The importance of maintaining constant conditions in the body, including osmosis | Biology

Starter quiz

Below is a simplified diagram of an enzyme. What is shown by A?

'Active site' ✓
Which of the following are effectors?

glands ✓

the brain

muscles ✓

the spinal cord

motor neurone
True or false? Enzymes are catalysts.

True ✓

False
The graph shows the rate of an enzyme controlled reaction. Point A represents the ______ temperature for the enzyme.

'optimum' ✓
The graph shows the rate of an enzyme controlled reaction. Why is the rate of reaction decreasing at point c?

The enzyme is being killed.

The enzyme is too hot.

The enzyme has run out of active sites.

The enzyme is becoming denatured. ✓

The enzyme has run out of substrate.
If a significant increase in body temperature is sustained, it can lead to ...

hypeothermia

hyperthermia ✓

Exit quiz

The maintenance of a constant internal environment is known as...

'homeostasis' ✓
What name is given to enzymes whose active site has changed shape and no longer fits to its substrate?

'denatured' ✓
Water moves in and out of cells by ...

'osmosis' ✓
Order the statements below to describe how the body responds to an increase in body temperature.

1

⇔

A temperature receptor detects an increase in temperature.

2

⇔

A signal is sent to the coordination centre e.g. brain.

3

⇔

The coordination centre sends a message to the sweat glands.

4

⇔

Sweat glands increase sweat production.

5

⇔

Sweat evaporates.

6

⇔

The body cools down.
Match the water level to the effect on cells.

Too little water outside the cell

⇔

water will leave cells by osmosis and they will shrivel. ✓

Too much water inside the cell

⇔

water will enter cells and they will swell and may burst. ✓
Which of the following are antagonistic effects?

insulin which decreases blood sugar, and glucagon which increases blood sugar ✓

thyroid stimulating hormone which increases the production of thyroxine

sweating to cool the body down, and shivering to warm the body up ✓

the brain sending signals down a relay neurone to a motor neurone

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Lesson Details

Key learning points

If conditions in the body change too much, this can be dangerous to our health.
Changes in body temperature affect the rate of chemical reactions and can impact enzyme activity.
Extreme changes in body temperature can lead to hypothermia or hyperthermia and death.
Changes in water content of the fluid around cells can lead to cells shrinking or bursting due to osmosis.
Use of antagonistic effects to maintain a constant environment.

Common misconception

It is common for pupils to misunderstand the links between increased or decreased body temperature and the impact on enzyme function, and changes in water concentration and cell structure.

Explanations of the effect of temperature on enzyme activity, the link between body temperature and enzyme function, and conditions such as hyper- and hypo-thermia are made. The link between water balance, osmosis and cell shapes are also explored.

Keywords

Enzyme - a protein which acts as a biological catalyst
Internal body temperature - the optimal internal temperature of our body, which is about 37°C
Homeostasis - the regulation of the internal conditions to maintain optimum conditions for enzyme action and all cell functions
Osmosis - the net movement of water molecules through a selectively-permeable membrane from high to low concentration of water molecules
Antagonistic - effectors and effects that work against each other