Engineering Questions with Answers - Multiple Choice Questions

MCQs on Cytoplasmic Membrane Systems – Endocytosis

1 - Question

Endocytosis and phagocytosis refer to the same process.
a) True
b) False

View Answer

Answer: b
Explanation: Endocytosis is the process where the cell engulfs cell surface receptors bound with ligands; whereas phagocytosis is the process where the cell uptakes particulate matter.




2 - Question

Which of the following is a type of endocytosis?
a) Pinocytosis
b) Phagocytosis
c) Hemolysis
d) Cytogenesis

View Answer

Answer: a
Explanation: Pinocytosis, also called bulk–phase endocytosis is the non–specific uptake of extracellular material. This process also removes portions of the plasma membrane and function in membrane recycling.




3 - Question

The process in which cell uptakes extracellular material bound to cell surface receptors is known as __________________
a) phagocytosis
b) pinocytosis
c) receptor–mediated endocytosis
d) bulk–phase endocytosis

View Answer

Answer: c
Explanation: The specific uptake of extracellular materials in which they are bound to external surface of the plasma membrane, is known as receptor–mediated endocytosis.




4 - Question

Receptor–mediated endocytosis (RME) leads to the formation of ___________ coated pits.
a) clathrin
b) lipid
c) lysosome
d) mannose

View Answer

Answer: a
Explanation: Substances bound to receptors enter a cell by receptor–mediated endocytosis and collect in specialized domains of the plasma membrane called the ‘coated pits’. Clathrin is present on the electron–dense coat of these pits.




5 - Question

A molecule of clathrin has a ______________ structure.
a) triskelion
b) spherical
c) cylindrical
d) polygonal

View Answer

Answer: a
Explanation: A molecule of clathrin has three heavy and three light chains joined at the center, forming a three–legged structure called triskelion.




6 - Question

Which adaptor molecule operate in clathrin–mediated endocytosis?
a) GGA
b) AP1
c) AP2
d) Sar1

View Answer

Answer: c
Explanation: AP2 adaptor molecules are associated with clathrin coated pits formed in the plasma membranes as a result of receptor–mediated endocytosis.




7 - Question

Dynamin is a _____________________
a) adaptor molecule
b) accessory protein
c) integral membrane protein
d) phospholipids

View Answer

Answer: b
Explanation: Dynamin is a large GTP–binding accessory protein that aids in the release of clathrin–coated vesicle from the membrane on which it is formed.




8 - Question

. Receptor down regulation leads to a decrease in the sensitivity of the cell towards further stimulation.
a) True
b) False

View Answer

Answer: a
Explanation: There are two different types of receptors involved in the endocytosis. The endocytosis mediated by the second group of receptors leads to their destruction, called the receptor down regulation. This decreases the sensitivity of the cell towards further stimulation.




9 - Question

Following internalization, vesicle–bound materials are transported to _________________
a) nucleus
b) peroxisomes
c) lysosomes
d) endosomes

View Answer

Answer: d
Explanation: Following the internalization of materials from the extracellular environment to the intracellular environment, the vesicle bound materials are transported to endosomes.




10 - Question

Late endosomes are located near the _____________
a) membrane
b) nucleus
c) mitochondria
d) peroxisomes

View Answer

Answer: b
Explanation: The complex network of tubules and vesicles is collectively known as endosomes. There are two classes of endosomes: early endosomes, located near the cell periphery, and late endosomes, located near the nucleus.




11 - Question

Transformation from an early to a late endosome is characterized by a decrease in ______________
a) mobility
b) lipid content
c) pH
d) protein content

View Answer

Answer: c
Explanation: Transformation from an early endosome to a late endosome is characterized by a decrease in the pH and a major change in the internal morphology of the structure.




12 - Question

Receptors dissociate from their bound ligands as a result of ________________
a) high H+ concentration
b) low H+ concentration
c) high Cl– concentration
d) low Cl– concentration

View Answer

Answer: a
Explanation: The receptors dissociate from their bound ligands as a result of high H+ concentration in the early endosomes. Following which they are concentrated into specialized tubular compartments representing the recycling centers of endosomes.




13 - Question

Where do the materials ingested by endocytosis, reach after travelling through the late endosome?
a) nucleus
b) lysosome
c) mitochondria
d) early endosome

View Answer

Answer: b
Explanation: After endocytosis materials reach the late endosome, where the bound ligands are concentrated. After late endosome the materials reach lysosome for further processing.




14 - Question

‘Niemann–Pick type C disease’ is caused due to deficiency of a specific ________________
a) protein
b) receptor
c) ligand
d) gene

View Answer

Answer: a
Explanation: ‘Niemann–Pick type C disease’ is an inherited disorder in which a protein required to transfer cholesterol out of the lysosomes is lacking. Consequently, cholesterol is accumulated in these organelles leading to nerve degeneration.




15 - Question

Mycobacterium tuberculosis inhibits the fusion of its phagosome with _________________ following phagocytosis.
a) membrane
b) lysosome
c) endosome
d) chromosome

View Answer

Answer: b
Explanation: Mycobacterium tuberculosis is the agent responsible for tuberculosis. Following its phagocytosis, the bacterium inhibits the fusion of phagosome with the lysosome, preventing its deactivation in the cell.

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