Co-ordination and Response CHECK ALL

Question 1

What is homeostasis?

Answer 1

The maintenance and self-regulation of a constant internal environment

Question 2

Which physiological factors are controlled in mammals through homeostasis?

Answer 2

Body temperature
Water concentration
Glucose concentration
Blood pH
Levels of metabolic waste in blood
Carbon dioxide concentration

Question 3

What are the four things which a co-ordinated response requires?

Answer 3

A stimulus (e.g. change in body temperature)
A receptor (e.g. receptor cells)
A co-ordination centre (e.g. brain or spinal chord which receives and processes information from receptors
An effector (e.g. muscle shivering) which brings about the response

Question 4

What is the difference between a phototrophic response and a geotrophic response in plants?

Answer 4

A photrophism is a directional growth-response to the stimulus of light
A geotrophism is a directional growth-response to the stimulus of gravity

Question 5

What are the phototrophisms which happen in plants and are the responses positive or negative?

Answer 5

Plants will grow their leaves towards the sun (to absorb more light for photosynthesis), this is a positive photrophism
Plants will grow their roots into the soil away from the sun, this is a negative phototrophism

Question 6

What are the geotrophisms which happen in plants and are the responses positive or negative?

Answer 6

Plants grow their shoots up against gravity, this is a negative geotropism
Plants will grow their roots down (to anchor the plant and absorb nutrients), with gravity, this is a positive geotropism

Question 7

What is auxin and what are its effects on plants?

Answer 7

Auxin is a growth regulator (similar to a hormone) which coordinates growth responses such as geotropisms and phototropisms
In shoots, auxin promotes cell elongation (so growth), in roots, auxin inhibits cell elongation (so less growth)

Question 8

What determines auxin distribution in a plant and what happens to the plant as a result of this distribution?

Answer 8

In shoots, gravity causes auxins to be more concentrated in the lower side of the shoot, therefore stimulating growth in this area and causing the shoot to grow upwards
Also in shoots, light will cause auxins to collect on the shady side, stimulating growth in this area and causing the shoot to bend towards the light
In roots, gravity causes auxins to be more concentrated on the lower side, which inhibits growth in this area meaning the upperside will grow faster, causing the root to bend downwards towards the nutrients

Question 9

What are the two control systems our body use to respond to stimuli?

Answer 9

The endocrine (hormonal) system
The nervous system

Question 10

How does the encdocrine (hormonal) system work generally?

Answer 10

Chemical substances known as hormones are produced and released by glands
These hormones are carried by the blood and circulate the whole body
The are received by specific receptors and instigate a change on the target organ

Question 11

What does the central nervous system consist of?

Answer 11

The brain
The spinal chord

Question 12

What is the central nervous system linked to and what does that consist of?

Answer 12

It is linked to the peripheral nervous system
It contains all the nerves in the body

Question 13

What are the three types of neurones?

Answer 13

Sensory
Relay
Motor

Question 14

How does the nervous system work to carry out a response?

Answer 14

A stimulus is received by sensory neurones (in nerves)
When stimulated, the sensory neurone produces an electrical signal which travels along other sensory neurones (in nerves) to the co-ordinator (spinal chord or brain)
In the CNS, the electrical impulse is transferred to a relay neurone
The relay neurone links to a motor neurone, and along motor neurones the impulse travels until it reaches the effector, e.g. a muscle

Question 15

Why are neurotransmitters needed?

Answer 15

The neurones do not come into direct compact to eachother, instead, the junction where the dendrites meet is called a synapse (where there is a small gap between the neurones)
Since the electrical impulse cannot jump the gap, it is briefly converted into a chemical messenger known as a neurotransmitter

Question 16

How do electrical impulses pass from neurone to neurone?

Answer 16

Neurotransmitters are released and diffuse across the gap between neurones

Neurotransmitters are detected by receptor molecules on the second neurone

Another electrical impulse is released

Question 17

What is the cornea and what is its function?

Answer 17

The cornea is a transparent, dome-shaped layer at the front of the eye.
Its function is to refract (bend) light entering the eye and help focus it onto the retina.

Question 18

What is the iris and what is its function?

Answer 18

The iris is the colored part of the eye, made of muscles surrounding the pupil.
Its function is to control the size of the pupil, regulating the amount of light entering the eye.

Question 19

What is the lens and what is its function?

Answer 19

The lens is a transparent, flexible structure located behind the iris and pupil.
Its function is to focus light onto the retina by changing its shape to focus on objects at different distances.

Question 20

What is the retina and what is its function?

Answer 20

The retina is a layer of light-sensitive cells at the back of the eye.
Its function is to detect light and convert it into electrical signals, which are sent to the brain for visual processing.

Question 21

What is the optic nerve and what is its function?

Answer 21

The optic nerve is a bundle of nerve fibers that connects the retina to the brain.
Its function is to transmit electrical signals from the retina to the brain for visual processing.

Question 22

What is the pupil and what is its function?

Answer 22

The pupil is the circular opening in the center of the iris.
Its function is to allow certain amounts of light into the eye, dictated by the iris.

Question 23

How does the eye change when focusing on objects which are close up?

Answer 23

The ciliary muscles contract, causing the lens to become thicker and more curved.
This increases the lens’ refractive power, allowing it to focus light from close objects onto the retina.

Question 24

How does the eye change when focusing on objects which are far away?

Answer 24

The ciliary muscles relax, causing the lens to become thinner and less curved.
This decreases the lens’ refractive power, allowing it to focus light from distant objects onto the retina

Question 25

How does the eye change when we are in a low-light environment?

Answer 25

• In bright light the circular muscles relax and the radial muscles contract.
• This causes the pupil to dilate, increasing the volume of light entering the eye

Question 26

How does the eye change when we are in a light-abundant environment?

Answer 26

• In bright light the circular muscles contract and the radial muscles relax.
• This causes the pupil to constrict, reducing the light entering the eye and protecting the retina from damage.

Question 27

Where are the receptors and co-ordination centre for temperature?

Answer 27

Temperature receptors are located in the skin
The coordination centre for temperature regulation is the hypothalamus, which processes information from the receptors and triggers appropriate responses.

Question 28

What is the process of sweating and how does it help us to cool down?

Answer 28

• High temperature is detected, and sweat is released from pores in the skin
• Sweating increases heat loss when sweat evaporates from the skin surface.
• The evaporation of sweat transfers heat energy away from the skin.

Question 29

What is the process of vasodilation and how does it help us to cool down?

Answer 29

• Vasodilation is a cooling mechanism in which the diameter of skin arterioles increases.
• This increases blood flow to capillaries in the skin surface
• Thus transferring heat to the environment by radiation.

Question 30

What is the process of vasoconstriction and how does it help to warm us up?

Answer 30

• Vasoconstriction is a warming mechanism in which the diameter of skin arterioles decreases.
• This decreases blood flow to capillaries in the skin surface
• Thus reducing transfer of heat to the environment by radiation.

Question 31

What other involuntary temperature control methods do we have?

Answer 31

• Shivering
• Hair Erection

Question 32

What are the effects of adrenaline?

Answer 32

Prepares body for Fight or Flight

Increased heart rate

Increased breathing rate

Diversion of blood flow to muscles

Breaking down glycogen to release glucose

Question 33

What is the source, role and effect of insulin?

Answer 33

Source:
- Insulin is produced in the pancreas.
Role:
- Insulin helps regulate blood glucose levels by promoting the uptake of glucose into cells for energy or storage.
Effect:
- It lowers blood glucose levels by facilitating the conversion of glucose into glycogen for storage in the liver and muscles.

Question 34

What is the source, role and effect of ADH?

Answer 34

Source:
- ADH released by the posterior pituitary gland.
Role:
- ADH regulates water balance in the body by controlling the amount of water reabsorbed by the kidneys.
Effect:
- Increase in water retention: This leads to a decrease in urine output, concentrating the urine.