B4: Photosynthesis Flashcards
Why is the top surface of a leaf waxy?
To stop water escaping from the leaf.
Which gas diffuses into a leaf?
Carbon dioxide
Why are there fewer chloroplasts in the cells of the bottom side of a leaf?
Because sunlight mainly hits the top of leaves so chloroplasts aren’t needed on the bottom as much.
Stomata (holes) in leaves are opened and close by special cells called…
……..guard cells
How does being thin help a leaf to carry out photosynthesis?
Gases can move in and out of the leaf easily.
Why is a leaf normally dark green on top but lighter on the bottom?
There are fewer chloroplasts on the bottom so there is less chlorophyll.
How do gases and water get in and out of a leaf?
Through holes called stomata
What is the name of the tube that carries glucose around the plant?
Phloem tubes
How is the structure of a leaf suited to carry out photosynthesis?
- Contain chlorophyll to capture sunlight.
- They are thin
- They have a large surface area
- They have veins
How do veins help a leaf to carry out photosynthesis?
They are made from xylem tubes which can transport water for photosynthesis to take place.
How does a large surface area help a leaf to carry out photosynthesis?
A large surface area can absorb as much light as possible.
Which gases are made during photosynthesis and diffuse out of a leaf?
Oxygen
(Water vapour)
By which process do plants produce their own food?
Photosynthesis
What is the equation for photosynthesis?
Carbon dioxide + water (+ sunlight) –> glucose + oxygen
Name the reactants of photosynthesis.
carbon dioxide + water
Name the products of photosynthesis.
glucose + oxygen
Where does photosynthesis take place inside plant or algal cells?
Within the chloroplasts
What is the name of the green pigment found inside chloroplasts?
Chlorophyll
What does chlorophyll do?
Absorbs light energy from the Sun
Describe the journey of water through a plant.
- Water enters through the root hair cells of the roots.
- Water travels through tubes called xylem tubes
- Water evapourates out of the leaves.
Why do roots not contain chloroplasts?
Because they are underground and so cannot capture sunlight.
Plants store the glucose produced in photosynthesis as…
……..starch
Describe (step-by-step) can we test a leaf to see if it has been photosynthesising?
- Remove the waxy cuticle with boiling water
- Remove the chlorophyll with hot ethanol
- Drop iodine on to leaf
- If the iodine turns blue/black - starch is present
- This means the leaf has been photosynthesising
What colour does iodine change to if starch is present?
From orange to blue/black
If a plant is lacking in magnesium it might be pale in appearance. Can you explain this?
Magnesium is a mineral needed by plants to make chlorophyll. The plant would be lacking in chlorophyll and appear pale.
