Site author Richard Steane
The BioTopics website gives access to interactive resource material, developed to support the learning and teaching of Biology at a variety of levels.

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transverse section through a leaf
Above is a diagram of a section of a leaf, with labelling lines and brackets for some layers.
Write in the names of the parts or layers indicated.

What do the red dots inside the cells represent?

> nuclei

What do the white spaces inside the cells represent?

> vacuole

What do the white spaces between the cells represent?

> air spaces

Which layer/layers is/are not made of cells?

>cuticle (upper & lower)

There are 4 factors required for photosynthesis to take place. List them, under the following headings:

raw materials: > carbon dioxide > water

energy > light

accessory > chlorophyll

similar transverse section through a leaf By means of labelled arrows drawn on the diagram above, show the pathway taken by each of the two raw materials to a cell in the centre of the leaf.

Show with another labelled arrow the direction the energy comes from.

Give "one word names" for the processes by which these raw materials move across the leaf, as seen in the diagram.

>water - osmosis > CO2 - diffusion

Not all of the cells in the leaf have the "accessory" factor. Using an appropriately coloured crayon or felt-tip, mark in the structures on the diagram that contain this.

You may need to look rather hard at your textbook!

What is the name of the organelles that contain this factor?

> chloroplasts

Why do you think that the upper cuticle is thicker than the lower one?

> to resist dehydration due to sun's heat, and rain etc from above

Why are leaves usually thin?

> so CO2 and water can reach inner cells easily

Why are leaves usually broad and flat?

> to absorb as much light possible

Give two functions of stomata in photosynthesis.

> allow CO2 in

> allow O2 out

What functions do "veins" perform which relate to photosynthesis?

> bring in water

> carry away products of photosynthesis

What can you discover about a plant by looking at the pattern of veins on its leaves?

> whether it is a monocot or a dicot

What is the biological term for a single pore (hole) in a leaf?

> stoma

How many cells make up each pore, and what is their name?

> 2 > guard cells

What is the biological term for the part of rhubarb that is eaten?

> petiole

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