Question 1

Which of the following best explains why humans can digest starch but not cellulose, even though both are polymers of glucose?

Accepted Answer

Starch contains $$\alpha-$$glycosidic linkages, which human enzymes can hydrolyze, while cellulose contains $$\beta-$$glycosidic linkages, which human enzymes cannot break.

Question 2

A mutation causes a eukaryotic cell to produce histones that cannot be acetylated. What is the most likely effect on gene expression?

Accepted Answer

Gene expression will decrease because chromatin will remain more condensed, limiting access to transcription machinery.

Question 3

During cellular respiration, what is the primary role of oxygen?

Accepted Answer

It acts as the final electron acceptor in the electron transport chain, forming water.

Question 4

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It uses ATP to move 3 Na$$^+$$ ions out of the cell and 2 K$$^+$$ ions into the cell, both against their concentration gradients.

Question 5

A researcher uses PCR to amplify a gene from a bacterial sample. Which sequence of steps correctly describes the PCR cycle?

Accepted Answer

Denaturation $$\rightarrow$$ Annealing $$\rightarrow$$ Extension

Question 6

Which of the following best describes the function of microRNAs (miRNAs) in eukaryotic cells?

Accepted Answer

They bind to complementary mRNA sequences to degrade the mRNA or block its translation.

Question 7

A patient is exposed to cyanide, which inhibits cytochrome c oxidase in mitochondria. What is the immediate effect on cellular respiration?

Accepted Answer

Electron transport halts, preventing ATP synthesis by oxidative phosphorylation.

Question 8

Which of the following is a direct result of alternative RNA splicing in eukaryotes?

Accepted Answer

A single gene can produce multiple protein isoforms.

Question 9

In the lac operon, what is the role of allolactose?

Accepted Answer

It acts as an inducer by binding to the repressor, inactivating it and allowing transcription.

Question 10

A cell is placed in a hypertonic solution. What will happen to an animal cell and a plant cell, respectively?

Accepted Answer

The animal cell will shrivel; the plant cell will undergo plasmolysis.

Question 11

Which enzyme is responsible for relieving the torsional strain ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

Question 12

Which of the following best describes the difference between euchromatin and heterochromatin?

Accepted Answer

Euchromatin is loosely packed and transcriptionally active, while heterochromatin is densely packed and transcriptionally inactive.

Question 13

Which of the following is a function of the Golgi apparatus in eukaryotic cells?

Accepted Answer

It modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Question 14

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 15

Which of the following statements about the Calvin cycle is correct?

Accepted Answer

It uses ATP and NADPH to reduce CO$$_2 to G3P$$, a 3-carbon sugar.

Question 16

Which process is responsible for the movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration?

Accepted Answer

Osmosis

Question 17

Which of the following is a direct consequence of a frameshift mutation?

Accepted Answer

The reading frame of the mRNA is altered, potentially changing every amino acid downstream of the mutation.

Question 18

Which of the following best describes the role of Rubisco in photosynthesis?

Accepted Answer

It catalyzes the fixation of CO$$_2 to $$RuBP in the Calvin cycle.

Question 19

Which of the following is true regarding the semi-conservative model of DNA replication?

Accepted Answer

Each daughter DNA molecule consists of one parental strand and one newly synthesized strand.

BIO510 Integrative Biology I: Genetics and Molecular Biology Study Guide

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