14) Coordination and response (1.4, 2.2, 3.2/5)

Question 1

1.1 What do electrical impulses travel along?

Answer 1

Neurones

Question 2

1.2. Describe the mammalian nervous system

Answer 2

CNS (brain, spinal cord) and PNS (spinal cord, nerves outside brain)

Question 3

1.3. Describe the role of the nervous system

Answer 3

Coordination and regulation of bodily functions
Sensitivity: ability to detect and respond to changes in the internal and external environment

Question 4

1.4. Identify the parts of neurones

Question 5

1.5. Describe a simple reflex arc

Answer 5

Stimulus -> receptor -> sensory neurone -> relay neurone -> motor neurone -> effector

Question 6

1.6. Describe a reflex action

Answer 6

Automatically and rapidly integrating and coordinating and stimuli with the response of effectors (muscles and glands)

Question 7

1.7. Describe a synapse

Answer 7

A junction between two neurones

Question 8

1.8. Describe the structure of a synapse

Answer 8

Vesicles in presynaptic bulb contain neurotransmitters

Synaptic gap separates neurones

Receptors in the postsynaptic membrane specific for neurotransmitter

Question 9

1.9. Events at a synapse

Answer 9

1. An impulse travels down the axon of a neurone and arrives at the synaptic bulb
2. It stimulates the vesicles to release neurotransmitters into the synaptic gap
3. Neurotransmitters diffuse across the synaptic gap
4. They bind with receptors at the postsynaptic membrane
5. An impulse is stimulated in the next neurone

Question 10

1.10. What is the function of synapses?

Answer 10

To ensure that impulses travel in one direction only

Question 11

2.1. Describe sense organs

Answer 11

A group of receptor cells that respond to specific stimuli (light, touch, sound, temperature, chemicals)

Question 12

2.2. Structure of the eye

Question 13

2.3. Describe the functions of each part of the eye

Answer 13

Cornea: refracts light
Iris: controls how much light enters pupil
Lens: focuses light onto retina
Retina: Contains light receptors, sensitive to light of all colours
Optic nerve: Carries impulses to the brain

Question 14

2.4. Explain the pupil reflex in terms of pupil diametre

Answer 14

Pupil constricts in bright light to protect the retina and dilated in the dark to protect us from not seeing objects

Question 15

2.5. Explain the pupil reflex in terms of antagonistic action

Answer 15

Radial muscles and circular muscles - antagonist muscles (when one contracts, the other relaxes)

Dark: Radial contract, circular relax, more light
Light: Radial relax, circular contract, less light

Question 16

2.6. Explain accommodation to view near and distant objects

Answer 16

Near: ciliary muscles contract, causing suspensory ligaments to loosen, lens becomes fatter and more light is refracted

Far: ciliary muscles relax, causing suspensory ligaments to tighten, lens become thinner and less light is refracted

Question 17

2.7. Describe the distribution of cone and rod cells in the retina

Answer 17

Found all over retina except blind spot where the optic nerve attaches to the retina

No rod cells in fovea, has the most cone cells

Question 18

2.8. Describe the function of rods and cones

Answer 18

Rods: night vision
Cones: colour vision

Question 19

2.9. State the function of the fovea

Answer 19

Where you can see in the best detail (most cone cells)

Question 20

3.1. Describe a hormone

Answer 20

A chemical substance secreted by a gland and carried by the blood that affects one or more specific target organs

Question 21

3.2/5. Identity in diagrams specific endocrine glands

Question 22

3.3/6. Describe adrenaline

Answer 22

The hormone secreted by the adrenal gland in “fight or flight” situations

Can cause increased breathing rate, heart rate, blood glucose concentration, pupil diametre

Question 23

3.4. Compare nervous and hormonal control

Answer 23

Nervous system faster speed of action but shorter duration of effect (electrical vs chemical)

Question 24

4.1. Describe homeostasis

Answer 24

The maintenance of a constant internal environment

Question 25

4.2/4. Describe the control of blood glucose concentration by the liver

Answer 25

Insulin is produced in the pancreas when blood glucose rises and stimulates the liver to convert excess glucose into glycogen to be stored

Glucagon is produced in the pancreas when blood glucose falls and stimulates the liver and muscles to convert stored glycogen into glucose

Question 26

4.3. Describe negative feedback

Answer 26

Occurs when conditions change from an ideal set point and returns conditions back to the set point

Question 27

4.5. Outline the treatment of Type 1 diabetes

Answer 27

Injecting insulin into the patient
Taking blood glucose tests, controlling blood glucose level through exercise and diet

Question 28

4.7. Describe the maintenance of a constant internal body temperature in mammals

Answer 28

Brain contains receptors sensitive to blood temperature

Skin has temperature receptors, sends impulses to the brain via sensory neurones

Brain sends nerve impulses to effectors to maintain the optimum temperature

Fatty tissue acts as insulation

Sweat secreted when hot so the body loses heat energy as it evaporates

Hairs lie flat to let air circulate, increasing heat transfer to environment by radiation

Skeletal muscles contract rapidly and causes shivering. These involuntary contractions need energy from respiration, and some is released as heat

Erect hairs to trap a layer of air around the skin for insulation

Question 29

4.8. Describe vasodilation and vasoconstriction of arterioles

Answer 29

Vasoconstriction: arterioles get narrower, blood flow in capillaries slower, reduces amount of blood flowing through skin surface and heat lost by radiation

Vasodilation: arterioles get wider, blood flow in capillaries faster, increases amount of blood flowing through skin surface and heat lost by radiation

Question 30

5.1. Describe gravitropism

Answer 30

A response in which plants grow towards (positive) or away (negative) from gravity

Question 31

5.2. Describe phototropism

Answer 31

A response in which plants grow towards (positive) or away (negative) from light

Question 32

5.3. Investigate and describe gravitropism and phototropism in shoots and roots

Answer 32

Shoots: positive phototropism, negative gravitropism
Grow upwards for more light and photosynthesise and grow more

Roots: negative phototropism, positive gravitropism
Grow downwards into soil, absorb water and minerals and anchor the plant

Question 33

5.4/5. Explain phototropism and gravitropism of a shoot and the role of auxin in controlling shoot growth

Answer 33

1. Auxin is produced in the apical meristem at the shoot tip
2. It diffuses to the plant towards (a side)
3. Auxin is unevenly distributed in response to light/gravity
4. Auxin stimulates cell elongation
5. (Side) becomes longer and causes the shoot to bend