Year 8 Science · Unit 1 · Lesson 22
Challenge Worksheet
Learning Goals
Evaluate the claim
Someone claims...
"Humans should all become vegetarian because it is more energy efficient. Eating plants directly means we get 10 times more energy than eating animals that have already eaten the plants. If everyone switched to a plant-based diet, we could feed ten times as many people on the same land. Eating meat is basically wasting 90% of the planet's food energy, which is why we're running out of food."
(a) What part of this claim is supported by the science you have learned? Quote a specific figure from the lesson and explain how it supports the claim.
(b) What is misleading or oversimplified in this claim? Identify at least TWO things the claim ignores or gets wrong. (Think: does energy efficiency tell the whole story about food production? Are all plants equally efficient? Are all land types equal?)
(c) What evidence or extra information would you need to decide if this claim is fully reliable? List at least THREE specific pieces of information a scientist would want before accepting this claim.
1. An Australian mulga grassland food web includes: mulga tree → caterpillar → lizard → wedge-tailed eagle. A drought severely reduces the mulga tree population. Using energy pyramid principles, explain why the eagle population would be affected more severely than the lizard population.
2. Construct a short argument (3–4 sentences) that a scientist might make to a government policymaker about why protecting producers (e.g. grasses, algae, trees) is the most critical conservation priority for any ecosystem. Use at least two concepts from this lesson.
Wrap Up
In one sentence, what was the main idea of this lesson?