TOPIC 1 - CELL BIOLOGY

Question 1

Cell Membrane - function?

Answer 1

Controls what goes in and out of the cell

Question 2

Nucleus - function?

Answer 2

Controls the activities of the cell

Question 3

Cytoplasm - function?

Answer 3

Where chemical reactions occur

Question 4

Mitochondria

Answer 4

Aerobic Respiration

Question 5

Cell Wall

Answer 5

Supports and strengthens the cell

Question 6

Chloroplasts

Answer 6

Where photosynthesis happens
Contains chlorophyll

Question 7

Vacuole

Answer 7

Contains cell sap

Question 8

Ribosomes

Answer 8

Protein synthesis

Question 9

What are the three differences between the prokaryotic and eukaryotic cells?

Answer 9

• eukaryotic have a nucleus, pro does not
• pro are small, eur is bigger
• pro’s genetic material is held in plasmids

Question 10

Light Microscopy Required Practical 1

Answer 10

1. Peel a thin layer of onion
2. Put a drop of water on the slide using a pipette
3. Place the onion flat on top
4. Add 2 drops of iodine - this stains the nucleus and cell wall
5. Put the cover slip over slowly to avoid bubbles
6. Look at the slide on coarse focus (upclose) and fine focus (focus image)

Question 11

Adaptations and Function of a sperm cell

Answer 11

• tail to allow them to swim to the egg
• many mitochondria to allow energy to be released for movement
• to fertilise the egg

Question 12

Adaptations and Function of a nerve cell

Answer 12

• branched connections that join other nerve cells to send messages around the body
• to transport electrical impulses around the body

Question 13

Adaptations and Function of a muscle cell

Answer 13

• contains filament proteins that slide over each other allowing muscle contraction
• allows muscle contractions

Question 14

Adaptations and Function of a root hair cell

Answer 14

• having a large surface area to increase the rate of absorption
• absorb water and mineral ions from the soil

Question 15

Adaptations and Function of a xylem cell

Answer 15

• hollow tubes for a free passage of water
• to transport water and mineral ions from the roots to the stems and leaves of a plant

Question 16

Adaptations and Function of a phloem cell

Answer 16

• sieve tubes to allow substances to flow easily
• transports sugars from leaves to other parts of the plant

Question 17

What is the importance of cell differentiation?

Answer 17

Allows cells to become specialised for specific functions, leading to the formation of different tissues and organs, enabling complex processes.

Question 18

How are electron microscopes better than light microscopes?

Answer 18

• much higher magnification
• much higher resolution
  This means cells can be studied in much finer detail

Question 19

Formula for magnification

Answer 19

Magnification = image size
—————-
actual size

Question 20

How to calculate the area of a circular colony?

Answer 20

Pie r ^2

Question 21

Method for investigating the effect of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibation

Answer 21

1. Sterilize all glassware and prepare agar plate
2. Spread bacteria over the entire agar plate
3. Apply antibiotics/antiseptics in spots of agar
4. Incubate plates at an appropriate temp
5. Leave for 24-48 hours
6. Measure zones of inhibation using a ruler
7. Calculate an area and record results

Question 22

What are the 3 steps to the cell cycle?

Answer 22

1. Interphase
2. Mitosis
3. Cytokinesis

Question 23

What happens during the interphase of the cell cycle?

Answer 23

Cell grows, replicates its DNA, increase its number of sub-cellular structures and prepares for cell division.

Question 24

What happens during mitosis?

Answer 24

• two sets of chromosomes are pulled to the side of the cell
• two new nuclei are formed

Question 25

What happens during cytokinesis?

Answer 25

Cytoplasm and cell membrane split and two new daughter cells are formed

Question 26

What is the function of a stem cell in an embryo?

Answer 26

- contribute to the growth of development of all tissues and organs in the developing embryo

Question 27

What is a stem cell?

Answer 27

A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

Question 28

What is diffusion?

Answer 28

The net movement of particles from an area of high concentration to low concentration.

Question 29

What are the 3 factors that affect the rate of diffusion?

Answer 29

- concentration - temperature - surface area

Question 30

Why do multicellular organisms need exchange surfaces and a transport system? Give 3 reasons

Answer 30

- supply of nutrients - removal of wastes - support the function of larger organisms

Question 31

How is the small intestine and lungs adapted for efficient exchange of materials in mammals?

Answer 31

Small intestine = lots of villi makes bigger surface area, thin cell wall allows short diffusion pathway, rich blood supply maintains concentration gradient Lungs = lots of alveoli makes bigger surface area for gas exchange, thin cell wall for short diffusion pathway

Question 32

How is the small intestine and lungs adapted for efficient exchange of materials in gills in fish?

Answer 32

Small intestine = lots of villi makes bigger surface area, thin cell wall allows short diffusion pathway, rich blood supply maintains concentration gradient Lungs = lots of alveoli makes bigger surface area for gas exchange, thin cell wall for short diffusion pathway

Question 33

Osmosis Required Practical 3

Answer 33

1. Cut 5 potato cylinders using a balance to make sure all are the same mass - record this mass 2. Measure 10cm^3 of 1.0M sugar solution and transfer to boiling tube 3. Repeat step 2 for different concentrations of sugar solution 4. Add one cylinder to each boiling tube 5. Leave overnight in test tube rack 6. Remove cylinders and dab dry 7. Measure mass of potato cylinders to see the osmosis result of change in mass

Question 34

What is osmosis?

Answer 34

The net movement of water molecules from an area of high concentration to low concentration through a partially permeable membrane.

Question 35

What is active transport?

Answer 35

Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.