Genetics

Question 1

Two true breeding parents are crossed similar to Mendel’s P generation. A tall plant is crossed with a short plant. What is the expected outcome for the F1 generation?

• all short
• all tall
• all medium height
• half tall, half short

Answer 1

All tall

Question 2

If the cross from #1 is continued, what would be the expected outcome in the F2 generation?

• all short
• all tall
• 3 tall, 1 short
• half tall, half short

Answer 2

3 tall, 1 short

Question 3

If a plant that has round seeds has a parent that has wrinkled seeds, what is its genotype? (Assume that round is dominant. So dominant: R, recessive: r)

Answer 3

Rr

Question 4

This principle states that alleles separate during gamete formation:

• principle of multiple alleles
• principle of dominance and recessiveness
• principle of independent assortment
• principle of segregation

Answer 4

Principle of segregation

Question 5

If you crossed two heterozygous plants, how many of the offspring will also be heterozygous?

Answer 5

Half

Question 6

A plant that has purple flowers is crossed with one that has white flowers. The offspring were half white and half purple. What were the genotypes of the parents?

Answer 6

Pw x ww

Question 7

A dihybrid cross (AaBb x AaBb) will result in what offspring ratio?

Answer 7

9:3:3:1

Question 8

Phenotype refers to an organisms:

Answer 8

Physical appearance (not genetic code)

Question 9

In each case where Mendel crossed true breeding plants as parents, the offspring displayed only one of the two traits seen in the parents. This observation supports which principle of genetics?

• segregation
• independent assortment
• dominance and recessiveness
• allele frequency

Answer 9

Dominance and recessiveness

Question 10

Which of the following outcomes would you expect from the following cross: tall, round (TTRR) x short, wrinkled (ttrr)

Answer 10

All offspring are tall and round

Question 11

In Wisconsin Fast Plants, purple (P) stems is dominant to green stems. Green (G) leaves are dominant to yellow leaves.

1. A plant with purple stems and green leaves (PpGg) is self pollinated. What are the phenotypic ratios of the offspring?
2. A plant with purple stems and green leaves (PpGg) is crossed with a plant that has green stems and yellow leaves.. What are the phenotypic ratios of the offspring?
3. A plant that is homozygous dominant for both traits is crossed with one that has green stems and yellow leaves. What are the phenotypic ratios of the offspring?
4. A plant that is heterozygous for both traits is crossed with one that is heterozygous for purple stems and has yellow leaves. What are the phenotypic ratios of the offspring?

Answer 11

1. 9 purple stems, green leaves/ 3 purple stems, yellow leaves / 3 green stems, green leaves / 1 green stems, yellow leaves
2. 1:1:1:1
3. All tall and purple
4. PpGg x Ppgg; 3/4 purple stems & 1/4 green stems; 1/2 green leaves & 1/2 yellow leaves;

3/4 * 1/2 = 3/8 purple stems, green leaves
3/4 * 1/2 = 3/8 purple stems, yellow leaves
1/4 * 1/2 = 1/8 green stems, green leaves
1/4 * 1/2 = 1/8 green stems, yellow leaves