Science7- Genetics: The Science of Heredity



Science7- Genetics: The Science of Heredity

Name: Date: Period:

I. 1. For the genotype below, indicate whether it is a heterozygous (He) OR homozygous (Ho).

TT Bb DD Ff

2. Determine the phenotype for each genotype using the information provided.

Brown hair color is dominant to blonde.

BB Bb bb

Long tails in cats are dominant to short tails.

Ll ll LL

3. For each phenotype, give ALL the genotypes that are possible.

Tall height (T) is dominant to short (t)

Tall = Short =

Purple flowers are dominant to white

Purple = White =

II. Completion

Fill in the line to complete each statement.

4. An offspring of a plant will always have the same alleles as the parent.

5. A(n) organism has two different alleles for a trait.

6. is the “Father of Genetics”.

7. -pollination was used to bred the Parental Pea Plants in Mendel’s

experiments.

8. If a allele is present, its trait will appear in the organism.

9. In pea plants, the tall stem allele and short stem allele are different forms of the same

10. If D represents the dominant allele of a gene, then represents the recessive allele.

III. Match each word with its definition

Write the letter of the correct answer on the line to the left.

11. Codominance A. An organisms genetic makeup or allele

combination.

12. Hybrid B. An organism’s physical appearance.

13. Dominant Allele C. The scientific study of heredity

14. Homozygous D. An organism that always produces the

same trait in their offspring.

15. Trait E. Different forms of a gene

16. Purebred F. Alleles are neither dominant or recessive

17. Allele G. Different characteristics

18. Genetics H. An organism that has two of the same alleles

for the same trait.

19. Genotype I. An organism that has two different alleles

for the same trait.

20. Phenotype J. An allele that always shows up if it is present.

IV. Multiple Choice

Write the letter of the correct answer on the line at the left.

21. Gregor Mendel’s work was the foundation for understanding why

a. the results of one genetic cross do not affect the outcome of the second

b. sex cells have half the number of chromosomes that body cells have.

c. Protein synthesis occurs in the cytoplasm.

d. Offspring have traits similar to those of their parents.

22. What did Gregor Mendel do to study different characteristics in his genetics experiments?

a. He studied only asexual animals.

b. He studied only self-pollinating plants.

c. He cross-pollinated plants.

d. He cross-pollinated animals.

23. In Mendel’s experiments , what portion of the plants in the F2 generation had a trait that had been

absent in the F1 generation?

a. None c. half

b. one fourth d. three fourths

24. Factors that control traits are called

a. genes c. recessives

b. purebreds d. parents

25. Scientists call an organism that has two different alleles for a trait a

a. hybrid c. purebred

b. trait d. factor

26. What does the notation “TT” mean to geneticists?

a. two dominant alleles c. at least one dominant allele

b. two recessive alleles d. one dominant allele and one recessive allele

27. What does the notation “Tt” mean to geneticists?

a. two dominant alleles c. at least one dominant allele

b. two recessive alleles d. one dominant allele and one recessive allele

28. What is probability?

a. the actual results from a series of events

b. the likelihood that a particular event will occur

c. the way the results of one event affect the next event

d. the number of times a coin lands heads up

29. What does a Punnett square show?

a. all the possible outcomes of a genetic cross

b. only dominant alleles in a genetic cross

c. only the recessive alleles in the genetic cross

d. all of Mendel’s discoveries about genetic crosses

30. If a homozygous black guinea pig is crossed with a homozygous white guinea pig (bb), what is

the probability that the offspring will have black fur?

a. 25 percent c. 75 percent

b. 50 percent d. 100 percent

31. An organism that has two alleles for the same trait is

a. codominant c. heterozygous

b. tall d. homozygous

32. An organism that has two different alleles for the same trait is

a. codominant c. heterozygous

b. tall d. homozygous

33. When Mendel crossed purebred short pea plants with purebred tall plants, the offspring were

a. all tall c. ¾ tall and ¼ short

b. all short d. 75% tall and 25% short

34. For codominant traits, heterozygotes have the phenotype of

a. both alleles b. only recessive alleles

c. neither dominant or recessive d. only dominant alleles

35. An organism’s phenotype is its

a. physical appearance b. genetic makeup

c. allele combination d. probability of occurring

36. An allele whose trait always shows up in an organism when the allele

is present is a

a. gene b. dominant allele

c. recessive allele d. hereditary factor

V. True or False

Write down true if the statement is true, and false if the statement is false.

37. If a coin lands heads up once, there is a 75 percent chance that the

coin will land heads up the next time.

38. The passing of traits from parents to offspring is called genetics.

39. Probability is the likelihood that a particular event will happen.

40. A pea plant that is heterozygous for short stems has the alleles Tt.

VI. Using Science Skills

Use the diagram below to answer questions 41-45. Write your answers in the spaces provided.

41. What are ALL the genotypes of the

offspring?

42. What are ALL the phenotypes of the

offspring?

43. What is the probability (percentage) that the offspring will have short hair?

44. What is the probability (percentage) that the offspring will have long hair?

45. Which trait is dominant, short hair or long hair?

• Using Science Skills (2 points each)

46. SpongeBob Squarepants and his wife SpongeSusie Roundpants recently had a Baby Sponge. SpongeBob is homozygous for his long nose, and SpongeSusie has stubby nose.

A. Create a Punnett square using the symbols “L” and “l” to represent dominant and recessive traits.

B. What is the probability that the Baby Sponge will look like his daddy?

C. What is the probability that the Baby Sponge will be purebred?

D. Baby Sponge grows up and marries a Sponge just like his mom, show the possible combinations of his offspring using a Punnett square.

E. What is the probability that this offspring will look like their daddy?

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