Unit 1: 2 - Responding to Change

Question 1

What do receptors do?

Answer 1

Detect stimuli.

Question 2

Where are receptors found?

Answer 2

In sense organs (Eyes, ears, nose, tongue and skin).

Question 3

How do signals from receptors arrive at the brain?

Answer 3

Electrical impulses from the receptors pass to the brain along neurons (nerve cells).

Question 4

What do the brain and spinal cord form?

Answer 4

The central nervous system (CNS).

Question 5

What do sensory neurons do?

Answer 5

Carry impulses from receptors to the CNS.

Question 6

What do motor neurons do?

Answer 6

Carry impulses from the CNS to effector organs (which may be muscles or glands. The muscles respond by contracting, the glands respond by secreting chemicals).

Question 7

Giev the 6 main steps involved in reflex actions.

Answer 7

• A receptor detects a stimulus (e.g. a sharp pain);
• A sensory neuron transmits the impulse to the CNS;
• A relay neuron passes the impulse on across synapses;
• A motor neuron is stimulated;
• The impulse passes to an effector (muscle or gland);
• Action is taken (the response).

Question 8

What are synapses and why sre they needed?

Answer 8

They are gaps in which chemicals travel across between neurons. These are needed to stop signals bouncing back.

Question 9

What is FSH, where is it made and what does it do?

Answer 9

Follicle Stimulating Hormone is made in the pituatry gland and causes eggs to mature.

Question 10

What is oestrogen, where is it made and what does it do?

Answer 10

Oestrogen is a hormone made in the ovaries, and inhibits the further production of FSH.

Question 11

What is LH, where is it made and what does it do?

Answer 11

Luteinising hormone is made by the pituitary gland and stimulates ovulation.

Question 12

What hormones does the contraceptive pill (oral contraceptive) contain?

Answer 12

Oestrogen and progesterone (some pills are progesterone-only and have fewer side effects).

Question 13

Give at least 2 advantages and at least 2 disadvantages of fertility treatment.

Answer 13

Question 14

Why must we keep a constant bobdy temperature of 37° Celcius?

Answer 14

So our enzymes work properly, else they would work inefficiently or not at all.

Question 15

What organ controls the levels of sugar in our blood?

Answer 15

The pancreas.

Question 16

What is phototropism?

Answer 16

Where plant shoots grow towards the light.

Question 17

What is gravitropism (or geotropism)?

Answer 17

When plant roots grow towards gravity.

Question 18

What substance do roots grow towards?

Answer 18

Water.

Question 19

What is auxin?

Answer 19

The hormone that controls phototropism and geotropism.

Question 20

What does unequal distrobution of auxin cause?

Answer 20

Unequal growth, which bends the shoot or root.

Question 21

The root grows more on the side with …

Answer 21

The least auxin.

Question 22

The shoot grows on the side with …

Answer 22

The most auxin.

Question 23

Give 2 agricultural uses for hormones.

Answer 23

Encouraging roots to grow from cuttings, and to encourage fruit to ripen.