B1 - Controlling Body Temperature, Glucose and Plant Growth

Question 1

When will your cells not function well? Why is this?

Answer 1

If you body

• is the wrong temperature
• does not have the right amount of water
• has too much carbon monoxide in the blood

This is because the enzymes cannot work properly

Question 2

How can you measure body temperature?

Answer 2

• a clinical thermometer, in the ear or mouth
• temperature - sensitive strips on the forehead
• digital recording probes on a finger, linked to a computer

Question 3

What are the temperature limits of the human body? What happens if these are crossed?

Answer 3

• above 40°C you will get heat stroke and dehydration. If this is not treated , you may die.
• Below 35°C your body hypothermia and if not treated this also leads to death

Question 4

How does the body gain heat in cold conditions?

Answer 4

• respiration in cells releases some energy as heat
• shivering ( muscles contracting ) generates heat
• less blood flows near the skin surface ( vasoconstriction )
• Exercise generates heat because muscles need to respire more to contract more
• Wearing more clothes insulates the body

Question 5

How does the body lose heat in hot conditions?

Answer 5

• More blood flows near the skin surface and gives off heat to the environment ( vasodilation )
• More sweating. The water in sweat evaporates. This takes heat from the skin and transfers it to the environment
• Wearing fewer clothes allows heat loss

Question 6

Describe how negative feedback works

Answer 6

• the level changes away from steady
• sense organs in your body detect the change
• they send information to a control centre in the brain
• this sends information back to particular body structures
• threat sets processes in motion that redress the balance and bring the level back to steady

Question 7

What are hormones? How do they work?

Answer 7

They are chemicals. They are secreted from glands into the bloodstream and travel to target organs where they regulate the functions of many organs and cells. They also coordinate many processes in the body.

Question 8

How does insulin regulate blood glucose level?

Answer 8

If there is too much glucose in the blood:
the pancreas secretes insulin which travels in the blood to the liver and makes the liver take up the extra glucose and change it to another carbohydrate called glycogen. This is a way of storing energy.

Question 9

What is this cause of type 1 diabetes and how is it controlled?

Answer 9

Cause - the persons own immune system has destroyed the cells in the pancreas that make insulin

Method of control - controlled with insulin injections at mealtimes. Patients should also eat a balanced diet and take exercise.

Question 10

What is the cause of type 2 diabetes and how is it controlled?

Answer 10

Cause - occurs in later life. It may be linked with being overweight. The persons own cells do not respond to insulin and their pancreas may also not make enough insulin.

Method of control - may be controlled by eating a balanced diet with more fibre and less sugar. People may also take medicine to make their pancreas make more insulin. In some cases they may need insulin injections.

Question 11

Why does exercise help diabetes?

Answer 11

Some excess glucose in the body is converted to energy during exercise. Th amount of insulin a person needs to inject depends on how much sugar they eat and how active they are.

Question 12

What do plant hormones control?

Answer 12

• the growth of shoots and roots
• flowering
• ripening of fruits

Question 13

Why are plants positively phototropic?

Answer 13

• they make a plant hormone called auxin and this moves through the plant in solution.
• When light strikes one side of the shoot tip , more auxin builds up on the other side of the shoot tip which causes the shoot to bend over, towards the light
• this increases the plants chance of survival because it needs light to photosynthesis and make food.

Question 14

How does auxin make the shoot bend?

Answer 14

Auxin is made in the shoot tip and is unevenly distributed when the shoot is exposed to the light from one side. This auxin moves down the stem and causes cells on the side of the shoot further from the light to elongate more than those nearest the light.

Question 15

What are some uses of auxin?

Answer 15

• Weed killers
• rooting powder > if cuttings are dipped into auxin powder, this helps the cuttings make new roots, which means they can anchor in soil and take up water and minerals
• fruit ripening > auxin can be sprayed into fruit trees to prevent the ripe fruit from dropping.
• control of dormancy > seeds are usually dormant when they are shed from the parent plant. Applying auxin can break the dormancy.