Chapter 1: Cell Structure and Organisation

Question 1

Name the parts of an animal cell

Answer 1

Cell membrane
Cytoplasm
Nucleus
Small and numerous vacuoles
Mitochondria

Question 2

Name the parts of a plant cell

Answer 2

Cell membrane
Cytoplasm
Nucleus
Cell wall
Chloroplasts
Large central vacuole
Mitochondria

Question 3

Describe the cell membrane (+function)

Answer 3

-Partially permeable
-Made up of lipids and proteins
-Forms the boundary of the cell
-Holds contents of the cell in place
-Regulates the movement of substances in and out of the cell

Question 4

Describe the cytoplasm (+function & involved structures)

Answer 4

-Where most cell activities occur
-Contains RER, SER, Golgi body/apparatus and ribosomes

Question 5

Describe the nucleus (+function & structures involved)

Answer 5

-Controls all cell activities such as cell growth and the repair of worn out parts
-Essential for cell division
-Contains genetic material
-Contains
1. Chromatin
2. Nuclear envelope/membrane
3. Nucleolus
4. Nucleoplasm

Question 6

What is chromatin?

Answer 6

-Network of threadlike structures that controls cell activities like cell growth, cell division and protein production
-Made up of deoxyribonucleic acid (DNA) which carries hereditary information
-Chromatin threads coil and condense into chromosomes when the cell is dividing

Question 7

What is the function of the nuclear envelope?

Answer 7

• Separates contents of nucleus from the rest of the cytoplasm

Question 8

What is the function of the nucleolus?

Answer 8

Plays a part in making proteins in a cell

Question 9

What is nucleoplasm?

Answer 9

Dense material within then nucleus

Question 10

Describe the cell wall (+function)

Answer 10

-Made of cellulose
-Fully permeable
-Protects plant cells from injury
-Gives cell a rigid shape

Question 11

Describe the Rough Endoplasmic Reticulum (+function)

Answer 11

-Surface is continuous w/ nuclear membrane
-Appears rough, bc ribosomes are attached to its outer surface
-TRANSPORTS/ SYNTHESISES proteins to Golgi apparatus for secretion out of the cell

Question 12

Describe the Smooth Endoplasmic Reticulum (+function)

Answer 12

-Connected to RER
-No ribosomes (and more tubular)
-SYNTHESISES substances e.g. fats & steroids(e.g. sex hormones-> androgen and estrogen in testes and ovaries)
-Involved in detoxification (liver cells)

Question 13

Describe ribosomes (+function)

Answer 13

• Small round structures
• Needed to synthesise proteins
• Free ribosomes
  ->Synth. proteins used within cell
• Ribosomes on RER
  ->Synth. proteins transported out of cells

Question 14

Describe the Golgi body/apparatus (+function)

Answer 14

-Consists of flattened spaces surrounded by a membrane (spotify shape)
-STORES and MODIFIES substances made by ribosomes on ER
-PACKAGES the substances in VESICLES for secretion out of the cell

Question 15

Summarise movement of substances out of the cell

Answer 15

1. Vesicles containing substances made in ER (RER & SER) pinch off from the ER
2. Vesicles fuse w/ Golgi body/apparatus
3. Substances in vesicles are released into the Golgi body and are MODIFIED
4. Secretory vesicles containing modified substances pinch off from Golgi body and move towards cell surface membrane
5. Secretory vesicles fuse w/ cell surface membrane and release contents to exterior of cell

Question 16

Describe mitochondria (+function)

Answer 16

-Site of aerobic respiration where glucose is oxidised to release energy
-Sausage-shaped

Question 17

Where does aerobic respiration occur?

Answer 17

In the mitochondria

Question 18

Where does anaerobic respiration occur?

Answer 18

In the cytoplasm

Question 19

Application: Which cells of the body contain larger amounts of SER?

Answer 19

Liver cells-> involved in detoxification
Cells in testes & ovary-> synthesises sex hormones

Question 20

Which cells contain larger amounts of mitochondria?

Answer 20

• Muscle cells
• Root hair cells
• Villus
• Sperm cells

Question 21

State differences between a plant cell and an animal cell.

Answer 21

ANIMAL CELL: No cell wall
PLANT CELL: Cell wall

ANIMAL CELL: Chloroplast absent
PLANT CELL: Chloroplast present

ANIMAL CELL: Numerous temporary vacuoles
PLANT CELL: A large central vacuole

Question 22

Function of chloroplast?

Answer 22

Contains chlorophyll which absorbs light energy to carry out photosynthesis

Question 23

Purpose of the vacuole?

Answer 23

• Store substances within the cell
• Animal cells->water & food substances
  Plant cells->cells sap (made up of sugars, mineral salts and amino acids)

Question 24

Purpose of tonoplast?

Answer 24

Enclose the large central vacuole

Question 25

How is a RBC's structure adapted to its function? (Structure to function qn)

Answer 25

Function: Transport oxygen from lungs to all parts of the body Structure: 1. Haemoglobin present in cytoplasm of RBC->binds to O2 reversibly to transport it around the body 2. No nucleus->enables cell to maximise space to store more haemoglobin 3. Circular biconcave shape->increases surface are to volume ratio, increases rate of diffusion of oxygen in an out of the cell 4. Flexible->turn bell-shaped to allow cell to travel along tiny blood capillaries

Question 26

How is the muscle cell adapted to its function? (Structure to function qn)

Answer 26

Function: Contract & relax to bring about movement Structure: 1. Elongated and cylindrical shape 2. Contains many nuclei 3. Contains many mitochondria->release more energy for contraction of the muscle cell 4.Contains many contractile protein fibres ->contract and relax to bring about movement

Question 27

How is the root hair cell adapted to its function? (Structure to function qn)

Answer 27

Function: To absorb water & mineral salts from the soil into the roots Structure: 1. Long and narrow extension/protrusion-> increases surface area to volume ratio, faster rate of absorption of water and mineral salts 2. More mitochondria (compare to general plant cells)->higher rate of aerobic respiration for release of more energy to carry out active transport of mineral salts from soil sol. to root hair cell

Question 28

Compare the similarities and differences between the structure plant and animal cells as seen under a **light microscope**. (4m) (TYS 2010/P2/Q10EITHER)

Answer 28

- A plant cell has a cell wall while an animal cell does not have a cell wall (1m) - A plant cell has chloroplasts while an animal cell does not have chloroplasts (1m) - Both plant cells and animal cells have -a cell membrane -a nucleus -contain cytoplasm (1m) - A plant cell has a large central vacuole that is visible under a light microscope, while an animal cell has small, temporary vacuoles not visible under a light microscope (1m)

Question 29

Name two structures in a cell visible only under an electron microscope and state the function of each one. (2m) (TYS 2010/P2/Q10EITHER)

Answer 29

- Ribosome: synthesises protein which is either transported out of the cell or used within the cell OR - Mitochondrion: oxidises glucose through aerobic respiration to release energy OR - Rough endoplasmic reticulum: transports proteins to the Golgi body for secretion of of the cell OR - Golgi body: modifies, stores and packages proteins in vesicles for secretion out of the cell

Question 30

State the function of a plant cell vacuole.

Answer 30

Contains cell sap which stores sugars, mineral salts and amino acids.

Question 31

Explain the importance of a large quantity of ribosomes and golgi body inside a pancreatic cell. (3m)

Answer 31

- The pancreas secretes pancreatic juice containing enzymes for digestion. Enzymes are protein in nature (1m) - Large amount of ribosomes allows pancreatic cells to synthesise proteins (1m) - Golgi body helps to **chemically modify**, **store** and **package enzymes into vesicles** for secretion out of the cell (1m)