Question 1

Which of the following best describes incomplete dominance as shown in Mendel’s pea plant experiments?

Accepted Answer

The heterozygote phenotype is intermediate between the two parental phenotypes.

Question 2

In a cross between a red-flowered plant ($$RR) $$and a white-flowered plant ($$rr) $$showing incomplete dominance, what is the expected phenotype ratio in the F2 generation?

Accepted Answer

1 red : 2 pink : 1 white

Question 3

Why does the cross shown in Figure 9.11A not support the blending hypothesis?

Accepted Answer

Because the F2 generation includes both parental phenotypes, not just a blend.

Question 4

Which genotype(s) correspond to type AB blood in humans?

Accepted Answer

$$I^A I^B$$

Question 5

If Maria has type O blood ($$ii) $$and her sister has type AB blood ($$I^A I^B$$), what are the possible genotypes of their parents?

Accepted Answer

One parent is $$I^A i$$ and the other is $$I^B i$$

Question 6

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene affecting both hemoglobin structure and resistance to malaria.

Question 7

Why are sickle-cell and nonsickle alleles considered codominant at the molecular level?

Accepted Answer

Both normal and abnormal hemoglobin are produced in heterozygotes.

Question 8

Human height is an example of which type of inheritance?

Accepted Answer

Polygenic inheritance

Question 9

Which equation best represents the expected genotype ratio for a polygenic trait with three genes, each with two alleles?

Accepted Answer

$$2^3 = 8$ possible genotypes

Question 10

Which of the following statements about the environment’s effect on phenotype is correct?

Accepted Answer

Environmental factors can influence the expression of genetic traits.

Question 11

Which phase of meiosis provides the physical basis for Mendel’s law of independent assortment?

Accepted Answer

Metaphase I

Question 12

Linked genes are most likely to be inherited together because:

Accepted Answer

They are located close together on the same chromosome.

Question 13

Crossing over during meiosis can result in:

Accepted Answer

Recombinant gametes with new combinations of alleles.

Question 14

In mammals, which chromosome combination determines a male?

Accepted Answer

XY

Question 15

Why was King Henry VII’s belief that his wives were responsible for only bearing daughters genetically incorrect?

Accepted Answer

Because the male determines the sex of the offspring by contributing either an X or Y chromosome.

Question 16

Which of the following is true about X-linked recessive disorders in humans?

Accepted Answer

They are more commonly expressed in males than females.

Question 17

If neither parent has hemophilia but their son does, what is the probability that their next child will also have hemophilia?

Accepted Answer

$$\frac{1}{4}$$

Question 18

Which genotype results in severe disease due to inability to make LDL receptors?

Accepted Answer

$$hh$$

Question 19

Which of the following best explains codominance in the ABO blood group system?

Accepted Answer

Both $$I^A$$ and $$I^B$$ alleles are fully expressed in heterozygotes.

Question 20

A white-eyed female Drosophila is crossed with a red-eyed male. What is the expected eye color of their male offspring?

Accepted Answer

All male offspring will have white eyes.

Variations on Mendel’s Laws: Patterns of Inheritance Beyond Mendel

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