B6. Plant nutrition Flashcards
(29 cards)
What is photosynthesis?
The process by which plants use light energy to convert carbon dioxide and water into glucose and oxygen.
Write the word equation for photosynthesis.
Carbon dioxide + Water → Glucose + Oxygen
Write the balanced chemical equation for photosynthesis.
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Where in the plant does photosynthesis occur?
In the chloroplasts of plant cells.
What pigment in chloroplasts absorbs light for photosynthesis?
Chlorophyll
Why is chlorophyll important for photosynthesis?
It absorbs the light needed to drive the chemical reactions of photosynthesis
What are the raw materials needed for photosynthesis?
Carbon dioxide and water
What are the products of photosynthesis?
Glucose and oxygen
How does carbon dioxide enter a plant?
Through the stomata in the leaves.
How does water enter a plant?
Through the roots by osmosis, and then through the xylem to the leaves.
What is the role of the xylem?
To transport water and mineral ions from the roots to the leaves.
What is the role of the phloem?
To transport sugars (mainly sucrose) made in the leaves to other parts of the plant.
What are the limiting factors of photosynthesis?
Light intensity, carbon dioxide concentration, and temperature.
How does light intensity affect photosynthesis?
As light intensity increases, the rate of photosynthesis increases — until another factor becomes limiting.
How does carbon dioxide concentration affect photosynthesis?
As carbon dioxide concentration increases, the rate of photosynthesis increases — until another factor becomes limiting.
How does temperature affect photosynthesis?
Rate increases with temperature up to an optimum, then decreases if temperature is too high (because enzymes denature).
Why are nitrates needed by plants?
For making amino acids and proteins for growth.
What happens to a plant if it lacks nitrates?
It shows stunted growth and yellowing of older leaves.
Why are magnesium ions important for plants?
Magnesium is needed to make chlorophyll.
What happens to a plant if it lacks magnesium?
Leaves become yellow
Describe an experiment to show that light is necessary for photosynthesis.
Cover part of a leaf with black paper. After exposure to light, test the leaf with iodine solution; only uncovered areas turn blue-black (showing starch is made where light was available).
Describe an experiment to show that carbon dioxide is necessary for photosynthesis.
Place a plant in a sealed container with soda lime (which absorbs CO₂). After some time in light, test the leaves for starch — no starch will be made without carbon dioxide.
How can you test a leaf for starch?
Boil the leaf in water, then boil in ethanol (to remove chlorophyll), rinse in warm water, and add iodine solution. A blue-black color indicates starch.
What is the function of the upper epidermis?
It protects the leaf and is transparent to let light through to the palisade layer.
