Question 1

Which of the following best describes the difference between mitosis and meiosis in terms of genetic variation?

Accepted Answer

Meiosis increases genetic variation through independent assortment and crossing over, while mitosis produces genetically identical cells.

Question 2

A cell is observed to have chromosomes aligned at the center of the cell, attached to spindle fibers. Which phase of mitosis is this cell in?

Accepted Answer

Metaphase

Question 3

Which of the following equations correctly represents the number of possible chromosome combinations due to independent assortment in a diploid organism with $$n$$ chromosome pairs?

Accepted Answer

$$2^n$$

Question 4

A patient is diagnosed with Trisomy 21. Which event during meiosis most likely led to this condition?

Accepted Answer

Nondisjunction during anaphase I or II

Question 5

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

Information flows from DNA to RNA to protein.

Question 6

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 7

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA} ($$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 8

Which of the following best explains why the lac operon is not expressed when glucose is present, even if lactose is also available?

Accepted Answer

Glucose prevents CAP from binding to the promoter, reducing transcription of the lac operon.

Question 9

Which of the following is a key difference between gene regulation in bacteria and eukaryotes?

Accepted Answer

Bacteria use operons to regulate groups of genes, while eukaryotes typically regulate genes individually.

Question 10

A researcher finds that a eukaryotic gene is not expressed because its promoter region is heavily methylated. What is the most likely explanation?

Accepted Answer

DNA methylation condenses chromatin, preventing transcription factors from binding.

Question 11

Which of the following best describes the function of the p53 protein in the cell cycle?

Accepted Answer

It is a tumor suppressor that can halt the cell cycle in response to DNA damage.

Question 12

Which of the following is true about alternative splicing in eukaryotes?

Accepted Answer

It allows a single gene to code for multiple proteins by including or excluding different exons.

Question 13

A cell with a mutation in the gene encoding telomerase is likely to experience which of the following?

Accepted Answer

Progressive shortening of chromosome ends with each cell division.

Question 14

Which of the following best explains why a frameshift mutation is often more deleterious than a point mutation?

Accepted Answer

A frameshift mutation changes the reading frame, potentially altering every amino acid downstream.

Question 15

Which of the following equations correctly represents the relationship between genotype and phenotype according to Mendel's principles?

Accepted Answer

$$	ext{Genotype} + 	ext{Environment} ightarrow 	ext{Phenotype}$$

Question 16

In a testcross between a plant with genotype $$Rr ($$round seeds) and a plant with genotype $$rr ($$wrinkled seeds), what is the expected phenotypic ratio of the offspring?

Accepted Answer

1 round : 1 wrinkled

Question 17

Which of the following best describes the role of cyclin-dependent kinases (Cdks) in the cell cycle?

Accepted Answer

They phosphorylate target proteins to regulate progression through the cell cycle.

Question 18

Which of the following is a real-world example of post-translational control of gene expression?

Accepted Answer

Phosphorylation of the p53 protein in response to DNA damage.

Question 19

A scientist discovers a mutation that prevents the formation of the TATA box in a eukaryotic gene. What is the most likely consequence?

Accepted Answer

Transcription initiation will be impaired because the core promoter cannot bind transcription factors.

Cell Cycle, Meiosis, Mendelian Genetics, DNA Replication, Gene Expression, and Regulation: Comprehensive Study Guide

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