Main biology (what i need to revise)

Question 1

what are the equations for finding:
- the magnification of a microscope
- the magnification of a drawing

Answer 1

• objective x eyepiece lens
• actual size divided by image size

Question 2

what is the rate of diffusion affected by?

Answer 2

• surface area
• concentration gradient
• temperature

Question 3

name a test for carbon dioxide

Answer 3

• using limewater (it will turn cloudy/milky)

Question 4

describe ventilation

Answer 4

1. the intercostal muscles contract
2. this causes the rib cage to lift up and out
3. the diaphragm contracts and moves down
4. the volume inside the lungs increases (decreasing the pressure)
5. air is drawn in

Question 5

what are the health risks associated with:
- carbohydrates
- fats
- (lack of) protein
- (lack of) vitamins/minerals

Answer 5

• obesity, type 2 diabetes
• heart disease/strokes
• poor growth
• deficiency symptoms

Question 6

what are the chemical tests/colour changes for:
- starch
-sugar/glucose
-proteins

Answer 6

• iodine —> black
• benedicts —> orange/red
• biuret —> lilac

Question 7

describe absorption

Answer 7

• the small intestine is a long tube so has a large surface area for diffusion/active transport
• there are many villi which also increase SA for absorption. they are finger-like projections
• there is a dense blood supply to take absorbed food away and maintain a high diffusion gradient
• villus has a single celled wall so short distance for diffusion
• villus also has a lacteal to absorb fat

Question 8

what is the purpose of stents and statins? How do they work?

Answer 8

stent = goes into blocked arteries and opens them up so blood flows
statin = a pill that unblocks arteries, it reduces cholesterol levels and reduces the build-up of fat.

Question 9

what do white blood cells do? What are the two types? What do they do?

Answer 9

white blood cells fight infection

• phagocytes = engulf and digest bacteria
• lymphocytes = make antibodies to kill bacteria (and anti-toxins neutralises poisons)

Question 10

what do platelets do?

Answer 10

help form blood clots

Question 11

what is in liquid plasma?

Answer 11

water and dissolved substances e.g. glucose, carbon dioxide, salts, proteins