Question 1

Which of the following best describes the main structural feature that allows phospholipids to form bilayers in cell membranes?

Accepted Answer

They have a hydrophilic head and two hydrophobic tails, causing them to arrange into bilayers in aqueous environments.

Question 2

A red blood cell is placed in a solution and swells until it bursts. Which term best describes the solution, and why does this occur?

Accepted Answer

The solution is hypotonic; water enters the cell because the solute concentration is lower outside than inside.

Question 3

Which of the following statements about passive and active transport across membranes is correct?

Accepted Answer

Passive transport moves molecules down their concentration gradient without energy input, while active transport requires energy to move molecules against their gradient.

Question 4

Which factor would most likely increase the permeability of a cell membrane to small, nonpolar molecules?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in the membrane.

Question 5

A scientist observes a cell with a nucleus, mitochondria, and endoplasmic reticulum. Which type of cell is this, and what is a key difference from prokaryotic cells?

Accepted Answer

It is a eukaryotic cell; eukaryotes have membrane-bound organelles, unlike prokaryotes.

Question 6

According to the endosymbiotic theory, which organelle is believed to have originated from a free-living prokaryote, and what evidence supports this?

Accepted Answer

The mitochondrion; it has a double membrane and its own circular DNA.

Question 7

Which cytoskeletal component is primarily responsible for muscle contraction and cell movement, and what is its main protein subunit?

Accepted Answer

Microfilaments; actin.

Question 8

A protein is synthesized in the rough endoplasmic reticulum (ER) and must be delivered to the lysosome. Which sequence of organelles does it most likely pass through?

Accepted Answer

Rough ER → Golgi apparatus → lysosome

Question 9

Which of the following best describes how lipid-soluble hormones typically signal target cells?

Accepted Answer

They diffuse through the plasma membrane and bind to intracellular receptors, often affecting gene expression.

Question 10

Which of the following is a major component of the animal extracellular matrix and its primary function?

Accepted Answer

Collagen; provides structural support and strength.

Question 11

Gap junctions in animal cells and plasmodesmata in plant cells serve similar functions. What is their primary role?

Accepted Answer

They allow direct cytoplasmic exchange of ions and small molecules between adjacent cells.

Question 12

Which of the following best explains selective permeability of the plasma membrane?

Accepted Answer

The membrane allows some substances to cross more easily than others due to its lipid and protein composition.

Question 13

A cell is placed in a hypertonic solution. What will most likely happen to the cell, and why?

Accepted Answer

The cell will shrink because water leaves due to higher solute concentration outside.

Question 14

Which of the following is NOT a function of the Golgi apparatus in eukaryotic cells?

Accepted Answer

Synthesizing ATP for cellular energy.

Question 15

Which of the following best describes how a signal transduction pathway involving a G protein-coupled receptor (GPCR) is typically activated?

Accepted Answer

A ligand binds to the GPCR, which activates a G protein by exchanging GDP for GTP, leading to downstream signaling.

Question 16

Which organelle is primarily responsible for detoxifying harmful substances and synthesizing lipids in eukaryotic cells?

Accepted Answer

Smooth endoplasmic reticulum

Question 17

A mutation prevents the addition of signal sequences to proteins destined for the nucleus. What is the most likely consequence?

Accepted Answer

Proteins will accumulate in the cytosol and fail to enter the nucleus.

Question 18

Which of the following best describes the role of microtubules in eukaryotic cells?

Accepted Answer

They are involved in chromosome separation during cell division and serve as tracks for vesicle movement.

Question 19

Which of the following is a key difference between plant and animal extracellular matrices?

Accepted Answer

Plant ECM is primarily composed of cellulose, while animal ECM is rich in collagen.

Question 20

A cell needs to import glucose against its concentration gradient. Which process will it most likely use, and what is required?

Accepted Answer

Active transport; requires a carrier protein and ATP.

Unit 2 - Cells: Lipids, Membranes, Cell Structure, and Communication

Study Guide - Practice Questions

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