Question

The Golgi apparatus is primarily involved in

Select one:

a. Protein sorting/routing

b. Lysosome reabsorption

c. Protein catabolism

d. Protein synthesis

e. mRNA processing

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Which of the following would make a plasma membrane more fluid at room temperature?

Select one:

a. All of these factors would increase plasma membrane fluidity at room temperature

b. Saturation of fatty acyl chains

c. Presence of double bonds in the fatty acyl chains

d. Presence of cholesterol

e. Long of fatty acyl chains

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You would expect the cell membranes of an animal that lives in a very cold climate to have a higher proportion of

Select one:

a. Approximately equal amounts of saturated and unsaturated phospholipids

b. Mostly saturated phospholipids

c. Mostly unsaturated phospholipids

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In lungs, O2 moves freely across the cell membrane of alveoli, down its concentration gradient, and without the requirement of any carrier protein or any input of external energy. This is an example of

Select one:

a. Passive diffusion

b. Facilitated diffusion

c. Osmosis

d. Cotransport

e. Active transport

Answer 1

Q1

a. Protein sorting/routing

Explanation: It is the process of the transport of the protein to either outside the cell or in the targeted cell organelles. Following figure indicates role of the golgi complex in protein sorting.

Explanation for wrong answers

b. Lysosome reabsorption: it is the part of protein sorting process. However, golgi complex do not have any direct role.

c. Protein catabolism: it takes place in cytoplasm and golgi complex is the site for the post translations modifications.

d. Protein synthesis: it also take place in cytoplasm. No role of golgi complex in protein synthesis.

e. mRNA processing: It is also take place in cytoplasm and DNA and RNA will not enters in the golgi complex.

Q2

c. Presence of double bonds in the fatty acyl chains

Explanation: Presence of double bond will leads to unsaturated fatty acids. This double bond gives kink and creat problem in the packing of the fatty acyl chain and hence increase the fluidity of the membrane.

Explanation for wrong answers

a. All of these factors would increase plasma membrane fluidity at room temperature

Explanation: presence of long fatty acid and saturated fatty acid will not provide fluidity to the membrane.

b. Saturation of fatty acyl chains

Explanation: Saturated fatty acid chain will allow packing and decreases fluidity of the membrane.

d. Presence of cholesterol: It will increase the fluidity marginally at room temperature. but unsaturated fatty acids has more contributions in fluidity than the cholesterol.

e. Long of fatty acyl chains: it will decrease the fluidity by allowing packing by hydrophobic interaction of acyl chains.

Q3

c. Mostly unsaturated phospholipids

Explanation: To maintain the fluidity of the membrane in cold temperature. The unsaturated fatty acid concentration increases.

Explanation for the wrong answers.

a. Approximately equal amounts of saturated and unsaturated phospholipids

Explanation: There is no logic in having equal amount of both types of fatty acids.

b. Mostly saturated phospholipids

Explanation: If they will increase saturated fatty acids, then membrane fluidity will be decreases therefore cell functions may get affected.

Q4

a. Passive diffusion

Explanation: Movement along the concentration gradient and without requirement of energy and carrier protein is called as passive diffusion.

Explanation for wrong answers

b. Facilitated diffusion: it requires carrier protein to mediate transport along concentration gradient.

c. Osmosis: it involves the movement of solvents molecules from lower concentration to higher concentration along the semipermeable membrane.

d. Cotransport: It involves the movement of molecule along the concentration growth stimulates the movement of other molecule against the concentration gradient.

e. Active transport: It requires the energy for the transport and takes place from lower concentration to higher concentration.