Homeostasis is one of the most important processes within the human body.

What is homeostasis?

Using an example, explain why homeostasis is important in humans. 

The control of internal body temperature involves negative feedback.

Describe what is meant by negative feedback.

In humans, when body temperature drops below 35°C, positive feedback causes a continued decrease in body temperature.

This process is referred to as hypothermia.

Explain how positive feedback accelerates the process of hypothermia.

The table below lists three statements about temperature receptors in mammals.

Complete the table by placing a tick if the statement is true and a cross if the statement is false.

When the internal temperature of the human body falls, several physiological responses are activated.

Explain how shivering helps to return body temperature to its optimum.

Explain how vasoconstriction helps to return body temperature to its optimum.

Explain how the secretion of adrenaline helps to return body temperature to its optimum.

Homeostasis involves the process of positive feedback.

Describe what is meant by positive feedback.

Homeostasis also involves negative feedback.

Describe how a negative feedback mechanism works.

The diagram below shows the system that controls the concentration of the hormones testosterone in a man’s body.

The concentration of testosterone in the body is controlled by negative feedback.

Use information from the diagram above to explain why this is negative feedback.

A stable body temperature is controlled via the process of thermoregulation.

State the part of the brain that monitors core body temperature.

Human core body temperature is maintained around 37°C.

Describe and explain two physiological mechanisms that help to increase human core body temperature in a cold environment.

Animals have both physiological and behavioural adaptations to help them maintain their core body temperature.

Elephants have large, thin ears which move forwards and backwards in hot conditions.

Suggest and explain how this adaptation allows elephants to control their body temperature.

Naked mole rats are unusual as they regulate their temperature in a different way to other mammals.

They live in underground tunnel systems that usually have a temperature ranging from 30°C to 32°C and their body temperature stays close to this range.

When the tunnels increase in temperature, naked mole rats will move to cooler parts of the tunnel.

When the tunnels decrease in temperature, naked mole rats will lie together in groups to stay warm.

Describe two ways in which thermoregulation of naked mole rats is different from thermoregulation in humans.

A scientist investigated the behaviour of ectotherms in response to temperature.

They placed a lizard in a choice chamber in which one half was maintained at 20°C and the other half at 40°C.

They observed the behaviour of the lizard using an infrared camera that records 20°C surfaces as black, 40°C surfaces as white and temperatures between 20°C and 40°C as shades of grey.

Suggest and explain why the lizard appeared lighter in the 40°C side and darker in the 20°C side.

The scientist observed that the lizard spent several minutes in each side of the choice chamber.

Suggest the advantage to the lizard of this behaviour.

Endotherms are able to regulate their body temperature using the process of thermoregulation.

Name the type of sensory cell in the skin that detects changes in the temperature of the environment.

Penguins have ‘shunt’ blood vessels that link arterioles carrying blood towards their feet with small veins that carry blood away from their feet.

Explain how this adaptation helps penguins to control their body temperature.

The nervous and hormonal systems are involved in maintaining a constant internal temperature.

Complete the table below by giving the most suitable word or term that matches each definition.

Many insects covered with scales and hair, such as honeybees, are known as facultative endotherms.

Their metabolism maintains an internal temperature above the environmental temperature using exercise.

Explain why many of these types of insect are described as endothermic.

Explain why it is more difficult for insects to maintain a constant body temperature than it is for mammals.

The maintenance of a constant body temperature is very important for larger mammals.

How does maintaining a constant body temperature increase the efficiency of metabolic reactions?