The smart way to improve grades

Comprehensive & curriculum aligned

Try an activity or get started for free

Understand Diffusion

In this worksheet, students will define diffusion.

Worksheet Overview

QUESTION 1 of 10

Image of a pair of socks

 

Why can you smell someone's stinky PE socks from all the way across the classroom? Yuk! Normally it's because sweat and other molecules are moving away from the socks and spread out in the air. This is called diffusion

Diffusion is the spreading out of the particles of any substance in a solution, or particles of a gas, resulting in movement from an area of higher concentration (where there are more particles in a certain solution or area) to an area of lower concentration (where there are fewer particles).

                                  
                                                                                                        Diffusion                                                                            

Living organisms need different substances to be able to survive and function. These substances need to be transported into and out of their cells through diffusion (as well as osmosis and active transport - you will learn more about these later!). During diffusion, molecules move from an area of high concentration to an area of low concentration. They are said to move down concentration gradient. Particles diffuse until they are evenly spaced apart. Diffusion is a passive process which means that no energy is needed and it happens naturally. 

 

Image of gas exchange in alveolus

 

 

Diffusion in organisms

 

In multicellular organisms, surfaces and organ systems are specialised for exchanging materials. This is to allow sufficient molecules to be transported into and out of cells for the organism’s needs. Diffusion is the main way substances move over short distances in organisms.

 

Diffusion happens in the lungs where breathing involves exchanging gases in the lungs. When you breathe in, oxygen in the inhaled air diffuses through the tiny air sacs (alveoli) in your lungs into your bloodstream. The oxygen is transported around your body. Carbon dioxide is the waste gas produced by respiration. Carbon dioxide diffuses from cells into the bloodstream and is exhaled by the lungs

 

Image of villi in intestine

 

Another example of diffusion is in the small intestine. Digested food is broken down into small molecules such as glucose and amino acids. These important molecules need to be transported around the body via the blood. The small intestine is lined with many finger-like projections called villi. The molecules diffuse through the villi of the small intestine into the blood to be transported around the body.

 

                                                                       Image of plant photosynthesising 

 

Diffusion also occurs in plants. The structure of the leaf is adapted for gas exchange. There are tiny pores called stomata in the surface of the leaf. It is through these that plants take in carbon dioxide for photosynthesis and produce oxygen. These enter and leave the plant through the process of diffusion.

 

 

Factors affecting diffusion

 

Different factors can affect diffusion and how quickly it happens. Some of these factors are:

 

The difference in concentrations (concentration gradient) - having a large difference in concentrations means that diffusion can occur at a quicker rate as particles will naturally move from a high to low concentration. 
The temperature - the higher the temperature, the more energy the particles will have to move and spread out.
The surface area of the membrane - the larger the surface area, the faster the rate of diffusion. This is because more particles can pass through the membrane as there is more area, as in the alveoli in the lungs.

 

In the following activity, you will define and describe diffusion.

Stuart can smell someone's smelly socks in class.

 

How can he smell socks from a distance?

 

Image of noseImage of a pair of socks

Stuart has a really good sense of smell

The socks are REALLY smelly

The sweat particles diffuse into the air from the socks and spread out

Image of noseImage of a pair of socks

 

Stuart can smell someone's smelly socks in class.

 

Where is the smell strongest? 

The smell is strongest at the sock

The smell is strongest away from the sock

The smell is strongest everywhere

Describe the process of diffusion by filling in the blanks below.

 

Image of particles diffusing

The smell is strongest at the sock

The smell is strongest away from the sock

The smell is strongest everywhere

Diffusion allows many important processes to occur in different organisms.

 

Which of the following are examples of diffusion?

 

Image of plant photosynthesisingImage of gas exchange in alveoli

Oxygen entering the blood from the lungs

Carbon dioxide entering the lungs from the blood

Carbon dioxide entering the leaf of a plant for photosynthesis

Water entering the lungs

Why is diffusion important?

Diffusion allows substances to be taken in for various cell processes

Only gases diffuse

Diffusion removes unwanted substances

Diffusion allows water to enter the lungs

Diffusion is a process that doesn't need energy.

 

What is the scientific name for a process that does not need energy?

 O O O O O

Cell A 

 O O O O O O O O O O O

Cell B

 

 

The diagram above shows two cells. Cell A has five particles and Cell B has eleven particles.

 

In which direction will the particles diffuse?

From Cell A to Cell B

From Cell B to Cell A

No movement

The rate of diffusion is affected by different factors.

 

Match up the sentences describing how these factors affect the rate of diffusion.

Column A

Column B

The greater the difference in concentration...
...The greater the movement of particles, resultin...
The greater the temperature...
...The more space for particles to move through, r...
The greater the surface area...
...The faster the rate of diffusion because more p...

What is the name of the structure of the plant where gas exchange happens?

Certain gases diffuse into and out of plants.

 

What are these gases needed for?

For absorbing water

For photosynthesis

For metabolism

Which gases diffuse into and out of the plant due to photosynthesis?

 

image of a plant

Hydrogen

Carbon dioxide

Nitrogen

Oxygen

  • Question 1

Stuart can smell someone's smelly socks in class.

 

How can he smell socks from a distance?

 

Image of noseImage of a pair of socks

CORRECT ANSWER
The sweat particles diffuse into the air from the socks and spread out
EDDIE SAYS
It is possible that all three of these options might be true!! However, we can only guess at how good Stuart's sense of smell is and how smelly the socks are so these two are not the correct options. The scientific explanation for why Stuart can smell the socks is that they can be smelt because sweat and other molecules are moving away from them and spreading out in to the air. This is called diffusion.
  • Question 2

Image of noseImage of a pair of socks

 

Stuart can smell someone's smelly socks in class.

 

Where is the smell strongest? 

CORRECT ANSWER
The smell is strongest at the sock
EDDIE SAYS
Don't you just love thinking about smelly socks! The socks can be smelt because the sweat molecules are moving away from the socks and spreading out in the air. The smell becomes weaker further away from the sock. Maybe Stuart needs to sit further away from the person with smelly socks on!
  • Question 3

Describe the process of diffusion by filling in the blanks below.

 

Image of particles diffusing

CORRECT ANSWER
EDDIE SAYS
Did you remember which way the molecules move? In diffusion, particles will move from more concentrated areas to low concentrated areas down a concentration gradient. This is a pretty standard answer when describing diffusion, so it's worth remembering for your exams.
  • Question 4

Diffusion allows many important processes to occur in different organisms.

 

Which of the following are examples of diffusion?

 

Image of plant photosynthesisingImage of gas exchange in alveoli

CORRECT ANSWER
Oxygen entering the blood from the lungs
Carbon dioxide entering the lungs from the blood
Carbon dioxide entering the leaf of a plant for photosynthesis
EDDIE SAYS
There were three correct options here. The only one that was incorrect was the final option. If water were to enter the lungs, this would not be a good thing since it would make breathing extremely difficult! Diffusion allows gas exchange to occur in the lungs of humans -there is a higher concentration of oxygen in the lungs compared to the blood, so oxygen moves into the blood. Carbon dioxide does the opposite and moves from the blood to the lungs to be exhaled. Carbon dioxide, oxygen and water vapour also diffuse into and out of the leaves of a plant.
  • Question 5

Why is diffusion important?

CORRECT ANSWER
Diffusion allows substances to be taken in for various cell processes
Diffusion removes unwanted substances
EDDIE SAYS
There were two correct options here. Diffusion is really important for cells to get the things they need for different processes like respiration or photosynthesis. At the same time, diffusion allows cells to get rid of waste products. It is not true that only gases diffuse because water and other liquids can also diffuse. However, water does not diffuse into the lungs - that would cause all sorts of problems!
  • Question 6

Diffusion is a process that doesn't need energy.

 

What is the scientific name for a process that does not need energy?

CORRECT ANSWER
passive
EDDIE SAYS
Don't worry if you didn't know this one - it is a tricky word to remember. Particles move from a high concentration to a low concentration but this process doesn't need energy - it just happens. Try to imagine it as a ball rolling down a hill compared to trying to roll a ball uphill. Rolling downhill won't require any energy, whereas trying to roll a ball uphill certainly would!
  • Question 7

 O O O O O

Cell A 

 O O O O O O O O O O O

Cell B

 

 

The diagram above shows two cells. Cell A has five particles and Cell B has eleven particles.

 

In which direction will the particles diffuse?

CORRECT ANSWER
From Cell B to Cell A
EDDIE SAYS
Particles will move from a higher concentration to a lower concentration. Cell B has more particles than Cell A, so particles will move out of Cell B and into Cell A until there are an equal number of particles in each cell.
  • Question 8

The rate of diffusion is affected by different factors.

 

Match up the sentences describing how these factors affect the rate of diffusion.

CORRECT ANSWER

Column A

Column B

The greater the difference in con...
...The faster the rate of diffusi...
The greater the temperature...
...The greater the movement of pa...
The greater the surface area...
...The more space for particles t...
EDDIE SAYS
These statements might look daunting because they are so long, but careful reading will show you that most of it is common sense. The greater the temperature, the more molecules will move around; the greater the surface area, the more space there will be; and any change in concentration will change the concentration gradient. Take some time to learn these key factors as you are often asked about them in exams. Maybe you could try this question a few times to consolidate your knowledge.
  • Question 9

What is the name of the structure of the plant where gas exchange happens?

CORRECT ANSWER
Stomata
Stoma
EDDIE SAYS
Did you write the word leaf or leaves here? If so, you weren't exactly wrong but a more precise answer was required. The stomata are really important. They are the pores in a leaf where carbon dioxide enters for photosynthesis and oxygen is removed.
  • Question 10

Certain gases diffuse into and out of plants.

 

What are these gases needed for?

CORRECT ANSWER
For photosynthesis
EDDIE SAYS
There were a couple of possible looking answers here - did you go for the right one? Carbon dioxide and oxygen are needed for photosynthesis to occur. Without these gases, plants won't be able to respire or grow.
  • Question 11

Which gases diffuse into and out of the plant due to photosynthesis?

 

image of a plant

CORRECT ANSWER
Carbon dioxide
Oxygen
EDDIE SAYS
The final question - hopefully, you were able to eliminate hydrogen and nitrogen without too much trouble. Carbon dioxide is an important gas needed for photosynthesis. Oxygen is released into the atmosphere as a product of photosynthesis. Both gases diffuse in and out of the plant. Well done for completing this activity. How do you feel about this topic now?
---- OR ----

Get started for free so you can track and measure your child's progress on this activity.

What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Get started
laptop

Try an activity or get started for free