Question 1

Which of the following best describes the genetic basis for the 'ebony' phenotype in Drosophila melanogaster, as shown in the image with wild type, ebony, and heterozygote flies?

Accepted Answer

The ebony phenotype is caused by a recessive allele, and only homozygous recessive individuals display the ebony phenotype.

Question 2

A couple, both heterozygous for the ability to roll their tongues (Rr), have a child. What is the probability that their child will NOT be able to roll their tongue? Use the Punnett square provided.

Accepted Answer

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

Question 3

In snapdragons, red flowers ($$R^1R^1$) crossed with white flowers (R^2$R^2) $$produce pink flowers ($$R^1R^2$). What type of inheritance is demonstrated here?

Accepted Answer

Incomplete dominance

Question 4

The ability to roll your tongue is dominant (R) and non-rolling is recessive (r). If two heterozygous parents (Rr) have four children, what is the expected ratio of tongue rollers to non-rollers?

Accepted Answer

3:1

Question 5

Which of the following best explains why the arctic fox changes coat color between summer and winter?

Accepted Answer

Environmental effects on temperature-sensitive alleles

Question 6

A healthy person with PKU (phenylketonuria) is shown. What is the most likely explanation for their healthy phenotype?

Accepted Answer

They are homozygous recessive but follow a phenylalanine-free diet.

Question 7

Which of the following best describes the molecular mechanism behind the heterozygote advantage in sickle cell anemia?

Accepted Answer

Heterozygotes have increased resistance to malaria due to the presence of both normal and sickled hemoglobin.

Question 8

A child with blood type AB is born to a mother with genotype $$I^A I^O$$ and a father with genotype $$I^B I^O. $$What is the probability that their next child will have blood type O?

Accepted Answer

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

Question 9

The Manx cat displays a shortened tail due to a dominant mutation. However, homozygous dominant (MM) embryos do not survive. What is the expected ratio of Manx to non-Manx kittens in a cross between two Manx cats (Mm x Mm)?

Accepted Answer

2:1

Question 10

In summer squash, fruit color is determined by two genes. The presence of a dominant allele A results in white fruit, regardless of the second gene. What type of gene interaction is this?

Accepted Answer

Dominant epistasis

Question 11

A mouse with genotype ccAA is albino, even though the A allele normally produces agouti fur. What genetic phenomenon explains this result?

Accepted Answer

Recessive epistasis

Question 12

Two Drosophila with mutations causing wingless phenotypes are crossed. Their offspring have normal wings. What does this indicate about the mutations?

Accepted Answer

The mutations are in different genes (complementation occurs).

Question 13

Marfan syndrome is caused by a single autosomal dominant mutation that affects multiple body systems. What is this phenomenon called?

Accepted Answer

Pleiotropy

Question 14

A woman who is a carrier for X-linked color blindness ($$X^C X^c) $$has children with a man with normal vision ($$X^C Y). $$What is the probability that a son will be color blind?

Accepted Answer

$$\frac{1}{2}$$

Question 15

Which of the following best describes sex-influenced inheritance?

Accepted Answer

A trait is expressed differently in males and females due to hormonal differences.

Question 16

A Siamese cat has darker fur on its ears, tail, and feet. What is the most likely explanation for this pattern?

Accepted Answer

Temperature-sensitive allele affecting pigment production

Question 17

Which of the following is an example of a conditional lethal allele?

Accepted Answer

An allele that causes death only at high temperatures

Question 18

Which of the following best describes gene redundancy?

Accepted Answer

Loss of function in one gene is compensated by another gene with a similar function

Question 19

A person with the Bombay phenotype appears to have blood type O, but genetically has alleles for type B. What is the molecular explanation for this?

Accepted Answer

They lack the H antigen required for A or B antigen expression.

Extensions of Mendelian Genetics: Comprehensive Study Notes

Guida di studio - Domande di pratica

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