B8 - Photosynthesis

Question 1

How does photosynthesis produce glucose?

Answer 1

Photosynthesis uses energy from the sun to change CO2 and water into glucose and oxygen.

Question 2

Where does photosynthesis take place?

Answer 2

It takes place in the chloroplasts in green plant cells - they contain pigment like chlorophyll that absorb light

Question 3

What does endothermic mean?

Answer 3

It means that energy is transferred from the environment in the process

Question 4

What is the word equation for photosynthesis?

Answer 4

Carbon dioxide + water ——–light—–> glucose + oxygen

Question 5

What does photosynthesis use energy to do?

Answer 5

Photosynthesis uses energy to change carbon dioxide and water into glucose and oxygen

Question 6

Whats the symbol equation for photosynthesis?

Answer 6

6CO2 + 6H20 ———light——> C6 H12 O6 + 6O2

Question 7

What are the 5 main ways that plants use glucose?

Answer 7

• for respiration - this transfers energy from glucose which enables the plants to convert the rest of the glucose into various other useful substances
• Making cellulose - Glucose is converted into cellulose for making strong plant cell walls
• Making amino acids - Glucose is combined with nitrate ions ( absorbed from the soil ) to make amino acids, which are then made into proteins
• Stored as oils or fats - glucose is turned into lipids ( fats and oils ) for storing in seeds
• Stored as starch - Glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn’t happening, like in the winter

Question 8

What are the limiting factors of photosynthesis?

Answer 8

• at night it’s pretty obvious that light is the mimiting factor
• in winter it’s often the temp
• if it’s warm enough and bright enough, the amount of CO2 is usually limiting
• Chlorophyll can also be a limiting factor - because of lack of Mg ions or because the plant has a disease like for e.g. tobbaco mosaic virus

Question 9

How does oxygen production shows the rate of photosynthesis ( rate of photosynthesis rp )

Answer 9

Pondweed can be used to measure the effect of light intensity on the rate of photosynthesis.
The rate at which the pondweed produces oxygen corresponds to the rate at which it’s photosynthesising - the faster the rate of oxygen production, the faster the rate of photosynthesis.

Question 10

Rate of photosynthesis RP ( show the steps )

Answer 10

1) Cut a piece of pondweed 8–10 cm long (pre cut). Place it in a boiling tube of water/bicarbonate with the cut end upwards.
2) Use the thermometer to measure the temperature of the water in the boiling tube.
3) Place the boiling tube in a large beaker of water to act as a heat shield and position it 10cm away from the lamp.
4) Wait until there is a steady flow of bubbles from the cut end of the pondweed. Count the number of bubbles in 2 minutes. Record this in the first blank column of the results table.
5) Measure the temperature of the water in the boiling tube again to make sure it has not changed.
6) Repeat steps 1–5 four more times but in step 3 increase the distance between the lamp and boiling tube by 10 cm each time.
7) Repeat the whole investigation (steps 1–6) two more times and record the results in the second and third blank columns of the table.
8) Calculate the mean number of bubbles for each distance, leaving out any anomalous values from your calculations. Record it in the fourth blank column, giving your answer to the nearest whole number.

Question 11

What is the formula of light intensity?

Answer 11

Light intensity ( is proportional to ) 1/distance2

Question 12

How can you artifcially create ideal conditions for farming?

Answer 12

The most common way to create the ideal environment for plant to grow is in a greenhouse

Question 13

List all the things that greenhouses do?

Answer 13

-Greenhouses help to trap the Sun’s heat and make sure the the temperature doesn’t become limiting. In the winter a farmer might use a heater to keep the temp to the ideal level.

-Light is always needed for photosynthesis so farmers usually use artificial light to their plants so they get more time to photosynthesise.

-Keeping the plants enclosed in a greenhouse also makes it easier to keep pests away and the farmers can also use fertilisers to give the plant all the minerals it needs for a healthy growth.

Question 14

What is respiration?

Answer 14

Respiration is the process of Transferring Energy From Glucose which goes on in every cell

Question 15

What type of reaction is Respiration?

Answer 15

It is exothermic - it transfers energy to the environment

Question 16

Give 3 examples of how organisms use the energy transferred by respiration

Answer 16

• To build up larger molecules from smaller ones ( like amino acids to protiens )
• In animals it’s used to allow the muscles to contract
• In mammals and birds the energy is used to keep their body temp steady in colder surroundings

Question 17

What is metabolism?

Answer 17

Metabolism is all the chemical reactions in a organism. For e.g. glucose joining together to make starch or glucose getting broken down in respiration

Question 18

Describe and explain how the rate of photosynthesis varies with temperature

Answer 18

At first the rate of photosynthesis rises with temperature as the particles have more energy and move more quickly. This means they can react more quickly and so the rate is higher.

However, as temperature rises above the optimum temperature for the enzymes involved, the enzymes may start to break down. This decreases the rate until it falls to zero (when the enzymes are denatured)

Question 19

How can gardeners increase the level of carbon dioxide in the greenhouse ?

Answer 19

By using a paraffin heater to heat the greenhouse
As the paraffin burns it makes carbon dioxide as a by product but is mainly use to heat the greenhouse

Question 20

What makes starch a useful long term storage moelcule ?

Answer 20

-Its compact
-Its insoluble in water
-It can be easily broken down when needed