Question 1

Which of the following changes to the lipid composition of a cell membrane would most likely increase its fluidity at lower temperatures?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in phospholipids

Question 2

Which property of mitochondria and chloroplasts best supports the endosymbiotic theory of their origin?

Accepted Answer

They contain their own circular DNA, similar to bacterial genomes

Question 3

A scientist observes that a certain organelle can grow and reproduce independently within a eukaryotic cell, but still relies on the cell for most of its proteins. Which organelle is most likely being described?

Accepted Answer

Mitochondrion

Question 4

Which of the following would NOT support the endosymbiotic origin of mitochondria and chloroplasts?

Accepted Answer

Mitochondria and chloroplasts acquire all of their proteins from the cytosol

Question 5

Which of the following best describes the arrangement of phospholipids in a biological membrane?

Accepted Answer

A bilayer with hydrophobic tails facing inward and hydrophilic heads facing outward

Question 6

Which of the following is a function of membrane proteins?

Accepted Answer

Transport of ions and molecules across the membrane

Question 7

A red blood cell is placed in a hypotonic solution. What will most likely happen to the cell?

Accepted Answer

It will swell and may burst due to water entering the cell by osmosis

Question 8

Which of the following processes requires energy input from ATP?

Accepted Answer

Pumping sodium ions from low to high concentration across the membrane

Question 9

Which statement best explains why cell membranes are described as 'fluid mosaics'?

Accepted Answer

They consist of a variety of proteins and lipids that can move laterally within the layer

Question 10

Which of the following would make a cell membrane more rigid at cold temperatures?

Accepted Answer

A high proportion of saturated phospholipids and cholesterol

Question 11

Which of the following best describes the role of glycosylation in cell membranes?

Accepted Answer

It provides markers for cell-cell recognition

Question 12

Which type of membrane protein is embedded within the lipid bilayer and often spans the entire membrane?

Accepted Answer

Integral (transmembrane) protein

Question 13

A plant cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell will lose water and the plasma membrane will pull away from the cell wall (plasmolysis)

Question 14

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules down their concentration gradient through a transport protein, without energy input

Question 15

Which of the following is an example of secondary active transport?

Accepted Answer

Using a proton gradient established by ATP hydrolysis to import sucrose into the cell

Question 16

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the movement of water across a selectively permeable membrane from low to high solute concentration

Question 17

Which of the following is NOT a function of proteins in the cell membrane?

Accepted Answer

Storage of genetic information

Question 18

Which of the following best describes the difference between primary and secondary active transport?

Accepted Answer

Primary active transport uses ATP directly, while secondary active transport uses an ion gradient established by primary active transport

Question 19

Which of the following processes is responsible for the uptake of large particles, such as bacteria, by a cell?

Accepted Answer

Phagocytosis

Question 20

A cell is actively transporting potassium ions into the cytoplasm against their concentration gradient. Which equation best represents the energy source for this process?

Accepted Answer

$$ \mathrm{ATP} ightarrow \mathrm{ADP} + \mathrm{P_i} + 	ext{energy} $$

Cell Membranes and Semiautonomous Organelles: Structure, Function, and Evolution

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