Communication and Homeostasis

Question 1

What are some processes that need to be controlled within the cell to survive?

Answer 1

1. Temperature levels
2. Suitable PH level
3. Aqueous environment
4. The removal of toxins.

Question 2

Why does temperature need to be controlled within the cell?

Answer 2

when temperature is too low there wont be enough kinetic energy for enzymes to form reactions as there wont be as many collisions. And if its too high then the enzymes will denature and therefor stop creating reactions.

Question 3

Why does the PH level need to be controlled within the cell?

Answer 3

Enzymes have very specific active sites and a slight change in the ph will stray away from its optimum and could denature it and cause less reactions.

Question 4

Why does it need to have an aqueous environment within the cell?

Answer 4

To keep substrates and products in the solution.

Question 5

Why does the removal of toxins need to be controlled within the cell?

Answer 5

Toxins damage enzymes and metabolic pathways can be stopped therefor they need to be controlled for the cell to work.

Question 6

How does the coat of the arctic fox differ in the summer and winter?

Answer 6

The coat of the arctic fox changes in summer, a brown, to a white in winter. It will also become a lot thicker in the winter.

Question 7

Why is it advantageous that the coat of the arctic fox changes?

Answer 7

It is an advantage as it will be mire suited to the environment as the arctic fox will be able to camouflage in with the snow for it to help hunt it’s prey.

Question 8

What could the environmental stimulus be that leads to the change of the arctic fox’s coat?

Answer 8

An example of an environmental stimulus would be temperature that causes the coat to become thicker, or the change of scenery it would become snowy the colour of the coat will change for it to be able to camouflage.

Question 9

Explain how changing internal environment could affect cells, with reference to carbon dioxide.

Answer 9

when transporting CO2 out of the body H+ and H2CO3 are produces, too much of these can denature enzymes, so toxins are monitored.

Question 10

Explain the role of blood and tissue fluid in maintaining the internal environment.

Answer 10

They remove waste products, hydrostatic pressure pushes out plasma and nutrients and oncotic pressure pushes it back.

Question 11

Name the features that make a good communication system.

Answer 11

1. Covers the whole of the body.
2. Rapid communication enabled.
3. Allows cells to communicate with each other
4. Enables specific communication
5. Enables both long term and short term responses.

Question 12

How do cells communicate in the neural system?

Answer 12

The neural system is a system of neurones that send electrical signals throughout the body. This is a quick response however it is short lasting.

Question 13

How do cells communicate in the endocrine system?

Answer 13

Hormone signals are sent through the blood stream, this is longer lasting but a slower response time.

Question 14

What conditions need to be regulated in the body?

Answer 14

1. Temperature level
2. Blood glucose
3. Carbon dioxide
4. Blood pressure
5. Water levels
6. Blood salt context

Question 15

What is negative feedback?

Answer 15

Maintaining a constant internal environment, any change away from optimum conditions must be reversed.

Question 16

Give an example of negative feedback.

Answer 16

An example of negative feedback would be if internal temperature rises too high the response is to reverse the effect and produce sweat or blood vessels vasodilate.
Another example would if there is too much glucose in the blood, insulin is produced which turns the glucose into glycogen which is then able to be stored reducing the blood sugar levels.

Question 17

What is positive feedback?

Answer 17

the mechanism that increases the change, taking the system further way from the optimum.

Question 18

What does endothermic mean?

Answer 18

An organism that uses heat from their metabolic reactions to maintain their body temperature

Question 19

What are the advantages of being an endotherm?

Answer 19

1. Maintain a fairly constant body temperature whatever the temperature is externally.
2. Remain active when the temperature is low therefor are able to escape from predators.
3. Can take advantage of available prey.

Question 20

What are the disadvantages of being an endotherm?

Answer 20

1. A lot of their energy intake is used to maintain body temperature.
2. Need a lot more food.
3. A low proportion of energy is used for growth.
4. There is a possibility of overheating.

Question 21

What are some behavioural responses of an endotherm when they need to regulate their temperature?

Answer 21

1. Moving into shaded areas when too warm and moving to more sunny areas when cold.
2. Going for a swim to cool down,

Question 22

What are some physiological responses of an endotherm when they need to regulate their temperature?

Answer 22

1. Muscle contractions like shivering. Uncontrollably when cold.
2. Controlling the blood flow by vasodilation (when warm) and vasoconstriction (when cold)

Question 23

Explain the role of the hypothalamus.

Answer 23

The receptors in the hypothalamus detect the change in temperature straying from optimum. Then the hypothalamus with send out an impulse to cause different responses that will reverse the change. Some will need to be quick so the signal will go through the neural system and others may need a longer lasting response so the signal will go through the endocrine system.

Question 24

Explain the role of the peripheral temperature receptors.

Answer 24

Monitor the temperature in the extremities. Sensing the information to the thermoregulatory system centre this will signal the brain whether the outside environment is too cold or too hot.

Question 25

What is vasodilation?

Answer 25

Increasing the size of the arterioles making them wider to allow more blood to go to the surface of the skin allowing for heat loss.

Question 26

What is vasoconstriction?

Answer 26

Decreasing the size of the arterioles. So the blood bypasses the surface of the skin and goes straight to the heart so it won’t loose as much heat.

Question 27

What are the advantages of being an ectotherm?

Answer 27

1. Less of the energy they gained from food goes towards maintaining body temperature so it can go towards others things like growth.
2. They don’t need to find as much food.
3. Can survive without food for long periods of time.

Question 28

What are the disadvantages of being an ectotherm?

Answer 28

1. They are less active in cooler temperatures.
2. They are more at risk from predators while they are cold as they are unable to escape.
3. Cannot take advantage of food that is available while they are cold.

Question 29

What are some behavioural responses of an ectotherm when they need to regulate their temperature?

Answer 29

1. Moving into spaces that are either shaded when they are too warm or moving to places with more sun when they are cold.
2. In the night they will burrow into the ground as the heat will be trapped under the ground.

Question 30

What are some physiological responses of an ectotherm when they need to regulate their temperature?

Answer 30

1. Maximising the surface area of the ribcage to be able to absorb more sun.
2. Minimising the surface area of the ribcage to be able to reduce the amount of sunlight is absorbed.
3. Able to change colour darker colours when cold to absorb more sun and lighter colours when warm.
4. Increasing the rate and depth of breathing to allow more warm air in when too warm so the water evaporates from the spiracles to cool down.

Question 31

Why is it so important to control body temperature?

Answer 31

It is important as it can have a drastic effect on the activity of a cell. If it gets too cold there wont be enough kinetic energy within the enzymes therefore will cause less reactions and will cause the cell to not work to its potential. And if the temperature gets too warm the enzymes will denature and will be unable to use them again.

Question 32

What does the term stimulus mean?

Answer 32

It is when there is a change in the external or internal conditions that can cause harm to the body.

Question 33

What does the term response mean?

Answer 33

An action to the stimulus that returns it to the ideal conditions, back to optimum.