Q: A cross between a red-flowered (RR) and a white-flowered (rr) snapdragon produces all pink-flowered offspring. What is the expected phenotypic ratio in the F2 generation if two pink-flowered plants are crossed?

$$1:2:1$$ \,\text{(red:pink:white)}$

Question 1

Which of the following best describes incomplete dominance as observed in snapdragon flowers?

Accepted Answer

Heterozygotes display a phenotype that is intermediate between the two homozygotes.

Question 2

A cross between a red-flowered (RR) and a white-flowered (rr) snapdragon produces all pink-flowered offspring. What is the expected phenotypic ratio in the F2 generation if two pink-flowered plants are crossed?

Accepted Answer

$$1:2:1$$ \,	ext{(red:pink:white)}$

Question 3

Which genotype would result in type AB blood in the ABO blood group system?

Accepted Answer

$$I^A I^B$$

Question 4

A person with genotype $$I^A i$$ for the ABO blood group will have which blood type and which antibodies in their plasma?

Accepted Answer

Type A blood; anti-B antibodies

Question 5

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

Accepted Answer

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

Question 6

A woman with type O blood and a man with type AB blood have a child. What are the possible blood types of their child?

Accepted Answer

Type A or Type B

Question 7

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene causing sickle-cell anemia, which affects multiple organs and causes various symptoms.

Question 8

In sickle-cell disease, the abnormal hemoglobin causes red blood cells to become sickle-shaped. Which of the following best describes the consequences of this change?

Accepted Answer

It leads to a cascade of symptoms affecting many organs, such as pain, organ damage, and paralysis.

Question 9

Familial hypercholesterolemia is caused by a mutation affecting LDL receptors. What is the genotype of an individual who has half the normal number of LDL receptors?

Accepted Answer

Heterozygous (Hh)

Question 10

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes contribute additively to a single trait, resulting in continuous variation.

Question 11

A child has type O blood, but both parents have type A blood. Which genotypes must the parents have?

Accepted Answer

Both parents are heterozygous ($$I^A i)$$

Question 12

If a person with sickle-cell trait (heterozygous) lives in a malaria-endemic region, what is the likely advantage?

Accepted Answer

They are more resistant to malaria compared to individuals without the trait.

Question 13

Which of the following crosses would produce offspring with a 1:1 phenotypic ratio in snapdragons (incomplete dominance)?

Accepted Answer

Pink-flowered (Rr) crossed with white-flowered (rr)

Question 14

A person with genotype $$hh$$ for the LDL receptor gene will have which phenotype?

Accepted Answer

Severe disease; no LDL receptors on liver cells

Question 15

Which of the following best explains why blood transfusions require matching of both ABO and Rh blood groups?

Accepted Answer

To prevent immune reactions caused by antibodies against foreign carbohydrates and proteins on red blood cells.

Question 16

Which of the following is NOT a feature of polygenic inheritance?

Accepted Answer

Traits are determined by a single gene with two alleles.

Question 17

If a person has genotype $$I^A I^B$$ for the ABO blood group and is Rh negative, what is their blood type?

Accepted Answer

AB negative

Question 18

Which of the following best describes the effect of pleiotropy in sickle-cell disease?

Accepted Answer

A single gene mutation leads to multiple symptoms affecting different organs.

Question 19

A person with genotype $$I^B i$$ for the ABO blood group receives blood from a donor with type A blood. What is the likely outcome?

Accepted Answer

The recipient's anti-A antibodies will react with the donor's blood, causing clumping.

Extensions of Mendelian Genetics: Incomplete Dominance, Codominance, Multiple Alleles, Pleiotropy, and Polygenic Inheritance

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