Topic 4: Life Processes In Plants - Photosynthesis

Question 1

In the experiment to determine whether oxygen is released during photosynthesis, what was absent in the CONTROL and why was it necessary?

Answer 1

Light - it is a requirement for photosynthesis

Question 2

In the experiment to determine whether oxygen is released during photosynthesis, was a gas given off by the control and what was it?

Answer 2

Yes - Carbon Dioxide because the plant was not photosynthesizing (only respiring)

Question 3

In the experiment to determine whether oxygen is released during photosynthesis, what happened when a glowing splinter was placed in the gas in the CONTROL?

Answer 3

Glowing splint does not reignite - Carbon Dioxide

Question 4

What does Carbon Dioxide do during photosynthesis? (3)

Answer 4

• It diffuses from the atmosphere through the stomata.
• It then diffuses through the intercellular air spaces to the palisade mesophyll.
• It then diffuses through the cell membrane, cytoplasm and into the chloroplast.

Question 5

Name the 3 types of cells in the leaf where photosynthesis takes place.

Answer 5

• Guard cells
• Palisade mesophyll
• Spongy mesophyll

Question 6

In the experiment to determine whether CO2 is essential for photosynthesis, why did the apparatus need to be in sunlight? (2)

Answer 6

• To ensure that photosynthesis could take place
• In order to keep all other variables constant

Question 7

In the experiment to determine whether oxygen is released during photosynthesis, what happened when a glowing splint was placed in the gas in the CONTROL?

Answer 7

Glowing splint reignites - Oxygen

Question 8

Name 2 substances that can absorb carbon dioxide

Answer 8

• Soda lime
• Caustic soda

Question 9

In the experiment to determine whether CO2 is essential for photosynthesis, what was the colour of the leaf that was deprived of CO2 after the starch test?

Answer 9

Yellow/brown

Question 10

In the experiment of the effect of increased light intensity on plants, what conclusions were made?

Answer 10

The number of gas bubbles per minutes increases as light intensity increase Up until a point where a limiting factor will cause the photosynthetic rate to stay the same. (Plateau)

Question 11

What is the purpose of the bell jars in the Carbon Dioxide experiment?

Answer 11

• Provide controlled environment so no other variables affect apparatus
• Control flow of gases into apparatus
• Transparent sides so sunlight isn’t blocked

Question 12

What is the greenhouse effect in relation to greenhouses?

Answer 12

It is when the atmosphere/ air of the greenhouse is significantly warmer than the air outside.

Question 13

How do you destarch a plant?

Answer 13

Leave it in a dark area devoid of sunlight for a day or two

Question 14

What is done with the starch of a plant?

Answer 14

It is stored by the plant in various organs (root) and is converted back into glucose during respiration.

Question 15

How can stomata affect the rate of photosynthesis? (3)

Answer 15

• During the day when the rate of photosynthesis is high, the stomata are open to allow the diffusion of CO2 into leaf.
• When light intensity decreases the rate of photosynthesis slows down and CO2 builds up in the leaf and stomata close.
• The stomata can close due to excessive water loss. This leads to the rate of photosynthesis decreasing because less CO2 can enter the leaf.

Question 16

What do many glucose molecules joined together form?

Answer 16

Starch

Question 17

List several ways Greenhouses make the optimal conditions for photosynthesis? (4)

Answer 17

• Built in places with high amounts of sunlight
• Short wavelength infra radiation from the sun can easily pass the glass or thick clear plastic walls to warm up the Greenhouse
• The warmth of the soil and air gives off longer wavelength radiation that can’t easily pass through and is reflected back
• The glass or plastic traps the heat energy.

Question 18

What is the by-product of photosynthesis?

Answer 18

Oxygen (O*2)

Question 19

How can we measure the effect of increased levels of carbon dioxide concentration on the rate of photosynthesis?

Answer 19

Measure the dry mass of plants

Question 20

In the experiment to determine whether oxygen is released during photosynthesis, was a gas given off by the experiment and what was it?

Answer 20

Yes - Oxygen because the plant was respiring

Question 21

In the investigation to investigate whether oxygen is released during photosynthesis; provide 2 separate CONTROLS that can be set up.

Answer 21

• An apparatus with a methylene blue solution and no water plants. If the solution doesn’t turn blue, it’ll show that Oxygen is given off by the plant.
• An apparatus in the dark with a plant. If the solution stays colorless, this indicates that Oxygen must be given off by a plant in the light.

Question 22

In the experiment to prove that chlorophyll is essential for photosynthesis, what could be deduced about the need for chlorophyll during photosynthesis?

Answer 22

Light is require for photosynthesis there chlorophyll is essential for photosynthesis

Question 23

What is the light energy converted to?

Answer 23

Chemical energy

Question 24

What does Water do during photosynthesis? (4)

Answer 24

• Water is absorbed into the roots from the soil water.
• It travels up the xylem tissue of the root and stem due to transpiration pull.
• It passes into the xylem of the petiole and then into the veins of the leaf.
• From veins, it diffuses as water vapour to the chloroplast.

Question 25

In the experiment to determine whether oxygen is released during photosynthesis, what purpose did the glass funnel serve?

Answer 25

To hold down the water plant and the test tube used to collect the gas produced by the plant

Question 26

In the experiment to determine whether CO2 is essential for photosynthesis, what was the colour of the leaf that was given CO2 after the starch test?

Answer 26

Blue/black

Question 27

In the experiment to test for starch in a green leaf, why must a leaf that has been exposed to sunlight be chosen?

Answer 27

To ensure that the leaf had undergone photosynthesis

Question 28

In the experiment to determine whether oxygen is released during photosynthesis, what conclusion can be made?

Answer 28

Oxygen is released during photosynthesis

Question 29

How do plants use their glucose? (5)

Answer 29

- Form starch - Form cellulose - Make fats - Form sugars i.e. fructose - Form amino acids (then into protein and then enzymes)

Question 30

Where is the chemical energy stored in a plant?

Answer 30

In glucose molecules

Question 31

What happens to the rate of photosynthesis when the temperature becomes too high?

Answer 31

The rate of photosynthesis will decrease since high temperatures will destroy the enzymes that control the rate of photosynthesis.

Question 32

How do we measure the rate of photosynthesis? (2)

Answer 32

- By the amount of food that plants make - By the amount of oxygen that plants give off

Question 33

In the experiment to determine whether oxygen is released during photosynthesis. Predict, with reasons, what effect an increased light intensity will have on the production of gas.

Answer 33

It would increase the rate of photosynthesis therefore there would be increased production of O2 gas, until a limiting factor affected it

Question 34

In the experiment of carbon dioxide on food production, what conclusions were made?

Answer 34

The dry mass of the plant (cabbage) increased with the increase of carbon dioxide (% in the air) up to a point until it began to decrease due to the presence of a limiting factor.

Question 35

In the experiment to determine whether oxygen is released during photosynthesis, why was the glass funnel raised slightly?

Answer 35

To allow free flow of water to the plant, so that the plant could access the CO2 in the water, in order to photosynthesize

Question 36

What do light & chlorophyll do during photosynthesis? (3)

Answer 36

- Light (as radiant energy from sun) is absorbed through the transparent cuticle and transparent epidermis. - Light is then absorbed by the chlorophyll molecules in the chloroplasts of the palisade & spongy mesophyll cells. - Absorption of light initiates photosynthesis.

Question 37

In the experiment to test for starch in a green leaf, what colour did the clear alcohol become after boiling the leaf in it and why?

Answer 37

Green - the chlorophyll had been extracted out of the leaf by the alcohol.

Question 38

In the investigation to investigate whether oxygen is released during photosynthesis, what conclusion can be made?

Answer 38

Oxygen is released during photosynthesis

Question 39

What are the 3 main limiting factors?

Answer 39

- Light intensity - Carbon dioxide concentration - Temperature

Question 40

In the investigation to investigate whether oxygen is released during photosynthesis, what was the colour of the methylene blue solution at the start and end of the experiment?

Answer 40

Start: colourless End: blue

Question 41

What is the equation/formula of photosynthesis in words?

Answer 41

Carbon Dioxide + Water + Light + Chlorophyll ---> Glucose + Oxygen

Question 42

Name 2 variables that would need to be kept constant during an experiment that measures the dry mass of plants kept in separate greenhouses to see the effect on Carbon dioxide concentrations?

Answer 42

- Same plant species - Same soil type - Same amount of sunlight - Same amount of water

Question 43

What happens when temperature increases up until the optimum for photosynthesis?

Answer 43

The rate of photosynthesis becomes constant due to carbon dioxide and light becoming a limiting factor.

Question 44

In the experiment to prove that chlorophyll is essential for photosynthesis, how could you describe the areas that tested positive for starch and those that testes negative?

Answer 44

- The areas that tested positive were the green areas which contain chlorophyll which means they were able to photosynthesize. - The areas that tested negative were the white areas and had no chlorphyll.

Question 45

What is a limiting factor?

Answer 45

A limiting factor is an environmental condition that restricts the rate of photosynthesis if it's in short supply.

Question 46

In the experiment to prove that chlorophyll is essential for photosynthesis, why was a variegated leaf used?

Answer 46

To show that the variable, chlorophyll, is required for photosynthesis

Question 47

If a plant were to receive an increase in light intensity, would the rate keep increasing forever?

Answer 47

No, eventually another limiting factor will keep the rate of photosynthesis the same.

Question 48

In the experiment to test for starch in a green leaf, what colour does the decolourised leaf turn into and what does that tell us?

Answer 48

- It turns blue-black - Indicates the presence of starch in leaf

Question 49

In the experiment to prove that light was essential for photosynthesis, what could be concluded if all the areas (even those under the foil) test positive?

Answer 49

Starch was present at the start of the investigation. Making the investigation meaningless.

Question 50

In the experiment to prove that light was essential for photosynthesis, what could be said about the correlation between the areas that tested positive and negative (starch test) and the areas of the leaf exposed to light?

Answer 50

The area of the leaf exposed to light tested positive and the the areas that were not exposed to light tested negative

Question 51

In the experiment to prove that light was essential for photosynthesis, why was it important to ensure that the potted plant was destarched?

Answer 51

To ensure that the starch produced had only been produced during the experiment/investigation

Question 52

What affects the rate of photosynthesis? (4)

Answer 52

- Different amounts of Carbon Dioxide - Different light intensities - Different temperatures - The opening & closing of stomata

Question 53

How is oxygen released out of a plant?

Answer 53

It diffuses from the chloroplast through cytoplasm and cell membrane of the palisade mesophyll cells into the intercellular air spaces. From there, it diffuses through the stomata to the outside of the leaf.

Question 54

In the experiment to test for starch in a green leaf, give 2 reasons why the green leaf must be boiled first.

Answer 54

- To remove the waxy cuticle - To denature the cell membrane so that chlorophyll can be extracted from leaf - To stop all metabolic process in the leaf

Question 55

Give the balanced equation of photosynthesis

Answer 55

6CO*2 + 6H*2 O ---> C*6 H*12 O*6 + 6O*2

Question 56

What conclusion could be made from the experiment that tested whether light was essential for photosynthesis?

Answer 56

Light is required for photosynthesis

Question 57

What is the optimum temperature for photosynthesis?

Answer 57

25 Degrees Celsius

Question 58

What is glucose used for?

Answer 58

As energy for the plant.

Question 59

Give 2 precautions that must be observed when working with alcohol.

Answer 59

- Ensure that it does not come into contact with a flame (high flammability) - Ensure that alcohol does not boil over.