Coordination

Question 1

Why do organisms need to respond to change and what are the two types of changes

Answer 1

espond to changes in the internal or external environment (stimuli) for survival
There are two types of response: chemical and nervous

Question 2

What is nervous change and who is responsible for it

Answer 2

nervous system is responsible for nervous change it allows the body to respond to stimuli in the internal and external environment and is coordinated by the brain and / or spinal cord

Question 3

What is chemical change and who is responsible for it

Answer 3

The endocrine system is responsible for chemical change it also allows the body to respond to stimuli in the external and internal environment and is coordinated by glands throughout the body

Question 4

What is homeostasis and why is it required with examples and

Answer 4

Homeostasis is the maintenance of a constant internal environment
It necessary to maintain optimal conditions for all cell function throughout the body
1.blood glucose concentration
2.body temperature
3.water levels

Question 5

What do all control systems have and their function

Answer 5

1. Receptors = detect stimuli (a sound, an image, a change in pressure on the skin, paind, a change in body temperature etc)
2. Coordination center = the brain, spinal cord, pancreas or pituitary gland, which receives and processes information from receptors around the body
3. Effectors = bring about response which restore optimum levels such as core body temperature or react to stimulus to prevent harm. Effectors include muscles and glands. and responses include muscle contractions or hormone release.

Question 6

What stimuli do plants respond to and how and where can they grow and what are the changes know as

Answer 6

1. respond to light, water, gravity.
2. are usually much slower than animals and by producing a growth hormone called auxin which controls the direction of growth of roots or stems.
3. towards a stimulus (known as a positive response) or away from a stimulus (known as a negative response), and changes known as tropisms

Question 7

What is the name of the responses to gravity ligth and water stimuli

Answer 7

gravity : geotropism
light : phototropism
water : hydrotropism

Question 8

Describe the geotropic and phototropic responses of roots and stems

Answer 8

• very important to a plant that its roots and shoots grow in the right directions
  1. Shoot must grow upwards, away from gravity towards light therefore is known as positive phototropism and negative geotropism
  2. Roots need to grow downwards away from light and towards gravity therefore is known as negative phototropism and positive geotropism.

Question 9

What is the role of auxin in the phototropic response of stems and how does it work

Answer 9

*auxin : role of auxin in the phototropic response of stems
it mostly made up in growing stems and roots and can diffuse to other parts of the stems or roots.
1. Auxin make the cells behind tip get longer, more the auxin the faster they will grow.
2. If light is shining on plant the auxin is distributed evenly so all cells grow at same rate.
3. if light is shining more on one side, the auxin in the tip concentrates on the shady side, making the cells on that side grow faster than the cells on the sunny side
4. the unequal growth will result to the plant bending towards one side.

Question 10

Investigating phototropic responses if tips have been removed

Answer 10

reason: This proves auxin is made in the tips, and if the seedling still grows towards light auxin is made elsewhere.
effect on auxin concentration: no auxin is produced
Result: The stems don’t grow longer.

Question 11

Investigating phototropic responses if no light reaches tips

Answer 11

reason: Proves it is the effect of light on auxin that causes phototropism
effect on auxin concentration: equal concentration of auxin on both sides
result: The stems grow evenly and longer on both sides.

Question 12

Investigating phototropic responses if more light reaches side of the tips

Answer 12

reason: This proves that shoots grow towards the light
effect on auxin concentration: Greater concentration of auxin on the shaded side
result: Cells on darker side grow of the stems grow longer.

Question 13

What are the two main methods of transmitting information around the body and controlling responses:

Answer 13

the nervous system and via the endocrine system

Question 14

What does the nervous system consist of, the type of message it sends, method of transmission, effectors, speed of transmission and length of effect

Answer 14

made of:
central nervous system (CNS) = Brain spinal cord 
perpheral nervous system (PNS) = Nerves
 type of message: electrical impulse 
method of transmission: nerve cells 
effectors: muscles or glands
speed of transmission: very fast
length of effect: Short- until nerve impulses stop

Question 15

What does the endocrine system consist of, the type of message it sends, method of transmission, effectors, speed of transmission and length of effect

Answer 15

made of: glands
type of message: Chemical hormone
method of transmission: Bloodstream
effectors: target cells in specific tissue
speed of transmission: slower
length of effect: Longer- until hormone is broken down

Question 16

What are nerve cells called and what is a nerve and what are three main types of neurone

Answer 16

1.Nerve cells are called neurones
2.A bundle of neurones is called a nerve
There are three main types of neurone: sensory, relay and motor

Question 17

Function of sensory, relay and motor neurone

Answer 17

1. Sensory neurones carry impulses from sense organs to the CNS
2. Relay neurones are found inside the CNS and connect sensory and motor neurones
3. Motor neurones carry impulses from the CNS to effectors

Question 18

What is an receptor, what do they do and what are sense organs

Answer 18

1. Receptors are groups of specialised cells
2. They detect a change in the environment and stimulate electrical impulses in response
3. Sense organs contain groups of receptors that respond to specific stimuli

Question 19

What are the different sense organs and what do they sense and how

Answer 19

1. skin: Sensitive to pressure, heat and cold temperature and pain. Sensed by touch and temperature
2. Tongue: Chemicals in food and drink, sensed by taste
3. Nose: Chemicals in air, sensed by smell.
4. Ear: Sound and movement, sensed by hearing and movement
5. Eye sensitive to light, sensed by sight.

Question 20

What happens when a cell in the receptor has been stimulated?

Answer 20

1. Once the cell has been stimulated it generates an electrical impulse
2. The electrical impulse is passed to sensory neuron that carries it to the CNS
3. Here a response would have been decided and the impulse will be passed to the motor neuron via relay neurone
4. The motor neurone carries the impulse to the effector
5. Effector carries out the change
   * pathway is extremely fast so the response is rapid because of the adaptation of neurones to allow for fast transmission of impulses.

Question 21

What is structure of a nerve cell. adaptations of the cell and the result of it.

Answer 21

1. Have long fibre called axon
   * therefore less time is wasted transferring the impulse from one cell to another.
2. Axon is insulated by fatty sheath with small uninsulated sections called nodes
   * therefore electrical impulse does not travel down the whole axon, but jumps from one node to the next
3. Axon cell body may contain dendrites
   * Allows them to connect to many other neurones receive impulses from them, forming a network for easy communication.

Question 22

What is a synapse, and what’s their role

Answer 22

Neurones never touch each other, the junctions ( gaps) in between them are called synapses.
They ensure the electrical impulses all travel in one direction.

Question 23

What is a neurotransmitter

Answer 23

Chemical messengers that transmit a message from a nerve cell across the synapse to a target cell.

Question 24

How do neurotransmitter work?

Answer 24

1. Once the electrical impulse hits the end of nerve it causes release of some chemicals.
2. These chemicals diffuse into the next nerve cell and bind with receptor molecules.
3. stimulates the second neurone to generate an electrical impulse that travels down the second axon
4. The transmitter are destroyed in first to prevent continued stimulation of the second neurone which would cause repeated impulses to be sent.

Question 25

What is a reflex, what 3 types of reflex are there and what’s the function of reflexes.

Answer 25

Reflex is an involuntary response that doesn’t involve the brain as the coordinator of the reaction and you don’t realise you have done it until it’s been carried out
Reflexes are automatic, fast or protective.
Reflexes helps to minimise the damage to the body.

Question 26

State the reflex pathway

Answer 26

Stimulus 
Receptor
Sensory neurone
relay neurone
motor neurone 
effector 
response

Question 27

Example of an reflex action. ( stepping on a pin)

Answer 27

1. The stimulus is detected by a pain receptor in the skin
2. Sensory neurone sends electrical impulse to the spinal cord ( coordinator)
3. Electrical impulse is passed on to relay neurone in the spinal cord
4. Relay neurone connects to motor neurone and passes impulse.
5. Motor neurone carries impulse to the muscle in the leg (the effector)
6. The muscle will contract and pull the leg up and away from the sharp object (the response)