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
why do guard cells get turgid?
turgid is when they are swollen with water and this is when the stomata open
why does the guard cells get flaccid?
flaccid is low on water and limp and they close
when do stomata close automatically?
when water supplies dry up and they are sensitive to light and close at night to save water
what cells carry out translocation?
phloem
what helps the movement of substances in the phloem?
holes inbetween cells
what direction does the phloem carry things in?
any direction
what does the phloem do?
translocates sugar from photosynthetic tissues to non photosynthetic issue
- leaves to roots
how does sugar enter the phloem?
through active transport and pushed by water that enters through osmosis
what is the zylem made from?
dead cells with no ends
structure of xylem
one long hollow tube
what direction does the mineral ions and waater travel in?
up
what are xylem walls strengtheed in ?
lignin
what does the xylem do?
transports water and mineral ions from roots to leaves
what is transpiration?
the evaporation of water from leaves
what affects transpiration rate?
light intensity, temoerature, air movement
what affects transpiration rate?
light intensity, temoerature, air movement
how do plants get healty?
by absorbing mineral ions
how do plants absorb mineral ions?
diffusion, active transport or osmosis?
active transport as there is a high concentration of mineral ions in root hair cells that soil
what does a lack of magnesium lead to?
yellow leaves as magnesium makes chlorophyll
hat does a lack of nitrates lead to?
stunted growth as there is a lack of amino acids coding for protein
what are carbohydrates, lipids and proteins?
biological molecules and nutrients
carbohydrates
- made of C, H, O
- single sugars can join together to make complex carbohydrates
- broken down by enxzymes in mouth and small intestine
proteins
- made of long chains of amino acids
- made of C, H, O, N
- broken down in stokmach and small intestine
lipids
- made of C, H, O
- both fats and oils - dependent on temp
- contain single glycerol mcl attached to fatty acid mcls
- not polymers- monomers
- broken down in small intestine
how do you test fror sugars?
benedicts
* heat in water bath
what color will positive benedicts turn?
green, yellow, red
how do you test for starch?
iodine
what colour will opositive iodine be?
blueish black
how do you test for lipids?
ethanol/ emulsion test
what happens if there is lipids present?
milky emulsion forms
how to test for proteins?
bieurets
* sodium hydroxide and copper sulphate
how happens if proteins are present?
solution turns purple
what happens in the water cycle?
- energy causes water to evaporate
- water vapour condenses in clouds then water falls back as rain
- cycle starts again
what happens in the water cycle?
- energy causes water to evaporate
- water vapour condenses in clouds then water falls back as rain
- cycle starts again
what happens in the carbon cycle?
- photosynthesis means CO2 goes into plants which get eaten by animals or passed into atmos
- when organism die, they decay and release CO2 into the atmos or become fossil fuels which gets burnt by humans
what is a population?
all organisms of one speiceis in a habitat
what is a community?
all organisms in one habitat
what is an ecosystem?
community of organisms and abiotic conditions
what is meant by biotic?
living factors such as food, number of predators and competion
what is meant by abiotic
non living factors such as temperature, soil ph and mineral content
what is interdependence?
all species depend on other species in someway so if something happens to one species, if affects the whole ecosystem
what is eutraphication?
when a body of water becomes enriched with minerals
- lading to rapid growth of algae whcih builds up on water, blocking sunlight which affects rate of oxygen in water, causing fish and plants to die
what is a potometer used for?
to measure the rate of transpiration thats proportional to water uptak
w can you measure the ecosystem?
