6.1 photosynthesis? Flashcards
What is photosynthesis?
Photosynthesis is the process by which plants synthesize carbohydrates from raw materials (carbon dioxide and water) using energy from light.
What is the word equation for photosynthesis?
The word equation is:
carbon dioxide + water → glucose + oxygen
(in the presence of light and chlorophyll)
What is the balanced symbol equation for photosynthesis?
The balanced symbol equation is:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
What is chlorophyll and why is it important?
Chlorophyll is a green pigment found in chloroplasts, which traps light energy and converts it into chemical energy, enabling the plant to make carbohydrates.
What are the uses and storage forms of carbohydrates made in photosynthesis?
Starch for energy storage
Cellulose to build cell walls
Glucose used in respiration for energy
Sucrose for transport in the phloem
Nectar to attract insects for pollination
What are the functions of nitrate ions and magnesium ions in plants?
Nitrate ions are used to make amino acids, which are needed for protein synthesis.
Magnesium ions are used to make chlorophyll.
What happens to plants if they lack nitrate ions or magnesium ions?
Lack of nitrate ions causes slow or stunted growth.
Lack of magnesium ions leads to yellowing of leaves due to insufficient chlorophyll.
What are the limiting factors in photosynthesis?
Light intensity, carbon dioxide concentration, and temperature are limiting factors, meaning when one is in short supply, it can restrict the rate of photosynthesis.
How does light intensity affect the rate of photosynthesis?
As light intensity increases, the rate of photosynthesis increases, but only up to a point. After that, other factors like carbon dioxide or temperature may limit the rate.
What is the effect of carbon dioxide concentration on photosynthesis?
As carbon dioxide concentration increases, the rate of photosynthesis also increases, until a point where it becomes a limiting factor.
What is the effect of temperature on photosynthesis?
Temperature affects the enzymes that catalyze photosynthesis. The optimum temperature is around 25°C. Too low or too high temperatures slow down the process.
What is an experiment to test for the need for chlorophyll in photosynthesis?
Use a variegated leaf (green and white).
De-starch the plant by keeping it in darkness for 48 hours.
Expose the plant to sunlight for a few days.
Boil the leaf, then soak it in ethanol, and test with iodine.
Green areas will turn blue-black (starch present), while white areas remain orange-brown, showing photosynthesis only occurs where chlorophyll is present.
How does light affect photosynthesis in plants?
To test for the need for light:
Keep a plant in the dark for 48 hours to de-starch it.
Clip a piece of aluminum foil over a leaf, then expose the plant to light.
Test with iodine: The area with light will turn blue-black, but the area with foil will remain orange-brown, showing light is needed for photosynthesis.
How does carbon dioxide affect photosynthesis in plants?
De-starch two plants.
Cover one plant with sodium hydrogencarbonate (to release CO₂) and the other with soda lime (to absorb CO₂).
Expose them to light. After testing with iodine:
The plant with CO₂ will show blue-black (starch produced).
The plant without CO₂ will remain orange-brown (no starch).
What are the effects of light and dark conditions on gas exchange in aquatic plants?
Light: Photosynthesis removes CO₂, turning the solution purple (due to reduced CO₂).
Dark: No photosynthesis, so CO₂ is released, turning the solution yellow.
No light but partial light: The rate of photosynthesis and respiration balance, leaving the solution orange.
