B2.2 Organelles and compartmentalisation

Question 1

Why is the cell wall not considered to be an organelle?
A. It contains cellulose.
B. It is too big.
C. It is not surrounded by a membrane.
D. It contains DNA.

Answer 1

C.

Question 2

Which of the following units is the most useful as the unit of size of a mitocondrion?
A. A.
B. μm
C. mm
D. nm

Answer 2

B

Question 3

Which of the following apparatus and techniques was used in determining the function of individual organelles?
I. Fractionation
II. Ultracentrifugation
III. Electron microscopy
IV. Light microscopy

A. All of the above
B. I, II, and IV only
C. I only
D. II only

Answer 3

B

Question 4

Which of the following are advantages of the presence of a nuclear membrane surrounding the nucleus of eukaryotic cells?
I. Separation of the DNA from the cytoplasm.
II. Separation of gene transcription of from translation.
III. Concentration of enyzmes for DNA replication and transcription.
IV. Increased efficiency of nuclear division.

A. All of the above
B. I, II, and IV only
C. I only
D. II only

Answer 4

A.

Question 5

List four organelles that would be found in a photosynthetic cell of a leaf.

Answer 5

Nucleus
Chloroplast
Permanent vacuole
Mitochondrion
Ribosome
Plasma/cell membrane

(not cosidered organelles: cell wall, cytoskeleton and cytoplasm)

Question 6

Explain the advantage to cellular function of organelles being surrounded by a membrane. Illustrate your answer with an example.

Answer 6

Compartmentalisation by organelles in a cell creates several separate parts each with its own solution.
(Because of compartmentalisation) the cell can maintain conditions in an organelle different to the cytoplasm.
Organelles can contain high concentrations of enzymes.
Organelles can contain high concentrations of substrate molecules (or other metabolites).
Organelles permit the separate of (incompatible) functions.

Any 3 of these for 3 marks

Question 7

Image B2.2.1 shows a mitochondrion.

Outline 3 ways in which a mitochondrion is adapted to its function (3 marks)

Answer 7

The folded inner membrane (Cristae) provides a large surface area to hold more enzymes for respiration.
They have a high concentration of molecules/enzymes for the Krebs cycle in the matrix to speed up this process.
They have an intermembrane space / double membrane which makes a narrow space helping to form a high proton concentrations.
Mitochondria contain DNA and ribosomes which enable them to replicate themselves.

Any three which must link structure to its function.