AQA GCSE Biology B4

What are the four main components of blood?

Red blood cells, white blood cells, platelets, plasma

Function of red blood cells

Transport oxygen around the body

How are red blood cells adapted to their function?

Biconcave shape, no nucleus, contain haemoglobin

Function of white blood cells

Defend the body against pathogens

Two ways white blood cells work

Phagocytosis and producing antibodies

Function of platelets

Help blood clot to prevent blood loss

Function of plasma

Transports cells, nutrients, hormones, carbon dioxide and urea

Function of arteries

Carry blood away from the heart at high pressure

One adaptation of arteries

Thick muscular walls to withstand high pressure

Function of veins

Carry blood towards the heart

One adaptation of veins

Valves prevent backflow of blood

Function of capillaries

Exchange substances between blood and cells

One adaptation of capillaries

Walls one cell thick for short diffusion distance

Name the four chambers of the heart

Left atrium, right atrium, left ventricle, right ventricle

Which side of the heart pumps oxygenated blood?

Left side

Function of ventricles

Pump blood out of the heart

Why is the left ventricle wall thicker?

Pumps blood to the whole body at higher pressure

Function of heart valves

Prevent backflow of blood

What is a pacemaker?

Device that controls heart rhythm

Why might someone need a pacemaker?

Irregular heartbeat

What are stents used for?

Keep coronary arteries open

What do statins do?

Lower cholesterol and reduce risk of heart disease

Where does gas exchange occur in the lungs?

Alveoli

How are alveoli adapted for gas exchange?

Large surface area, thin walls, good blood supply

Gas that diffuses into the blood

Oxygen

Gas that diffuses out of the blood

Carbon dioxide

Difference between inhaled and exhaled air

Exhaled air has less oxygen and more carbon dioxide

Function of xylem

Transports water and minerals from roots to leaves

Function of phloem

Transports sugars around the plant

Function of palisade mesophyll cells

Photosynthesis

Why do palisade cells contain many chloroplasts?

To absorb more light

What is transpiration?

Loss of water vapour from leaves

Where does transpiration occur?

Stomata

Function of guard cells

Open and close stomata to control water loss

What creates the transpiration stream?

Evaporation and diffusion from leaves

Effect of light on transpiration

Higher light increases transpiration

Effect of temperature on transpiration

Higher temperature increases transpiration

Effect of wind on transpiration

Increased wind increases transpiration

Effect of humidity on transpiration

Higher humidity decreases transpiration

What is a potometer used for?

Measure rate of water uptake