8. Two true-breeding pink-flowered plants are crossed to produce a pink F1. The

Question

8. Two true-breeding pink-flowered plants are crossed to produce a pink F1. The F1 are interbred to produce an F2 that consists of 317 pink plants and 73 red ones. Which of the following accounts best for this result?

• monohybrid cross with complete dominance

• monohyrid cross with incomplete dominance

• dihybrid cross with two complementary genes

• dihybrid cross with dominant suppression

9. When two genes affect a trait so that both genes are necessary for expression of the trait, this gene interaction is called • complementation • epistasis • penetrance • suppression 10. The phenotypic ratio of the F2 in a cross involving genes that interact as described above would be

• 13:3

• 12:3:1

• 9:7

• 9:3:4

11. If members of one gene pair interact with another gene pair in such a way as to mask variation in the second pair, this type of interaction is called

• complementation

• epistasis

• penetrance

• suppression

12. A particular biochemical pathway consists of a colorless precursor, a colorless intermediate and a bright red final product. How many genes would be associated with this pathway?

• one

• two

• three

• cannot be determined

13. For the pathway above, what would be the phenotypic ratio in the F2 of a cross between two colorless parents that produced a bright red F1?

• 3:1

• 9:7

• 1:2:1

• 9:3:4

14. In the cross above, what would be the genotypes of the two colorless parents?

• aa bb

• aa BB AA bb

• aa bb AA BB

• aa bb aa bb

Two different true breeding flower color mutants (red and blue) are crossed to produce a purple F1. The F1 is selfed. From this information, answer the questions below.

15. How many phenotypic categories would be expected in the F2?

• 1 • 2 • 3 • 4

16. What fraction of these would look like the F1? • all • 3/4 • 3/16 • 9/16

17. What fraction would resemble neither the F1 nor the original parents? • none • 1/4 • 1/16 • 3/16

Explanation / Answer

8)

Here, the two true-breeding pink plants express Pink colors in F1 generation, so the pink is a dominant character. In the F2 it gives high number of pink flower than red ones. Thus, it is a dihybrid cross with dominant suppression (13:3 epistasis) and the correct option is (d).

9)

When two genes affect a trait so that both genes are necessary for expression of the trait, this gene interaction is called complementation. Thus, the correct option is (a).

10)

The phenotypic ratio of the F2 in a cross involving genes that interact as described above would be 12:3:1. Thus, the correct option is (b).

11)

If members of one gene pair interact with another gene pair in such a way as to mask variation in the second pair, this type of interaction is called epistasis. Thus, the correct option is (b).

12)

Two genes would be associated with this pathway. Thus, the correct option is (b).

Related Questions

Navigate

• Browse (All)
• Browse 8
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.