To Investigate The Influence Of Light Intensity/CO2 On The Rate Of Photosynthesis

Question 1

Where in the cell does the dark stage take place?

Answer 1

Chloroplast (stroma)

Question 2

Why is the dark stage called the dark stage?

3

Answer 2

It can occur in the dark

It is light independent

Light is not required

Question 3

Name the plant you used for this experiment.

Answer 3

Elodea

Question 4

Why did you use Elodea in this experiment?

2

Answer 4

It is an aquatic plant so it will produce bubbles of gas which can be easily seen

Bubbles of O2 visible in water

Question 5

How did you measure the rate of photosynthesis?

Answer 5

Counted the number of bubbles per unit time/per minute

Question 6

Explain the shape of the graph produced during your investigation of the influence of light intensity on the rate of photosynthesis.
(4)

Answer 6

X- axis = light intensity
Y-axis =Rate of number of bubbles per minute

As light intensity increases the rate of photosynthesis increases

Rate levels of as saturated point is reached (plant is said to be saturated with light)

Question 7

Define an anabolic reaction..

Answer 7

Anabolic reactions use energy to convert smaller molecules into larger molecules

Question 8

Define a metabolic reaction.

Answer 8

Metabolism is the sum of all the chemical reactions in an organism

Question 9

State one possible source of error for your experiment.

3

Answer 9

Error in counting bubbles

Error in measuring lamp distance from flask

Error in measuring time interval

Question 10

Explain what is meant by the term energized electrons.

Answer 10

The electrons have gained energy/excited

Question 11

High energy electrons are used in photosynthesis, where are these electrons located?

Answer 11

Chlorophyll

Question 12

Explain how you ensured the temperature remained constant throughout the investigation.

Answer 12

Thermostatically controlled water bath

Question 13

What factor did you keep constant?

2

Answer 13

Lamp wattage kept constant

Temperature kept constant at 25 degrees

Question 14

What factor did you vary?

Answer 14

Varied the lamp distance from the plant

Question 15

Name the organelle in which chlorophyll is found.

Answer 15

Chloroplast

Question 16

What is the importance of chlorophyll in photosynthesis?

Answer 16

To trap sunlight

Question 17

What would happen if you carried this experiment out at a higher temperature?

Answer 17

The rate of photosynthesis would increase

Question 18

Why would the rate of photosynthesis increase at a higher temperature?
(2)

Answer 18

Because a greater temperature allows for a greater rate of photosynthesis

Temperature is not limiting

Question 19

Name the stage which requires light.

Answer 19

Stage one - Light stage (light-dependent stage)

Question 20

Oxygen is an important by-product of photosynthesis. Explain why.

Answer 20

Oxygen is needed for respiration

Question 21

At what temperature did you carry out the experiment?

Answer 21

25 degrees Celsius

Question 22

Explain why you carried out this experiment at 25 degrees Celsius.

Answer 22

This is the optimum temperature for enzymes

Question 23

Name the food product of photosynthesis.

Answer 23

Glucose

Question 24

Name the non-food product of photosynthesis.

Answer 24

Oxygen

Question 25

Name the green pigment needed for photosynthesis.

Answer 25

Chlorophyll

Question 26

In what organelle is chlorophyll found?

Answer 26

Chloroplast

Question 27

State a role for carbon dioxide in photosynthesis.

Answer 27

Supplies carbon

Question 28

State a role of water in photosynthesis.

2

Answer 28

Supplies protons (H+)

Supplies electrons