Homeostasis

Hormones are released from endocrine glands.

Which gland releases hormones to control other glands?

Tick () one box.

Several hormones can affect blood glucose concentration.

Adrenaline can increase blood glucose concentration.

What is one other effect of adrenaline?

Tick () one box.

Cells in the pancreas detect changes in blood glucose concentration.

What type of cell in the body detects changes?

Scientists investigated whether blood glucose concentration affects reaction time.

The reaction times of ten people with Type 1 diabetes were measured.

This is the method used.

1. Tell one person to drink a glucose solution.

2. Monitor the person’s blood glucose concentration.

3. Record the person’s reaction time when the person’s blood glucose concentration is:

16 mmol/dm³

6 mmol/dm³

3 mmol/dm³

4. Repeat steps 1 to 3 for the nine other people.

People with Type 1 diabetes were selected for the investigation instead of people who did not have diabetes.

Explain why.

Control variables between the different people in the investigation included:

• age

• sex

• food and drink consumed before and during the test.

Suggest two other control variables that should be used in the investigation.

It was important for the scientists to monitor the health of each person during the investigation.

Suggest one reason why.

Figure 6 shows the results.

People who do not have diabetes usually have a blood glucose concentration in the range of 4.0 mmol/dm³ to 7.8 mmol/dm³.

Describe how the results in Figure 6 show the importance of homeostasis.

Describe how blood glucose concentration is maintained within narrow limits in people who do not have diabetes.

The scientists gave the hypothesis:

‘Optimum blood glucose concentration increases the production of chemicals that diffuse across synapses.’

Describe how an increase in the chemicals could decrease reaction time.

Homeostasis is the control of internal body conditions. Control of body temperature is an example of homeostasis.

Draw one line from each part involved in temperature control to the function of that part. Part involved in

Why is homeostasis important? Tick (✓) two boxes.

The body temperature of a long-distance swimmer can change with the

length of time swimming in cold water. Figure 6 shows how the body temperature of one swimmer changed in the first 4 hours of a 6-hour swim.

Describe the trend shown in Figure 6.

Determine the change in body temperature in the first 4 hours of the swim.

Hypothermia is a dangerously low body temperature of 35 °C or colder. Predict when the swimmer was first at risk of hypothermia. You should extend the line on Figure 6.

Swimming in cold water decreases the insulin concentration in the blood.

Complete the sentence. Choose the answer from the box.

Insulin is a hormone. Which organ system produces hormones?

Complete the sentence. Choose the answer from the box.

When insulin concentration in the blood increases, blood glucose concentration

Give one risk factor for Type 2 diabetes.

The control of body temperature is an example of homeostasis.

Give one other internal condition controlled by homeostasis. Do not refer to temperature in your answer.

Explain why the control of body temperature is important.

The body temperature of long-distance swimmers can change as the

length of time swimming in cold water increases. Figure 4 shows how the body temperature of one swimmer changed in the first 4 hours of a long-distance swim.

Calculate the mean rate of body temperature decrease per hour in the first 4 hours of the swim.

Hypothermia is a dangerously low body temperature. For this swimmer, a 5.5% decrease in body temperature from the start of the swim will cause hypothermia. Determine the body temperature at which this swimmer will start to have hypothermia. Give your answer to 2 significant figures.

A decrease in body temperature causes the adrenal glands and the thyroid gland to

be stimulated.

Which gland secretes hormones to stimulate the adrenal glands?

Explain the role of the adrenal glands in responding to a decrease in body temperature.

Explain how the thyroid gland controls the response to a decrease in body temperature by negative feedback.

Conditions inside the human body are controlled.

What is the control of conditions inside the body called?

Tick (✓) one box.

What are the two ways information is sent to control body conditions?

Tick (✓) two boxes.

One condition in the body that needs to be controlled is the level of water.

Give one other condition in the human body that needs to be controlled.

Figure 1 shows the volumes of water taken in and lost by one person.

The volume for water taken in on a hot day has not been plotted on the bar graph.

The person lost 1400 cm³ of water on the cold day.

How much extra water did they lose on the hot day?

Explain why the volume of water lost on a hot day is higher than on a cold day.

A boy drank 750 cm³ of water.

His total intake of water for that day was 3000 cm³

Calculate the percentage of the boy’s total intake that the 750 cm³ represents.

This question is about homeostasis.

Define the term homeostasis.

Name the hormone released if the blood glucose concentration falls too low.

Two people were sent to a hospital to find out if they have diabetes. This is the method used at the hospital.

• Do not eat or drink after midnight. This is called fasting.

• Measure blood glucose concentration at 9.30 am

• Drink a glucose solution at 10.00 am

• Measure blood glucose concentration for the next 3 hours.

Figure 4 shows the results.

Person A and person B have diabetes.

Describe how Figure 4 shows that person B has diabetes. Use data from Figure 4.

Person A and person B had a test to measure the concentration of insulin in their blood when they were fasting. Table 4 shows the results.

Suggest which type of diabetes person A and person B have. Give a reason for each answer. Person A

Person B

Toxic hypoglycaemia syndrome (THS) has caused the deaths of hundreds of starving children in some tropical countries.

• The starving children have had nothing to eat all day.

• The starving children then eat many lychee fruits.

• The lychee fruits contain a molecule which stops an enzyme in the liver working.

• This enzyme normally converts stored fats into glucose.

Children who have eaten during the day are not affected by eating many lychee fruits.

Starving children may die from eating many lychee fruits but children who have eaten during the day are not affected. Explain why.