Topic 2 Flashcards
Define osmosis
the net movement
of particles from an area of high water potential to an area of low water potential through a partially permeable plasma membrane, requiring no energy to do so
Where does the energy for diffusion come from
kinetic energy of random movement of
molecules and ions
What does equilibrium mean in the case of diffusion?
When particles are evenly distributed through a space, we say equilibrium, particles still move but no net movement in specific directions
Why is diffusion important? [3]
1) Getting nutrients into the blood
2) Gas exchange for respiration
3) Abosrbing carbon dioxide into leaf
4 factors to speed up/down diffusion [4]
1) Concentration gradient- the bigger the gradient the faster it is
2) Temperature, more energy at higher heat
3) Surface area
4) Distance - the larger the distance, the longer time to diffuse
Plasma membrane
Semi-permeable/organelles are semi-permeable
define diffusion
Net movement of particles from a region of high concentration to lower concentration over time, requiring no energy to do so (passive transport)
Water potential
Potential energy in water
ψ
Turgor pressure [2]
1) pressure within cells that pushes against the cell
2) more water in cell = high turgor pressure
Hypertonic solution[2]
higher solute concentration outside the cell, plasmolysed
Hypotonic solution [2]
Lower concentration outside the cell, turgid
cell being plasmolysed [3]
1) plant cell is placed in a hypertonic solution
2) net movement of water out of the cell
3) causing a reduction in turgor pressure and the cell membrane to peel back from the cell wall.
Cytolysis effects [2]
1) hypotonic
2)swell and expand until it eventually burst
effect of isotonic
No net movement of water, cell is the same
Active transport in plant cells [2]
1) Plant need ions
2) Ions are lower concentration in the soil than they are in the root hair cells, plant is forced to use active transport to get enough ions
Describe how Ions move into guard cells [2]
(Ions) move against the concentration gradient; [1 mark]
(Through) proteins (in the cell membrane) ; [1 mark]
(Which) uses/requires energy; [1 mark]
From respiration
Two environmental factors that cause plants to wilt [2]
Lack of water; [1 mark]
High temperature; [1 mark]
Low humidity / dry air; [1 mark]
Wind; [1 mark]
Explain why Plant roots cannot absorb these mineral ions by diffusion [2]
Diffusion is the movement of a substance down a concentration gradient [1 mark]
To be taken up by the root the ions must be moved against the concentration gradient [1 mark]
Define active transport
the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration.
How is active transport done [3]
1) Protein carriers are required for active transport
2) Has a specific shape to only transport certain molecules
3) Requires energy
Why do plants need active transport
Soil has a low mineral ion concentration compared to root hair cell
Give 1 similiarity and 1 difference between osmosis & active transport
1) Osmosis does down a concentration gradient, active transport is against a concentration gradient
2) Both go through a semi-permeable membrane
Give 1 similiarity and 1 difference between diffusion and osmosis
1) Both go down the concentration gradient
2) Diffusion doesn’t need to go through a semi-permeable cell membrane
