Q: Which equation correctly calculates the genetic map distance between two genes?

$$\text{Map distance} = \frac{\text{Number of recombinant offspring}}{\text{Total number of offspring}} \times 100$$

Q: A geneticist observes 20 double recombinants in a test cross, but expected 40 based on independent assortment. What is the coefficient of coincidence?

$$\text{Coefficient of coincidence} = \frac{20}{40} = 0.5$$

Question 1

Which scientist(s) provided the first experimental evidence that DNA, and not protein, is the genetic material in T2 bacteriophage?

Accepted Answer

Hershey and Chase

Question 2

Which of the following is NOT a criterion for a molecule to be considered the genetic material?

Accepted Answer

It must be able to catalyze metabolic reactions.

Question 3

A nucleoside differs from a nucleotide in that a nucleoside:

Accepted Answer

Contains only a nitrogenous base and a five-carbon sugar

Question 4

Which equation correctly calculates the genetic map distance between two genes?

Accepted Answer

$$	ext{Map distance} = \frac{	ext{Number of recombinant offspring}}{	ext{Total number of offspring}} 	imes 100$$

Question 5

Which chromosome type is characterized by having the centromere located at the very end, resulting in only one visible chromosomal arm?

Accepted Answer

Telocentric

Question 6

A woman is found to have 47 chromosomes, including three X chromosomes (47, XXX). Which statement is most accurate?

Accepted Answer

She will likely live a normal life with no major symptoms.

Question 7

Which of the following best describes the difference between B-DNA and Z-DNA?

Accepted Answer

B-DNA is the most common form in cells, Z-DNA is a less common secondary structure

Question 8

A geneticist observes 20 double recombinants in a test cross, but expected 40 based on independent assortment. What is the coefficient of coincidence?

Accepted Answer

$$	ext{Coefficient of coincidence} = \frac{20}{40} = 0.5$$

Question 9

Which scientist’s work directly led to the discovery of the base pairing rules (A=T, C=G) in DNA?

Accepted Answer

Erwin Chargaff

Question 10

Which of the following is an example of aneuploidy?

Accepted Answer

A human with 47 chromosomes due to an extra chromosome 21

Question 11

In humans, what is the genetic basis for maleness?

Accepted Answer

Presence of a Y chromosome

Question 12

Which of the following best describes dosage compensation in mammals?

Accepted Answer

One X chromosome in females is inactivated, forming a Barr body

Question 13

A chromosome with the centromere located near, but not at, the end is called:

Accepted Answer

Submetacentric

Question 14

Which chromosomal abnormality is associated with a 'cry of the cat' sound in infants?

Accepted Answer

Cri-du-chat syndrome

Question 15

If a gene pair shows a recombination frequency of 50%, what does this indicate?

Accepted Answer

The genes are unlinked and assort independently

Question 16

Which of the following is true about polyploidy?

Accepted Answer

It involves extra complete sets of chromosomes

Question 17

A chromosome rearrangement in which a segment is reversed end to end is called:

Accepted Answer

Inversion

Question 18

Which of the following best describes allopolyploidy?

Accepted Answer

An organism with chromosome sets derived from different species

Question 19

Which of the following is a correct sequence of increasing resolution in chromosome mapping?

Accepted Answer

Genetic map → Cytogenetic map → Physical map → DNA sequence

Question 20

A child is diagnosed with Down syndrome due to mosaicism. Which of the following best describes this condition?

Accepted Answer

Only some cells have an extra chromosome 21

Genetics Exam II Study Guide: DNA as Genetic Material, Chromosome Structure, and Mapping

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