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Explain the Process of Photosynthesis

In this worksheet, students will explain the process of photosynthesis

'Explain the Process of Photosynthesis' worksheet

Key stage:  KS 4

GCSE Subjects:   Biology: Single Subject, Biology: Combined Science

GCSE Boards:   Pearson Edexcel

Curriculum topic:   Plant Structures and Their Functions

Curriculum subtopic:   Plant Structures and Their Functions

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

Virtually everything we eat can be traced back to plants. Either we eat food from plants or we eat food from animals, that in turn have eaten plants. How do plants get their food then? Let's find out the answer to this question below. 

 

Image of photosynthesis

 

Plants use sunlight to make their own food - this process is called photosynthesis. Plants contain a special green pigment called chlorophyll that traps sunlight. The chlorophyll is found in structures called chloroplasts, which are found in plant cells - mainly in palisade cells in the leaf.

Photosynthesis is an endothermic reaction because light energy is absorbed by the plant to power photosynthesis.  Enzymes speed up this process - without enzymes, the reactions in photosynthesis would happen really slowly. Water and carbon dioxide are essential for photosynthesis. Water is absorbed by root hair cells in the plant's roots, and carbon dioxide enters the leaf of a plant through small pores called stomata (or stoma when we're talking about just one).  Stomata are normally surrounded by cells called guard cells that open and close. They control the movement of gases entering or exiting the leaf.

 

Image of leaf anatomy

 

 

Photosynthesis can be broken up into two main stages: 

First StageLight energy is used to split water into oxygen and hydrogen. The oxygen is released into the atmosphere.

 

Second Stage: The hydrogen is combined with carbon dioxide taken in from the atmosphere to make glucose


 

The table below summarises the inputs (what is taken in) and outputs (what is released or produced) from each stage of photosynthesis:​
 

Stage of photosynthesis  Input  Output 

First Stage

Light

Chlorophyll (structure)

Water

Oxygen

Hydrogen

Second Stage

 

Hydrogen

Carbon Dioxide

Glucose

 

The glucose made by photosynthesis is used for many processes:

It provides energy for respiration.
It is used to make cellulose - the main structural material in cell walls.

It is used to turn sugars, nitrates and other nutrients into amino acids which build up proteins.

It is stored as starch (in leaves, seeds, roots and tubers).

It is used to make fats and oils (energy stored in seeds).


In the following activity, you will explain the process of photosynthesis.

Glucose from photosynthesis can be used in many different processes.

 

Describe these processes by matching up the sentences below. 

Column A

Column B

Used to make cellulose which is...
...the main structural material in cell walls
Stored as starch for example in...
...for respiration
Used to turn sugars and nitrates...
...leaves, seeds, roots and tubers
Provides an energy source...
...and oils often stored in seeds
Used to make fats...
...into amino acids which build up proteins

The image below shows the structure of a leaf.

 

What is the name of structure X that allows carbon dioxide and oxygen to enter and leave the plant? 

 

Image of leaf anatomy  

Photosynthesis is a process that takes place in green plants.

 

What type of energy is needed for this process to occur?

Heat energy

Light energy

Kinetic energy

Explain how chloroplasts are involved in photosynthesis.

Chloroplasts contain a pigment called chlorophyll that absorbs sunlight

Chloroplasts contain root hair cells that absorb water

The water is used in the first stage of photosynthesis

This light energy is used to split water in the first stage of photosynthesis

Photosynthesis occurs in two stages. 

 

Explain what happens in these two stages.

Column A

Column B

In the first stage of photosynthesis, light energy...
...with carbon dioxide to make glucose
The oxygen is released...
...used to split water into oxygen and hydrogen
In the second stage, carbon dioxide is taken in...
...into the atmosphere
The hydrogen from the first stage is combined...
...from the atmosphere

Photosynthesis is a process that takes place in green plants.

 

Explain why light energy is needed for this process to occur.

Column A

Column B

In the first stage of photosynthesis, light energy...
...with carbon dioxide to make glucose
The oxygen is released...
...used to split water into oxygen and hydrogen
In the second stage, carbon dioxide is taken in...
...into the atmosphere
The hydrogen from the first stage is combined...
...from the atmosphere

Match up the definitions to the keywords below.

Column A

Column B

The storage carbohydrate found in plants
Water
The process where plants use sunlight to make glu...
Glucose
The gas produced during photosynthesis
Starch
The source of energy needed by plants for photosy...
Carbon dioxide
The gas needed by plants for photosynthesis
Oxygen
The sugar made by plants during photosynthesis
Photosynthesis
The liquid needed by plants for photosynthesis
Light

In an exam question on photosynthesis, Sam wrote that enzymes don't have a part to play in photosynthesis, whereas Lenny wrote that enzymes speed up the reactions involved in photosynthesis.

 

Who's correct, Sam or Lenny?

Sam

Lenny

Neither of them

What are some of the inputs and outputs of the first stage of photosynthesis? 

Explain why enzymes are needed for photosynthesis. 

Enzymes speed up the reactions needed for photosynthesis

Enzymes are turned on when there's sunlight

Enzymes are chemicals that slow down reactions

  • Question 1

Glucose from photosynthesis can be used in many different processes.

 

Describe these processes by matching up the sentences below. 

CORRECT ANSWER

Column A

Column B

Used to make cellulose which is.....
...the main structural material i...
Stored as starch for example in.....
...leaves, seeds, roots and tuber...
Used to turn sugars and nitrates....
...into amino acids which build u...
Provides an energy source...
...for respiration
Used to make fats...
...and oils often stored in seeds
EDDIE SAYS
If you weren't too confident with this one, have a go at this question a few times to consolidate your knowledge. The uses of glucose often comes up in exams!
  • Question 2

The image below shows the structure of a leaf.

 

What is the name of structure X that allows carbon dioxide and oxygen to enter and leave the plant? 

 

Image of leaf anatomy  

CORRECT ANSWER
Stomata
Stoma
EDDIE SAYS
The stomata are pores that allow gas exchange to occur. They are normally surrounded by cells called guard cells that open and close, controlling which gases enter or exit the leaf. It is important to know which way the gases flow. Carbon dioxide passes in through the stomata and oxygen is released into the atmosphere.
  • Question 3

Photosynthesis is a process that takes place in green plants.

 

What type of energy is needed for this process to occur?

CORRECT ANSWER
Light energy
EDDIE SAYS
Photosynthesis is an endothermic reaction because light energy is taken into the plant cells to start the process. Without light, the process could not happen, which is why photosynthesis doesn't happen at night.
  • Question 4

Explain how chloroplasts are involved in photosynthesis.

CORRECT ANSWER
Chloroplasts contain a pigment called chlorophyll that absorbs sunlight
This light energy is used to split water in the first stage of photosynthesis
EDDIE SAYS
Many structures are needed for photosynthesis to occur. Chloroplasts contain the pigment chlorophyll, which absorbs the sunlight and enables the process of photosynthesis to occur. Chlorophyll also gives plants their green colour!
  • Question 5

Photosynthesis occurs in two stages. 

 

Explain what happens in these two stages.

CORRECT ANSWER

Column A

Column B

In the first stage of photosynthe...
...used to split water into oxyge...
The oxygen is released...
...into the atmosphere
In the second stage, carbon dioxi...
...from the atmosphere
The hydrogen from the first stage...
...with carbon dioxide to make gl...
EDDIE SAYS
Many reactions occur during photosynthesis but are summarised in two main stages. In the first stage, light energy is absorbed and used to split water into its components - that is oxygen and hydrogen. The oxygen is not needed, so it is released into the atmosphere. In the second stage, the hydrogen created from the first stage is combined with carbon dioxide taken from the atmosphere to produce glucose.
  • Question 6

Photosynthesis is a process that takes place in green plants.

 

Explain why light energy is needed for this process to occur.

CORRECT ANSWER
EDDIE SAYS
Light energy is needed to kick start the process of photosynthesis, without which humans would not have the oxygen needed for respiration!
  • Question 7

Match up the definitions to the keywords below.

CORRECT ANSWER

Column A

Column B

The storage carbohydrate found in...
Starch
The process where plants use sun...
Photosynthesis
The gas produced during photosyn...
Oxygen
The source of energy needed by p...
Light
The gas needed by plants for pho...
Carbon dioxide
The sugar made by plants during p...
Glucose
The liquid needed by plants for ...
Water
EDDIE SAYS
A quick summary activity to test your knowledge of the key terms found in this topic. If you weren't totally sure about it, it would be a good idea to have a few tries to get it sorted in your head. Well done for completing another activity!
  • Question 8

In an exam question on photosynthesis, Sam wrote that enzymes don't have a part to play in photosynthesis, whereas Lenny wrote that enzymes speed up the reactions involved in photosynthesis.

 

Who's correct, Sam or Lenny?

CORRECT ANSWER
Lenny
EDDIE SAYS
Well done if you went with Lenny! Without enzymes, the reactions involved in photosynthesis would occur very slowly, if at all.
  • Question 9

What are some of the inputs and outputs of the first stage of photosynthesis? 

CORRECT ANSWER
EDDIE SAYS
Did you notice that the question was only asking about the first stage of photosynthesis? In the first stage of photosynthesis, water is split up by light to produce oxygen and hydrogen.
  • Question 10

Explain why enzymes are needed for photosynthesis. 

CORRECT ANSWER
Enzymes speed up the reactions needed for photosynthesis
EDDIE SAYS
How did you get on with this first question? Enzymes are catalysts, which means that they speed up reactions but without being used up in the process themselves. Without enzymes, photosynthesis would happen very slowly.
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