B1.4: Photosynthesis

Question 1

Name the two reactants needed for the reaction of photosynthesis

Answer 1

Water and Carbon dioxide

Question 2

How do plants take in carbon dioxide?

Answer 2

Carbon dioxide diffuses from the air into the plant through the stomata

Question 3

How do plants take in water?

Answer 3

Water enters the roots from the soil through root hair cells by osmosis

Question 4

In order for the reaction of photosynthesis to take place, what two things need to be present?
(Not reactants or products)

Answer 4

Sunlight (light energy) and chlorophyll

Question 5

Name the two products formed in the reaction of photosynthesis

Answer 5

Glucose and Oxygen

Question 6

What is the word and balanced symbol equation for photosynthesis?

Answer 6

Carbon dioxide + water ——–> glucose + oxygen

6CO2 + 6H20 ——–> C6H12O6 + 6O2

*in subscript

Question 7

Name structure in the plant where photosynthesis takes place

Answer 7

Chloroplasts

Question 8

Which tissues in the leaf contains the most chloroplasts?

Answer 8

Mesophyll and palisade

Question 9

What is the name of the green pigment found in the leaves and stem?

Answer 9

Chlorophyll

Question 10

What does chlorophyll absorb?

Answer 10

Light energy needed for photosynthesis

Question 11

What type of reaction is photosynthesis?

Energy wise

Answer 11

Endothermic

Energy needs to absorbed for the reaction to occur

Question 12

Name six things that the glucose produced can be used for

Answer 12

respiration - to release energy
sucrose - stored in fruit 
starch - food store 
cellulose - to form cell walls
proteins - for growth and repair
fats and oils - food store and growth

Question 13

The product of photosynthesis, glucose, can be converted into protein by adding…

Answer 13

nitrates / nitrate ions

Question 14

What are the four limiting factors of photosynthesis?

Answer 14

Light intensity
Carbon dioxide concentration
Temperature
Chlorophyll

Question 15

State four ways in which the rate of photosynthesis can be increased

Answer 15

Increase light intensity.
Increase temperature.
Increase concentration of carbon dioxide.
Increase amount of chlorophyll

Question 16

What is the formula that can be used to calculate the rate of photosynthesis?

Answer 16

rate = 1 / t*

*where t is the time for the measurement to occur

Question 17

Explain how light intensity affects the rate of photosynthesis

Answer 17

As light intensity increases the rate of photosynthesis increases
Light provides the energy needed for photosynthesis
At very high light intensity not all the light can be absorbed as there is insufficient chlorophyll

Question 18

Explain how temperature affects the rate of photosynthesis

Answer 18

As temperature increases the rate of photosynthesis increases.
Diffusion of carbon dioxide into the leaf increases
Molecules will move faster and are more likely to collide and react.
Enzymes catalyse these reactions and have an optimum temperature
At very high temperatures the enzymes will denature and photosynthesis will decrease

Question 19

Explain how the amount of chlorophyll affects the rate of photosynthesis

Answer 19

As the amount of chlorophyll increases the rate of photosynthesis increases
More light can be absorbed by the chlorophyll
Light is needed to provide the energy for photosynthesis.

Question 20

Explain how carbon dioxide concentration affects the rate of photosynthesis

Answer 20

As carbon dioxide concentration increases the rate of photosynthesis increases.
More carbon dioxide can diffuse into the leaf
Increases number of collisions that occur between carbon dioxide and water

Question 21

State one way which can investigate the rate of photosynthesis
(experiment)

Answer 21

By using Elodea (pondweed), you are able to see the volume of oxygen given off per minute by counting the number of bubbles produced per minute

Question 22

Why can counting the oxygen bubbles be inaccurate?

State the error and suggest a more accurate method

Answer 22

Human error - may miscount the bubbles

You can use a gas syringe, a piece of apparatus which has a precise scale to measure the amount of oxygen.

Question 23

How can you alter light intensity to study its effect on the rate of photosynthesis?
(typically in an experiment)

Answer 23

Place a light source at different distances from the Elodea

Question 24

There is a law which describes the relationship between the distance of a light source from a plant and light intensity.
State the name and formula of this law

Answer 24

The inverse square law:

relative light intensity = 1 / distance from light source^2

Question 25

How can you alter the concentration of carbon dioxide to study its effect on the rate of photosynthesis?

Answer 25

By adding different masses of potassium hydrogen carbonate powder to the water, as it releases carbon dioxide to the atmosphere

Question 26

How can you alter temperature to study its effect on the rate of photosynthesis?

Answer 26

By placing the apparatus in water baths at different temperatures