when a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip, with more auxin on the lower side. this causes the lower side to grow faster, bending the shoot upwards.
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explain why roots grow towards gravity
a root growing sideways will also have auxin on its lower side. but in a root the extra auxin inhibits growth. this means the cells on top elongate faster and the root bends downwards
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explain why roots grow towards moisture
an uneven amount of moisture either side of a root produces more auxin on the side with more moisture. this inhibits growth on that side, causing the root to bend in that direction, towards the moisture
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state the stages of developing new drugs
first drugs are tested on computer models & extracted human cells then on to animal testing, then on clinical trials on healthy volunteers then lastly on ill volunteers.
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what is a double blind trial
a placebo designed to appear exactly the same as the drug, but it doesnt contain any of the drug, the doctor and the patients are not told who have received the drug or the placebo.
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talk about thalidomide
is a drug that caused unexpected and serious damage to unborn babies in the 1950's. it was developed as a sleeping pill but it was also found to be useful for morning sickness in pregnant women. drug led to the arms or legs of the babies being short.
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Talk performance enhancing drugs
they artificially improve athletes performance, such as stimulants- these boost heart rate and other body functions, anabolic steroids- these stimulate the growth of muscles. some are banned by law.
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why do plar bears have an excellent sense of smell, thick white fur and strong legs.
smell for finding their prey, fur to blend in with the snow and to stay warm, legs for swimming fast through icy water
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what are extremophiles
some organisms have adaptations to help survive usually inhabitable conditions e.g high temperatures(volcanoes) or high salt content like the dead sea.
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why is camouflage important
so predators can blend in with their surroundings and sneak up on prey. and so prey can hide from predators to avoid being eaten.
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what do plants compete for
nutrients and water because reduced leaf surface area to water loss, long deep roots to find water/nutrients and space to grow wide and tall.
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what are the factors affecting organsim distribution
temp, light, PH, local climate, water oxygen availability, food sources and availability
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state 3 things in how biomass is used and lost as
faeces and urine, movement and respiration
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talk about decay
warmth is needed to speed up enzyme action and chemical reactions, moist for dissolving food easier and prevents drying out, oxygen for bacteria to respire, importance is in sewage treatments to break down bodily waste.
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Other cards in this set
Card 2
Front
explain why roots grow towards gravity
Back
a root growing sideways will also have auxin on its lower side. but in a root the extra auxin inhibits growth. this means the cells on top elongate faster and the root bends downwards
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