GCSE 2 (section B) Flashcards
How do you calculate the rate of osmosis?
Change in weight/time
How do you calculate the rate of diffusion?
Surface area x concentration difference / distance
How do you calculate percentage change?
Change in weight / starting weight
What is diffusion?
The movement of molecules from a religion of high concentration to low concentration
What is osmosis?
The movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration
What is active transport?
The movement of ions and molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy
What does hypertonic mean?
There is a higher solute concentration than the fluid inside the cell
What does hypotonic mean?
There is a lower solute concentration than the fluid inside the cell
What does isotonic mean?
The osmotic pressure inside the cell is the same as the osmotic pressure outside the cell
What does turgid mean?
(Relating to hypotonic)
when a cell is swollen - there is more liquid inside a cell then outside
What does flaccid mean?
(Relating to hypertonic)
The state of which the cell is lacking in water - the plasma membrane is not tightly in touch with the cell wall
What are three factors that could affect active transport?
- temperature
- oxygen concentration
- pH
What are four factors that could affect diffusion?
- density
- temperature
- distance
- concentration difference
What are four factors that could affect osmosis?
- temperature
- surface area
- pressure
- concentration gradient
How does density affect diffusion?
Heavier particles will travel slower than light ones; light particles are more mobile and are smaller
How does temperature affect diffusion?
Heat gives energy to particles, so increasing the temperature will increase the rate of diffusion and vice versa
How does concentration difference affect diffusion?
If there is already a near-equal amount of a particle on either side the rate of diffusion will be slower as the particles have to move to make it equal and vice versa
How does distance affect diffusion?
Particles will take a shorter time to travel shorter distances, so the rate of diffusion will be faster
+ gas will diffuse faster through a thin wall than a thick one
How does the surface area affect osmosis?
The larger the surface area, the easier the particles can cross the membrane
How does the temperature affect osmosis?
Energy is expended to permeate the membrane to allow water to flow through, the higher the temperature the more energy is produced
How does pressure affect osmosis?
The higher the pressure on one side of the membrane the higher the rate of osmosis on the other
How does the concentration gradient affect osmosis?
The lower the concentration of solute in water, the faster it moves through the water as there are no particles interrupting the flow
How does temperature affect active transport?
Enzymes work best at an optimum temperature and denature after a certain temperature is reached. The rate of chemical reaction will increase at an enzymes optimum temperature.
How does oxygen concentration affect active transport?
Oxygen produces energy when it breaks down food. When the oxygen concentration is low less energy is produced which slows down the rate of active transport.
How does pH affect active transport?
Enzymes only work at specific pH’s. When a ph is altered the enzyme activity will be slowed or stopped which will stop all chemical reactions
What is photosynthesis?
The process in which plants absorb visible light and carbon dioxide and produce glucose and oxygen
What is the word equation for the reaction that occurs in photosynthesis?
(6) water + (6) carbon dioxide —> glucose + (6) oxygen
What is the symbol equation for the reaction that occurs in photosynthesis?
6 CO2 + 6 H2O —> C6H12O6 + 6 O2
What nutrients are needed in photosynthesis and why?
Nitrates ; used in making amino acids
Magnesium ; part of the chlorophyll molecule
Phosphate ; making DNA
Potassium ; needed for enzymes of respiration
Why is photosynthesis important?
- converts light energy into usable chemical energy
- produces oxygen
- produces food
- removes carbon dioxide from the air
What can affect photosynthesis?
If a plant gets more light, carbon dioxide; water or a higher temperature (and no other factors increase) then it will not be able to photosynthesize
Where in a leaf do the most chloroplasts occur?
The palisade layer
What are the two top layers of a leaf?
The waxy cuticle and upper epidermis
