Radioactive $$^{32}\text{P} ($$phosphorus)

Question 1

Which of the following best describes the relationship between DNA, genes, chromosomes, and the genome?

Accepted Answer

Chromosomes are segments of DNA, genes are specific instructions within DNA, and the genome is all genetic material in an organism.

Question 2

Which experiment disproved the theory of spontaneous generation and established biogenesis?

Accepted Answer

Louis Pasteur's swan-neck flask experiment

Question 3

What is the main reason the blending theory of inheritance was rejected?

Accepted Answer

It was disproved by Mendel's experiments showing traits are particulate and can reappear in later generations.

Question 4

Which of the following is NOT a requirement for genetic material?

Accepted Answer

Permanent stability without mutation

Question 5

In the Hershey-Chase experiment, which radioactive label was found inside the bacteria, proving DNA is the genetic material?

Accepted Answer

Radioactive $$^{32}	ext{P} ($$phosphorus)

Question 6

Which of the following correctly matches the number of hydrogen bonds between base pairs in DNA?

Accepted Answer

Adenine–Thymine: 2, Guanine–Cytosine: 3

Question 7

Why are the bonds between base pairs in DNA weaker than the bonds attaching a base to deoxyribose?

Accepted Answer

Base pairs are connected by hydrogen bonds, which are weaker than the covalent (glycosidic) bonds attaching bases to deoxyribose.

Question 8

Which of the following is a purine?

Accepted Answer

Adenine

Question 9

If the DNA strand is 5'–A T G C C A–3', what is the complementary strand?

Accepted Answer

3'–T A C G G T–5'

Question 10

What does 'antiparallel' mean in the context of DNA structure?

Accepted Answer

One strand runs 5' to 3', while the other runs 3' to 5'.

Question 11

What happens to double-stranded DNA when it is heated above its melting temperature ($$T_m$$)?

Accepted Answer

The hydrogen bonds between base pairs break, separating the strands into single-stranded DNA.

Question 12

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 13

Why is a lagging strand needed during DNA replication?

Accepted Answer

Because DNA polymerase can only synthesize DNA in the 5'→3' direction, so the opposite strand must be copied in short fragments.

Question 14

What is the main goal of PCR (Polymerase Chain Reaction)?

Accepted Answer

To amplify a specific segment of DNA.

Question 15

Which step of PCR involves heating the reaction mixture to 94–98°C to separate DNA strands?

Accepted Answer

Denaturation

Question 16

Which of the following is a real-world application of bacterial plasmids in molecular genetics?

Accepted Answer

Gene cloning for production of human insulin in bacteria.

Question 17

Which of the following is NOT a difference between RNA and DNA?

Accepted Answer

RNA is double-stranded, DNA is single-stranded.

Question 18

If the DNA template strand is 3'-TACGGT-5', what is the mRNA sequence transcribed?

Accepted Answer

5'-AUGCCA-3'

Question 19

Which codon is the start codon in mRNA, and what amino acid does it code for?

Accepted Answer

AUG; Methionine

Question 20

Why is RNA thought to be the first form of genetic material that evolved on Earth?

Accepted Answer

RNA can both store genetic information and act as a catalyst, and is chemically simpler than DNA and proteins.

Genetics Study Guide: Foundations, DNA Structure, Replication, and Expression

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