Module 6 - Homeostasis

Question 1

What may happen to enzyme activity if the temperature is too high?

Answer 1

A high body temperature may lead to denaturing of enzymes due to breaking of H bonds as they vibrate too much. This reduces the rate f metabolic reactions.

Question 2

What may happen to enzyme activity is the pH changes?

Answer 2

When the pH changes, the H bonds on the enzyme change. This causes the enzyme to denature as the active site changes shape.

Question 3

What may happen to cells if the blood glucose concentration is too high?

Answer 3

Water will leave the cells via osmosis, down the water potential gradient. This may cause cells to shrivel up and die.

Question 4

What is the system that restores the body’s internal environment back to normal?

Answer 4

Negative feedback mechanism

Question 5

Why is having multiple negative feedback mechanisms beneficial?

Answer 5

It gives the body more control over changing the internal environment

Question 6

What is a positive feedback mechanism?

Answer 6

This is when the body doesn’t restore the internal environment back to normal but instead moves it further away from the internal environment

Question 7

What is a positive feedback example that takes place in the body?

Answer 7

Blood clotting or hypothermia

Question 8

How is hypothermia an example of positive feedback?

Answer 8

When the body reaches a certain low temperature, the brain cannot function properly and the body can no longer shiver, dropping the temperature even more. This means that the temperature in someone’s body will continue to drop

Question 9

What are two hormones that detect glucose concentration?

Answer 9

Insulin and glycagon

Question 10

What is the name of the part of the body that secretes insulin and glycagon?

Answer 10

islets of langerhans

Question 11

What type of cells do glucagon and insulin release?

Answer 11

Beta cells secrete insulin and alpha cells secrete glucagon

Question 12

What effect does insulin and glucagon have on the bloody glucose concentration

Answer 12

Insulin lowers the blood glucose concentration when its too high and glucagon raises the blood glucose concentration when its too low

Question 13

How does insulin lower the blood glucose concentration?

Answer 13

1. insulin binds to specific receptors on liver and muscle cells
2. it increases the permeability to muscle cell-membrane so it takes up more glucose
3. It also activates enzymes to convert glucose into glycogen (glycogenesis)
4. The cells store the glycogen as an energy source
5. Increases respiration of glucose

Question 14

How does glucagon work to increase the blood glucose concentration?

Answer 14

1. Binds to specific receptors on liver cells
2. Glucagon activates enzymes in liver cells to convert glucagon into glucose (glycogenolysis)
3. Glucagon also activates enzymes that from glucose from glycerol and amino acids (gluconeogenesis)
4. Decreases the rate of respiration

Question 15

What is an example of a glucose transporter and how is it activated?

Answer 15

The skeletal and cardiac muscle have a channel protein known as GLUT4.
GLUT4 is stored in vesicles in the cytoplasm and when insulin binds to specific receptors on the surface membrane, GLUT4 moves allowing glucose to be transported in

Question 16

Where is adrenaline found and when is it secreted?

Answer 16

It is found in the adrenal glands and it is secreted when there is a low conc of glucose in the blood, when you are stressed or exercising.

Question 17

How does adrenaline work?

Answer 17

It binds to specific receptors on liver cells and then activates the break down of glucagon to glucose and inhibits the synthesis of glucagon into glucose.

Question 18

Explain how the second messenger model works?

Answer 18

When adrenaline and glucagon bind to specific receptors, this causes the enzyme adenylate cyclase to be activated. This enzyme converts ATP into the second messenger known as cAMP. cAMP activates an enzyme called protein kinase A that causes the break down of glycogen into glucose.

Question 19

What is the simple difference between type I diabetes and type II?

Answer 19

Type I means the immune system attacks B cells in the islets of langerhans so they cannot produce insulin and type II means the B cells don’t produce enough insulin or cells don’t respond properly to it

Question 20

Explain simply how type I diabetes work?

Answer 20

The immune system attacks the B cells in the islets of langerhans so they can’t produce enough insulin.
The blood glucose levels remain high known as hyperglycaemia.
Patients must use insulin therapy such as regular injections

Question 21

Explain simply how type II diabetes work?

Answer 21

B cells do not produce as much insulin or body cells don’t respond properly.
This may occur if the membrane receptors on cells don’t work properly and so insulin cannot bind and glucose cannot be taken in by cells.
Blood glucose levels will remain high

Question 22

What are 3 main things health advisors recommend to help reduce the number of people wit Type II diabetes.

Answer 22

1. Eat a low fat, sugar and salt diet. Eat a high in whole grain, fruit and vegetable diet
2. Take regular exercise
3. Lose weight if necessary

Question 23

What are 3 things health advisors have recommended the food industry do to help reduce the cases of type II diabetes?

Answer 23

• Reduced advertising of junk food
• improve the nutritional value of their products
• clearer labelling on products

Question 24

What are 2 ways businesses have responded to health advisors?

Answer 24

• Using sugar alternatives to sweeten drinks
• Reducing the sugar, fat and salt content of products

Question 25

What is glycogenesis?

Answer 25

Glucose into glycogen

Question 26

What is gluconeogenesis?

Answer 26

Non carbohydrates into glucose

Question 27

What is glycogenolysis?

Answer 27

Glycogen into glucose