The smart way to improve grades

Comprehensive & curriculum aligned

Affordable pricing from £10/month

Analyse Transport Systems in Multi-Cellular and Single-Celled Organisms

In this worksheet, students will analyse the impact of surface area to volume ratios on diffusion in organisms and the need for transport systems.

'Analyse Transport Systems in Multi-Cellular and Single-Celled Organisms' worksheet

Key stage:  KS 4

Curriculum topic:  

Curriculum subtopic:  

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

To travel from A to B, we use specially designed modes of transport like cars, and multicellular and single-celled organisms move substances the same way!

 

Single-celled organisms use simple diffusion to move substances across their body surface, but when there are many cells, the volume increases meaning the organism has a higher demand for supplies.

 

However the surface area available for things to move through doesn’t increase with it, slowing down diffusion and potentially causing cell death.

 

To battle this, multicellular organisms increase their SURFACE AREA TO VOLUME RATIO by using specialised exchange surfaces and transport mediums to take substances in and out and around organisms, mostly by DIFFUSION

 

 

1. Gas Exchange

In mammalian gas exchange, specially designed ALVEOLI increase the surface area of lung tissue connected to the capillary walls, aiding the uptake of oxygen by red blood cells and the removal of carbon dioxide from the pulmonary capillary blood.

 

In plants, however, carbon dioxide comes in and diffuses through the tissue fluid to the cells to be used for photosynthesis, while the oxygen made diffuses out to the surrounding tissues and into the environment using the concentration gradient.

 

2. Urea

Diffusion also helps remove waste products like urea from protein breakdown, where blood transports it from the liver to the kidneys, where urea can be made into urine and excreted out of the body.

 

 

3. Dissolved Food

When we eat, food is broken in the digestive system into dissolved food molecules that diffuse from the gut lumen, across the wall of the small intestine and into the bloodstream.

The small intestine is the site of most food absorption and have specially designed MICROVILLI that increase its surface area to maximise the amount of surface that interacts with the blood in absorption.

                          

4. Water transport via OSMOSIS

The water content of a cell is determined by the water concentration surrounding it due to OSMOSIS (the diffusion of water which it relies strongly on concentration gradients).

Plant cells have strong permeable cell walls around the cell membrane that support the cell to prevent it from bursting during water uptake. This happens when plant cells are placed in dilute or low concentration solutions, where osmosis occurs from the high volume of water on the outside and the cell fills up to become TURGID.

 

But if plant cells are placed in solutions that are highly concentrated, meaning lots of solute but little water, cells release water via osmosis. This makes the cell vacuole and cytoplasm volume decrease and shrink away from the cell wall, making the cell flaccid, becoming PLASMOLYSED.

 

 

Animal cells don’t have cell walls so osmosis can make the cell drastically change shape as it gains or loses water which can affect their performance, for example red blood cells. Blood plasma and tissue fluid must be tightly controlled, or else the red blood cell will gain too much water it could burst, or too much is lost and it shrivels up and stops being able to transport oxygen.

 

 

5. Active Transport of Mineral Ions

Sometimes diffusion isn’t enough, and ENERGY has to be spent. In plants, the uptake of MINERAL IONS by root hair cells is also dependent on active transport. Their large surface area makes them ideal for pulling mineral salts from the low concentration in the soil into the already highly saturated cells AGAINST the concentration gradient, using energy from respiration.  

As soon as we have more than a few cells, specially designed transport systems are needed. 

How are different substances transported in and out of cells and the blood?

What is the journey of Urea?  

Blood ⇒ Liver ⇒ Kidneys

Liver ⇒ Blood ⇒ Kidneys

Kidneys ⇒ Blood ⇒ Liver

Active transport is a method of substance transport across exchange surfaces, for example, root hair cells and the soil.

Blood ⇒ Liver ⇒ Kidneys

Liver ⇒ Blood ⇒ Kidneys

Kidneys ⇒ Blood ⇒ Liver

What structures allow the intestines and lungs to increase their surface areas? 

Blood ⇒ Liver ⇒ Kidneys

Liver ⇒ Blood ⇒ Kidneys

Kidneys ⇒ Blood ⇒ Liver

Both plants and mammals have very sophisticated methods of gas exchange because of the importance of effective respiration for cell survival.

Column A

Column B

In Plant Cells...
Oxygen Diffuses IN and Carbon Dioxide Diffuses OUT...
In Mammalian Lungs...
Carbon Dioxide Diffuses IN and Oxygen Diffuses OUT...

When placed in different solutions, plant cells change their shape due to the effect of osmosis.

In what real-world scenario would plant cells become plasmolysed? 

DROUGHT or FLOOD

Unlike animal cells, plant cells have cell walls which stop them…? 

True or False:

 

The cell wall controls substance diffusion 

  • Question 1

As soon as we have more than a few cells, specially designed transport systems are needed. 

CORRECT ANSWER
EDDIE SAYS
Single-celled organisms can easily exchange substances across their surface because the thickness of one cell is a short distance, so diffusion is fast. In more complicated creatures like humans, many layers of cells mean more time is needed for substances to travel to all the cells around the body, and more cells mean a higher demand for nutrients. These two things together demonstrate the need for special transport systems to speed up the delivery of substances throughout organisms.
  • Question 2

How are different substances transported in and out of cells and the blood?

CORRECT ANSWER
EDDIE SAYS
How did you get on with this question? This is a summary of the different transportation methods used by different key nutrients that cells need to function. Diffusion is used in gas exchange with oxygen and carbon dioxide in both plants and animals, but also with dissolved foods across the small intestine wall and waste products like urea. Osmosis is simply the diffusion of WATER and is important in determining cell shape. And finally, active transport is necessary for mineral ions to be transported into root hair cells in plants.
  • Question 3

What is the journey of Urea?  

CORRECT ANSWER
Liver ⇒ Blood ⇒ Kidneys
EDDIE SAYS
When proteins are broken down into amino acids and the excess is changed into fat and carbohydrate stores, this conversion in the liver, unfortunately, makes toxic ammonia waste, which has to be made into urea so it can be safely removed. Urea is therefore made by the LIVER and then diffuses into the BLOOD to be transported into the KIDNEYS to be made into urine and excreted out of the body.
  • Question 4

Active transport is a method of substance transport across exchange surfaces, for example, root hair cells and the soil.

CORRECT ANSWER
EDDIE SAYS
Active transport is a type of diffusion, but it's trying to fight natural concentration gradients in living beings. When substances need to move substances into an already saturated area, simple diffusion won't work, so cells RESPIRE and use the ENERGY gained to push substances AGAINST the concentration gradient from an area with little to an area with a lot.
  • Question 5

What structures allow the intestines and lungs to increase their surface areas? 

CORRECT ANSWER
EDDIE SAYS
The alveoli look like cotton plants or grapes, having a bumpy formation rather than being smooth spheres, increasing the amount of surface that has contact with the circulation for optimal diffusion. Microvilli also increase the surface area for dissolved food molecules to diffuse into the blood, creating peaks and troughs in the lumen of the small intestine instead of a regular circular tunnel.
  • Question 6

Both plants and mammals have very sophisticated methods of gas exchange because of the importance of effective respiration for cell survival.

CORRECT ANSWER

Column A

Column B

In Plant Cells...
Carbon Dioxide Diffuses IN and Ox...
In Mammalian Lungs...
Oxygen Diffuses IN and Carbon Dio...
EDDIE SAYS
Plant cells take in carbon dioxide for photosynthesis, creating oxygen which diffuses out of the cells. But in the alveoli, oxygen is needed for respiration while carbon dioxide waste is gathered in the blood from cells, escorted to the lungs, diffused across the capillary wall into the alveoli and breathed out.
  • Question 7

When placed in different solutions, plant cells change their shape due to the effect of osmosis.

CORRECT ANSWER
EDDIE SAYS
All these different phrases actually only refer to two different solutions, but it's important that your understanding of osmosis, concentration gradients and plant shapes is strong. TURGID means the plant cell is full of water and the cell wall stops it bursting like human cells. This happens when there is a lot of water around the cell like a low solute or dilute solution, as the cell takes up water across the concentration gradient through the permeable cell wall and cell membrane. PLASMOLYSED is when the cell vacuole and cytoplasm have lost so much water that the cell membrane starts peeling off the cell wall as the cell shrinks. A cell loses water when osmosis takes water across a concentration gradient into an area with little water like highly concentrated solutions (meaning concentrated in SOLUTE NOT WATER- this is called a dilute solution!)
  • Question 8

In what real-world scenario would plant cells become plasmolysed? 

CORRECT ANSWER
DROUGHT or FLOOD
EDDIE SAYS
As we've said, plasmolysed means the cell loses water, so if the soil is very dry because there hasn't been any rainfall for a long time, the cell loses water down the concentration gradient via osmosis to the surrounding environment. Well done on making it through this activity and remember to jot down any useful phrases or explanations that have helped you wrap your head around this topic!
  • Question 9

Unlike animal cells, plant cells have cell walls which stop them…? 

CORRECT ANSWER
BURSTING
EDDIE SAYS
The additional support provided by the cell wall gives plant cells strength so when they take up water by osmosis they don't burst, which is a problem in humans cells like red blood cells.
  • Question 10

True or False:

 

The cell wall controls substance diffusion 

CORRECT ANSWER
EDDIE SAYS
The cell wall is permeable, meaning it lets everything through for the partially permeable cell membrane to sort through. Remember: the role of the cell wall is to provide support for the cell!
---- OR ----

Sign up for a £1 trial 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

Start your £1 trial today.
Subscribe from £10/month.