En anglais

Keeping Your Body's Temperature Steady

Science · Organisms & Life Processes · ages 12-14

Name ______________________ Date ____________

Which response removes heat from the skin when the body is too hot?
- Muscles contracting during shivering
- Sweat evaporating from the skin
- Skin blood vessels narrowing in the cold
Which description matches homeostasis of body temperature?
- Adjusting core temperature to stay near 37°C
- Making core temperature match every outdoor change
- Keeping all parts of the skin at exactly 37°C
Shivering helps the body produce extra heat when it is cold.
Circle one: True False
A person's temperature starts at 37°C and rises by 3°C. What is the new temperature in °C?
Answer: ______________
The blood vessels supplying Mia's skin widen, increasing blood flow through the skin. What is this response called?
- Vasoconstriction
- Evaporation
- Vasodilation
Why does regulating core temperature help cells work?
- It supports the enzymes that speed up cell reactions
- It keeps every patch of skin at exactly the same temperature
- It makes cell reactions independent of temperature changes
A student says, 'If cooling slows enzyme reactions, making the body hotter and hotter must always help them.' Which explanation corrects this idea?
- Enzyme reactions always speed up without any temperature limit
- Cooling permanently destroys every enzyme in the body's cells
- Very high heat can change enzyme shape and disrupt reactions
Jake says, 'Sweat cools the skin equally well whether it evaporates or only drips off.' Which explanation corrects his idea?
- Dripping removes more heat because liquid sweat is always colder
- Evaporation takes heat from skin; dripping provides less cooling
- Evaporation adds heat because the skin must make fresh sweat first

Answer key

For grown-ups. Fold this page away before handing over the rest.

Keeping Your Body's Temperature Steady W1-mt_zaXr5wcJD2-s1

Sweat evaporating from the skin · Evaporation takes heat from the skin. Shivering produces heat, while narrowing skin blood vessels reduces heat loss.
Adjusting core temperature to stay near 37°C · Homeostasis regulates internal conditions within suitable limits. Core temperature is usually near 37°C, with some variation.
True · Shivering involves repeated muscle contractions that produce extra heat.
40 · A rise is added to the starting temperature: 37 + 3 = 40°C.
Vasodilation · Vasodilation is widening of blood vessels. In skin circulation, it increases blood flow through the skin.
It supports the enzymes that speed up cell reactions · Enzyme-controlled reactions are affected by temperature. Keeping core temperature near its usual level supports these reactions.
Very high heat can change enzyme shape and disrupt reactions · Cooling can slow reactions, but very high temperatures can change enzyme shape. Higher temperature does not always improve enzyme activity.
Evaporation takes heat from skin; dripping provides less cooling · Sweat evaporation takes heat from the skin. Sweat that only drips away provides much less cooling.