1,2. Indicate the PHENOTYPE RATIO you would expect from the following crosses: 1

Question

1,2. Indicate the PHENOTYPE RATIO you would expect from the following crosses:

1. AaBb x AaBb

A 3:1

B 9:3:3:1

C 1:1

D 1:1:1:1

2. Aa x Aa

A 3:1

B 9:3:3:1

C 1:1

D 1:1:1:1

3 Assuming that A and B represent independent genes on different chromosomes, which of the following could be a normal genotype for a gamete (egg or sperm) following meiosis?

A AaBb

B Abb

C Ab

D AA

E Two of the above are possible.

4 In humans, pointed eyebrows, B, are dominant over smooth eyebrows, b. Mary’s father has pointed eyebrows, but she and her mother have smooth. What is Mary’s genotype?

A BB

B Bb

C bb

D Bbbb

E Either b or c, you must do a test-cross to tell.

5 In humans, mitosis is necessary to:

A grow and repair tissue

B form gametes (eggs or sperms)

C maintain the chromosome number in body cells

D destroy unnecessary or worn-out cells

E Both a and c are correct.

6 A cell that has 13 chromosomes could:

A undergo mitosis but not meiosis

B undergo meiosis but not mitosis

C undergo either mitosis or meiosis

D not undergo any kind of division - either mitosis or meiosis.

7 If a mother cell has fourteen chromosomes prior to mitosis, how many chromosomes will the daughter cells have?

A Fifty-six

B Twenty-eight

C Fourteen

D Seven

8 If a mother cells has fourteen chromosomes prior to meiosis, how many chromosomes will the daughter cells have?

A Fifty-six

B Twenty-eight

C Fourteen

D Seven

9 At metaphase I of meiosis there are:

A individual chromosomes each consisting of a single chromatid.

B unpaired chromosomes each consisting of two chromatids.

C homologous pairs of chromosomes each consisting of two chromatids

D always an even number of chromosomes each consisting of a single chromatid.

10 Two parents have freckles (dominant) and attached earlobes (recessive). Some of their children do not have freckles. What are the chances that their next child will have freckles and attached earlobes?

A 100%

B 75%

C 25%

D 0%

E It cannot be determined.

Explanation / Answer

1. (B) = 9:3:3:1

2. (A) = 3:1

3. (A) = AaBb

4. (C) = bb

5. (A) = grow and repair tissue

6. (C) = undergo either mitosis or meiosis

7. (C) = fourteen

8. (D) = seven

9. (C) = homologous pair of chromosomes each consisting of two chromatids

10. (B) = 75%

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