GCSE Biology revision

Active transport

Transport in cells

AQA 4.1.1.1

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AQA student objectives

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All · Most · Some

ALL 🎯

Identify and describe What is Active Transport?, How Does Active Transport Differ from Diffusion? and The Role of Cellular Respiration in Active Transport in the context of active transport.

MOST 🎯🎯

Explain the relationships between What is Active Transport?, How Does Active Transport Differ from Diffusion? and The Role of Cellular Respiration in Active Transport and how they contribute to active transport.

SOME 🎯🎯🎯

Apply and analyse knowledge of What is Active Transport?, How Does Active Transport Differ from Diffusion? and The Role of Cellular Respiration in Active Transport to interpret unfamiliar information about active transport.

Revision summary

Key knowledge

Read on screen, then print for Cornell-style active revision.

What is Active Transport?

Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration — that is, against the concentration gradient
Unlike diffusion, active transport is an active process, meaning it requires energy from the cell to occur
Active transport always takes place across a membrane and uses special carrier proteins embedded in the membrane to transfer molecules from one side to the other

1. What is Active Transport?AQA

Notes

Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration — that is, against the concentration gradient
Unlike diffusion, active transport is an active process, meaning it requires energy from the cell to occur
Active transport always takes place across a membrane and uses special carrier proteins embedded in the membrane to transfer molecules from one side to the other

How Does Active Transport Differ from Diffusion?

Diffusion is a passive process where substances move down their concentration gradient, from high to low concentration, requiring no energy
Active transport moves substances up their concentration gradient, from low to high concentration, which is why energy is needed
Diffusion can be thought of as water flowing downhill naturally, whereas active transport is like pumping water uphill — it won't happen without an energy input

2. How Does Active Transport Differ from Diffusion?AQA

Notes

Diffusion is a passive process where substances move down their concentration gradient, from high to low concentration, requiring no energy
Active transport moves substances up their concentration gradient, from low to high concentration, which is why energy is needed
Diffusion can be thought of as water flowing downhill naturally, whereas active transport is like pumping water uphill — it won't happen without an energy input

The Role of Cellular Respiration in Active Transport

The energy required for active transport comes from cellular respiration, a process that occurs mainly in the mitochondria
During cellular respiration, glucose is broken down to release energy, which is stored in molecules called ATP (adenosine triphosphate)
ATP molecules act like tiny batteries, carrying energy from the mitochondria to the parts of the cell that need it, including the membrane proteins involved in active transport

3. The Role of Cellular Respiration in Active TransportAQA

Notes

The energy required for active transport comes from cellular respiration, a process that occurs mainly in the mitochondria
During cellular respiration, glucose is broken down to release energy, which is stored in molecules called ATP (adenosine triphosphate)
ATP molecules act like tiny batteries, carrying energy from the mitochondria to the parts of the cell that need it, including the membrane proteins involved in active transport

Root Hair Cells and Their Function

Plants absorb water and mineral ions from the soil through specialised cells called root hair cells, found on the outside of plant roots
Root hair cells have long, hair-like protrusions that extend into the soil, giving them a large surface area to maximise absorption
Mineral ions such as magnesium ions (needed to produce chlorophyll) and nitrates (needed to produce proteins) are often at a higher concentration inside the root hair cell than in the surrounding soil

4. Root Hair Cells and Their FunctionAQA

Notes

Plants absorb water and mineral ions from the soil through specialised cells called root hair cells, found on the outside of plant roots
Root hair cells have long, hair-like protrusions that extend into the soil, giving them a large surface area to maximise absorption
Mineral ions such as magnesium ions (needed to produce chlorophyll) and nitrates (needed to produce proteins) are often at a higher concentration inside the root hair cell than in the surrounding soil

Why Root Hair Cells Use Active Transport

Because mineral ions are at a higher concentration inside the root hair cell than in the soil, they cannot be absorbed by diffusion alone
Root hair cells must use active transport to absorb mineral ions against their concentration gradient, which requires energy
This energy is supplied by cellular respiration taking place in the mitochondria within the root hair cells

5. Why Root Hair Cells Use Active TransportAQA

Notes

Because mineral ions are at a higher concentration inside the root hair cell than in the soil, they cannot be absorbed by diffusion alone
Root hair cells must use active transport to absorb mineral ions against their concentration gradient, which requires energy
This energy is supplied by cellular respiration taking place in the mitochondria within the root hair cells

Adaptations of Root Hair Cells

Root hair cells are adapted for efficient absorption by having a large surface area due to their hair-like extensions into the soil
Root hair cells contain a large number of mitochondria, which carry out cellular respiration to provide the ATP energy needed for active transport
These two key adaptations — large surface area and many mitochondria — make root hair cells highly efficient at absorbing mineral ions from the soil

6. Adaptations of Root Hair CellsAQA

Notes

Root hair cells are adapted for efficient absorption by having a large surface area due to their hair-like extensions into the soil
Root hair cells contain a large number of mitochondria, which carry out cellular respiration to provide the ATP energy needed for active transport
These two key adaptations — large surface area and many mitochondria — make root hair cells highly efficient at absorbing mineral ions from the soil

Key Definitions to Remember

Active transport: the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, requiring energy from cellular respiration
Cellular respiration: the process occurring mainly in the mitochondria where glucose is broken down to release energy stored as ATP
Carrier proteins: specialised proteins found in the cell membrane that facilitate the movement of molecules during active transport

7. Key Definitions to RememberAQA

Notes

Active transport: the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, requiring energy from cellular respiration
Cellular respiration: the process occurring mainly in the mitochondria where glucose is broken down to release energy stored as ATP
Carrier proteins: specialised proteins found in the cell membrane that facilitate the movement of molecules during active transport