Mitochondria, plastids and ribosomes — practice questions

Question 1 · difficulty L1 · recall

Where does oxidative phosphorylation occur in a mitochondrion?

• A. Inner mitochondrial membrane
• B. Outer mitochondrial membrane
• C. Matrix only
• D. Intermembrane space only

Question 2 · difficulty L2 · understanding

Why are mitochondria and chloroplasts described as semi-autonomous organelles?

• A. They contain their own DNA and ribosomes but still depend on nuclear genes
• B. They function completely independently of the cell
• C. They contain no proteins encoded by nuclear genes
• D. They reproduce only when the entire cell divides

Question 3 · difficulty L2 · understanding

From the statements given below choose the correct option : A. The eukaryotic ribosomes are 80S and prokaryotic ribosomes are 70S. B. Each ribosome has two sub-units. C. The two sub-units of 80 S ribosome are 60 S and 40 S while that of 70 S are 50 S and 30 S . D. The two sub-units of 80 S ribosome are 60 S and 20 S and that of 70 S are 50 S and 20 S . E. The two sub-units of 80 S are 60 S and 30 S and that of 70 S are 50 S and 30 S .

• A. A, B, E are true
• B. B, D, E are true
• C. A, B, C are true
• D. A, B, D are true

Question 4 · difficulty L3 · application

A cell contains numerous chloroplasts with extensive thylakoid membranes. Which activity is most directly supported by these structures?

• A. Light-dependent reactions of photosynthesis
• B. Protein digestion
• C. Chromosome movement
• D. Lipid storage

Question 5 · difficulty L3 · application

An antibiotic specifically blocks 70S ribosomes. Which cellular structures in a eukaryotic plant cell could be directly affected?

• A. Mitochondria and chloroplasts
• B. Golgi apparatus and lysosomes
• C. Nucleus and smooth ER
• D. Peroxisomes and vacuoles

Question 6 · difficulty L3 · understanding

Non-membrane bound cell organelles found in both prokaryotic and eukaryotic cells are $\_\_\_\_$ .

• A. Ribosomes
• B. Lysosomes
• C. Centrosomes
• D. Mitochondria

Question 7 · difficulty L3 · understanding

How many different proteins does the ribosome consist of?

• A. 60
• B. 40
• C. 20
• D. 80

Question 8 · difficulty L3 · understanding

Which of the following statements about inclusion bodies is incorrect?

• A. These are involved in ingestion of food particles
• B. They lie free in the cytoplasm
• C. These represent reserve material in cytoplasm
• D. They are not bound by any membrane

Question 9 · difficulty L5 · analysis

Organelle P has an inner membrane folded into cristae and carries out aerobic ATP production. Organelle Q has thylakoids arranged into grana and fixes carbon in its stroma. Which conclusion is correct?

• A. P is a mitochondrion and Q is a chloroplast
• B. P is a chloroplast and Q is a mitochondrion
• C. Both are mitochondria
• D. Both are chloroplasts