1 the Diagram Shows the Cells in a Cross-Section from a Leaf

Homework C2 A food factory

A HELP

1 The diagram shows the cells in a cross-section from a leaf. D a What is the name of the structure Layer B labelled E? b What type of cell is in layer B? E c What is the function (job) of part C? d i A is a waxy layer. What does it do? ii Explain why this is important. e Why is structure D green? f Copy and complete the following sentences. C i Most leaves are wide and flat because … . ii Chloroplasts are mostly in the upper surface of a leaf because … .

2 Look again at the diagram for question 1. a Explain how the shape and position of the cells in layer B helps photosynthesis. b Other than the shape and position, how can you tell that these cells are where most photosynthesis takes place? c i Which gas enters the leaf through point C? ii Which gas leaves through the same point? d Explain how the water needed for photosynthesis reaches the leaves. e Conifers have very narrow leaves, which they keep all year round. Broad-leaved trees develop leaves in spring and lose their leaves in the autumn. Describe how this affects how broad-leaved trees and conifers photosynthesise.

EXTENSION

3 a Explain why green plants photosynthesise. b Fungi are usually white or pale brown. They live on rotting tree trunks or rotting vegetation in the soil. i Explain why fungi do not photosynthesise. ii Suggest why fungi only grow on rotting vegetation. 4 The graph shows the light levels in Gary′s greenhouse during a day in March. x u l

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a How many hours of growing time do the plants in Gary′s greenhouse have, on the day shown? b What might have caused the dips in light levels around 11 am and 3 pm? c At what time will photosynthesis be fastest? d What will be happening to the rate of photosynthesis between 2 pm and 3 pm? e Suggest one way in which GaryTime could of day increase the number of growing hours for his plants.