Question 1

Which of the following best explains why DNA moves toward the positive electrode during gel electrophoresis?

Accepted Answer

DNA is negatively charged due to its phosphate backbone.

Question 2

A DNA fingerprinting experiment uses PCR to amplify STR regions. Why is PCR preferred over RFLP analysis in modern forensic labs?

Accepted Answer

PCR can amplify small or degraded DNA samples, making it more versatile.

Question 3

If you ran your DNA gel for 5 hours instead of 30 minutes, what would most likely happen to the DNA bands?

Accepted Answer

The DNA bands would run off the end of the gel and be lost.

Question 4

Why is it important to use a new pipette tip for each DNA sample when loading a gel?

Accepted Answer

To avoid cross-contamination between samples.

Question 5

In a PCR-based DNA fingerprinting experiment, you observe bands at 1568 bp and 825 bp in both the crime scene and Suspect 2 lanes. What does this suggest?

Accepted Answer

Suspect 2's DNA matches the crime scene DNA at these loci.

Question 6

Why do different individuals have different patterns of DNA fragments after restriction enzyme digestion (RFLP analysis)?

Accepted Answer

Individuals have different DNA sequences, resulting in different distances between restriction sites.

Question 7

Which of the following best describes a short tandem repeat (STR)?

Accepted Answer

A region of DNA where a short sequence is repeated multiple times.

Question 8

A student loads DNA samples into the wells at the top of the gel and connects the black lead to the end with the wells. What is the significance of this setup?

Accepted Answer

DNA will migrate toward the positive (red) electrode, away from the wells.

Question 9

Which of the following is NOT a use of DNA fingerprinting?

Accepted Answer

Diagnosing bacterial infections.

Question 10

What are the three parts of a nucleotide?

Accepted Answer

A phosphate group, a deoxyribose sugar, and a nitrogenous base.

Question 11

In a cross between two fruit flies with genotype Bb x Bb (B = brown, b = black, brown is dominant), what is the expected phenotype ratio?

Accepted Answer

$$3:1$$

Question 12

A horse with genotype AA (smooth mane) is crossed with a horse with genotype Aa (smooth mane). What percent of their offspring will have a smooth mane?

Accepted Answer

$$100\%$$

Question 13

In a flower, red (R) is incompletely dominant to white (r). If a pink flower (Rr) is crossed with a white flower (rr), what is the expected phenotype ratio?

Accepted Answer

$$1$$ pink $$: 1$$ white

Question 14

In chickens, black feathers (X) and white feathers (W) are codominant. If a black-feathered chicken (XX) is crossed with a black-and-white-feathered chicken (XW), what percent of offspring will have both black and white feathers?

Accepted Answer

$$50\%$$

Question 15

A man with mid-digital hair (M, dominant) marries a woman without mid-digital hair (mm). The man's father does not have mid-digital hair. What is the probability their child will have mid-digital hair?

Accepted Answer

$$50\%$$

Question 16

Cystic fibrosis is a recessive trait. Roger has cystic fibrosis (ff) and Samantha is a carrier (Ff). What is the probability their child will have cystic fibrosis?

Accepted Answer

$$50\%$$

Question 17

Why is it necessary to compare multiple bands (loci) in DNA fingerprinting?

Accepted Answer

To increase the probability of a unique match and reduce the chance of coincidental similarity.

Question 18

Which of the following best describes the role of agarose in gel electrophoresis?

Accepted Answer

It acts as a molecular sieve, allowing smaller DNA fragments to move faster than larger ones.

Question 19

If you used the same pipette tip for all DNA samples when loading a gel, what would be the most likely result?

Accepted Answer

Cross-contamination would occur, making it difficult to distinguish between samples.

Question 20

A student is analyzing a DNA ladder with bands at 6751, 3652, 2827, 1568, 1118, 825, and 630 base pairs. If a suspect's DNA band matches the 1568 bp band from the crime scene, what does this indicate?

Accepted Answer

The suspect's DNA contains a fragment of the same size as the crime scene DNA at that locus.

DNA Fingerprinting and Genetics: Laboratory Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards