Year 8 Science · Unit 1 · Lesson 4
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Learning Goals
Compare two
Complete the table to compare a root hair cell and a leaf mesophyll cell. Use what you know from the lesson to fill in as many cells as possible.
| Feature | Root hair cell | Leaf mesophyll cell |
|---|---|---|
| Location in the plant | ||
| Key structural adaptation | ||
| Main function | ||
| Contains chloroplasts? (yes/no) | ||
| Why the adaptation suits the function |
Real-world context
Grey mangroves (Avicennia marina) grow along the tidal mudflats and estuaries of the NSW coast, including Homebush Bay in Sydney. Their roots are submerged in mud that is both waterlogged (anaerobic, very little oxygen) and extremely salty. To survive, mangroves have evolved pneumatophorespencil-like aerial roots that poke up above the mud to absorb oxygen directly from the air. Their leaves also have special salt glands that excrete excess salt absorbed from the seawater.
(a) Explain why normal underground roots would struggle to function in anaerobic, salty mud. Use the terms absorption, minerals and oxygen in your answer.
(b) How do pneumatophores demonstrate that plant root structure is shaped by the environment it lives in? Link your answer to the idea that plants are organised living systems.
1. Describe how the large surface area of root hair cells helps the root system carry out its function. Why is surface area important here?
2. A Banksia plant has very deep roots that can reach water far below the surface, and its seeds need fire to open. Explain how its deep root system helps it survive in the dry Australian environment.
Wrap Up
In one sentence, what was the main idea of this lesson?