Biology 1.4 Flashcards
(27 cards)
What is photosynthesis word equation
Carbon dioxide + water —> Oxygen + glucose
What is photosynthesis symbol equation (balanced)
6CO2 + 6H2O —> C6H12O6 + 6O2
Where does photosynthesis occur
In the chlorophyll
What is stage 1 of photosynthesis
Energy transferred from light splits water molecules into oxygen gas and hydrogen atoms
What is stage 2 of photosynthesis
Carbon dioxide gas combines with the hydrogen ions to make glucose
What are the ways a plant uses glucose
Respiration, made into other sugar like fructose and sucrose, converted to starch,
How do you test for starch
Boil the leaf for 1 minute, then put it into a tube of boiling ethanol for a minute to remove chlorophyll, wash with water to remove ethanol, add iodine,if it turns blue-black it has starch present.
How do you destarch a plant?
Keep it in dark for a minimum of 24 hrs
How do you prove chlorophyll is needed for photosynthesis?
Place a destarched, variegated plant in sunlight for several hours, then test a leaf for presence of starch
How can you prove light is needed for photosynthesis?
Take a destarched plant and cover half a leaf with black card or tinfoil. After several hours test the leaf for starch.
How can you prove carbon dioxide is needed for photosynthesis
Put a destarched plant inside a polythene bag, add a pot of soda lime, before sealing the bag, place in sunlight for several hours, then test a leaf for starch.
How can you prove oxygen is given off during photosynthesis
Place an upside down test tube above an aquatic plant like pondweed, after a while, take the tube and put a glowing splint inside of it, where it will then relight because of the oxygen produced during photosynthesis by the pondweed.
What does testing for starch do?
It proves that photosynthesis has happened if starch is present because it means glucose has been produced to make starch and the glucose comes from photosynthesis as it is a product.
What factors can affect photosynthesis?
Light intensity, carbon dioxide and temperature.
What is a limiting factor
anything that constrains somethings rate of reaction, size, etc.
How do you measure the rate of photosynthesis
Measure how much oxygen or glucose a plant makes in a given time, or how much the biomass increases due to glucose being used to make new cells.
What is the formula for rate of photosynthesis?
Rate = 1/t where t is the time it takes for the measurement to occur. Units can be s^-1 m^-1 and h^-1 meaning per second, per minute, and per hour respectively.
How does light intensity affect the rate of photosynthesis?
The higher the light intensity, the faster the rate of photosynthesis. This
continues until photosynthesis reaches its maximum rate. In
very low light levels or if there is no light, photosynthesis stops.
How does carbon dioxide affect the rate of photosynthesis
Carbon dioxide is one of the reactants for photosynthesis. The greater the
carbon dioxide concentration, the faster the rate of reaction.
However, the atmosphere only contains about 0.04% carbon dioxide. This
means that carbon dioxide is most commonly the limitinq factor.
Farmers artificially increase the levels of carbon dioxide in greenhouses.
This increases the rate of photosynthesis.
How does temperature affect the rate of photosynthesis
Photosynthesis is a series of enzyme-controlled reactions. Therefore, the
higher the temperature the faster the reactions occur. However, if the
temperature is too high the enzymes will denature the reactions will stop.
What does light intensity graph look like
Gradual increase as light intensity goes up but levels out once it is no longer the limiting factor
What does carbon dioxide graph look like
Gradual increase as carbon dioxide goes up but levels out once it is no longer the limiting factor
What does temperature graph look like
Gradual increase as temperature goes up but levels out once it is no longer the limiting factor. Then goes down sharply as enzymes denature
What is the inverse square law
Relative light intensity = 1/ distance from light source^2
