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Back to AI Flashcard MakerBiology /LGS A-Level OCR Biology - Unit 2 - Diffusion/Osmosis/Active Transport Part 1

LGS A-Level OCR Biology - Unit 2 - Diffusion/Osmosis/Active Transport Part 1

Biology20 CardsCreated about 1 month ago

This deck covers key concepts of diffusion, osmosis, and active transport as part of the LGS A-Level OCR Biology curriculum. It includes definitions, mechanisms, and factors affecting these processes.

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Define diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration
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Key Terms

Term
Definition
Define diffusion
The net movement of particles from a region of higher concentration to a region of lower concentration
Is diffusion active or passive?
Passive
Define passive transport
Movement of substances that does not require energy
Define osmosis
The movement of water from a region of high water potential to a region of low water potential across a partially permeable membrane
Define facilitated diffusion
Diffusion across a plasma membrane through protein channels
Is facilitated diffusion passive?
Yes
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LGS A-Level OCR Biology - Unit 2 - Diffusion/Osmosis/Active Transport Part 1
TermDefinition
Define diffusion
The net movement of particles from a region of higher concentration to a region of lower concentration
Is diffusion active or passive?
Passive
Define passive transport
Movement of substances that does not require energy
Define osmosis
The movement of water from a region of high water potential to a region of low water potential across a partially permeable membrane
Define facilitated diffusion
Diffusion across a plasma membrane through protein channels
Is facilitated diffusion passive?
Yes
Is osmosis passive or active?
Passive
Define active transport
The movement of molecules from an area of low concentration of that molecule to an area of high concentration of that molecule. This movement requires ATP

What sort of molecules tend to move via diffusion across a membrane?

  • small molecules (e.g. gases)

  • lipid soluble molecules

  • non-polar molecules

How does water tend to move across membranes?
Through aquaporins (via osmosis)
Why can steroid hormones easily cross a membrane by simple diffusion?
They are lipid soluble - They are non-polar
Which 2 factors affect the rate of diffusion?
Temperature Concentration difference
What effect does an increase in temperature have on the rate of diffusion?
It increases the rate of diffusion
What effect does a greater difference in concentration of two regions have on the rate of diffusion?
It increases the rate of diffusion
Why does a higher temperature increase rate of diffusion?
-higher temperature means particles have more kinetic energy and move at higher speeds
Why is it easier for oxygen to diffuse across a membrane than water?
oxygen molecules are small and non-polar whereas water molecules are polar the hydrophobic interior of the phospholipid bilayer repels the charged molecules water is only partially charged so is still able to diffuse through the membrane, though only slowly

What 4 factors affect the rate of diffusion across a membrane?

  • temperature

  • concentration gradient

  • surface area

  • thickness of membrane

An increase in surface area of an exchange surface has what effect on rate of diffusion?
increases rate of diffusion
An increase in membrane thickness has what effect on the rate of diffusion?
Decreases rate of diffusion
Why are membranes containing protein channels selectively permeable?
Most protein channels are specific to one molecule or ion - Therefore only these specific molecules/ions are able to move across the membrane