Mitochondria

1. Mitochondria are known as: (BPSC 66th Prelims)
   a) Brain of the cell
   b) Powerhouse of the cell
   c) Guard of the cell
   d) Skeleton of the cell
   Answer: b
   Explanation: Mitochondria are called the "powerhouse" of the cell because they generate ATP through cellular respiration.

2. Energy currency of the cell is: (UPSC Prelims 2013)
   a) DNA
   b) RNA
   c) ATP
   d) GTP
   Answer: c
   Explanation: Adenosine triphosphate (ATP) is the main energy-carrying molecule in cells.

3. Which cell organelle contains its own DNA? (BPSC 64th Prelims)
   a) Nucleus
   b) Ribosome
   c) Mitochondria
   d) Golgi apparatus
   Answer: c
   Explanation: Mitochondria have their own circular DNA and ribosomes, enabling them to synthesize some of their own proteins.

4. Which of the following organelles is responsible for aerobic respiration? (UPSC Prelims 2011)
   a) Ribosome
   b) Mitochondria
   c) Golgi body
   d) Lysosome
   Answer: b
   Explanation: Mitochondria perform aerobic respiration, converting glucose into energy.

5. Which of the following is a semi-autonomous organelle? (BPSC 63rd Prelims)
   a) Lysosome
   b) Ribosome
   c) Mitochondria
   d) Golgi body
   Answer: c
   Explanation: Mitochondria are semi-autonomous as they have their own DNA and can replicate independently.

6. What is the main function of mitochondria? (UPPSC 2016)
   a) Protein synthesis
   b) Energy production
   c) Cell division
   d) Hormone production
   Answer: b
   Explanation: The primary role of mitochondria is to generate ATP, the energy currency of the cell.

7. Mitochondria are present in: (BPSC 68th Prelims)
   a) Prokaryotic cells
   b) Eukaryotic cells
   c) Both
   d) Only plant cells
   Answer: b
   Explanation: Mitochondria are found only in eukaryotic cells, not in prokaryotes.

8. Mitochondrial cristae are: (UPSC Prelims 2014)
   a) Outer membrane folds
   b) Inner membrane folds
   c) Golgi vesicles
   d) Ribosomes
   Answer: b
   Explanation: Cristae are folds of the inner mitochondrial membrane that increase surface area for ATP production.

9. The double membrane structure is found in: (BPSC 65th Prelims)
   a) Lysosome
   b) Mitochondria
   c) Ribosome
   d) Centriole
   Answer: b
   Explanation: Mitochondria have a double membrane: outer smooth membrane and inner folded membrane (cristae).

10. Which enzyme system is located in the mitochondria? (UPSC Prelims 2010)
    a) DNA polymerase
    b) Electron transport chain enzymes
    c) Amylase
    d) Peptidase
    Answer: b
    Explanation: The electron transport chain enzymes are embedded in the inner mitochondrial membrane.

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NCERT-Based Questions (Q11–30)

1. The main function of mitochondria is to:
   a) Produce hormones
   b) Carry genetic information
   c) Produce energy
   d) Store food
   Answer: c
   Explanation: Mitochondria produce energy in the form of ATP through aerobic respiration.

2. Which of the following processes occurs in mitochondria?
   a) Glycolysis
   b) Krebs cycle
   c) Photosynthesis
   d) Transcription
   Answer: b
   Explanation: The Krebs cycle occurs in the mitochondrial matrix.

3. Mitochondria are absent in:
   a) Animal cells
   b) Plant cells
   c) Bacterial cells
   d) Algal cells
   Answer: c
   Explanation: Bacteria are prokaryotes and lack membrane-bound organelles like mitochondria.

4. Which part of the mitochondria is responsible for ATP synthesis?
   a) Matrix
   b) Outer membrane
   c) Inner membrane
   d) Ribosomes
   Answer: c
   Explanation: The inner membrane contains the enzymes and proteins for ATP synthesis.

5. The inner membrane of mitochondria is folded into:
   a) Grana
   b) Cristae
   c) Cisternae
   d) Lamellae
   Answer: b
   Explanation: Cristae are folds of the inner membrane which increase surface area for respiration.

6. Mitochondria are called semi-autonomous because:
   a) They lack membrane
   b) They contain enzymes
   c) They have their own DNA and ribosomes
   d) They cannot divide
   Answer: c
   Explanation: Mitochondria possess their own DNA and machinery for protein synthesis.

7. Which organelle is involved in oxidative phosphorylation?
   a) Golgi apparatus
   b) Endoplasmic reticulum
   c) Mitochondria
   d) Chloroplast
   Answer: c
   Explanation: Oxidative phosphorylation occurs in mitochondria, producing ATP.

8. The outer membrane of mitochondria is:
   a) Porous and permeable
   b) Folded
   c) Non-permeable
   d) Pigmented
   Answer: a
   Explanation: The outer mitochondrial membrane contains porins making it permeable to small molecules.

9. ATP stands for:
   a) Adenosine triphosphate
   b) Adenine tetraphosphate
   c) Adenosine monophosphate
   d) Adenine triphosphate
   Answer: a
   Explanation: ATP stands for adenosine triphosphate, the energy molecule in cells.

10. Mitochondrial DNA is:
    a) Linear
    b) Double-stranded and circular
    c) Single-stranded
    d) Absent
    Answer: b
    Explanation: Mitochondrial DNA is double-stranded and circular, similar to bacterial DNA.

11. The mitochondrial matrix contains:
    a) Cristae
    b) Ribosomes
    c) DNA
    d) Both b and c
    Answer: d
    Explanation: The matrix contains mitochondrial DNA and ribosomes.

12. Number of mitochondria in cells:
    a) Is the same in all cells
    b) Depends on energy demand
    c) Is fixed
    d) Is highest in blood cells
    Answer: b
    Explanation: Cells with higher energy requirements (e.g., muscle cells) have more mitochondria.

13. Which type of ribosome is found in mitochondria?
    a) 70S
    b) 80S
    c) 100S
    d) 60S
    Answer: a
    Explanation: Mitochondria contain 70S ribosomes, similar to prokaryotic cells.

14. Endosymbiotic theory explains origin of:
    a) Lysosome
    b) Mitochondria
    c) Nucleolus
    d) Centriole
    Answer: b
    Explanation: The endosymbiotic theory proposes mitochondria originated from engulfed bacteria.

15. Mitochondria are found in:
    a) Mature red blood cells
    b) Bacteria
    c) Eukaryotic cells
    d) Viruses
    Answer: c
    Explanation: Only eukaryotic cells possess mitochondria.

16. The site of electron transport chain is:
    a) Mitochondrial matrix
    b) Inner mitochondrial membrane
    c) Cytoplasm
    d) Golgi membrane
    Answer: b
    Explanation: Electron transport chain enzymes are located in the inner membrane of mitochondria.

17. Which of the following is not a function of mitochondria?
    a) ATP production
    b) DNA replication
    c) Protein synthesis
    d) Photosynthesis
    Answer: d
    Explanation: Photosynthesis occurs in chloroplasts, not mitochondria.

18. Which of these organelles is involved in cell metabolism?
    a) Golgi apparatus
    b) Mitochondria
    c) Lysosome
    d) Nucleus
    Answer: b
    Explanation: Mitochondria are central to metabolic processes, especially energy generation.

19. The number of mitochondria is highest in:
    a) Skin cells
    b) Muscle cells
    c) Fat cells
    d) Bone cells
    Answer: b
    Explanation: Muscle cells have high energy demands and thus more mitochondria.

20. The term "Powerhouse of the cell" was first coined by:
    a) Altmann
    b) Robert Hooke
    c) C. Benda
    d) Kolliker
    Answer: a
    Explanation: Richard Altmann is credited with discovering mitochondria and highlighting their role in energy production.

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Predicted/Reference Book-Based Questions (Q31–50)

1. Mitochondrial diseases are often inherited through:
   a) Father’s DNA
   b) Mother’s DNA
   c) Both parents
   d) Environment
   Answer: b
   Explanation: Mitochondrial DNA is maternally inherited.

2. Which enzyme is associated with ATP synthesis in mitochondria?
   a) Ligase
   b) ATP synthase
   c) Peptidase
   d) Isomerase
   Answer: b
   Explanation: ATP synthase, located in the inner mitochondrial membrane, synthesizes ATP.

3. Mitochondria are most abundant in which type of cells?
   a) Skin
   b) Neurons
   c) Liver cells
   d) Muscle cells
   Answer: d
   Explanation: Muscle cells need continuous energy and contain abundant mitochondria.

4. The process of mitochondria dividing is called:
   a) Mitosis
   b) Fission
   c) Fusion
   d) Budding
   Answer: b
   Explanation: Mitochondria replicate by binary fission, like bacteria.

5. Which structure is found only in mitochondria and chloroplasts?
   a) DNA
   b) Cell wall
   c) Plasma membrane
   d) Vacuole
   Answer: a
   Explanation: Mitochondria and chloroplasts are the only organelles with their own DNA.

6. Mitochondria participate in which of the following processes?
   a) Protein digestion
   b) Glycolysis
   c) Apoptosis
   d) Translation
   Answer: c
   Explanation: Mitochondria play a key role in programmed cell death (apoptosis).

7. The outer membrane of mitochondria is:
   a) Impermeable
   b) Smooth and porous
   c) Folded
   d) Crystalline
   Answer: b
   Explanation: The outer membrane is smooth and contains porins that make it permeable.

8. Which scientist first observed mitochondria under a microscope?
   a) Altmann
   b) Leeuwenhoek
   c) Schleiden
   d) Schwann
   Answer: a
   Explanation: Richard Altmann observed mitochondria in 1890 and called them "bioblasts."

9. Mitochondrial ribosomes resemble those of:
   a) Viruses
   b) Bacteria
   c) Fungi
   d) Plants
   Answer: b
   Explanation: Mitochondrial 70S ribosomes are like bacterial ribosomes, supporting endosymbiotic origin.

10. Which of the following is synthesized in mitochondria?
    a) Carbohydrates
    b) ATP
    c) RNA only
    d) DNA only
    Answer: b
    Explanation: Mitochondria synthesize ATP during aerobic respiration.

11. How many membranes surround a mitochondrion?
    a) One
    b) Two
    c) Three
    d) None
    Answer: b
    Explanation: Mitochondria have a double membrane — outer and inner membranes.

12. The space between inner and outer mitochondrial membrane is called:
    a) Matrix
    b) Stroma
    c) Intermembrane space
    d) Cytosol
    Answer: c
    Explanation: The intermembrane space is the region between the inner and outer membranes.

13. What is the pH of mitochondrial matrix approximately?
    a) 5
    b) 6
    c) 7.8
    d) 9
    Answer: c
    Explanation: Mitochondrial matrix has a slightly alkaline pH of around 7.8.

14. The folded inner membrane of mitochondria is meant to:
    a) Store fat
    b) Store DNA
    c) Increase surface area
    d) Store water
    Answer: c
    Explanation: Cristae increase the surface area for enzymes involved in ATP production.

15. Which pathway begins in the cytoplasm and ends in mitochondria?
    a) Glycolysis
    b) Krebs cycle
    c) Electron transport
    d) Protein synthesis
    Answer: a
    Explanation: Glycolysis occurs in the cytoplasm and the resulting pyruvate enters mitochondria.

16. How many ATP molecules are formed per glucose during aerobic respiration?
    a) 2
    b) 8
    c) 18
    d) 36–38
    Answer: d
    Explanation: Complete oxidation of one glucose molecule in mitochondria yields about 36–38 ATP.

17. The term ‘cellular respiration’ mainly refers to activity in:
    a) Lysosomes
    b) Chloroplasts
    c) Mitochondria
    d) Endoplasmic reticulum
    Answer: c
    Explanation: Cellular respiration primarily takes place in mitochondria.

18. Which of the following statements about mitochondria is correct?
    a) Found in all prokaryotic cells
    b) Found in viruses
    c) Absent in red blood cells
    d) Contain 80S ribosomes
    Answer: c
    Explanation: Mature red blood cells lack mitochondria.

19. Mitochondrial dysfunction is linked to:
    a) Asthma
    b) Diabetes
    c) Alzheimer’s disease
    d) All of the above
    Answer: d
    Explanation: Mitochondrial dysfunction contributes to many chronic diseases including neurological and metabolic disorders.

20. The energy stored in ATP is in the form of:
    a) Protein bonds
    b) High-energy phosphate bonds
    c) DNA bonds
    d) Hydrogen ions
    Answer: b
    Explanation: ATP stores energy in its high-energy phosphate bonds, particularly between the last two phosphate groups.