Characteristics of Living Things



Characteristics of Living Things

Chapter 2: It’s Alive Or Is It?

Ga. Std.: S7L2: Students will describe the structure and function of cells.

Ga. Std.: S7L3(b) – compare and contrast sexual and asexual reproduction.

Most organisms must eat other organisms in order to obtain energy for survival or make their own food (plants and photosynthesis), but we have also found some organisms that obtain their energy from hydrogen sulfide. These organisms are bacteria. Other organisms then feed on the bacteria. These bacteria are found in deep ocean trenches.

Chapter 2: Section 1

Every living thing has cells. Humans are composed of about 80 trillion cells. A cell is a membrane-covered structure that contains all of the materials necessary for life.

Most cells are too small to be seen with the naked eye. Organisms with many cells have cells that carry out special functions. Example: Your nerve cells carry impulses to your brain. These impulses may be signals to walk, laugh, talk or be silent.

All organisms have the ability to sense change in their environment and respond to that change. (Getting more cloths if you are cold, taking a sweater off if you are hot).

Living organisms respond to change.

A change in the organism’s environment that affects the activity of the organism is called a stimulus. (Plural - stimuli).

Stimuli can be chemicals, gravity, darkness, pain, light, sounds, tastes, or anything that causes an organism to respond.

Homeostasis

The maintenance of a stable internal environment is called homeostasis.

Even though an organism’s external environment changes, their internal environment must remain fairly constant. Example: the human body must remain at 37o Celsius. If it falls below this, we could go into hypothermia (hypo – below, thermia – temperature) or if it rises much above we could go into hyperthermia (hyper – above, thermia – temperature). Both of these conditions may result in death.

**The maintenance of a stable internal environment is called homeostasis.

If you are too hot, your body sweats. This is your body’s method to cool itself off and maintain homeostasis. If you are cold, your body shivers. This creates heat from the muscles and raises your body temperature to maintain homeostasis.

Living Things Reproduce

Organisms make other organisms like themselves. They can do this in one of two ways: asexual reproduction, or sexual reproduction.

In asexual reproduction a parent produces offspring that are identical to the parent. (Hydra producing buds on page 38).

In sexual reproduction, it requires two organisms to serve as parents to produce offspring, which will have traits from both parents. (Bears).

Can you think of other asexual and sexual organisms?

Living Things Have DNA

The cells of all living things contain a special molecule called DNA (deoxyribonucleic acid). DNA provides the instructions to build the proper proteins in the organism. These proteins take part in the organism’s cells activities.

The transmission of the characteristics from one generation to the next is called heredity. What are some traits you received due to heredity?

Living Things Use Energy

All living organisms must have energy in order to carry out daily activities. An organism’s metabolism is the total of all of the chemical activities that it performs.The cells in your body must transport materials into and out of them in order to remain alive. All of this requires energy and the total energy needs is your metabolism.

Living Things Grow and Develop

All living things, whether they are made up of one cell or many cells, grow during periods of their lives. (Single celled organisms have their cell get larger. Multi-cellular organisms add cells to become larger.)

Organisms also go through different stages of development. Humans go through different stages as we develop. (Embryo, fetus, baby, child, adolescent, young adult, middle aged, senior citizen.) (An oak tree begins as an acorn, seedling, sapling, and then a tree).

Review

1.     What characteristics of living things does a river have? Is a river alive?

A river has energy (it moves – kinetic energy), and can grow larger (flooding). But it is not alive because it is not made of cells, cannot respond to stimuli, has no DNA, and cannot reproduce.

2.     What does a fur coat on a bear have to do with homeostasis?

Homeostasis is the maintenance of a stable internal environment. The fur coat of a bear helps it keep a stable body temperature.

3.     How is reproduction related to heredity?

Heredity is the passing of characteristics from parents to offspring. When organisms reproduce, offspring inherit copies of their parents DNA.

4.     What are some of the stimuli that you respond to in your environment?

Characteristics of Life

Chapter 2 Section 2 Notes

GPS: S7L4

The Simple Bare Necessities of Life

Food

All living things need food. They must produce their own or capture and consume other organisms.

Making Food

Some organisms such as plants are called producers because they can produce their own food. Like plants, most producers use the energy from the sun to produce their food by photosynthesis. The bacteria in deep sea trenches that use hydrogen sulfide are carrying our chemosynthesis to produce their food (producing food from chemicals).

Getting Food

Organisms that get their food by feeding on other organisms are called consumers.

Some consumers are decomposers. These organisms get their food by breaking down the nutrients in dead organisms or animal wastes. Fungi are decomposers (mushrooms).

Water

The cells of all organisms are made up of approximately 70% water. We can only live without water for about 3 days. We can live without food for over a week. Most of the metabolism processes must have water in order to function properly. Some organisms get all of their water in the food they consume (kangaroo rat).

Air

Air is a mixture of gases, mainly nitrogen, oxygen and some carbon dioxide. Animals must take in air and use the oxygen for respiration in order to survive. Plants take in carbon dioxide and carry out photosynthesis and release oxygen a by-product.

A Place to Live

All organisms must have somewhere to live that contains all the things they need to survive. Some organisms require a large amount of space (elephants, wolves). Some need very little space (bacteria).Space is limited so organisms compete for space, food, water, air and other necessities. Many organisms become territorial and defend their space and resources.

Review

1.     Why are decomposers categorized as consumers? How do they differ from producers?

Because they must obtain the food they need from other organisms. Decomposers cannot make their own food like producers are able to do.

2. Why are most cells 70% water?

Most of the chemical reactions that occur in cells depend on the presence of water.

3. Could life on Earth as we know it exist if air contained only oxygen?

No! Green plants, algae and some bacteria need carbon dioxide gas as well as oxygen. Without the carbon dioxide, they could not survive and other organisms could not rely on them as a food source.

4. How might a cave, an ant, and a lake meet the needs of an organism to survive?

The cave could serve as a place to live, the ant could be food and the lake could provide water.

Characteristics of Life

Chapter 2 Section 3 The Chemistry of Life

All living things are made of cells, but what are cells and non-living things made of? They are made of tiny building blocks known as atoms.

Atoms are made up of sub-atomic units, the proton, neutron and electron.

A substance made of only one type of atom is called an element. When two or more atoms join together, they form a molecule.

The molecules found in living things are usually made of different combinations of six elements: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. These elements combine to form proteins, carbohydrates, lipids, nucleic acids, and ATP (adenosine triphosphate). Remember the elemental symbols for carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S).

Proteins

Proteins are large molecules made up of amino acids. Organisms break down proteins in food they eat to provide their cells with amino acids. These amino acids are then linked together to form new proteins based on the cells needs.

Proteins in Action

Proteins have many different functions. Example: hemoglobin is the protein that allows for the transportation of oxygen from our lungs to our cells. Some proteins are called enzymes and these help speed up chemical reactions in an organism’s body.

Carbohydrates

These are a group of compounds made from sugars. Cells use carbohydrates as a source for energy storage.

Types of Carbohydrates

Simple carbohydrates (simple sugars) are made of one sugar molecule or a few linked together. (Table sugar, natural sugars from fruits).

Complex carbohydrates are made of hundreds of sugar molecules linked together. (Plants make a complex carbohydrate called starch). (Potato)

Lipids

These are compounds that cannot mix with water. These also store energy and form membranes of cells.

Fats and Oils

These are lipids that store energy. At room temperature, fats are solid and oils are liquid. Most lipids in plants are oils and most lipids in animals are fats.

Phospholipids

A membrane surrounds all cells. This membrane is composed of a double phospholipid layer. The head of the phospholipid is hydrophilic and the tail is hydrophobic. (See figure 13 in text).

Nucleic Acids

Nucleic acids are composed of subunits called nucleotides. These subunits include a nitrogenous base, a phosphorus, and a sugar. Nucleic acids are sometimes referred to as the blueprints of life because they contain all of the information for cells to make the proteins they need. DNA (deoxyribonucleic acid) is a nucleic acid and contains all of the information to make the proteins that cells need.

The Cells Fuel

All cells need fuel and this fuel is in the form of ATP (adenosine triphosphate). ATP is the major fuel for all cells that require energy.

REVIEW

What are the subunits of proteins? Of starch? Of DNA?

The subunits for proteins are amino acids. For starch, the subunits are complex carbohydrates or hundreds of sugars linked together. For DNA, the subunits are nucleotides.

What do carbohydrates, fats, and oils have in common?

They all store energy.

Are all proteins enzymes?

No. Not all proteins are enzymes. Enzymes are special proteins that speed up certain chemical reactions in the cell.

What would happen to the ATP in your body if you did not eat enough carbohydrates? How would this affect your cells?

The supply of ATP would decrease. The cells would still need ATP for energy, so they ATP would be obtained from other sources like lipids.

Characteristics of Life

Chapter 2: Section 1 Reading Worksheet

GPS: S7L2

A c is a membrane-covered structure that contains all of the materials necessary for life.

A change in the organism’s environment that affects the activity of the organism is called a

s .

The maintenance of a stable internal environment is called h .

Organisms make other organisms like themselves. They can do this in one of two ways: a reproduction, or

s reproduction.

In a reproduction a parent produces offspring that are identical to the parent.

In s reproduction, it requires two organisms to serve as parents to produce offspring, which will have traits from both parents.

The cells of all living things contain a special molecule called D .

The transmission of the characteristics from one generation to the next is called h .

All living organisms must have energy in order to carry out daily activities. An organism’s

m is the total of all of the chemical activities that it performs.

All living things whether they are made up of one cell or many cells g during periods of their lives. (Single celled organisms have their cell get larger. Multi-cellular organisms add cells to become larger.)

Organisms also go through different stages of

d .

Chapter 2 Section 2 Worksheet

All living things need f in order to survive. They must produce their own or capture and consume other organisms.

Some organisms such as plants are called p because they can produce their own food.

Like plants, most producers use the energy from the sun to produce their food by carrying out p______________.

Organisms that get their food by feeding on other organisms are called c .

Some consumers are d . These organisms get their food by breaking down the nutrients in dead organisms or animal wastes.

The cells of all organisms are made up of approximately ____% water. We can only live without water for about ___ days.

A is a mixture of gases, mainly nitrogen, oxygen and some carbon dioxide.

Plants take in c d and carry out photosynthesis and release oxygen a by-product.

All organisms must have somewhere to live that contains all the things they need to survive. This “somewhere is known as h .

What would a 100 kg organism’s mass be if there were no water?

Give an example of a producer, consumer, and decomposer.

Chapter 3 Section 3 Reading Worksheet

GPS: S7L2

All living things are made of cells, but what are cells and non-living things made of? They are made of tiny building blocks known as a .

A substance made of only one type of atom is called a e . When two or more atoms join together, they form an m .

The six elements that are found in different combinations with each other and make up living things are:

Proteins are large molecules made up of a a .

Simple c (simple sugars) are made of one sugar molecule or a few linked together.

Complex c are made of hundreds of sugar molecules linked together.

At room temperature, fats are solid and oils are liquid.

A membrane surrounds all cells. This membrane is composed of a double p layer.

Nucleic acids are composed of subunits called n .

D is a nucleic acid and contains all of the information to make the proteins that cells need.

All cells need fuel and this fuel is in the form of A (adenosine triphosphate).

Explain the difference in the two types of carbohydrates.

What are two functions of lipids?

How does an organism use proteins?

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