Cells

Question 1

What is the function of the nucleus?

Answer 1

The nucleus is the organelle that controls cell activities such as cell growth and repair of worn-out parts, and is essential for cell division.

Question 2

What is the function of the cytoplasm?

Answer 2

The cytoplasm is the part of the protoplasm where most cell activities occur.

Question 3

What is the function of chloroplasts?

Answer 3

Chloroplasts contain a green pigment called chlorophyll and are essential for photosynthesis.

Question 4

What is the function of the vacuole?

Answer 4

In animal cells: Numerous small vacuoles act as temporary stores of water and food substances.
In animal cells: Large central vacuole stores dissolved substances like sugars, amino acids and mineral salts.

Question 5

What is the function of the cell surface membrane?

Answer 5

Being selectively permeable, the cell surface membrane controls the movement of substances in and out of the cell.

Question 6

What is the function of the cellulose cell wall?

Answer 6

The cellulose cell was enclosed the plant cell completely, surrounds the cell surface membrane, protects the plant cell from injury and gives the plant cell as fixed shape.

Question 7

What is the function of the mitochondrion?

Answer 7

Mitochondrion is the site of aerobic stages of respiration and release of energy in the form of adenosine triphosphate (ATP).

Question 8

What is the function of the Golgi body?

Answer 8

Chemically modifies substances made by the ER, stores and packages these substances in vesicles for secretion out of the cell.

Question 9

What is the function of ribosomes?

Answer 9

Ribosomes are the site where proteins are synthesized in cells.

Question 10

What is the function of RER?

Answer 10

Ribosomes attached on the outer surface of the RER are sites of synthesis of proteins that are usually transported out of the cell.

Question 11

What is the function of SER?

Answer 11

Site of synthesis of fats and steroids and converts harmful substances into harmless substances through a process known as detoxification.

Question 12

Define differentiation.

Answer 12

Differentiation is the process by which a cell becomes specialised for a specific function.

Question 13

State the function of the red blood cell, it’s unique structural features and how these features are adapted for the cell’s function.

Answer 13

Function: To transport and deliver oxygen to all parts of the body.
1. Is flexible — can squeeze through capillaries easily
2. Contains a red pigment called haemoglobin — haemoglobin binds to oxygen and transports it around the body
3. Lacks a nucleus — RBC can pack/store more haemoglobin to transport more oxygen
4. Has a circular biconcave shape — increases surface area-to-volume ratio of cell for increased rate of oxygen uptake through diffusion of oxygen into and out of the cell

Question 14

Explain compartmentalisation in eukaryotic cells.

Answer 14

Eukaryotic cells are partitioned into compartments by their internal membranes. This allows multiple processes to occur simultaneously in the cell.

Question 15

State the 4 basic functions performed by the structures and organelles in eukaryotic cells.

Answer 15

1. Genetic control of cell (nucleus, mitochondria)
2. Manufacture, distribution and breakdown of molecules (ER, Golgi body, vacuoles)
3. Energy processing (mitochondria, chloroplasts)
4. Structural support, movement and communication between cells (cell surface membrane, cellulose cell wall)

Question 16

State the function of the root hair cell, its unique structural features and how these features are adapted for the cell’s function.

Answer 16

Function: To absorb water and mineral slats from the soil
1. Has a long and narrow extension — increase surface area-to-volume ratio of cell for increased rate of absorption of water and mineral salts
2. Maintains a lower water potential in the vacuole as compared to the surroundings soil — allow water to enter the root hair cell via osmosis

Question 17

State the function of the muscle cell, it’s unique structural features and how these features are adapted for the cell’s function.

Answer 17

Function: To contract and relax to bring about movement
1. Has contractile protein fibres — contract and relax to bring about movement
2. Contains many mitochondria — provides energy in the form of ATP for contraction of muscle cell
3. Has many nuclei — allows for cell division

Question 18

How do you identify the following organelles in electron micrographs: nucleus, RER, SER, mitochondria, Golgi body, chloroplasts?

Answer 18

Nucleus: Largest organelle of cell
SER: Membrane continuous with membrane of nucleus
RER: Looks like SER, but with dense dots (ribosomes) on the outer surface
Mitochondria: Lines (membrane) perpendicular to organelle
Golgi Body: Stacks of membrane; smiley face
Chloroplasts: Thick chunks of membrane (denser inner membrane) in some places within organelle