Photosynthesis Flashcards
(24 cards)
What is photosynthesis?
Build up of food by means of light, autotrophic organisms perform this.
Give the chemical and word equation for photosynthesis.
6co2 + 6h20 -> c6h1206 + 602
Carbon dioxide + water —(light energy)— > glucose + oxygen
Where does photosynthesis take place?
Organ= leaf Tissue = palisade mesophyll layer Organelle= chloroplasts
What effect does white light have on chloroplast ?
It acts as a prism.
Explain difference colours on photosynthesis?
Blue to a slightly lesser extent red are the colours absorbed by the chloroplasts.
Blue light is best for photosynthesis.
What is a flat leaf good for?
To increase surface area for absorption.
What is a waxy cuticle good for?
Makes leaf waterproof.
What are Veins in leafs good for?
To pass substances to all leaf cells and for stability
How is a thin leaf good?
For gases to diffuse in and out faster
Why is a leaf green?
Rich in chloroplasts for photosynthesis
What is a leaf mosaic pattern?
When leaves are arranged in the best way to absorb light
Define the upper epidermis.
Transparent, allowing light to enter leaf.
Define the palisade mesophyll layer
Rich in chlorophyll
Close to light
Large SA
Define the spongy mesophyll layer.
For gaseous exchange
What are the guard cells used for?
These control gaseous exchange through stomata.
What are the factors affecting the rate of Photosynthesis?
Light
CO2 concentrate
Water availability
Temperature
What is the law of limiting factors?
At a certain point the rate won’t be able to increase any more because another factor might be limiting.
What is the assimilation of glucose?
Needed to produce lipids and vitamins
Used in respiration to release energy
Stored as starch
Converted to fructose found in fruits.
How do you detsrach a plant?
Put plant in the dark for 3 days (no photosynthesis therefore converted to glucose and broken down.
Explain an experiment to test a plant for starch.
1) de starch it
2) boil leaf 2 mins to kill it to stop more chemical reactions
3) dip leaf in hot ethanol for 2 mins, dissolving chlorophyll
4) dip leaf again in hot water to soften it
5) put iodine solution on leaf. Should turn from yellow to blue black If starch is present
Describe the method to show if light is necessary for photosynthesis
- Detsratch a potted plant
- Select a leaf and cover it with foil
- Expose the leaf to the light for about 7 hours
- Test the leaf for starch
(Results should be that the exposed pant becomes blue black because starch is detected and photosynthesis has taken place and the covered part gives a negative result because photosynthesis only occurs If light is present.
Describe an experiment showing if chlorophyll is necessary for photosynthesis
- De-starch a variegated plant
- Expose plant to light for 7 hours
- Detach the leaf, treat it with boiling water and ethanol to soften it and test for starch
Dark green parts should have a positive result with iodine white light patterns give no result thus chlorophyll is needed for photosynthesis
Describe an experiment showing if co2 is necessary for photosynthesis?
- Destarch 2 potted plants a and b
- Cover the shoots in polythene bags placing a dish of soda lime in one of the pot B to remove all co2 from the air around the plant
- Expose the plants to light for about 7 hours
- Detach a leaf from both pots and test for starch
Leaf B turns blue black while leaf A gives a negative result proving co2 is necessary for photosynthesis.
Describe an experiment in which one can see if oxygen is necessary for photosynthesis
Refer to page 10
