Chapter 2 - Cells

Question 1

State the function of the cell surface membrane. (2)

Answer 1

1) Partially permeable and only allows smaller molecules to pass through, not the larger ones
2) regulates the movement of substances in and out of the cell

Question 2

State the functions of a cytoplasm. (3)

Answer 2

1) Most cell activities occur here
2) contains enzymes
3) contains specialised structures called organelles

Question 3

What does the nucleus contain?

Answer 3

The nucleus consists of a small round denser protoplasm called nucleoplasm which is surrounded by a nuclear envelope. It also contains one or more nucleoli and chromatin.

Question 4

What does a cell consist of?

Answer 4

Each living cell consists of protoplasm which is made up of the cell surface membrane, cytoplasm and nucleus.

Question 5

State a structural difference between the RER and SER.

Answer 5

The smooth endoplasmic reticulum is more tubular and does not have ribosomes.

Question 6

What is chromatin?

Answer 6

Chromatin is a network of threadlike structures that contains DNA.

Question 6

What are chromatins made of?(spell)

Answer 6

It is made up of DEOXYRIBONUCLEIC ACID which carries heredity information.

Question 7

What happens to the chromatin when cell is dividing?

Answer 7

Chromatin threads condense into chromosomes when cell is dividing.

Question 8

What is the cell wall made of?

Answer 8

Cellulose

Question 9

What is the function of the cell wall?(3)

Answer 9

1) it protects the cell from injuries
2) hold the shape of the cell
3) fully permeable, molecules of any shape and size can pass through

Question 10

Why does the Rough Endoplasmic Reticulum appear rough?

Answer 10

It appears rough because small particles called RIBOSOMES are attached to its outer surface.

Question 11

What is the function of the ribosome?

Answer 11

Make proteins

Question 12

What is the function of the RER?

Answer 12

The RER transports proteins to the Golgi apparatus for secretion out of the cell.

Question 13

What is the function of the Smooth Endoplasmic Reticulum?(2)

Answer 13

1) Synthesizes substances like fats and steroids

2) Involved in detoxification

Question 14

What is the function of the Golgi apparatus?

Answer 14

Modifies the substances made by ribosomes on the Rough Endoplasmic Reticulum, and stores and packages them in vesicles for secretion out of the cell.

Question 15

Describe the process of proteins being packaged&secreted out of the cell. (5 steps)

Answer 15

1) Vesicles containing proteins made in the Rough Endoplasmic Reticulum(RER) pinch off from the RER.
2) The vesicles fuse with the Golgi apparatus.
3) The proteins in the vesicles are released into the Golgi apparatus and are modified.
4) Secretory vesicles containing the modified proteins pinch off from the Golgi apparatus and move towards the cell surface membrane.
5) Secretory vesicles fuse with cell surface membrane and release contents into exterior of cell

Question 16

What is the function of a Mitochondrion?

Answer 16

site where organic food substances like glucose is oxidised to release energy during respiration.
(Reject: oxidise glucose)

Question 17

What are chloroplasts?

Answer 17

Chloroplasts are oval structures containing chlorophyll which is required for photosynthesis to occur.

Question 18

What is the function of vacuoles?

Answer 18

Store substances within the cell.

Question 19

What are the differences between a plant cell and an animal cell?

Answer 19

1) cell walls are present in the plant cell but absent in the animal cell.
2) chloroplasts are present in leaf cells but absent in animal cells.
3) Centrioles absent in plant cells but present in animal cells
4) Plant cells have a large central vacuole, enclosed by partially permeable membrane known as tonoplast, while an animal cell has numerous small vacuoles that are temporary

Question 20

What is the function of the centriole?

Answer 20

Responsible for cell division

Question 21

What are the 3 adaptations of a red blood cell?

Answer 21

1) Haemoglobin in the cytoplasm of red blood cell binds to oxygen to form oxyhaemoglobin and transports oxygen from lungs to all parts of the body.
2) A red blood cell has no nucleus to store more haemoglobin.
3) circular, biconcave shape increases the surface area, thus increasing the rate of diffusion of oxygen into and out of the cell.

Question 22

What are the adaptations of a xylem vessel?(2)

Answer 22

1) lignified cell walls of xylem vessel for strength to support the plant.
2) narrow lumen, long and hollow vessel with no cross-walls and protoplasm for water and DISSOLVED minerals to transport from the roots to the rest of the plants without resistance to flow

Question 23

What are the 3 adaptations of the root hair cell?

Answer 23

1) long and narrow protrusion increases surface area for faster absorption of water and mineral salts.
2) large central vacuole increases concentration of salt and sugars in the cell sap which lowers the water potential. Water ABSORPTION increases at a faster rate.
3) rich in mitochondria to release more energy for active transport

Question 24

Define tissues and give 2 examples.

Answer 24

Tissue is a group if similar cells working together to perform a specific function.
Example: epithelial tissue in humans, epidermal tissue in plant

Question 25

Name 3 substances absorbed by the root hair cell.

Answer 25

Water and calcium ions&nitrate ions. (Mineral salts)

Question 26

State a functional difference between free ribosomes and bound ribosomes(on RER).

Answer 26

Free ribosomes produce proteins for the cell while bound ribosomes produce proteins that are transported out of the cell.

Question 27

Define organ.

Answer 27

Organ is a structure made up of different tissues working together for a specific function.