Fall 2025 Midterm 1

Questions 1-6: A true-breeding plant that produces red flowers and short fruits is crossed with a

true-breeding plant that produces white flowers and long fruits. All the F1 have pink flowers and

spherical fruits. When the F1 are self-fertilized, F2 progeny are produced with the following

phenotypes and numbers:

300 red flower and spherical fruit

150 red flower and long fruit

150 red flower and short fruit

300 white flower and spherical fruit

600 pink flower and spherical fruit

150 white flower and long fruit

150 white flower and short fruit

300 pink flower and long fruit

300 pink flower and short fruit

(Hint: examine one trait at a time)

1. (True/False) The flower color (red/white/pink) is determined by one gene.

2. (True/False) The fruit shape (spherical/long/short) is determined by two genes.

3. (True/False) All plants with red flowers and spherical fruits would have the same genotype.

4. (True/False) Considering only the gene(s) that determine(s) fruit shape, none of the spherical

plants is true breeding

Among 300 F2 plants that have pink flowers and short fruits, how many of them are true-

breeding?

a. 0

b. 100

c. 150

d. 300

e. None of these above

Among 150 F2 plants that have white flowers and long fruits, how many of them are true-

breeding?

a. 0

b. 50

c. 75

d. 150

e. None of these above

7. How many genes control color in this plant?

a. 1

b. 2

c. 3

d. 4

e. None of these above
DONT ERASE YET

8. In which of the following cross(es) both parents must be true-breeding?

a. I

b. II

c. IV

d. VI

e. None of these above or more than one of these above

DONT ERASE YET

DONT ERASE YET

9. In which of the following cross(es) both parents must be heterozygous for all gene(s)

involved?

a. II

b. III

c. V

d. VI

e. None of these above or more than one of these above

10. (True/False) There are more possible genotypes for a pink than for a purple plant.

11. What proportion of the pink progeny from cross IV is true-breeding?

a. 0%

b. 1/3

c. 50%

d. 100%

e. None of these above

12. What proportion of the pink progeny from cross VII is true-breeding?

a. 0%

b. 1/3

c. 50%

d. 100%

e. None of these above

13. What proportion of the lavender progeny from cross VI is true-breeding?

a. 0%

b. 1/3

c. 50%

d. 100%

e. None of these above

MEMORIZE THIS

18. An organism has a diploid number of 2n = 36 chromosomes. At the end of meiotic anaphase

II, what is the number of chromosomes present in each cell?

a. 9

b. 18

c. 36

d. 72

e. None of these above

18

What proportion of their progeny will be albino?

a. 0%

b. 1/16

c. 1/4

d. 1/3

e. None of these above

20. How many different genotypes can be found among their albino progeny?

a. 2

b. 4

c. 8

d. 9

e. None of these above

21. What proportion of their albino progeny would be true breeding?

a. 1/3

b. 1/4

c. 1/9

d. 1/16

e. None of the above

22. What proportion of their progeny will be yellow?

a. 9/64

b. 9/16

c. 3/16

d. ¾

e. None of the above

23. What proportion of their black progeny would be true breeding?

a. 1/64

b. 1/27

c. 1/9

d. 1/3

e. None of these above

4. What is the mode of inheritance of the yellow mutant?

a. autosomal recessive

b. autosomal dominant

c. X-linked recessive

d. X-linked dominant

e. Y-linked

MEMORIZE

25. The rare wild-type male in the F1 progeny was due to a non-disjunction event happened in

a. the father

b. the mother

c. either the mother or the father

26. The rare wild-type male in the F1 progeny was due to a non-disjunction event happened in

a. meiosis I

b. meiosis II

c. either meiosis I or meiosis II

27. The rare yellow female in the F1 progeny was due to a non-disjunction event happened in

a. the father

b. the mother

c. either the mother or the fathe

28. The rare yellow female in the F1 progeny was due to a non-disjunction event happened in

a. meiosis I

b. meiosis II

c. either meiosis I or meiosis II

29. (True/False) A non-disjunction event during meiosis I of the father might produce a rare

yellow female.

30. If a yellow male mated with a true-breeding wild-type female, what results would you

predict?

a. All male and female progeny are 99.9% wild-type and 0.1% yellow

b. All male progeny are wild-type; 99.9% female progeny are wild-type and 0.1% yellow

c. All male progeny are wild-type; 99.9% female progeny are yellow and 0.1% wild-type

d. All female progeny are wild-type; 99.9% male progeny are wild-type and 0.1% yellow

e. All female progeny are wild-type; 99.9% male progeny are yellow and 0.1% wild-type

31 What is the inheritance pattern of Rh blood type?

a. autosomal dominant

b. autosomal recessive

c. X-linked dominant

d. X-linked recessive

e. Y-linked

32. (True/False) I-3 must have blood type A.

33. (True/False) II-2 must have an i allele.

34. (True/False) II-5 must be heterogeneous for RHD gene.

35. The probability that I-1 and I-2 have the same genotype (for both genes) is:

a. 0%

b. 25%

c. 50%

d. 100%

e. None of these above

36. The probability that II-3 and II-5 have the same genotype (for both genes) is:

a. 0%

b. 25%

c. 50%

d. 100%

e. None of these above

37. What is the probability that II-2 is heterogeneous for RHD gene?

a. 0%

b. 25%

c. ½

d. 2/3

e. None of these above

38. Considering these two genes, there are possible genotypes for II-2.

a. 2

b. 4

c. 6

d. 9

e. None of these above

39. What is the probability that III-1 is O and Rh- blood type?

a. 1/12

b. 1/24

c. 1/32

d. 1/48

e. None of these above

40. What is the probability that III-1 has AB blood type?

a. ¼

b. 1/8

c. 1/16

d. 1/32

e. None of these above