Co-ordination And Response

Question 1

What are the two communication systems in mammals

Answer 1

Nervous system
Endocrine system

Question 2

What are physiological factors controlled by homeostasis in mammals

Answer 2

Core body temp
Metabolic waste
Blood pH
Concentration of glucose in blood
Water potential of blood
Concentration of respiratory gases

Question 3

What is homeostasis

Answer 3

the control or regulation of the internal conditions of a cell or organism

Question 4

What are some cooling mechanisms in humans?

Answer 4

1. Vasodilation of skin capillaries
2. Sweating
3. Flattening of hairs

Question 5

What are some Warming mechanisms in humans

Answer 5

1. Vasoconstriction of skin capillaries
2. Shivering
3. Erection of hairs

Question 6

SHOOTS - Phototropic/geotropic

Answer 6

As shoots grow upwards, away from gravity and towards light (so that leaves are able to absorb sunlight), shoots show a positive phototropic response and a negative geotropic response

Question 7

ROOTS - Phototropic/geotropic

Answer 7

As roots grow downwards into the soil, away from light and towards gravity (in order to anchor the plant and absorb water and minerals from the soil), roots show a negative phototropic response and a positive geotropic response

Question 8

What are auxins?

Answer 8

plant growth regulator that coordinate and control directional growth responses such as phototropisms and geotropisms

Question 9

Where are auxins produced?

Answer 9

produced in the tips of the shoots and the roots

Question 10

What effect do auxins have in shoots?

Answer 10

auxins promote cell elongation (growth); more auxin = more cell elongation = more growth

Question 11

What effect do auxins have in roots?

Answer 11

auxins inhibit cell elongation (growth); more auxin = less cell elongation = less growth

Question 12

How is the distribution of auxins determined?

Answer 12

If a shoot or root is placed on its side, auxins will accumulate along the lower side as a result of gravity; so the uppermost side has a lower auxin concentration

In the shoots, the lower side grows faster than upper side, so the shoot grows upwards
In the roots, the lower side grows slower than the upper side, so the root grows downwards

Question 13

How do auxins work?

Answer 13

Auxin is mostly made in the tips of growing shoots and then diffuses down to the region where cell division occurs

Question 14

Describe the role of auxin in phototropism

Answer 14

If light shines all around the tip, auxin is distributed evenly throughout and the cells in the shoot grow at the same rate

When light shines on the shoot predominantly from one side, the auxin produced in the tip concentrates on the shaded side, making the cells on that side elongate and grow faster than the cells on the sunny side
This unequal growth on either side of the shoot causes the shoot to bend and grow in the direction of the light

Question 15

NERVOUS VS ENDOCRINE: Parts of system

Answer 15

NERVOUS: Brain, spinal cord, neurones/ nerves

ENDOCRINE: Glands

Question 16

NERVOUS VS ENDOCRINE: Type of message

Answer 16

NERVOUS: electrical impulse

ENDOCRINE: Chemical hormone

Question 17

NERVOUS VS ENDOCRINE: Method of transmission

Answer 17

NERVOUS: Nerves/neurones

ENDOCRINE: Bloodstream

Question 18

NERVOUS VS ENDOCRINE: Effectors

Answer 18

NERVOUS: Muscles or glands

ENDOCRINE: Target cells in specific tissues

Question 19

NERVOUS VS ENDOCRINE: Speed of transmission

Answer 19

NERVOUS: Very fast

ENDOCRINE: Slower

Question 20

NERVOUS VS ENDOCRINE: Length of effect

Answer 20

NERVOUS: Short until electrical impulses stop

ENDOCRINE: Longer, until hormone is broken down.

Question 21

How are neurones adapted?

Answer 21

1. Many extensions called dendrites extend out from the cell body of the neurone and at the far end of the axon
2. This means neurones can connect to many other neurones and receive impulses from them, forming a network for easy communication

Question 22

Summarise the pathway through the nervous system.

Answer 22

stimulus → sensory neurone → relay neurone → motor neurone → effector → response

Question 23

Describe a reflex arc

Answer 23

1. The stimulus is detected by a receptor
2. A sensory neurone sends electrical impulses to the CNS (The coordinator)
3. An electrical impulse is passed to a relay neurone in the CNS
4. A relay neurone synapses with a motor neurone
5. A motor neurone carries an impulse to the effector
6. When stimulated by the motor neurone, a response will be produced by the effector.
   This all occurs within a fraction of a second

Question 24

How is an impulse passed along a synpase?

Answer 24

1. The electrical impulse travels along the first axon
2. This triggers the end of the presynaptic neurone to release chemical messengers called neurotransmitters from vesicles
3. The neurotransmitters diffuse across the synaptic cleft and bind with receptor molecules on the membrane of the second neurone
4. This stimulates the second neurone to generate an electrical impulse
5. The neurotransmitters are then destroyed to prevent continued stimulation of the second neurone
6. Synapses ensure that impulses only travel in one direction, avoiding the confusion that would be caused within the nervous system if impulses were able to travel in both directions

Question 25

What happens to the ciliary muscles, suspensory ligaments and lens when an object is close up?

Answer 25

The ciliary muscles contract
suspensory ligaments loosen
lens becomes fatter
Light is refracted more

Question 26

What happens to the ciliary muscles, suspensory ligaments and lens when an object is far away?

Answer 26

The ciliary muscles relax
suspensory ligaments tighten
Lens becomes thinner
Light is refracted less

Question 27

What happens to the pupil in dim light?

Answer 27

• Radial muscles CONTRACT
• Circular muscles RELAX
• Pupil DILATES

Question 28

What happens to the pupil in bright light?

Answer 28

Radial muscles RELAX
Circular muscles CONTRACT
Pupil CONSTRICTS

Question 29

Describe the role of sweating

Answer 29

This cools the skin by evaporation which uses heat energy from the body to convert liquid water into water vapour

Question 30

Describe the role of flattening hairs

Answer 30

The hair erector muscles in the skin relax, causing hairs to lie flat
This stops them from forming an insulating layer by trapping air and allows air to circulate over skin and heat to leave by radiation

Question 31

Describe the role of shivering

Answer 31

This is a reflex action in response to a decrease in core body temperature
Muscles contract in a rapid and regular manner
The metabolic reactions required to power this shivering generate sufficient heat to warm the blood and raise the core body temperature

Question 32

Describe the role of erection of hairs

Answer 32

The hair erector muscles in the skin contract, causing hairs to stand on end
This forms an insulating layer over the skin’s surface by trapping air between the hairs and stops heat from being lost by radiation

Question 33

Adrenaline and how it prepares the body for action

Answer 33

1. An increase in heart rate and breathing rate - ensures glucose and oxygen can be delivered to muscle cells at faster rate
2. Diverting blood flow towards muscles and away from non-essential parts of the body such as the alimentary canal - ensures an increased supply of the reactants of respiration
3. Dilation of the blood vessels inside muscles - ensures more blood can circulate through them
4. Breaking down of stored glycogen to glucose in the liver and muscle cells ensures a higher blood glucose concentration for increased respiration in muscle cells