Mitochondria are double-membraned organelles found in most eukaryotic cells. They generate energy in the form of ATP through cellular respiration, and have their own DNA. They play a crucial role in metabolism, calcium signaling, and programmed cell death, and are implicated in various diseases and aging processes. This MCQ on Mitochondria will help you to understand the structure and functions of mitochondria.
Cytology & Molecular Biology Notes | Cytology & Molecular Biology PPT
(1). Which of the following cell organelle can be viewed by a light microscope?
a. Ribosome
b. Endoplasmic Reticulum
c. Golgi
d. Mitochondria
(2). Which of the following statement about mitochondria is NOT true?
a. Size and shape of mitochondria varies in a cell
b. Mitochondria in the cell can fuse with one another
c. Large mitochondria in the call can split into two
d. In all cells, one mitochondria will be exceptionally larger than others
(3). Nebenkern of insect sperm cells is a modified _________.
a. Nucleus
b. Golgi apparatus
c. Mitochondria
d. Centrosome
(4). Mitochondria in the human sperm cell are occupied at _________.
a. Sperm head
b. Mid piece
c. Sperm tail
d. No mitochondria in the sperms
(5). Which of the following statement is true regarding the membrane system of mitochondria?
a. Chemical composition of both inner and outer membrane of mitochondria are same
b. Outer membrane contain more proteins/lipid ratio (by weight) than inner membrane
c. Inner membrane contain more proteins/lipid ratio (by weight) than outer membrane
d. Phospholipids are completely absent on the outer membrane of mitochondria
(6). Which of the following membrane lipid constituent can be considered as the lipid marker of inner mitochondrial membrane?
a. Lecithin
b. Cardiolipin
c. Ceramide
d. Sphingo-ceramide
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(7). The only other place where cardiolipin can be found naturally other than mitochondrial inner membrane is________.
a. Inner membrane of Golgi apparatus
b. Apoptosome
c. Bacterial plasma membrane
d. Membrane of glyoxysome
(8). Which of the following statement regarding the distribution of cholesterol is true in the membrane system of mitochondria?
a. Cholesterol is completely absent in mitochondrial membrane
b. Cholesterol is absent in the inner membrane
c. Cholesterol is present only in the inner membrane
d. Cholesterol is present in both inner and outer membrane
(9). Mitochondrial membrane system processes a variety of porin proteins which allow the passage of selective molecules. Which of the following statement is true regarding the porin protein in the mitochondrial membrane system?
a. Mitochondrial outer membrane possess porins but they lack the usual beta barrel structure of the usual porins
b. Both inner and outer mitochondrial membrane possess porin proteins
c. Only the inner mitochondrial membrane possess porin proteins
d. Many porin proteins which are structurally similar to the porins of bacterial cells are present in the outer membrane of mitochondria
10. ATP, NAD and CoA can be ___________.
a. Freely transported through both outer and inner membrane of mitochondria
b. Freely transported through the outer membrane of mitochondria
c. Freely transported through the inner membrane of mitochondria
d. Cannot be transported freely through outer and inner membrane of mitochondria
11. Cellular organelle(s) involved in the regulation of Ca2+ level in the cell ________.
a. Mitochondria
b. Endoplasmic Reticulum
c. Endoplasmic Reticulum and Mitochondria
d. Mitochondria and vesicles
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12. The only enzyme in citric acid cycle (Kreb’s cycle) which is attached to the inner mitochondrial membrane is:
a. Succinate dehydrogenase
b. NADPH dehydrogenase
c. Isocitrate dehydrogenase
d. Malate dehydrogenase
13. Which of the following can be used as an enzyme marker for inner mitochondrial membrane?
a. Succinate dehydrogenase
b. ATP synthase
c. Succinyl Co-A synthase
d. Cardiolipin
14. Which of the following is a mobile electron carrier in the mitochondrial electron transport system?
a. NADH dehydrogenase
b. FADH Dehydrogenase
c. Ubiquinone
d. Succinate dehydrogenase
15. Which of the following cellular event is NOT directly involved with mitochondria?
a. Apoptosis
b. ATP synthesis
c. Controlling cell cycle
d. Protein degradation
16. Which of the following statement is NOT true about mitochondria?
a. Hepatocytes have more than 2000 mitochondria per cell
b. RBC completely lack mitochondria
c. Sperm cells of Insects completely lack mitochondria
d. Mitochondrial number may change in each cell of a species
17. Example for autonomous organelle(s):
a. Mitochondria
b. Chloroplast
c. Mitochondria and chloroplast
d. Chloroplast, mitochondria and Golgi
18. Pick-out the odd one:
a. Kearns-Sayre syndrome
b. Tay-sach syndrome
c. MELAS syndrome
d. Leber’s hereditary optic neuropathy
19. Mitochondrial DNA (mtDNA) is considered as one of the best marker tool for population biologists and evolutionary biologists. The reason for this is:
a. Mitochondrial DNA undergo spontaneous mutation
b. Mitochondrial DNA can be easy isolated
c. Mitochondrial genes are specific to mtDNA
d. Absence of genetic recombination in mtDNA
20. Cyanide is a mitochondrial toxin. The mechanism of action of cyanide is by inhibiting:
a. NADH dehydrogenase
b. Succinate dehydrogenase
c. Cytochrome c oxidase
d. ATP synthase
Answer key, Explanations and References
1. Ans. (d). Mitochondria.
Mitochondria is a large cell organelle, Most probably the second largest cell organelle in the cells after nucleus in animal cells, and in plants probably the third largest cell after vacuole and nucleus. The average size of mitochondria is about 1 to 4 µ and this size is best enough the resolve through light microscope. (The maximum limit of resolution of light microscope is ~ 0.2µ)
For details, refer: Cell and Molecular Biology by Gerald Karp, Ed. 6, Chapter 5: Aerobic Respiration and Mitochondria, Page 174
2. Ans. (d). In all cells, one mitochondria will be exceptionally larger than others
This is a wrong statement, even though the size of mitochondria in a single cell varies, we cannot say that one is exceptionally larger than others
3. Ans. (c). Mitochondria
4. Ans. (b). Mid piece
Many spirally coiled mitochondria will be there in the mid-piece of sperm. They are situated around the basal region of flagella. The energy (ATP) produced by these mitochondria are used by the flagella for their beating.
5. Ans. (c). Inner membrane contain more proteins/lipid ratio (by weight) than outer membrane
The protein/lipid ratio of inner membrane of mitochondria is 3:1 by weight
6. Ans. (b). Cardiolipin
Cardiolipin is a diphosphatidylglycerol belongs to the class of glycerol-phospholipids. It is abundantly present in the inner mitochondrial membrane, where it contributes about 20% of the total lipid components. The only other place where cardiolipin can be found is the membrane of most bacterial cells. The presence of cardiolipin in the inner mitochondrial membrane is a strong evidence for the endosymbiot theory about the origin of mitochondria and chloroplasts in eukaryotes
For details: Mmembrane lipids: Properties, Structure and Classification
7. Ans. (c). Bacterial plasma membrane
For details, refer: Lehninger’s Principles of Biochemistry, Ed. 5, Chapter 10 – Lipids: Membrane lipids, page: 349-351
8. Ans. (b). Cholesterol is absent in the inner membrane of mitochondria
For details, refer: Cell and Molecular Biology by Gerald Karp, Ed. 6, Chapter 5: Aerobic Respiration and Mitochondria, Page 176
9. Ans. (d). Many porin proteins which are structurally similar to the porins of bacterial cells are present in the outer membrane of mitochondria
For details, refer: Cell and Molecular Biology by Gerald Karp, Ed. 6, Chapter 5: Aerobic Respiration and Mitochondria, Page 176
10. Ans. (b). Freely transported through the outer membrane of mitochondria
ATP, NAD and Co-A can be freely transported through the outer mitochondrial membrane through the porin protein channels with beta-barrel structures
11. Ans. (c). Endoplasmic Reticulum and Mitochondria
12. Ans. (a). Succinate dehydrogenase
13. Ans. (a). Succinate dehydrogenase
14. Ans. (c). Ubiquinone
Mitochondrial DNA (source wikipedia)
15. Ans. (d). Protein degradation
Main functions of mitochondria are energy conversion and energy production by electron transport system, citric acid cycle, heat production and storage of calcium ions. Apart from these main functions, mitochondria are also involved in cellular process like regulation of membrane potential, induction of apoptosis, regulation of cellular metabolism, synthesis of heme (porphyrin), and synthesis of some steroids.
16. Ans. (c). Sperm cell of insects completely lack mitochondria
17. Ans. (c). Mitochondria and Chloroplast
18. Ans. (b). Tay-sach syndrome
Kearns-Sayre syndrome, MELAS syndrome and Leber’s hereditary optic neuropathy are the metabolic disorders associated with the dysfunction of mitochondria in the cell.
Tay-sach syndrome is an autosomal genetic disorder due to the defect in membrane lipids turnover in the cell.
19. Ans. (d). Absence of genetic recombination in mtDNA
20. Ans. (c). Cytochrome c oxidase
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