Nutrition in flowering plants Flashcards
What is photosynthesis?
Photosynthesis is a process used by plants in which energy from sunlight is used to convert carbon dioxide and water into molecules needed for growth. These molecules include sugars, enzymes and chlorophyll.
Light energy is absorbed by the green chemical chlorophyll. This energy allows the production of glucose by the reaction between carbon dioxide and water. Oxygen is also produced as a waste product.
Word equation for photosynthesis
water + carbon dioxide –> glucose + oxygen
How does carbon dioxide concentration affect the rate of photosynthesis
Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide.
How does light affect the rate of photosynthesis?
Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis.
How does temperature affect the rate of photosynthesis
If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot.
If you plot the rate of photosynthesis against the levels of these three limiting factors, you get graphs like the ones above.
How is the structure of the leaf adapted
Features of leaves Adaption Purpose
Large surface area To absorb more light
Thin Short distance for carbon dioxide to diffuse into leaf cells
Chlorophyll Absorbs sunlight to transfer energy into chemicals
Network of veins To support the leaf and transport water and carbohydrates
Stomata Allow carbon dioxide to diffuse into the leaf
Shows the waxy cuticle on top of the upper epidermis.Under this is the palisade mesophyll layer and spongy mesophyll layer, which has air spaces in it. At the bottom, is the lower epidermis and wax cuticle. Gases are exchanged through the stoma. On each side of the stoma there is a guard cell with chloroplasts.
The internal structure of the leaf is also adapted to promote efficient photosynthesis:
Epidermis is thin and transparent to allow more light to reach the palisade cells
Thin cuticle made of wax to protect the leaf without blocking out light
Palisade cell layer at top of leaf to absorb more light
Spongy layer, air spaces allow carbon dioxide to diffuse through the leaf, and increase the surface area
Palisade cells contain many chloroplasts to absorb all the available light
Importants ion plants need
Mineral ions for growth
magnesium ions for chlorophyll
nitrate ions for amino acids
