Homeostasis

Question 1

Describe how the structures shown in Figure 2 help to coordinate a reflex action.

Answer 1

receptor detects stimulus
neurones conduct impulses / electrical signals
neurone A = sensory neurone
neurone B = relay neurone
neurone C = motor neurone
effector carries out response

Question 2

Describe the difference between the function of a receptor and the function of an effector. In your answer you should give one example of a receptor and one example of an effector

Answer 2

receptors detect / sense stimuli / change in surroundings
example of a receptor (eye)
effectors allow / make response (brain, spinal cord)
(effector) muscle / gland (arm, leg)

Question 3

A man and a woman decide to use the condom as their method of contraception. Suggest three reasons for this decision.
Use information from the table above and your own knowledge.

Answer 3

more reliable than diaphragm / spermicidal cream
low chance of pregnancy
no side effects

Question 4

Insulin acts on an organ called the _______. This organ then takes in excess glucose from the blood and changes the glucose into _________.

Answer 4

liver
glycogen

Question 5

A person is at risk of developing Type 2 diabetes.
Suggest two ways the person could lower the chance of developing Type 2 diabetes.

Answer 5

lose weight or maintain a healthy weight
(more) exercise

Question 6

Describe how the oral contraceptive pill stops a woman becoming pregnant.

Answer 6

inhibits FSH production / release
* prevents egg maturation / growth
* prevents ovulation

Question 7

Development of the female secondary sex characteristics is controlled by ____________ . Sperm production is stimulated by _____________ .

Answer 7

oestrogen
testosterone

Question 8

Many functions of the human body are controlled by chemicals called hormones. What is a hormone?

Answer 8

a (chemical) messenger
made by the endocrine system
affects (a) specific / target organ(s)
released into the blood

Question 9

Explain how negative feedback controls the blood glucose concentration during the first one and a half hours after the meal.

Answer 9

increase in blood glucose
glucose detected by pancreas
pancreas secretes insulin
(insulin causes) glucose to move (out of blood) into cells / liver
liver converts glucose to glycogen
causing a fall in blood glucose
low blood glucose detected by pancreas
pancreas releases glucagon
liver converts glycogen to glucose (which enters blood)
blood glucose rises

Question 10

A plant hormone is made in the root tip. The hormone diffuses from the tip into the tissues of the root. Explain how the hormone causes the appearance of the seedlings in Figure 2 to be different. You should refer to both seedlings in your answer.

Answer 10

uneven distribution of hormone in (root / seedling of) A
even distribution of hormone in B
(so) top grows fast(er) in (root / seedling of) A (and equal growth in B)

Question 11

Shoot A bent towards the light as it grew. Explain how.

Answer 11

reference to auxin / hormone
unequal (lateral) distribution
more hormone on dark side
causes growth on dark side

Question 12

Plants respond to different environmental factors.
Describe how different environmental factors affect:
* the direction of growth of roots
* the direction of growth of shoots.
In your answer you should refer to the role of plant hormones.
Do not refer to the artificial use of plant hormones by gardeners or scientists.

Answer 12

environmental factors:
-light (phototropism)
-gravity (gravitropism / geotropism)
-moisture / water (hydrotropism)