The smart way to improve grades

Comprehensive & curriculum aligned

Try an activity or get started for free

Explore the Process of Osmosis in Cells

In this worksheet, students will apply the process of osmosis to cells.

Worksheet Overview

QUESTION 1 of 10

Image of particles moving via osmosis

 

Osmosis is the diffusion of water molecules from a low concentration solution to a high concentration solution, across a partially permeable membrane.

A partially permeable membrane has holes or pores in it that allow water molecules through, but are too small to allow larger molecules through. 

During osmosis, water molecules diffuse from pure water or dilute solution to more concentrated solutions.

Dilute solutions have a high concentration of water molecules, so have a high water potential. 

Concentrated solutions have a low concentration of water molecules, so have a  low water potential.

 

 

Osmosis in plants

 

Plant and animal cells are surrounded by a partially permeable cell membrane. This allows water and other small molecules to diffuse across. Plant cells additionally have a strong cell wall surrounding the membrane, which offers support and protection. Animal cells don't have a cell wall. This means they respond differently to plant cells to the gain and loss of water.

 

Image of plant cells in different concentrations of water Image of root hair cell

 

 

Plants require water in order to photosynthesise. The roots of a plant contain root hair cells which are specialised cells that increase the surface area of the cells for maximum absorption of water by osmosis. In pure water, plant cells will take in water via osmosis and become firm or turgid. In a concentrated solution (not much water present), the cell loses water and starts to shrink and becomes flaccid.  

 

In humans, the concentration of water and salt in the blood is controlled by the kidneys. The kidneys ensure we have the right concentration of water by getting rid of the excess water as urine.

 


Calculations Involving Osmosis

 

Image of weighing scales

 

Osmosis can be demonstrated using cubes of potatoes of roughly the same mass. By placing the cubes in different concentrations of sugar solutions, the cubes might gain or lose mass, or might even stay the same mass.

Scientists will be able to calculate the percentage change in mass to see how much mass was gained or lost -  and converting to percentages often makes for easier comparison. Percentage mass is calculated by using the following equation:

 

(Final mass – initial mass) ÷ initial mass x 100 

 

For example, a potato cube has an initial mass of 1 g. After placing it in a sugar solution for 30 minutes, its mass was 1.1 g. Its percentage change in mass is 10%. 

(1.1 g - 1 g) ÷ 1 g) x 100 = +10%

The plus sign shows there was an increase in mass. A minus sign shows a loss in mass.

 

In the following activity, you will apply the process of osmosis to cells. 

 

Plant and animal cells use the process of osmosis to transport water into or out of their cells.

 

Describe osmosis. 
 

Image of particles moving via osmosis

 

Cell membranes are partially permeable.

 

What is a partially permeable membrane? 

 

Image of particles moving via osmosis

A partially permeable membrane does not have holes in it

A partially permeable membrane has holes in it

It only allows waste products through

It allows water molecules through but the holes are too small to allow larger molecules through

Plants take in water through their root hair cells.

 

What happens if too much water is taken into the cells? 

 

Image of plant cells in different concentrations of water

Cell gains water

Cell loses water

Cell becomes turgid

Cell stays the same

 Image of water molecules Image of water moleculesImage of water molecules

Cell A 

 < Permeable membrane

 Image of water moleculesImage of water molecules

Cell B

 

The diagram above shows two cells separated by a permeable membrane. Cell A has twelve molecules of water and Cell B has eight molecules of water.


In which direction will the water move? 

From Cell A to Cell B

From Cell B to Cell A

No movement

 

Osmosis can be demonstrated using cubes of potatoes of roughly the same mass. By placing the cubes in different concentrations of sugar solutions, the cubes might gain or lose mass, or might even stay the same mass.

Lara did an experiment at school on the effect of sugar solutions on potato pieces.  The potato pieces were of equal size. She measured the mass of each potato cube and placed each one in a beaker containing different concentrations of sugar solution. After two hours, each potato cube's mass was measured.

 

Beaker  1 2 3 4 5
Sugar concentration (M)  0.2 0.4 0.6 0.8 1
Initial mass (g) 2 2 2 2 2
Final mass (g) 2.20 2.15 1.96 1.80 1.73
% change in mass 10 7.5 -2 (a) -13.5

 

Calculate the percentage change in mass in beaker 4 (a). 

Lara did an experiment at school on the effect of sugar solutions on potato pieces.  The potato pieces were of equal size. She measured the mass of each potato cube and placed each one in a beaker containing different concentrations of sugar solution. After two hours,  the mass of each potato cube was measured.

 

Beaker  1 2 3 4 5
Sugar concentration (M)  0.2 0.4 0.6 0.8 1
Initial mass (g) 2 2 2 2 2
Final mass (g) 2.20 2.15 1.96 1.80 1.73
% change in mass +10 +7.5 -2 -10 -13.5

 

Explain why the mass decreased in the potatoes in beakers 3, 4 and 5.

Water entered the potato for respiration

Water left the potato cells by osmosis

The concentration of water outside the cells was higher than inside the cells

The concentration of water outside the cells was lower than inside the cells

 Image of water molecules Image of water moleculesImage of water molecules

Cell A 

 < Permeable membrane

 Image of water moleculesImage of water molecules

Image of water molecules

Cell B

 

The diagram above shows two cells separated by a permeable membrane. Cell A and Cell B both have twelve molecules of water.

 

In which direction will the water move?

From Cell A to Cell B

From Cell B to Cell A

No net movement

Match up the plant cells in the picture below and the type of solutions they are in. 

 

Image of plant cells in different concentrations of water

The image below shows two plant cells in a sugar solution. One solution is more dilute than the other. The plant cells respond differently to the solution they are placed in.

 

Explain what is happening to each cell.

 

Image of turgid and flaccid plant cell

In which of these scenarios is osmosis occurring? 

Oxygen entering the blood from the lungs

Glucose moving into the bloodstream from the small intestine

A plant absorbing water from the soil

  • Question 1

Plant and animal cells use the process of osmosis to transport water into or out of their cells.

 

Describe osmosis. 
 

Image of particles moving via osmosis

 

CORRECT ANSWER
EDDIE SAYS
What did you think of this first question? If you found it hard to fill in all the blanks correctly, it might be a good idea to go back and have another look at the Introduction before tackling the other questions. Osmosis is really important for cells - they're able to get the water they need for different processes like photosynthesis. Like gases in diffusion, water molecules move from a less concentrated (more water) solution to a more concentrated (less water) solution.
  • Question 2

Cell membranes are partially permeable.

 

What is a partially permeable membrane? 

 

Image of particles moving via osmosis

CORRECT ANSWER
A partially permeable membrane has holes in it
It allows water molecules through but the holes are too small to allow larger molecules through
EDDIE SAYS
There were two options to tick this time - did you get them both? A partially permeable membrane is selective and only allows water and small particles to pass through it.
  • Question 3

Plants take in water through their root hair cells.

 

What happens if too much water is taken into the cells? 

 

Image of plant cells in different concentrations of water

CORRECT ANSWER
Cell gains water
Cell becomes turgid
EDDIE SAYS
Did you remember which way the water moves in osmosis? Water moves from a higher concentration to a lower concentration. It is crucial to remember this fact! If the plant's surroundings are wet, then there is a higher concentration of water outside the cells than inside them. This means that water will enter the plant cells by osmosis making the cells firm and turgid. So it's important to water your plants, but not to overdo it!
  • Question 4

 Image of water molecules Image of water moleculesImage of water molecules

Cell A 

 < Permeable membrane

 Image of water moleculesImage of water molecules

Cell B

 

The diagram above shows two cells separated by a permeable membrane. Cell A has twelve molecules of water and Cell B has eight molecules of water.


In which direction will the water move? 

CORRECT ANSWER
From Cell A to Cell B
EDDIE SAYS
Remember the key fact about osmosis and you're well away with this one! Water will move from a higher concentration to a lower concentration! There are more water molecules in Cell A than in Cell B, so water will move from Cell A, through the partially permeable membrane and into Cell B, until there are an equal number of molecules in each cell.
  • Question 5

 

Osmosis can be demonstrated using cubes of potatoes of roughly the same mass. By placing the cubes in different concentrations of sugar solutions, the cubes might gain or lose mass, or might even stay the same mass.

Lara did an experiment at school on the effect of sugar solutions on potato pieces.  The potato pieces were of equal size. She measured the mass of each potato cube and placed each one in a beaker containing different concentrations of sugar solution. After two hours, each potato cube's mass was measured.

 

Beaker  1 2 3 4 5
Sugar concentration (M)  0.2 0.4 0.6 0.8 1
Initial mass (g) 2 2 2 2 2
Final mass (g) 2.20 2.15 1.96 1.80 1.73
% change in mass 10 7.5 -2 (a) -13.5

 

Calculate the percentage change in mass in beaker 4 (a). 

CORRECT ANSWER
-10
EDDIE SAYS
Don't be put off by questions like this one that ask for some calculation - just remember the formula and take it one step at a time. Here's the formula you need for this question - to calculate the percentage change in mass: (Final mass – initial mass) ÷ initial mass x 100 Add the values in: (1.80 - 2) ÷ 2 x 100 Remember the order of BIDMAS - brackets first, then divide and finally multiply and you get the answer of -10 It's simple once you've got the formula!
  • Question 6

Lara did an experiment at school on the effect of sugar solutions on potato pieces.  The potato pieces were of equal size. She measured the mass of each potato cube and placed each one in a beaker containing different concentrations of sugar solution. After two hours,  the mass of each potato cube was measured.

 

Beaker  1 2 3 4 5
Sugar concentration (M)  0.2 0.4 0.6 0.8 1
Initial mass (g) 2 2 2 2 2
Final mass (g) 2.20 2.15 1.96 1.80 1.73
% change in mass +10 +7.5 -2 -10 -13.5

 

Explain why the mass decreased in the potatoes in beakers 3, 4 and 5.

CORRECT ANSWER
Water left the potato cells by osmosis
The concentration of water outside the cells was lower than inside the cells
EDDIE SAYS
Did you remember your key fact about osmosis here? Water moves from where it is more concentrated to where it is less concentrated. In beakers 3, 4 and 5, the concentration of sugar is high, meaning that the concentration of water will be lower in the sugar solution than in the cells of the potato. This means that the water will move out of the potatoes, resulting in a decrease in mass.
  • Question 7

 Image of water molecules Image of water moleculesImage of water molecules

Cell A 

 < Permeable membrane

 Image of water moleculesImage of water molecules

Image of water molecules

Cell B

 

The diagram above shows two cells separated by a permeable membrane. Cell A and Cell B both have twelve molecules of water.

 

In which direction will the water move?

CORRECT ANSWER
No net movement
EDDIE SAYS
How did you get on with this one? There are equal numbers of water molecules in Cell A and Cell B, so water will continue to move at an equal rate between the cells.
  • Question 8

Match up the plant cells in the picture below and the type of solutions they are in. 

 

Image of plant cells in different concentrations of water

CORRECT ANSWER
EDDIE SAYS
Hopefully, you didn't get muddled with your different concentrations here! Remember that if you see a swollen plant cell, it's because lots of water has moved into it by osmosis. The opposite is true for a shrivelled looking plant cell. With the isotonic solution, water is moving into and out of the cell at the same rate. So the correct answers were that A is in a dilute solution - there are more water molecules in the solution than in the cell, so water moves into the cell. C is in a concentrated solution - there are more water molecules in the cell than in the solution, so water moves out of the cell. Cell B has the same number of water molecules in the cell and in the solution - they are in balance. Try and remember the important word for this state - isotonic.
  • Question 9

The image below shows two plant cells in a sugar solution. One solution is more dilute than the other. The plant cells respond differently to the solution they are placed in.

 

Explain what is happening to each cell.

 

Image of turgid and flaccid plant cell

CORRECT ANSWER
EDDIE SAYS
Did you match them all correctly? Don't worry if you got a bit muddled over those funny words - you just need to try to learn them. A flaccid cell is a cell that has lost water due to its surroundings. It will look shrivelled - a bit like if you forget to water your house plants! It's the opposite concept for a turgid cell, so when plants gain water from their surroundings, it causes the plant cells to swell. One way to remember which way these words go is to notice that flaccid starts with the same letter as the word floppy! Also, the word turgid sounds a bit like rigid.
  • Question 10

In which of these scenarios is osmosis occurring? 

CORRECT ANSWER
A plant absorbing water from the soil
EDDIE SAYS
Osmosis is all about the movement of water molecules! So, remember in questions like these to look for the answers that mention water. An answer that mentions gas is usually referring to diffusion. Well done for completing another 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