B2

Question 1

Give three examples of tissues

Answer 1

1. epithelial- lines the outer surface of organs and blood vessels
2. muscular
3. epidermal - e.g. skin and waxy covering of plants

Question 2

What is the digestive system made up of?

Answer 2

1. glands( salivary glands and pancreas)- produce digestive juices containing enzymes
2. oesophagus- carries food to the stomach
3. the stomach- produces hydrochloric acid
4. small intestine- where soluble molecules are absorbed into the blood
5. liver- produces bile which is stored in the gall bladder
6. large intestine- absorbs water from undigested food to produce faeces
7. rectum/anus - get rid of waste products

Question 3

What is the function of bile?

Answer 3

Bile is an alkaline to neutralise hydrochloric acid from the stomach and it emulsifies fat to form small droplets (increases the surface area)

Question 4

What is an enzyme?

Answer 4

a biological catalyst made of proteins (a substance that speeds up the rate of reaction without being used up)

Question 5

Explain the lock and key model

Answer 5

• Enzymes are specific so the shape of the active site is complementary to the shape of the substrate
• Once these two are bound, the reaction takes place

Question 6

What are the three types of enzymes involved in the digestive system? What are their functions?

Answer 6

Carbohydrase- break down carbohydrates into simple sugars

Protease- break down proteins into amino acids

lipase- break down lipids into glycerol and fatty acids.

Question 7

Where are the following enzymes made:
a)amylase
b)protease
c)lipase

Answer 7

• amylase- salivary glands, small intestine, pancreas
• protease- stomach, pancreas, small intestine
• lipase- small intestine, pancreas

Question 8

 How does temperature affect enzyme activity?

Answer 8

at low temperatures there is not enough energy so as the temperature increases, the rate of enzyme activity increases. Once it reaches its peak it is at the optimum temperature so after this temp, the enzyme is denatured

Question 9

How does pH affect enzyme activity?

Answer 9

As pH increases so does the rate of enzyme activity until it reaches the optimum pH. A continued increase in pH would result in a sharp decrease as the enzyme is denatured

Question 10

Why is the circulatory system a double circulatory system?

Answer 10

blood is pumped from the heart twice.
1. (once from the right ventricle to the lungs= pulmonary circulation
2. once from the left ventricle to the rest of the body= systemic circulation)

Question 11

What is the circulatory system made up of?

Answer 11

• vena cava- carries deoxygenated blood from the body into the right atrium
• right atrium- top chamber on the right side
• valve- between right atrium and ventricle
• right ventricle- bottom chamber on the right side
• pulmonary artery- carries the deoxygenated blood from the right ventricle to the lungs
• lungs- gaseous exchange happens (alveoli)
• pulmonary vein- carries oxygenated blood from the lungs into the left atrium
• left atrium- top chamber on the left side
• valve- between the left atrium and ventricle
• left ventricle- bottom chamber on the left side
• aorta- pumps blood to the body

Question 12

Why does the left side of the heart have much thicker walls?

Answer 12

the left side has to pump blood to the rest of the body at a much longer distance

Question 13

What are the three blood vessels and their functions?

Answer 13

Arteries - carry hight pressured oxygenated blood away from the heart

veins - carry low pressure deoxygenated blood to the heart

Capillaries - carry blood close to cells so substances can be exchanged

Question 14

Describe the structure of an artery

Answer 14

• thick outer walls and elastic tissue
• narrow central lumen
• high blood pressure

Question 15

Describe the structure of a vein

Answer 15

• thin outer walls and elastic tissue
• wide central lumen
• valves to prevent the backflow of blood
• low pressure

Question 16

Describe the structure of a capillary

Answer 16

• one cell thick (rapid diffusion)
• thin moist walls

Question 17

What is a pacemaker?

Answer 17

a group of cells located in the right atrium that controls the natural resting heart rate

Question 18

What are the components of blood?

Answer 18

red blood cells- carry oxygen

white blood cells- part of the immune system

platelets- fragments of cells that help with blood clotting (e.g. a cut)

plasma- the liquid part of the blood that contains useful substances such as glucose, amino acids, minerals as well as waste products(urea)

Question 19

How are red blood cells adapted for their function?

Answer 19

• biconcave shape- increases surface area
• no nuclei- more space for haemoglobin to carry oxygen

Question 20

What are risk factors of cardiovascular disease?

Answer 20

• a diet high in saturated fat
• a diet high in salt
• physical inactivity
• smoking( damages the lining of arteries, CO reduces the amount of oxygen, nicotine increases the heart rate which puts strain on the heart)

Question 21

What is coronary heart disease?

Answer 21

A non-communicable disease where layers of fatty deposits build up inside the coronary arteries and narrows them. This reduces blood flow the arteries and consequently results in a lack of oxygen for the heart

Question 22

What two methods can be used to combat coronary heart disease?

Answer 22

1. stents- a metal tube which mechanically keep the coronary arteries open
2. statins- medication that reduces the blood cholesterol levels

Question 23

Give disadvantages of using stents

Answer 23

• risk of bleeding, heart attack or stroke
• the patient must control their blood cholesterol after

Question 24

Give disadvantages of using statins

Answer 24

they must be taken long-term to prevent the cholesterol levels from rising

Pills have to be taken everyday - could forget to take them

Unwanted symptoms

Question 25

What are the consequences of faulty valves and how can this be solved?

Answer 25

- could restrict blood flow through the heart - allow the backflow of blood - biological valves can be used(more likely to wear out.) - mechanical valves can be used(last longer but blood can clot on them)

Question 26

Give examples of communicable diseases

Answer 26

- malaria - mumps - HIV - flu

Question 27

Give examples of non-communicable diseases

Answer 27

type 2 diabetes Lung cancer

Question 28

How might different types of diseases interact?

Answer 28

- defects in the immune system mean that an individual is more likely to suffer from infectious diseases - severe physical ill health can lead to depression and other mental illness - viruses living in cells can be a trigger for cancer

Question 29

What is a risk factor and give examples of lifestyle risk factors

Answer 29

A risk factor is anything that increases the likelihood of an individual suffering from a disease. 1. smoking 2. alcohol consumption 3. diet 4. amount of exercise

Question 30

Give examples of environmental risk factors

Answer 30

- overexposure to UV light - exposure to toxic chemicals

Question 31

What are the risks of smoking whilst pregnant?

Answer 31

- increased risk of of experiencing problems e.g. miscarriage, foetal death and premature labour - babies are then at increased risk of low birth weight, limb deformities, sudden infant death syndrome

Question 32

What are the two types of tumours and how do they differ?

Answer 32

malignant tumour- grow quickly, invade neighbouring tissues and spread to different parts of the body to form secondary tumours (cancerous) benign tumours- slow growths of abnormal cells which are contained in one area (non-cancerous)

Question 33

What is a tumour?

Answer 33

a lump of cells formed as a result of uncontrolled cell division

Question 34

The structure of a leaf

Answer 34

- **waxy cuticle** - a waxy layer that protects the leaf and reduces water loss - **upper epidermis** → no chloroplasts and allow light to pass through - **palisade mesophyll layer** → adapted to absorb light efficiently (packed with chloroplasts, column-shaped and arranged closely together, towards the upper surface of the leaf - **spongy mesophyll tissue** → packed loosely for efficient gas exchange - **air space**- allows gases to circulate the leaf - **guard cell**- found in pairs and control the opening and closing of the stoma - **stoma** → a pore on the underside of the leaf which allows gases to diffuse in and out of the leaf

Question 35

What is the function of the phloem and how is it adapted for the function?

Answer 35

Phloem tissue transports dissolved sugars from the leaves to the rest of the plant - made up of tubes of elongated cells - cell sap can move from one phloem cell to the next through pores in the end walls - active (direction= upwards and downwards)

Question 36

What is translocation?

Answer 36

the transport of dissolved sugars/nutrients within a plant through the phloem

Question 37

What is transpiration? Explain the transpiration stream

Answer 37

the loss of water from leaves by evaporation through the stomata. water evaporates from leaves → causes a shortage of water in the plant → water is drawn from the roots through the xylem to replace the lost water

Question 38

What factors affect the rate of transpiration?

Answer 38

- **temperature**- the warmer it is, the faster the transpiration happens because the water particles have more energy (to evaporate and diffuse out of the stoma) - **humidity**- (low humidity) the drier the air around a leaf the faster transpiration happens because their is a greater concentration gradient - **light intensity**- the brighter the light the greater the rate of transpiration because the stoma closes as it gets darker (to reduce the loss of water) - **airflow**- the better the airflow around a leaf the greater the transpiration rate because it increases the concentration gradient