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

$$\text{Adenine (A)}$$ and $$\text{Thymine (T)}$$ form 2 hydrogen bonds; $$\text{Guanine (G)}$$ and $$\text{Cytosine (C)}$$ form 3 hydrogen bonds.

Question 1

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

Accepted Answer

A gene is a segment of DNA; chromosomes are structures made of DNA and proteins that contain many genes; the genome is the complete set of DNA in an organism.

Question 2

Which of the following statements about the historical understanding of genetics is INCORRECT?

Accepted Answer

Mendel's laws of inheritance are no longer considered valid in modern genetics.

Question 3

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

Accepted Answer

It must be composed entirely of proteins.

Question 4

In the classic Hershey-Chase experiment, how did scientists demonstrate that DNA, and not protein, is the genetic material?

Accepted Answer

They used radioactive phosphorus to label DNA and radioactive sulfur to label protein, and found that only the radioactive phosphorus entered bacterial cells.

Question 5

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

Accepted Answer

$$	ext{Adenine (A)}$$ and $$	ext{Thymine (T)}$$ form 2 hydrogen bonds; $$	ext{Guanine (G)}$$ and $$	ext{Cytosine (C)}$$ form 3 hydrogen bonds.

Question 6

Which of the following best explains why the bonds between DNA base pairs are weaker than the bonds attaching a base to deoxyribose?

Accepted Answer

Hydrogen bonds between base pairs are weaker than the covalent bonds between the base and deoxyribose.

Question 7

If a DNA strand has the sequence 5'-ATGCCGTA-3', what is the complementary sequence, including the correct 5' and 3' ends?

Accepted Answer

3'-TACGGCAT-5'

Question 8

What would most likely happen to double-stranded DNA if it is heated above its melting temperature ($$T_m$$)?

Accepted Answer

The two strands would separate due to the breaking of hydrogen bonds.

Question 9

During DNA replication, why is a lagging strand necessary?

Accepted Answer

DNA polymerase can only synthesize DNA in the 5' to 3' direction, so the lagging strand is synthesized discontinuously.

Question 10

Which of the following best describes the role of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand by forming phosphodiester bonds.

Question 11

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

Accepted Answer

Producing human insulin in bacteria for diabetes treatment.

Question 12

Which of the following statements about PCR (Polymerase Chain Reaction) is correct?

Accepted Answer

PCR amplifies a specific DNA sequence through repeated cycles of denaturation, annealing, and extension.

Question 13

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

Accepted Answer

RNA is more stable than DNA under cellular conditions.

Question 14

Given the DNA template strand 3'-TACGGTACG-5', what is the mRNA sequence transcribed from it?

Accepted Answer

5'-AUGCCAUGC-3'

Question 15

If the mRNA codon is 5'-AUG-3', what is the anticodon sequence on the tRNA?

Accepted Answer

3'-UAC-5'

Question 16

Which of the following is the correct order of the main steps in protein translation?

Accepted Answer

Initiation, elongation, termination

Question 17

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 catalyze chemical reactions.

Question 18

A patient is suspected to have a chromosomal abnormality. Which technique would most likely be used to visualize specific DNA sequences on their chromosomes in a clinical setting?

Accepted Answer

Fluorescence in situ hybridization (FISH)

Question 19

Which of the following is a use of information obtained from a DNA sequencing service?

Accepted Answer

Identifying genetic predispositions to diseases

Question 20

Which of the following best defines 'antiparallel' as it relates to DNA structure?

Accepted Answer

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

Step-by-Step Genetics Study Guide: Exam 1 Preparation

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