Q: Which property of homopolysaccharides like cellulose is MOST responsible for its structural role in plant cell walls?

Presence of $eta$-1,4-glycosidic bonds leading to straight, rigid chains

Q: Which equation correctly represents the calculation of free energy change ($ riangle G$) for membrane transport?

$\triangle G = RT \ln \left( \frac{[C]_\text{in}}{[C]_\text{out}} \right) + zF\triangle \Psi$

Question 1

Which of the following statements best describes the difference between Fischer and Haworth projections for carbohydrates?

Accepted Answer

Fischer projections depict the linear (open-chain) form of sugars, while Haworth projections represent the cyclic (ring) form.

Question 2

Which property of homopolysaccharides like cellulose is MOST responsible for its structural role in plant cell walls?

Accepted Answer

Presence of $eta$-1,4-glycosidic bonds leading to straight, rigid chains

Question 3

Which of the following is a key function of glycosaminoglycans in the extracellular matrix?

Accepted Answer

Providing structural support and mediating cell signaling

Question 4

What is the main reason why O-linked glycosylation is important for protein function?

Accepted Answer

It affects protein folding, stability, and cell-cell recognition.

Question 5

Which of the following best explains the specificity of the bacterial potassium channel for K$^+$ ions over Na$^+$ ions?

Accepted Answer

The channel's selectivity filter stabilizes K$^+$ ions via optimal coordination geometry, which does not fit Na$^+$ ions.

Question 6

Which of the following DNA sequences is palindromic?

Accepted Answer

5'-GAATTC-3'

Question 7

A DNA sample has a high melting temperature ($T_m$). Which of the following is the most likely explanation?

Accepted Answer

It contains a high proportion of guanine-cytosine base pairs.

Question 8

Which of the following statements correctly distinguishes RNA from DNA?

Accepted Answer

RNA contains uracil instead of thymine.

Question 9

Which of the following is a common feature of facilitated diffusion and active transport across membranes?

Accepted Answer

Both involve specific membrane proteins.

Question 10

Which equation correctly represents the calculation of free energy change ($	riangle G$) for membrane transport?

Accepted Answer

$	riangle G = RT \ln \left( \frac{[C]_	ext{in}}{[C]_	ext{out}} ight) + zF	riangle \Psi$

Question 11

Which of the following best describes the role of second messengers such as cAMP in signal transduction?

Accepted Answer

They amplify the signal initiated by a receptor-ligand interaction.

Question 12

Which of the following is TRUE regarding the Na$^+$/K$^+$ ATPase?

Accepted Answer

It establishes an electrical potential across the membrane by pumping 3 Na$^+$ out and 2 K$^+$ in per ATP hydrolyzed.

Question 13

Which of the following is a distinguishing feature of sphingolipids compared to glycerophospholipids?

Accepted Answer

Sphingolipids contain a sphingosine backbone, while glycerophospholipids contain a glycerol backbone.

Question 14

Which of the following is NOT a class of membrane-associated protein?

Accepted Answer

Cytosolic ribosomal protein

Question 15

A patient is diagnosed with a defect in a GPCR (G-protein coupled receptor) involved in the cAMP signaling pathway. Which of the following symptoms is most likely?

Accepted Answer

Impaired regulation of glucose metabolism

Question 16

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 the energy stored in ion gradients.

Question 17

Which of the following is a correct description of the amphipathic nature of phospholipids?

Accepted Answer

They have both hydrophilic and hydrophobic regions.

Question 18

Which of the following is a direct effect of increasing the degree of unsaturation in fatty acids within a membrane?

Accepted Answer

Membrane fluidity increases due to kinks in the fatty acid chains.

Question 19

Which of the following is the correct order of events in GPCR signal transduction?

Accepted Answer

Ligand binding → G-protein activation → Second messenger production → Cellular response

Biochemistry Study Guide: Carbohydrates, Nucleic Acids, Lipids, Membranes, and Biosignaling

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