B4.2-Organisation

Question 1

What is a tissue?

Name a tissue in animals

Answer 1

A tissue is a group of cells with a similar structure
and function.
e.g. muscle tissue

Question 2

What is an organ?

Name 3 organs in the digestive system

Answer 2

An organ is a group of tissues performing a specific function.
e.g. stomach, liver, pancreas, small intestine

Question 3

What is an enzyme?

Answer 3

Enzymes are biological catalysts that speed up

chemical reactions.

Question 4

What affects the rate of enzyme activity? What

is denaturing?

Answer 4

Temperature:
Too low – molecules move slowly
Too high – enzyme is denatured
pH
Different enzymes work best at different pH
Denaturing is when the specific shape of the active
site is changed, so the enzyme can no longer work.

Question 5

Name the 3 digestive enzymes:
What do they break down?
What products are formed?

Answer 5

Amylase- Amylase breaks down starch into sugars
Protease- Protease breaks down protein into amino acids
Lipase- Lipase breaks down fats into fatty acids and glycerol

Question 6

What is bile?

Answer 6

• Bile is produced in the liver and stored in
the gall bladder.
• Bile is alkaline to neutralise the acid that
was added to food in the stomach.
• Bile also emulsifies fat into smaller droplets
• This provides a large surface area and
alkaline conditions for enzymes to break
down fat.

Question 7

Name the 4 main chambers of the heart

Answer 7

Left atrium, right atrium, right ventricle, left ventricle

Question 8

What is the role of valves in the heart and veins?

Answer 8

Valves prevent the backflow of blood when the
heart pumps.
Valves in the veins prevent the backflow of low
pressure blood returning to the heart

Question 9

State 2 differences between veins and arteries

Answer 9

• Arteries have thick elastic walls to carry high pressure blood, whereas veins have thin walls.
• Veins have valves but arteries don’t.

Question 10

Name the 4 components of blood and state the function of each

Answer 10

Plasma-Transporting carbon dioxide, digested food,
urea, hormones and heat.
Red blood cells-Transporting oxygen
White blood cells-Ingesting pathogens and producing
antibodies.
Platelets-Involved in blood clotting

Question 11

What is coronary heart disease?

Answer 11

Layers of fatty material build up inside the coronary
arteries, narrowing them.
This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle.

Question 12

Describe 3 methods of treating coronary heart

disease

Answer 12

Stents are used to keep the coronary arteries open.
Drugs called statins are widely used to reduce
blood cholesterol levels which slows down the rate
of fatty material deposit.
Heart transplants can also be used in some cases.

Question 13

State an advantage and a disadvantage of transplanting an artificial heart instead of a donor
heart to treat heart failure.

Answer 13

Advantage of artificial heart:
There is a shortage of donor hearts, so an artificial
heart can be used while waiting.
Disadvantage of artificial heart:
They do not last as long as a donor heart and would
need replacing.

Question 14

What problems does a leaky heart valve cause and

how can it be treated?

Answer 14

Leaky heart valves cause backflow of blood. You
may become breathless.
The heart will have to work harder to pump blood.
This could cause heart failure.
Faulty heart valves can be replaced using biological
or mechanical valves.

Question 15

What is a communicable disease?

Answer 15

Communicable: Infectious diseases. Caused by pathogens.

Question 16

Give 3 examples of risk factors for non-communicable disease

Answer 16

Diet and obesity are linked to cardiovascular disease.
Smoking is linked to lung disease and cancer.
Alcohol affects liver and brain function.

Question 17

What is cancer?

Answer 17

Cancer is the result of changes in cells that lead to
uncontrolled growth and division.
Benign tumours are growths of abnormal cells
which are contained in one area. They do not
invade other parts of the body.
Malignant tumour cells are cancers. They invade
neighbouring tissues and spread to different parts
of the body in the blood where they form secondary tumours.

Question 18

What is the role of epidermal tissue in a plant?

Answer 18

Epidermis: Thin layer of cells covering the leaf.

Question 19

What is transpiration?

Answer 19

Transpiration is the movement of water through the xylem and out of the leaves through stomata.
It is caused by evaporation of water from the leaf.

Question 20

State 3 factors that increase the rate of transpiration

Answer 20

The rate of transpiration is increased by:
• High temperature,
• Low humidity
• Increased air movement (wind)
• High light intensity

Question 21

What is translocation?

Answer 21

Translocation is the movement of sugars from the leaves through the plant in phloem tissue.

Question 22

Name the 2 types of mesophyll tissue in the leaf.

Answer 22

palisade mesophyll: Packed with chloroplasts for photosynthesis
Spongy mesophyll: Has large air spaces to allow the diffusion of carbon dioxide through the leaf.

Question 23

Describe the structure and function of 2 tissues in the stem

Answer 23

Xylem: Hollow and wide continuous tube carries water to the leaf
Phloem: Continuous tube of cells with pores in the end walls. Carries sugar from the leaf

Question 24

Describe the structure and function of

guard cell tissue

Answer 24

Guard cell tissue is on the underside of the leaf. It opens and closes to control the loss of water through holes in the leaf, called stomata.