B4d: Diffusion and osmosis Flashcards Preview

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Flashcards in B4d: Diffusion and osmosis Deck (17):

Describe diffusion

the net movement of particles from an area of higher concentration to an area of lower concentration, down a concentration gradient until an equilibrium is reached


What is diffusion the result of?

the constant random movement of individual particles; far more move from high to low concentration than vice versa


How do substances move in and out of cells?

by diffusion through the cell membrane


Factors increasing the rate of diffusion (3)

shorter distance for particles to travel

greater concentration difference/gradient - greater net movement

greater surface area - particles have more area to diffuse across


Describe osmosis

the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of
lower water concentration until an equilibrium is reached


Osmosis is a type of _



What is a partially-permeable membrane

membrane that has small pores through which small molecules such as water can pass, but not larger molecules such as proteins


What is osmosis a result of?

the constant random movement of individual water particles; far more move from high to low concentration than vice versa


How are plants supported

the entry of water into plant cells increases the pressure pushing on the cell wall, which is rigid and not elastic
-this turgor pressure supports the cell, stopping it, and the whole plant from collapsing


What is wilting

When too much water leaves a cell causing it to lose its turgor pressure


What is lysis

Animal cells absorb too much water through osmosis and swell up and burst


What is crenation

too much water leaves an animal cell through osmosis and it shrinks


What is turgid

a plant cell fully inflated with water, where turgor pressure helps keep cell firm


What is flaccid

a plant cell becoming limp due to a reduction a pressure inside the cell when too much water leaves the cell through osmosis


What is plasmolysed

cell membrane pulled away from the inside of the cell wall due to a loss of water through osmosis


Adaptations of the leaf for diffusion (5)

broad = large SA for gases to diffuse

thin = short diffusion distance for CO2 to diffuse to the mesophyll and palisade cells

air spaces in spongy mesophyll = allow CO2 to diffuse from stomata to palisade cells

air spaces = large internal SA:V ratio = maximum absorption of gases

stomata for gases to diffuse into leaf


Why do plant cells not burst when it is fully inflated with water

its inelatic cell wall stops the cell from bursting