This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Cytoplasmic Membrane Systems – Lysosomes”.
1. The main function of lysosomes is ____________
Explanation: Lysosomes are digestive organelles of a cell and contains over 50 diverse types of hydrolases. These enzymes work at an acidic pH and can hydrolyze mostly all types of biomolecules.
2. Where is the proton pump located in a lysosome?
c) attached with enzymes
d) extracellularly connected
Explanation: The high internal concentration of the lysosomes is maintained by the H+-ATPase proton pump present in the organelle’s boundary membrane.
3. Kupffer cells are located in the _________
Explanation: Kupffer cells are phagocytic cells situated in the liver which are responsible for engulfing the aging red blood cells. The lysosomes of these cells have irregular shape and variable electron density.
4. Which of the following are phagocytic cells?
a) neutrophils, macrophages
b) neutrophils, mast cells
c) mast cells, macrophages
d) mast cells, antibodies
Explanation: Neutrophils and macrophages are the phagocytic cells that ingest potentially dangerous microbes; the microbes are then inactivated by the low pH of lysosomes present in these cells followed by their enzymatic digestion.
5. Destruction and replacement of cell’s own organelles is called ____________
Explanation: Organelle turnover, also called autophagy is the process of regulated destruction and replacement of the cell’s own organelles. This function is performed by the lysosomes.
6. In autophagy, the organelle’s to be ingested are covered by a ______________
a) protein coat
c) double membrane
d) single membrane
Explanation: In autophagy, the organelles of the cell are fused and subsequently ingested by the lysosomes. Prior to fusion a double membrane wraps up the organelle to be degraded, forming an autophagosome.
7. When a cell is in nutrient deprived state, autophagy increases.
Explanation: Worn-out organelles are digested by fusion with the lysosomes and the contents are made available to the cell. In a state of nutrient deprivation the occurrence of autophagy in a cell increases.
8. After the digestive process in an autophagolysosome is over, it is termed as _______________
b) residual body
Explanation: Autophagolysosome is the structure that forms by the fusion of lysosome with double-membrane wrapped organelle. After the digestive process is over this structure is called residual body which is then ready for exocytosis.
9. Lipofuscin granules decrease in number as individual grows older.
Explanation: The residual bodies formed after the digestion of organelles by lysosomes are either discharged from the cell by exocytosis or retained inside the cell, known as ‘lipofuschin granules’. These granules increase in numbers as an individual grows older.
10. In the ‘I-cell disease’, lysosomes are ___________
Explanation: In the cells of individuals affected by the ‘I-cell disease’, lysosomes are bloated due to undegraded materials. This is because the hydrolytic enzymes are not in proper conformation.
11. The enzyme N-acetylglucosamine phosphotransferase is responsible for ____________
a) mannose phosphorylation
b) sucrose phosphorylation
c) tethering Golgi stack
d) modification of integral proteins
Explanation: Mannose 6-phosphate residues are present on the lysosomal enzymes that direct these proteins to the lysosomes after their synthesis from Golgi complex. N-acetylglucosamine phosphotransferase adds the mannose residues on lysosomal enzymes.
12. Lysosomal storage disorders are caused due to ______________
a) absence of lysosomes
b) absence of a single lysosome
c) absence of integral membrane proteins
d) accumulation of lipofuschin granules
Explanation: Lysosomal storage disorders are caused due to the absence of a single lysosomal enzyme. For example, the ‘Pompe disease’ is caused by the absence of alpha-glucosidase.
13. Gaucher disease is caused due to deficiency of ______________
a) hexosaminidase A
d) mannose phophate
Explanation: Gaucher’s disease is caused by the deficiency of the lysosomal enzyme glucocerebrosidase. Due to this deficiency, large quantities of glucocerebroside accumulate in the lysosomes of macrophages.
Sanfoundry Global Education & Learning Series – Cell Biology.
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