B3 Flashcards
what is a catalyst?
a substance that increases the speed of a reaction w/o being changed or used up
what is an enzyme?
catalystnmade by living organisms
- biological catalysts
what is an active site?
complimentary to substrate causing it to be specific
where does photosynthesis happen?
in the leaves
chloroplasts
what factors affect photosynthesis?
temperature, light intensity, carbon dioxide concentration
what happens to the RoP if light increases?
it increases then plateuas
what happens if RoP plateuas
something else is the limiting factor
What happens to RoP if temperature is ow
enzymes work more slowly
What factors affect enzyme action?
temperature, pH and substrate concentration
wha happens to enzyme action if:
temp is too high
temp is too low
high: enyme denatures
low: denatures, not enough energy
what happens to enzyme aaction if
ph is too high
ph is too low
denatures for both
what happens to enzyme rate of reaction if substrate concentration is too high or low
high: rate of reaction increases until plateaue
low: rate of reaction decreases
what is diffusion?
net movement of particles from area of low to high concentration
what does it mean if the cell membrane is partially permeable?
only some molecules can diffuse that are small enough
- water, glucose, amino acids
is duffusion passive or active?
passive, it doesnt r3equire energy from cell
what is osmosis?
net movement of water molecules across a partiallly permeable membrane from a region of low to high concentration
what is osmosis?
net movement of water molecules across a partiallly permeable membrane from a region of low to high concentration
what determines water concentration
the proportion of water to solutes
what is acyive transport?
movement of molecules against their concentration gradient
is active transport active or passive?
active, it requires energy from cell
how do mitochondria absorb mineral ions?
active transport
why cant plants absorb mineral ions by diffusion?
their concentration is higher in the root hair cell than the soil
organ system of a plpant
root, stem and leaves
what is the site of photosynthesis?
leaves
what is a stomata?
holes in the leaf
how does CO2 travel
lowwer epidermis(stomata), spongy mesophyll(gaps to diffuse), palisade mesophyll(most of photosynthesis lots of chloroplasts), upper epidermis(almost transparent)
how do plants reduce water loss?
waxy cuticle
what are the stomata?
openings of gurad cells
why do stomata open for as short as possible?
to minimise water loss but maximise CO2 absorption