 years to analyze a glacier.C. precipitation helps to break down pesticides.D. the decision of one human generation may have an impact on future generations.Example FiveThe northern elephant seal was almost hunted to extinction in the 1800s. By the late 1890s, approximately one hundred seals were left, reducing the gene pool of the population. What will be the consequence of this reduction??A. Competition within the population will increase.B. The surviving elephant seals will be better able to adapt.C. Inbreeding will be less frequent among the remaining population.D. The elephant seals will be more vulnerable to environmental change.?Example SixA community is concerned about the water quality of a nearby lake. Increased sedimentation in the lake is endangering the native habitat. The increased sedimentation is most likely caused by which of the following?A. trees planted along the shore of the lakeB. construction of homes along the lakeC. the amount of sunlight on the lakeD. the amount of fish in the lakeExample SevenWhen fertilizers run off farmland into streams and ponds, the nitrogen content of the water increases. This can lead to rapid growth of algae in a process called eutrophication. How can this process affect other organisms in the water??A. Oxygen is used up as algae is decomposed, reducing the amount available to other organisms.?B. The water becomes better able to support aerobic organisms.C. The algae provide food for fishes and other organisms, leading to decreased algae populations.?D. The extra nitrogen provides additional food for the other organisms, increasing their population.Example EightA strip mining company wants to lease some land that is currently part of a national park. They promise to reclaim the land should any minerals be mined from the area, and they are willing to pay top dollar for the rights. As an ecologist, what factors would you raise with the local government??A. the threat to local biodiversityB. management of the land after the company leavesC. the new jobs that would be createdD. the increased traffic in the areaExample NineWhaling was a very profitable profession until whale populations crashed. The global community came together to enact a ban on whaling. However, Japan and Norway have not agreed to stop whaling. Which of the following is the most likely consequence of their decision?A. The whale populations are bouncing back very successfully and are unaffected by Japan and Norway continuing to whale.B. The whale populations are not rebounding as quickly as they might if all of the countries agreed not to hunt whales.?C. The whale populations have mutated into new kinds of organisms.D. The whales are getting better at avoiding capture.Classification, Heredity, and EvolutionSC.912.L.15.1 Evolution Example OneThe scientific theory of evolution is supported by different types of evidence. The diagrams below show the skeletons of two different animal species. How does comparing the skeletons of these animals provide support for the scientific theory of evolution?A. It provides information about the organisms' habitats. B. It shows possible common ancestry between organisms. C. It provides information to determine the organisms' ages. D. It shows possible chromosomal similarities between organisms.Example TwoAccording to fossil records, the horses that lived 50 million years ago were much smaller, weaker and slower than modern horses. Which process is most likely responsible for the changes that have led to the increased size, strength, and speed in horses?A. commensalismB. inbreedingC. migrationD. evolution by natural selectionExample ThreeThe diagram illustrates an embryonic stage of two organisms.Which of the following can be determined by observing the embryos shown in the diagram??A. The organisms share a common ancestry.B. The organisms belong to the same genus.C. The organisms are native to the same geographic areas.D. The organisms will grow into anatomically similar adults.Example FourScientists have found evidence that about 2.4 million years ago a gene regulating jaw muscles mutated and may have led to the more graceful human jaw we see today. The diagram below shows the skulls of 3 hominid species.Which statement below most closely explains the link between jaw size and hominid evolution??A. The jaws of hominids evolved to be smaller and less protruding over time.?B. The jaws of hominids evolved to be larger and more protruding over time.?C. There appears to be no change in the jaws of hominids over time.D. The jaws of hominids changed over time due to a change in brain size.?SC.912.L.15.6 Classification Example OneOrganisms classified as fungi have unique characteristics. Which of the following characteristics is found only in organisms classified in the kingdom fungi?A. single cells without a nucleus B. multicellular with chloroplasts C. multicellular filaments that absorb nutrients D. colonies of single, photosynthetic cells that reproduce asexuallyExample TwoThe diagram below represents possible evolutionary pathways of certain organisms.?Which species is most closely related to species L?A. species EB. species FC. species GD. species IExample ThreeWhich kingdoms have photosynthetic organisms??A. fungi and plantsB. fungi and protistsC. protists and plantsD. plants and animalsExample FourSome characteristics of a recently discovered organism are listed in the following table.?Based on the given characteristics, this organism would be classified in which kindgom??A. eubacteriaB. fungiC. plantaeD. protistaExample FiveIn 1990, Carl Woese introduced the three domain system for classifying living things, after the advancement of DNA analysis allowed for a comparison of species genetic code. Which of the following is the best explanation for why domains were added to the previous system of classification??A. The old system of classification was wrong and needed to be corrected. B. New species are evolving too quickly to keep up with the old system of classificationC. Domains have always been included, they were just made official recently. D. Some organisms, which were previously characterized together, were determined to be genetically very different.?SC.912.L.15.8 Origin of Life Example OneOne of the accepted scientific theories describing the origin of life on Earth is known as chemical evolution. According to this theory, which of the following events would need to occur first for life to evolve?A. onset of photosynthesis B. origin of genetic material C. Synthesis of organic molecules D. formation of the plasma membraneExample TwoWhich types of organisms developed first due to the early environmental conditions on Earth??A. prokaryotic and aerobicB. prokaryotic and anaerobicC. eukaryotic and aerobicD. eukaryotic and anaerobicExample ThreeThe Miller-Urey experiment of 1953 was designed to test the hypothesis that lightning supplied the energy needed to turn atmospheric gases into organic molecules such as amino acids. Which of the following describes why the Miller-Urey theory is widely accepted today?A. Amino acids spontaneously form from molecules in the atmosphere today.B. Organic molecules are present today in extremely high concentrations.C. The process of synthesizing organic molecules from a mixture of gases has been successfully modeled in the laboratory.?D. No other alternative hypotheses have been introduced.?Example FourThe diagram below shows a proposed theory of the origin of eukaryotic cells, called endosymbiosis.Which of the following explains why cells that contained mitochondria-like organelles had an evolutionary advantage?A. They were able to photosynthesizeB. They had more DNAC. They were able to make more use of available energyD. They were immune to bacterial invasion.SC.912.L.15.13 Natural Selection Example OneOver time, the climate of an island became drier, which resulted in changes to the populations of various island finch species. Finch populations with a certain beak shape thrived, while those not having that beak shape decreased. Which of the following describes a necessary condition for these changes in the finch populations to occur?A. fewer mutations B. limited food resources C. limited beak variations D. overproduction of offspringExample TwoWhich of these would have the least effect on natural selection in a subspecies of giraffes that is geographically isolated from other subspecies of giraffes??A. available nichesB. existing predatorsC. chromosome numberD. available food resourcesExample ThreeMutations within a DNA sequence areA. natural processes that produce genetic diversityB. natural processes that always affect the phenotypeC. unnatural processes that always affect the phenotypeD. unnatural processes that are harmful to genetic diversityExample FourWhich of the following best illustrates natural selection??A. An organism with favorable genetic variations will tend to survive and breed successfully.?B. A population monopolizes all of the resources in its habitat, forcing other species to migrate.C. A community whose members work together utilizing all existing resources and migratory routes.D. The largest organisms in a species receive the only breeding opportunities.Example FiveA small population of chimpanzees lives in a habitat that undergoes no changes for a long period. How will genetic drift probably affect this population??A. It will accelerate the appearance of new traits.B. It will promote the survival of chimpanzees with beneficial traits.C. It will increase the number of alleles for specific traits.D. It will reduce genetic diversity.Example SixA small portion of the population that is geographically isolated from the rest of the population runs the risk of decreased.A. genetic driftB. mutation rateC. natural selectionD. genetic variationExample SevenIn his book On the Origin of the Species, Charles Darwin described how species change over time. Which of the following is NOT part of his observations that describes the mechanisms of natural selection??A. Organisms produce more offspring than can survive.B. Disease and natural disaster will limit population growth.C. Species today descended with modifications from ancestral species.D. Organisms with advantages will survive and reproduce.Example EightTheodosius Dobzhansky discovered that successful species tend to have a wide variety of genes that do not appear to be useful to the species in its present environment. What did this discovery help explain about genetics and the changes that occur in a species over time??A. Environments with more organisms tend to have more successful species.B. Species with greater genetic diversity adapt more easily to changing environments.C. Changing environments prevent species from adapting and surviving.D. Species in a stable environment are more resistant to a changing environment.SC.912.L.16.1 Genetics Example OneHemophilia is a sex-linked, recessive trait. Which of the following describes the probability of hemophilia in the offspring of a man who does not have hemophilia and a woman whose father is a hemophiliac?A. Each of their sons will have hemophilia. B. None of their daughters will have hemophilia. C. Their sons have a 25% chance of having hemophilia. D. There is a 50% chance that their daughters will have hemophilia.Example TwoAlleles for the A and B blood cell antigens are codominant. The condition where no antigens are present on the blood cells (type O blood) is a recessive trait. Which set of parents can most likely produce a child with type O blood??A. one parent with type AB blood, and the other parent with type A bloodB. one parent with type AB blood and the other parent with type O bloodC. one parent with heterozygous type A blood, and the other parent with type O bloodD. one parent with homozygous type A blood, and the other parent with homozygous type B bloodExample ThreeOne of the parents of a child has phenylketonuria (PKU), which is caused by recessive alleles. The other parent does not have the PKU alleles. What is the chance that the couple will have a child with phenylketonuria??A. 0%B. 50%C. 75%D. 100%Example FourHitchhiker's thumb (H) is dominant to no hitchhiker's thumb (h). A woman who does not have hitchhiker's thumb marries a man who is heterozygous for hitchhiker's thumb. What is the probable genotypic ratio of their children??A. 0% Hh: 100% hhB. 50% Hh: 50% hhC. 75% Hh: 25% hhD. 100% Hh: 0% hhExample FiveThis diagram shows a pedigree for a recessive genetic disorder.What is the genotype of individual 6?A. XHXHB. XHXhC. XHYD. XhYExample SixThis diagram shows a diploid cell with two pairs of homologous chromosomes.?Due to independent assortment, what is the possible genetic make-up of gametes produced by this organism?A. SsTtB. Ss, TtC. S, s, T, tD. ST, St, sT, stExample SevenThe table lists the trials for fruit color where allele R exhibits incomplete dominance over allele R'.?Heterozygous fruit have orange phenotypes. What percent of offspring are expected to have an orange phenotype if the parent plants are orange (RR') and yellow (R'R')?A. 25%B. 50%C. 75%D. 100%Example EightMendel hypothesized that reproductive cells have only one factor for each inherited trait. This hypothesis is supported by which observation??A. Haploid cells are produced by mitosis.B. Diploid cells are produced by mitosis.?C. Haploid cells are produced by meiosis.D. Diploid cells are produced by meiosis.Example NineA human baby boy inherits a recessive allele from his mother. In which circumstance would he most likely show the trait coded for by the recessive allele?A. The baby inherits the dominant allele from his father. B. The allele is on an autosomal chromosome and the baby is a twin. C. The allele is on the X chromosome.D. The allele is on the Y chromosome. AnswersNature of ScienceSC.912.N.1.1 Scientific MethodExample One C. Water enters the cell when placed in environments of high water concentration In both the vinegar (95% water) and distilled water (100% water) solutions, the egg gained mass after soaking. This means that water moved into the egg over time. The reason for this movement is that the solutions are both hypotonic to the concentration of the egg. Water always moves from a more hypotonic solution to a more hypertonic solution (which has more solutes and less water).Example Two C. The experiment is lacking a control group. Carmen should have also taken the pulse of people who were NOT listening to any music to make sure that a person’s pulse rate would not change randomly.Example ThreeD. Atmospheric carbon dioxide levels have been rising at an increasingly higher rate as the past century has progressed. Because the graph shows a curved line, instead of a straight one, you can conclude that as time has passed (on the x axis) the levels of atmospheric carbon dioxide (on the y axis) have risen at increasingly higher rates. If levels had increased at the same rate, the line would be diagonal from left to right, but it would be straight.Example Four D. High acidity is harmful to this type of plant. Plants in the lowest acidity group were adversely affected the most.Example Five A. Infection in embanked ponds increased during the sampling period. The percent infected continually rose for these ponds as time progressed. D is incorrect is because although the readings present on the graph are all relatively similar, there are no readings (or no infections) on some of the dates.Molecular and Cellular BiologySC.912.L.14.1 Cell TheoryExample OneC. Cells form through spontaneous generation. It was once believed that cells could form on their own. We now know that cells must form from preexisting cells.Example TwoC. the light microscope The light microscope allowed scientists to view actual cells for the first time. SC.912.L.14.3 Cell Structure Example OneD. ribosome Prokaryotic cells do not have membrane-bound organelles. They do contain ribosomes, which are the site of protein synthesis.Example TwoB. active transport using ATP and carrier proteins Active transport requires ATP and is used either when solutes need to move against a concentration gradient or when the pores in a semi-permeable membrane are too small to accommodate solute molecules.Example ThreeD. both plant and animal cells Both plant and animal cells are eukaryotic. Eukaryotic cells have DNA (genetic material) contained in a membrane-bound nucleus.Example FourD. they are autotrophic Almost all plants produce their own food using photosynthesisExample FiveA. ribosome - protein synthesis Ribosomes are the site of protein synthesis. Ribosomes are found both on the rough Endoplasmic reticulum and in the cytoplasm.Example SixD. D Structure A is the nucleus, Structure B is the cell membrane, Structure C is a vacuole and Structure D is a chloroplast. The chloroplast is where photosynthesis takes place converting solar energy into sugars that are then converted to energy in the form of ATP.Example SevenD. The water in the gums has moved out due to the high concentration of salt in the solution. The salt water solution is hypertonic to the cells of the gums. It contains a higher concentration of solute (salt) and a lower concentration of water. Water from inside the cells of the gums moves down the concentration gradient and out of the cells.Example EightB. 2 Structure 1 is a mitochondrion, Structure 2 is a ribosome, Structure 3 is the cell membrane and Structure 4 is the nucleus.Example NineD. a plant cell Plant cells have a rigid coat of cellulose, which animal cells do not have.Example TenB. semi-permeable A semi-permeable membrane allows some, but not all, molecules and ions to pass through.SC.912.L.16.3 DNA Replication Example OneC. The basic components of DNA are the same in humans and bacteria. Actually, the basic components of DNA are the same in ALL living things.Example TwoB. two molecules, each with one original and one new strand DNA separates into two strands during replication. Each original strand is used to make one complimentary new strand.Example ThreeA. before a cell divides, to provide each of the two resulting cells with a complete set of DNA instructions During mitosis, everything in the original cell must make a copy of itself so that the two daughter cells have as much DNA and chromosomes as the original.Example FourB. Segment 3 only In segment 3, Adenine is improperly paired with Cytosine. Adenine should be paired with Tyrosine, and Cytosine should be paired with Guanine in DNA.Example FiveA. 4 Each section of three nucleotides (called a triad) codes for one amino acid. Since there are four triads here, this piece of DNA codes for 4 amino acids.Example SixB. UUU codes for the amino acid phenylalanine. UUU coded for the amino acid phenylalanine to be created (synthesized) in the test tube. Each three DNA nucleotides codes for one amino acid.Example SevenB. the insertion of a nucleotide into DNA. Mutations are caused by changes in the DNA sequence. The insertion of just one nucleotide would change the sequence and alter the amino acids that are coded from that particular piece of DNA.Example EightA. Translation Translation is the process of the ribosomes reading messenger RNA (mRNA) and forming polypeptide chains with the correct sequence of amino acids.Example NineC. Even though the DNA sequence changed, the sequence still codes for the same amino acid, so no change in phenotype will occur. ACG and ACA both code for the amino acid Thr so no phenotypic change will occur.Example TenC. tRNA tRNA, or transfer RNA carries proteins to the ribosomes to be connected into polypeptide chains. mRNA carries the genetic code out of the nucleus and to the ribosomes. rRNA is what ribosomes are made of.SC.912.L.16.17 Mitosis and Meiosis Example OneC. daughter cells that are identical to the parent cell Mitosis is the process of cell division for all cells in the body except reproductive cells. Mitosis results in daughter cells that are identical to the parent cell in every way including number of chromosomes.Example TwoA. sexual reproduction requires two parents and asexual reproduction requires only one parent Example ThreeC. Sexual reproduction During sexual reproduction, the genetic information from each parent is combined and reorganized to provide a unique new individual. This process introduces genetic variation into a population.Example FourC. uncontrolled cell growth caused by mutations in genes that control the cell cycle Cancer cells lack the ability to recognize and control cell growth and reproduction. As a result, they replicate again and again.Example FiveB. metaphase During metaphase, chromosomes line up in the center of the cell and prepare to be pulled apart at the centromere.Example SixA. zygote The zygote is the first single cell of an organism. The DNA that is present in the zygote will be replicated each time the cell goes through mitosis.Example SevenD. row 4 The formation of eggs and sperm is a meiotic process resulting in daughter cells that have half of the genetic information of the parent cell. The growth of the embryo is a mitotic process resulting in daughter cells that are identical to the parent cell.Example EightA. meiosis In meiosis a diploid cell, containing two of each chromosome divides to create haploid daughter cells that have one of each chromosome.Example NineD. crossing-over, in which alleles are exchanged This process allows each chromosome to have genetic information from both parents, no matter which parent the chromosome originally came from. Crossing-over is responsible for offspring having some qualities of each parent and is also responsible for genetic variation in a population of species.Example TenB. It occurs only in cells in the reproductive structures of organisms. Meiosis only occurs in the reproductive cells, producing gametes with half of the genetic information as the parent cell.Example ElevenC. 56 Asexual reproduction results in an identical organism to the parent. All of the cells of the daughter organism will be the same as the cells of the parent organism. Asexual reproduction DOES NOT increase the variation in a population since all of the organisms are genetically identical.SC.912.L.18.1 Macromolecules Example OneA. It becomes inactive. Enzymes have an ideal pH, at which they best function. Many enzymes cannot function at all outside their ideal pH range. Pepsin functions best in the extreme acid environment of the stomach and will, therefore cease to function in the much higher pH of the small intestine.Example Two D. A catalyst decreases the activation energy needed for a reaction to occur. This allows the reaction to happen faster. Example ThreeB. protein Proteins are long chains of amino acids folded into specific shapes, which determine their properties and reactivity.Example FourC. carbohydrate Carbohydrates are made up of Carbon, hydrogen, and oxygen. See the video for the basic carbohydrate structure.Example FiveC. lipids See the structure of lipids in the video.Example SixC. nucleic acids DNA is deoxyribonucleic acid and RNA is ribonucleic acid.Example SevenA. The reaction rate will increase. Enzymes are molecules that increase the rate of reactions.Example EightC. nucleic acids See the video for the basic structure of nucleic acids.Example NineA. Enzymes function best at a specific temperature. Enzyme activity is affected by temperature. Each enzyme has a specific temperature range in which it works most effectively. Most biological enzymes present in the human body have an ideal temperature range of around 98.6 degrees.Example TenA. monosaccharides Sugars are made of building blocks called monosaccharides.SC.912.L.18.9 Photosynthesis and Cellular Respiration Example OneB. Carbon dioxide and water released by cellular respiration are used in photosynthesis. The products of cellular respiration (CO2 and H2O) are the reactants of photosynthesis. The overall equations for photosynthesis and cellular respiration are the reverse of each other.Example TwoD. carbon dioxide The reactants of photosynthesis are carbon dioxide and water.Example ThreeA. As the cells run out of oxygen they switch to anaerobic respiration, which allows the cell to make small amounts of ATP in the absence of oxygen. Anaerobic respiration is used by cells in the absence of ATP. This process converts sugars to alcohol and only creates a small amount of ATP compared to aerobic respiration.Example FourB. It is used to capture and transfer energy. ATP is the “energy currency” of cells. Energy is stored in the bonds of this molecule and is released to do work in the cell when the bonds are broken. ATP is created during cellular respiration.Example FiveA. The energy captured in photosynthesis is used to power cellular respiration. Energy from the sun is used captured during photosynthesis and stored in the bonds of glucose molecules. During cellular respiration, this energy transferred to ATP molecules to be used to do work in the cell.Example SixB. Only species Y is anaerobic. Anaerobic cellular respiration converts sugars to ethyl alcohol and carbon dioxide in the absence of oxygen.Example SevenD. Photosynthesis used carbon dioxide, while cellular respiration produces carbon dioxide. The reactants of photosynthesis are the products of cellular respiration.Example EightC. 1 - oxygen; 2 - carbon dioxide Photosynthesis by plants produces oxygen, which is then used by animals as a reactant in cellular respiration. The product of cellular respiration is carbon dioxide, which is used by plants in photosynthesis. And the cycle continues.SC.912.L.18.12 Properties of Water Example OneC. Water exhibits cohesive behavior. Cohesion means that water molecules are attracted to each other and attracted to other substances, such as the walls of the xylem of plants. The water molecules behave this way because they are polar.Example TwoC. Water has a high heat capacity. Water can absorb a large amount of energy without a large rise in temperature. This is called heat capacity. As the sun shines on bodies of water, they absorb great amounts of its energy without a large fluctuation in temperature.Example ThreeB. Ice is less dense than liquid water. As water freezes, its molecules spread apart into a specific arrangement that makes frozen water less dense than liquid water.Example FourB. polarity and cohesion Water molecules are polar. This means that they have slight positive and negatively charged ends. Water molecules are attracted to a wide variety of molecules because of those charges and thus, acts as a solvent for a variety of anisms, Populations, and EcosystemsSC.912.L.14.7 Plant Structure Example OneB. Gases for photosynthesis are exchanged through the surface of the leaf. Gas exchange in leaves is called transpiration and occurs through the stomata.Example TwoA. root tips As plant roots grow, the cells in their tips undergo constant mitosis to produce new tissue.Example ThreeD. absorbing water from the soil Xylem carries water and nutrients from the soil, up into the leaves. The water is used to carry out photosynthesis, the products of which are sugar and oxygen.Example FourB. large leaves Leave are the part of a plant that contains chloroplasts. Chloroplasts are structures that contain chlorophyll, a pigment that captures sunlight and allows the plant to make sugars. The larger the leaf surface a plant has, the more sunlight it can capture.Example FiveB. Leaves provide a place for photosynthesis to occur. Leaves contain chloroplasts, the site of photosynthesis in plants.Example SixD. The plant would not be able to transport nutrients and water. The xylem and phloem are responsible for the transportation of nutrients, and water throughout the plant. If cambium cells were damaged, the plant would not be able to make xylem and phloem.Example SevenC. Guard cells Guard cells surround stomata and control their opening and closing. The stomata are the site of gas exchange in leaves, a process called transpiration.Example EightA. It allows the intake of gases necessary for photosynthesis. The stomata are the site of gas exchange in leaves, a process called transpiration. Carbon dioxide is taken in by plants and oxygen is given off.Example NineD. Flowers contain cells that produce gametes. Flowers are the reproductive organs of plants.Example TenA. To protect and distribute the zygote. A seed contains a complete zygote wrapped in a seed coat. The seed’s hard outer covering protects the seed until it can be dispersed, by wind or animals, to another location. This adaptation allows for a wider distribution of seed plants than those that do not have seeds.Example ElevenB. the pistol, a female structure which collects pollen and passes it to the ovary The pistol is made of several carpals fused together. The tip of the pistol is usually sticky and holds pollen grains when they land there. The style is a tube that leads from the stigma to the ovary, where fertilization occurs to form the zygote.SC.912.L.14.26 The Brain Example One B. parietalExample Two D. temporal lobeSC.912.L.14.36 Cardiovascular System Example OneA. A high viscosity of blood causes an increased resistance in the blood vessels and leads to slow blood flow. Viscosity refers to the thickness of blood. This thickness is caused by the number of red blood cells. Thick blood travels through blood vessels at a slower rate than thin blood.Example TwoA. blood pressure The factors that most directly affect blood flow are blood pressure, blood volume, resistance and activity level.Example ThreeC. contraction of the ventricles in the heart Blood pressure is caused by contraction of the ventricles of the heart and also by the elasticity of the arterial walls. When the heart contracts, blood pressure is the highest. This is called systolic pressure. When the heart is relaxed, blood pressure is lowest. This is called diastolic pressure. Some pressure is maintained in the vessels at all times, even with the heart is in diastole. This pressure is kept relatively constant by the elastic properties of the walls of the arteries.Example FourA. The level of carbon dioxide increases during exercise because the cells are undergoing cellular respiration at a faster rate to make more ATP. Carbon dioxide is produced as a product of cellular respiration.Example FiveD. As people age, plaque builds up in the arteries increasing vessel resistance, which leads to disease. This condition is called atherosclerosis, where the walls of the arteries become thick and inflexible. Atherosclerosis increases resistance in the blood vessels leading to high blood pressure.SC.912.L.14.52 Immune System Example One A. Environmental influences can lead to mutations in the p53 gene, which can cause certain cancers. Environmental factors such as pollution, radiation from the sun and public health concerns can lead to changes or mutations in a person’s DNA, which can lead to cancers.Example TwoC. The B-cells produce antibodies more quickly if the measles virus is encountered again. After an initial infection with a virus, B cells are able to recognize the virus and produce antibodies against it the second time. The person’s reaction to the virus will be lessened.Example ThreeD. the skin The skin is the first line of defense against foreign organisms. It acts as a non-specific barrier to water and air-borne infectious agents.Example FourA. The body's ability to produce cells that inactivate foreign cells or substances. The immune system produces specific and non-specific responses to pathogens, and foreign cells and substances. This process helps maintain homeostasis in individuals.Example FiveB. an allergy Reactions to allergens release histamines which cause non-specific responses such as inflammation.Example SixD. They engulf and destroy bacteria. Phagocytes are whole cells that capture invading cells or pieces of cells by surrounding and engulfing them. Once the invading cell is inside the phagocyte it is killed by enzymes.Example SevenC. weakened viruses or antigens from the virus Vaccinations contain antigens or weakened viruses from specific infections. The viruses are too weak to cause illness in the patient, but strong enough to allow the body’s immune system to create B cells against the virus. These “memory cells” are stored in the body until the person is exposed to the virus at which point, they will create antibodies against the virus.Example EightA. provide protection against pathogens The antibodies pictured here are recognizing antigens on a foreign cell to mark it for destruction. In this way, the body is able to protect itself against dangerous invaders.Example NineB. A person with a family history of high blood pressure is more likely to have heart disease. Family history can affect a person’s health in some areas by making them more likely to contract certain diseases. The genes that code for some diseases are hereditary, and can be passed from generation to generation.Example TenC. Antibiotics should only be prescribed to people with bacterial infections. Antibiotics are only useful against bacterial infections. When antibiotics are prescribed to individuals that do not have a bacterial infection, any bacteria they may have in their body can become resistant to the antibiotic and the resistant bacteria can multiply.Example ElevenD. Bacterial diseases respond to antibiotics; viral diseases do not. There is no known treatment for viral infections. The best defense against a pathogenic virus is a vaccination, which prevents infection if given before exposure to the virus.SC.912.L.16.10 Biotechnology Example OneB. a decrease in genetic diversity of the crops Genetic modifications of organisms does not allow for random mutation in the genetic code. This random mutation is responsible for the genetic diversity seen in populations of organisms.Example TwoA. Cells for study are often taken from human embryos. Embryos contain cells that are non-differentiated and can turn into any type of cell in the body. These cells could be used to create new tissues for people with diseases or malformations.Example ThreeC. high-yield crops that are pest-resistant If space is limited, high-yield crops would be best. Wet-tropical climates are often plagued by pests so crops that are pest-resistant would do well in those climates.Example FourD. The genes on each chromosome had to be mapped and described. The human genome project mapped out each gene of humans making gene therapy possible.Example FiveB. DNA fingerprinting Even a tiny section of a person’s DNA, left behind at a crime scene can be multiplied many times to make identification possible.Example SixD. using recombinant DNA to produce human hormones from bacteria Insulin is a hormone used to regulate blood sugar levels. It is essential to the correct functioning of the body. If bacteria can create insulin, this hormone will be easier for diabetics to get.SC.912.L.16.13 Reproductive System Example OneB. uterus The blastocyst makes its way down the uterine tube and implants in the uterus.Example TwoC. many of the essential organs of the fetus are forming. Most of the essential organs and structures of a fetus are formed in the first 9 weeks of gestation.Example ThreeA. vas deferens The vas deferens leads out of the testes. Here sperm are mixed with fluids to nourish and protect them. This mixture is called semen and travels out of the urethra into the vagina for fertilization of the egg.Example FourD. It is made up of only one cell The zygote is a fertilized egg. It is the first cell of a human embryo and contains the same amount of genetic information as all other somatic cells.Example FiveC. a sperm joining an egg to form a zygote Fertilization of the egg by a sperm happens in the uterine tube and the zygote begins to undergo mitosis to form a blastocyst.Example SixD. epididymides The epidiymides lie adjacent to the testes and serve as a storage site for sperm on the way to the vas deferensExample SevenA. the development of the embryo The uterus is the site of implantation and development of the human embryo.Example EightC. a fetus Human gestation is divided into two phases: the embryonic phase, which lasts through the 8th week, and the fetal stage, which lasts from 9 weeks until birth. Most major organs and structures are formed during the embryonic stage. The fetal stage is characterized by rapid growth.SC.912.L.17.5 Population Size Example OneD. the amount of aquatic plants in the area decreased If the amount of the major producer in an area is reduced, populations of consumers will also be reduced. Since the mullet feed on aquatic plants, their population would decline in response to declining numbers of plants.Example TwoD. The relationship controls the population size of both species. The predators keep the prey population under control and the size of the population of prey limits the amount of predators an ecosystem can support.Example ThreeC. population of the species Population size is determined by births, deaths, immigration and emigration.Example FourA. Growth and immigration rate is equal to death and emigration rate. Carrying capacity is the maximum population size of a species that can exist in a given environment given the resources.Example FiveA. the decline of several fish populations Fish are sensitive to changes in pH and would experience a decrease in numbers if a shift in the pH of the water occurred.Example SixD. availability of food The availability of food is a limiting factor in a population of organisms. If there is not enough food, some of the organisms will die and the population will decrease in number.Example SevenB. wind, precipitation, and soil type Abiotic factors are those that are non-living.Example EightC. The possum population grew to a larger size. With no natural predators, the possum population was allowed to grow unchecked.Example NineC. The pythons could prey on native organisms and cause native population to decline. Introduced species often prey on native organisms declining their populations, sometimes to extinction.Example TenB. Most sunlight is absorbed before reaching these levels. Plants and phytoplankton are primary producers that rely on the sun to carry out photosynthesis. The bottom zones of the ocean have little to no light.SC.912.L.17.9 Food Webs and Energy Transfer Example OneD. There is less available energy in the fourth trophic level because of the loss of energy through metabolism in each of the lower trophic levels. Each successive trophic level contains about 10% of the available energy from the previous trophic level. The other 90% is lost as heat to the atmosphere through metabolism by the organisms in that level.Example TwoA. Hawk Available energy decreases as you go up a food chain or web. Secondary and tertiary consumers receive less energy than primary consumers.Example ThreeA. Producers Producers gather energy from the sun and convert it to useable molecules for consumers. Removing producers from any food chain or web will cause an immediate decrease in available energy.Example FourD. Atmosphere When plant material is burned, carbon is released as carbon dioxide, which enters the Earth’s atmosphere.Example FiveC. sharks - a secondary consumer Energy pyramids show the amount of available energy with the lowest levels having the most energy. Producers are found at the bottom of the pyramid, while secondary consumers would be found at the top.Example SixB. The amount of carbon dioxide in the atmosphere will decrease. Decomposers release carbon into the atmosphere, so if they were removed less carbon would reach the atmosphere.Example SevenC. evaporation Water that is released by plants through transpiration evaporates into the atmosphere to rejoin the water cycle.Example EightA. photosynthesis and respiration Photosynthesis captures carbon dioxide from the atmosphere and converts it to glucose. Cellular respiration converts glucose to carbon dioxide.Example NineB. Producers are at the bottom level of both the energy pyramid and the biomass pyramid. Both the biomass pyramid and the energy pyramid have producers at the bottom. Producers account for most of the biomass and most of the available energy in any given ecosystem.SC.912.L.17.20 Human Impact Example OneB. Alteration in ocean salt levels would cause loss of species and unbalanced populations in marine food webs. Any change in abiotic factors (such as salinity) will have effects on the organisms in an ecosystem.Example TwoA. reduce the use of nonrenewable resources. The use of nonrenewable resources has negative effects for many ecosystems as well as human beings. New ways to use renewable resources for energy are now being developed.Example ThreeA. ecosystems are interconnected and human action can alter ecosystem equilibrium. Human impacts on the environment can be far-reaching. What we do in our own area of the Earth, can effect what happens in other areas as well.Example FourD. the decision of one human generation may have an impact on future generations.Example FiveD. The elephant seals will be more vulnerable to environmental change. The more genetic variation a population has, the more easily the population can deal with environmental change. If the gene pool decreases, genetic variation decreases.Example SixB. construction of homes along the lake When homes are constructed, trees and plants are removed. Under natural conditions, trees and plants help to secure the soil and prevent erosion and sedimentation in lakes and rivers.Example SevenA. Oxygen is used up as algae is decomposed, reducing the amount available to other organisms. Algal blooms, often caused by high levels of nitrogen in water lead to low dissolved oxygen levels and the death of many species in these ecosystems.Example EightA. the threat to local biodiversity Any time land is modified from its original natural state, the local organisms will be affected.Example NineB. The whale populations are not rebounding as quickly as they might if all of the countries agreed not to hunt whales. All countries must work together to prevent major human impact on fragile ecosystems and populations of organisms.Classification, Heredity, and EvolutionSC.912.L.15.1 Evolution Example OneB. It shows possible common ancestry between organisms. Animals that evolved from a common ancestor will often have similar structures and organs.Example TwoD. evolution by natural selection Natural selection is the mechanism of evolution, where animals that are more “fit” for a certain environment will naturally be selected to reproduce more often. Over time, new species have evolved from similar ancestral species.Example ThreeA. The organisms share a common ancestry. During the embryonic stage, before organisms develop many specialized structures, embryos with common ancestry will tend to have many of the same characteristics.Example FourA. The jaws of hominids evolved to be smaller and less protruding over time. Over time, the jaws of hominid species evolved to be smaller, lighter and less protruding. Scientist are now collecting evidence to support the theory that this change in jaw size allowed for larger brains to develop in hominids.SC.912.L.15.6 Classification Example OneC. multicellular filaments that absorb nutrients These filaments, called hyphae extend into the fungi’s food source and absorb nutrients. Fungi are not able to make their own food.Example TwoB. species F Species L and species N share the common ancestor, species F.Example ThreeC. protists and plants Plant-like protists make their own food through photosynthesis, just like plants do.Example FourB. fungi Fungi do not have chlorophyll because they are autotrophs. However, they are non-motile (cannot move) so they must produce spores to distribute themselves to their food sources.Example FiveD. Some organisms, which were previously characterized together, were determined to be genetically very different. Using the analysis of RNA developed by Carl Woese, scientists are now able to classify living things based on genetic information instead of expressed characteristics. Genetic information is more specific and can give clues as to the evolutionary ancestry of organisms.SC.912.L.15.8 Origin of Life Example OneC. Synthesis of organic molecules During chemical evolution, organic molecules were synthesized by individual elements. All living things are made from organic molecules, so the presence of these molecules is required for life to exist.Example TwoB. prokaryotic and anaerobic Prokaryotic organisms are single-celled and would have evolved first. Since atmospheric oxygen was not initially present on Earth, the ability to use anaerobic respiration to produce energy would have been necessary for the first living organisms.Example ThreeC. The process of synthesizing organic molecules from a mixture of gases has been successfully modeled in the laboratory. The Miller-Urey experiments have been tested many times in the laboratory and organic molecules have continued to be successfully formed from mixtures of gases.Example FourC. They were able to make more use of available energy Mitochondria are the organelles which manufacture ATP from organic molecules.SC.912.L.15.13 Natural Selection Example One B. limited food resources Limited resources are a major driving factor for natural selection. Since there was not enough food for all of the finches, the finches that had beaks which allowed them to get food more easily were more likely to survive and reproduce.Example TwoC. chromosome number Chromosome number is not a factor that influences natural selection. The other three choices represent factors that drive the process of natural selection.Example ThreeA. natural processes that produce genetic diversity Random mutations in DNA provide genetic variation in a population of species and allow for natural selection to occur.Example FourA. An organism with favorable genetic variations will tend to survive and breed successfully.Example FiveD. It will reduce genetic diversity. Genetic drift is a change in the frequency of alleles due to change. Typically, genetic drift decreases genetic diversity in a population.Example SixA. genetic drift Isolated populations run the risk of genetic drift due to decreased variation in the species.Example SevenC. Species today descended with modifications from ancestral species. This answer represents evolution as a whole, not the process of natural selection.Example EightB. Species with greater genetic diversity adapt more easily to changing environments. Greater genetic diversity allows for a wide range of environmental changes to occur without harming the population of organisms.SC.912.L.16.1 Genetics Example OneB. None of their daughters will have hemophilia. Sex-linked traits are only present on sex chromosomes. Hemophilia is an X-linked chromosome so a father who does not have hemophilia must donate a non-hemophilia gene on the X chromosome he contributes to his daughter. For a girl to have a sex-linked condition, both of her X chromosomes have to have the allele for that condition.Example TwoC. one parent with heterozygous type A blood, and the other parent with type O blood In order for a recessive condition to be expressed, the individual must have two recessive alleles, one from the mother and one from the father. C is the only condition in which both parents possess an O allele to pass on to the offspring.Example ThreeA. 0% For a recessive condition to be passed on, the offspring must inherit one allele for that condition from each parent. In this case, the father has no PKU alleles to pass on to the child, so even if the mother passes one on, it will not be expressed.Example Four The Punnett square for this problem would look like this. So the answer is B: 50% Hh: 50% hh.Example FiveB. XhY Individual 6 is the offspring of individuals 1 and 2. Males are always represented with squares. If the disorder is recessive, the Father’s genotype must be XhY for the disorder to be expressed. Because the condition is expressed in the son (individual 6), we can infer that the mother’s genotype is heterozygous (XHXh) because she must have contributed an X chromosome with the allele for the gene to her son, but did not have the condition herself. Individual 6 has the genotype XhY.Example SixD. ST, St, sT, st Gametes are haploid and contain only half of the number of chromosomes of the parent cells (one of each chromosome type).Example SevenThe Punnett Square would look like this: So, the answer is B. 50% of the offspring would have an orange phenotypeExample EightC. Haploid cells are produced by meiosis. Although each cell in the human body has two copies of each chromosome with one allele for each trait on them, the gametes (egg and sperm) have only one copy of each chromosome with one allele for each trait.Example NineD. The allele is on the Y chromosome. Traits coded for on the Y chromosome are always expressed because there is no counterpart allele to mask the expression. Boys have XY genotype and girls have XX genotype. ................
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