Nutrition Flashcards
Define photosynthesis
The process by which plants make carbohydrates from raw materials, using energy from light.
Describe photosynthesis
- Light energy is absorbed by chlorophyll
- Absorbed light energy is used to convert CO2 from the air and water from the soil into a sugar called glucose
- Oxygen is released as a by-product.
Give the word equation for photosynthesis
Carbon dioxide + water -> (light) (chlorophyll) -> glucose + oxygen
Give the symbol equation for photosynthesis
6CO2 + 6H2O -> (light) (chlorophyll) -> C6H12O6 + 6O2
What is glucose used for
- some is used for respiration
- some is converted into starch (storage form)
Describe how light intensity affects photosynthesis
At first, as light intensity increases the rate of photosynthesis also increases as light energy is needed for photosynthesis. However, the rate then plateaus due to other limiting factors.
Describe how CO2 concentration affects rate of photosynthesis
As CO2 conc increases, rate of photosynthesis also increases as CO2 is one of the reactants in photosynthesis. However, the rate then plateaus due to other limiting factors.
Describe how temperature affects rate of photosynthesis
At a low temperature, enzymes do not have enough KE to complete photosynthesis so rate will be low. Post the optimum temperature, enzymes become denature so photosynthesis rate will be low.
Describe the waxy cuticle of a leaf.
Waterproof layer that protects the leaf
Describe the upper epidermis of a cell.
Transparent layer used for protection
Describe the palisade mesophyll of a cell
Tightly packed layer of cells for photosynthesis
Describe spongy mesophyll of a cell
Loosely packed for efficient gas exchange
Describe lower epidermis of a cell
Contains stomata which allow entry of gas
Describe guard cells of a leaf
Cells surrounding the stomata and controlling them.
Give 4 adaptations of leaves.
- large SA
- thin (short diffusion distance for CO2)
- thin waxy cuticle
- thin transparent epidermis
How are mineral ions absorbed in plants?
Through the roots by active transport, as mineral ions are dissolved in the soil water.
What is the use of magnesium in plants?
Needed for making chlorophyll
Give a result of magnesium deficiency in plants
Leaves turning yellow
What are nitrates needed for in plants
For making amino acids
Give one effect of nitrate deficiency in plants.
Stunted growth
Give a cause of eutrophication
Overuse of nitrogen fertilisers by farmers.
What is eutrophication?
When excess nitrates/phosphates enter rivers, lakes and fields leading to the death of fish by causing over bloom of algae, depleting oxygen.
Give the method for observing evolution of oxygen in a plant.
- Place pondweed in a beaker of water underneath an upturned funnel
- Fill a boiling tube with water and place it over the end of the funnel
- As oxygen is produced, bubbles of gas will collect in the boiling tube and displace the water.
How to test for presence of oxygen
Hold glowing splint near test tube to see if it relights.