1. CB2 Topic 6d Plant structure and function
What’s this, and what is it used for?
Explain why during the summer, trees lose more water at midday that at the end of the day?
Exam Style question:- In an experiment with a potometer, a faster wind speed causes the air bubble to move more quickly than a slower wind speed. Explain this?
Describe how xylem cells are adapted to allow water to flow through them easily.
How is the role of the xylem different to the phloem?

2. CB2 Topic 6d Plant structure and function
What’s this, and what is it used for?
Explain why during the summer, trees lose more water at midday that at the end of the day?
Its hotter at midday, so water molecules move faster. Light levels are higher and so the stomata are open wider allowing more space for diffusion to occur and so more diffusion.
Exam Style question:- In an experiment with a potometer, a faster wind speed causes the air bubble to move more quickly than a slower wind speed. Explain this?
Faster the wind speed, the more quickly water molecules are removed from around the stomata.
The steeper the concentration gradient the greater the difference in concentration between the inside and outside the leaf.
The faster diffusion occurs.
Describe how xylem cells are adapted to allow water to flow through them easily.
They have no cytoplasm, so water can flow easily and have no cell wall in places so that water can flow from cell to cell easily.
How is the role of the xylem different to the phloem? Plants make sucrose from glucose and starch, sucrose is transported in the phloem. A large central channel which sucrose flows. Its made of sieve tubes.