B1.4

Question 1

What are photosynthetic organisms?

Answer 1

Photosynthetic organisms are the main producers of food and therefore biomass on Earth

Question 2

Where does photosynthesis happen?

Answer 2

Inside the plants chloroplasts, so it many occurs in the leaf, but some of it happens in the green stem

Question 3

What is stage 1 of photosynthesis?

Answer 3

Stage 1 is where energy transferred from light splits water into hydrogen ions and oxygen gas

Question 4

What is stage 2 of photosynthesis?

Answer 4

Carbon dioxide gas combines with the hydrogen to make glucose

Question 5

What are the reactants and products for photosynthesis/

Answer 5

Reactants - carbon dioxide + water

Products - glucose + oxygen

Question 6

What type of reaction is photosynthesis?

Answer 6

Endothermic reaction, so energy is taken in from the surroundings

Question 7

How can you test for starch?

Answer 7

Take the leaf you’re about to test and using forceps place in boiling water to kill it. Then place into boiling ethanol to remove all chlorophyll

Then wash the leaf with water to remove ethanol and soften the leaf and spread it out onto a white tile

Add a few drops of iodine solution. If starch is present the iodine will turn from yellow-brown to blue-black

Question 8

How can you prove chlorophyll is needed for photosynthesis?

Answer 8

Take a destroyed variegated plant, and place in sunlight for several hours. Then test one of its leaves for starch

Question 9

How can you prove light is needed for photosynthesis?

Answer 9

Place card on one of the leaves and place in sunlight for several hours. Then, test for presence of starch

Question 10

How can you prove carbon dioxide is needed for photosynthesis?

Answer 10

Take a destarched plant and place in a polythene bag. Before sealing the bag add a pot of soda line, which will absorb carbon dioxide and water vapour. Place plant in sunlight for several hours and test of its leaves for starch

Question 11

How can you prove oxygen is given off in photosynthesis?

Answer 11

Place an upturned test tube over an aquatic plant and place in sunlight for max photosynthesis

Then place a glowing splint in the gas collecting. It will relight because of oxygen present

Question 12

What are limiting factors?

Answer 12

If one is too low then the rate of reaction is limited

Question 13

What factors affect the rate of photosynthesis?

Answer 13

Light intensity, carbon dioxide and temperature affect the rate of photosynthesis

Question 14

How do you measure the rate of photosynthesis?

Answer 14

1/t where t is a value in seconds, minutes of hours

Question 15

How does light intensity affect rate of photosynthesis?

Answer 15

The higher the light intensity, the faster the rate of photosynthesis, but this is limited up to when photosynthesis reaches its maximum rate

Question 16

How does carbon dioxide affect rate of photosynthesis?

Answer 16

The greater the carbon dioxide concentration the faster the rate of reaction, but the atmosphere has 0.04% so it is usually the limiting factor

Question 17

How does temperature affect the rate of photosynthesis?

Answer 17

The greater the temperature, the greater the rate of photosynthesis, until it passes the optimum temperature as the enzymes denature