Year 8 Science · Unit 1 · Lesson 16

Homeostasis, Maintaining Stable Internal Conditions

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Learning Goals

Apply the definition of homeostasis to real scenarios involving Australian animals
Explain what happens to a living thing when internal conditions fall outside the suitable range
Connect homeostasis to the idea that multiple systems work together

Warm Up

Odd one out

Circle the item that does not belong in each group. Then explain why it doesn't fit.

#	Group	Your answer (odd one + reason)
1	Body temperature Water balance Blood cell shape Gas levels
2	Suitable range Effective function Living system Decoration
3	Too much change affects function Conditions stay within limits Homeostasis Conditions change randomly and wildly

Your Turn

Real-world context

In the dry Australian outback, red kangaroos must keep their internal water balance within a suitable range to survive. During hot days, they limit activity, seek shade and reduce water loss. Their bodies respond to outside conditions so that internal conditions do not change too much. Marathon runners in the Sydney Marathon also work to keep their body temperature within a suitable range by sweating during hot weather. In both cases, the organism relies on multiple interacting parts working together, not just one structure acting alone.

(a) Using the passage and the lesson, explain what homeostasis means and identify which internal conditions the kangaroo and the marathon runner are each keeping within a suitable range.

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(b) What does the passage suggest about whether one structure alone can maintain homeostasis? Use evidence from the passage to support your answer.

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Show What You Know

1. A student writes: "Homeostasis means the body never changes." Rewrite this into a stronger scientific explanation using the term "suitable range." Explain why your version is more accurate.

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Wrap Up

In one sentence, what was the main idea of this lesson?