Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

Information flows from DNA to RNA to protein.

Question 2

During meiosis I, homologous chromosomes are separated. Which event contributes most directly to genetic variation during this process?

Accepted Answer

Crossing over (recombination) between homologous chromosomes.

Question 3

A geneticist is studying a pedigree where a trait appears in every generation and affects both males and females equally. Which inheritance pattern is most likely?

Accepted Answer

Autosomal dominant

Question 4

If a heterozygous individual ($$Aa) is $$crossed with a homozygous recessive individual ($$aa$$), what is the probability that their offspring will be heterozygous?

Accepted Answer

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

Question 5

Which mechanism ensures that males and females have similar levels of gene expression from the X chromosome in humans?

Accepted Answer

X-inactivation (dosage compensation)

Question 6

In Griffith's transformation experiment, what was the key finding regarding the nature of hereditary material?

Accepted Answer

A substance from dead virulent bacteria could transform live non-virulent bacteria into virulent ones.

Question 7

The Hershey-Chase blender experiment demonstrated that:

Accepted Answer

DNA, not protein, is the genetic material in bacteriophages.

Question 8

According to Chargaff’s rules, if a DNA sample contains 30% adenine, what percentage of guanine would you expect?

Accepted Answer

20%

Question 9

Which of the following best describes the antiparallel nature of DNA?

Accepted Answer

The two strands run in opposite directions: one 5' to 3', the other 3' to 5'.

Question 10

A DNA strand has the sequence 5'-ATCGGTA-3'. What is the complementary sequence?

Accepted Answer

3'-TAGCCAT-5'

Question 11

Which chemical bond links nucleotides together in a DNA strand?

Accepted Answer

Phosphodiester bond

Question 12

Which feature distinguishes RNA from DNA?

Accepted Answer

RNA contains uracil instead of thymine.

Question 13

Which of the following is a key feature of the Watson-Crick model for DNA structure?

Accepted Answer

Double helix with complementary base pairing

Question 14

A geneticist wants to determine the mode of inheritance for a trait using a pedigree. Which observation would suggest X-linked recessive inheritance?

Accepted Answer

Trait appears more frequently in males and is often passed from carrier mothers to sons.

Question 15

Which of the following best describes the packaging of eukaryotic chromatin from naked DNA to metaphase chromosome?

Accepted Answer

DNA wraps around histones to form nucleosomes, which coil to form chromatin fibers, further condensed into metaphase chromosomes.

Question 16

Which region of a eukaryotic chromosome is typically transcriptionally inactive and highly condensed?

Accepted Answer

Heterochromatin

Question 17

Which of the following is a typical feature of bacterial chromosomes?

Accepted Answer

Circular DNA molecule with few associated proteins

Question 18

A geneticist performs a dihybrid cross ($$AaBb 	imes AaBb). $$What is the expected phenotypic ratio in the offspring, assuming independent assortment?

Accepted Answer

$$9:3:3:1$$

Question 19

Which experiment provided evidence that DNA is the hereditary material by showing that only DNA, not protein or RNA, could transform bacteria?

Accepted Answer

Avery, MacLeod, and McCarty’s bacterial transformation experiment

Question 20

Which component is NOT part of a nucleosome?

Accepted Answer

RNA polymerase

Genetics Unit 1 Study Guide: Key Concepts and Applications

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