Cell Biology

Question 1

What is active transport?

Answer 1

The movement of particles from an area of low concentration to high concentration, against a concentration gradient.

Question 2

What does active transport require, which diffusion and osmosis do not?

Answer 2

Energy from respiration.

Question 3

Give 3 features of exchange surfaces which allow them to efficiently exchange substances.

Answer 3

1. Rich blood supplies for a steep concentration gradient (Speeds up diffusion)
2. Thin walls for short diffusion pathway
3. Large surface area
4. (FOR ALVEOLI) moist walls to dissolve gases

Question 4

What is the formula for the number of bacteria present after a certain amount of time?

Answer 4

a • 2^n where n is the number of divisions and a is the number of bacteria initially.

Question 5

Describe the concentrations (of water) in an isotonic solution

Answer 5

The concentration outside the cell is equal to the concentration inside the cell

Question 6

Describe the concentrations (of water) in a hypertonic solution and the effects on animal cells and on plant cells.

Answer 6

Outside the cell is more dilute, so water enters the cell.

Animal cells can burst, plants cells become turgid (swollen) as they have cell wall

Question 7

Describe the concentrations (of water) in a hypotonic solution

Answer 7

Outside the cell is more concentrated (more solute in it) so water moves out of the cell.

Question 8

What is the eyepiece lens’ magnification
How do you calculate the total magnification

Answer 8

10x
Eyepiece x objective lens