Question 1

Which of the following best explains why DNA moves through the gel 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 gel electrophoresis for 5 hours instead of 30 minutes, what would most likely happen to your 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 prevent contamination between samples, which could mix DNA and produce misleading results.

Question 5

In a DNA fingerprinting experiment, why do different individuals have different banding patterns?

Accepted Answer

Each person has a unique sequence of STRs or RFLPs, resulting in different fragment sizes after digestion or amplification.

Question 6

Why is it necessary to compare multiple bands (loci) in DNA fingerprinting rather than just one?

Accepted Answer

Multiple bands increase the probability of a unique match, reducing the chance of two unrelated individuals sharing the same profile.

Question 7

Which of the following is NOT a component of a nucleotide?

Accepted Answer

A carboxyl group

Question 8

A flower with genotype $$Rr ($$pink, due to incomplete dominance) is crossed with a white flower ($$rr). $$What is the expected phenotype ratio in the offspring?

Accepted Answer

1 pink : 1 white

Question 9

In chickens, feather color is 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 10

A man with genotype $$Bb ($$brown body, fruit fly) is crossed with a woman of the same genotype. What is the expected genotype ratio in their offspring?

Accepted Answer

$$1\ BB : 2\ Bb : 1\ bb$$

Question 11

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

Accepted Answer

$$50\%$$

Question 12

In a PCR-based DNA fingerprinting experiment, you observe a band at approximately 1118 base pairs in both the crime scene sample and Suspect 2. What does this suggest?

Accepted Answer

Suspect 2 may have contributed DNA to the crime scene.

Question 13

If you use the same pipette tip for all DNA samples when loading a gel, what is the most likely consequence?

Accepted Answer

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

Question 14

A child is born to Bob (who has mid-digital hair, but his father does not) and Linda (who does not have mid-digital hair). What is the probability their child will have mid-digital hair? (Assume M is dominant, m is recessive.)

Accepted Answer

$$50\%$$

Question 15

Which of the following best describes the difference between STRs and RFLPs in DNA fingerprinting?

Accepted Answer

STRs are short repeated sequences amplified by PCR, while RFLPs are fragment length differences detected after restriction enzyme digestion.

Question 16

If a DNA fragment is 3652 base pairs long, where would you expect to find it on the gel compared to a 1118 base pair fragment?

Accepted Answer

Closer to the well, because larger fragments move more slowly.

Question 17

Which of the following is a correct comparison between DNA and RNA structure?

Accepted Answer

DNA contains deoxyribose sugar, while RNA contains ribose sugar.

Question 18

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

Accepted Answer

$$100\%$$

Question 19

Why is a DNA ladder used in gel electrophoresis?

Accepted Answer

To provide reference bands of known sizes for estimating the size of sample DNA fragments.

Question 20

A child inherits one allele for Huntington’s disease (dominant, Hh) and two alleles for cystic fibrosis (recessive, ff). What is the probability of this occurring if one parent is HhFf and the other is hhff?

Accepted Answer

$$25\%$$

DNA Fingerprinting and Genetics: Laboratory Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards