Year 8 Science · Unit 1 · Lesson 8

Gas Exchange in Plants

Challenge Worksheet

Name

Date

Class

Learning Goals

Evaluate a scientific claim about plant oxygen production
Identify what is correct, misleading, and missing from a claim
Apply knowledge of respiration and photosynthesis to construct a nuanced argument

Go Deeper

Evaluate the claim

Someone claims…

"Plants don't need to breathe because they make their own oxygen from photosynthesis. Unlike animals, plants are completely self-sufficient when it comes to gas exchange, they never actually consume oxygen at all. This is why putting plants in a sealed room is perfectly safe, because the plant just keeps making fresh oxygen indefinitely."

(a) What part of this claim is supported by the science you've learned in this lesson?

Challenge 2 marks

(b) What is misleading or scientifically incorrect in this claim? Identify at least two errors.

Challenge 2 marks

(c) What evidence or extra information would you need to decide whether placing one small plant in a sealed room with a person would actually be safe?

Challenge 2 marks

Show What You Know

1. A scientist measures gas exchange in a banksia plant at three times: 2 am, 12 pm, and 8 pm. Predict which gas would be released in net at each time, and explain why the daytime and night-time results differ.

Challenge 4 marks

2. A student claims: "If guard cells lost their ability to change shape, the plant would die quickly." Do you agree? Construct an argument using evidence from this lesson about stomata, gas exchange, and transpiration.

Challenge 3 marks

Wrap Up

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