Question 1

Which of the following structures is present in plant cells but absent in animal cells, and what is its primary function?

Accepted Answer

Chloroplast; conversion of light energy to chemical energy via photosynthesis

Question 2

A mutation in the DNA sequence from CTT to CAT in the beta-globin gene leads to which amino acid substitution in the hemoglobin protein, and what disease does this cause?

Accepted Answer

Glutamic acid to valine; sickle cell disease

Question 3

Which level of protein structure is directly altered by a single amino acid substitution, such as in sickle cell disease?

Accepted Answer

Primary structure

Question 4

The Nobel Prize in Chemistry 2024 was awarded for advances in which area of biology?

Accepted Answer

Protein structure prediction and computational protein design

Question 5

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A dynamic mixture of lipids, proteins, and carbohydrates

Question 6

What is the effect of cholesterol on membrane fluidity at moderate and low temperatures?

Accepted Answer

Reduces fluidity at moderate temperatures and prevents solidification at low temperatures

Question 7

Which of the following molecules will diffuse most rapidly through a pure phospholipid bilayer?

Accepted Answer

CO$$_2$$

Question 8

A desert lizard is likely to have which type of fatty acid composition in its cell membranes to maintain proper fluidity?

Accepted Answer

More saturated and longer fatty acid tails

Question 9

Which process requires energy input in the form of ATP to move molecules across the plasma membrane?

Accepted Answer

Active transport

Question 10

The sodium-potassium pump (Na$$^+/K$^+$$ ATPase) moves ions in which direction and in what ratio during each cycle?

Accepted Answer

3 Na$$^+$$ out, 2 K$$^+ in$$

Question 11

Which of the following best explains why individuals with sickle cell disease experience reduced oxygen transport?

Accepted Answer

Hemoglobin molecules aggregate, distorting red blood cell shape and reducing oxygen-carrying capacity

Question 12

Which of the following is a function of membrane proteins?

Accepted Answer

Signal transduction

Question 13

Which type of transport protein is responsible for the rapid movement of water across cell membranes?

Accepted Answer

Aquaporin

Question 14

A patient receives an intravenous (IV) solution of 0.9% NaCl. This solution is considered:

Accepted Answer

Isotonic to red blood cells

Question 15

Familial hypercholesterolemia is caused by a defect in which cellular process?

Accepted Answer

Receptor-mediated endocytosis of LDL

Question 16

Which of the following best describes osmosis?

Accepted Answer

Net movement of water toward higher solute concentration

Question 17

Which of the following is a real-world example of bulk transport in cells?

Accepted Answer

Release of insulin from pancreatic cells via exocytosis

Question 18

Which of the following statements about the amphipathic nature of phospholipids is correct?

Accepted Answer

They have both hydrophilic heads and hydrophobic tails

Question 19

Which of the following best explains why ions such as Na$$^+$$ and K$$^+$$ cannot easily cross the plasma membrane by simple diffusion?

Accepted Answer

They are charged and require protein channels to cross the hydrophobic core

Question 20

Which of the following best describes the role of the Golgi apparatus in the secretory pathway?

Accepted Answer

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

Membrane Structure and Function, Cell Structure, and Protein Organization

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