PAPER 2 - practice questions Flashcards
describe how an organism is able to respond to a sharp pin touching the skin
receptor - sensory - synapse - relay - motor - effector
- sharp pin detected by pressure recptor in skin
- creates impluse along sensory neurone
- diffuses across synapse and generates a impluse acorss the replay neurone
- this travels to motor neuron and to effector
- effect is a muscle that contracts and so hand moves away from pin
describe and explain how gravity effects the grwoth of plants
- shoots grow against gravity
- roots grow towards gravity
- this is due to unequal distribution of auxin
- auxin promotes grwoth in shoots and inhibits grwoth in roots
- shoots grow up and roots grow down
explain how phototropism in a plant shoot helps rhe plant survive
- grow towards light bc more auxin on shaded side so enlonagtes and grow up
- more light abrovbed for phtosynthesis
- more glucose for grwoth
explain how gravotropism in pkant roots helps a plant survive
- towards gravity so grow into earth
- so provide anchorage and absorb more minerals and water
P17 - LOOK AT DIAGRAM
what happens when blood glucose levels rise
- this is detected by the pancreas
- which secretes insulin
- this causes glucose to enter muscle and liver cells where its converted into glycogen
- the glycogen is stored and blood glucose levels fall
hormones are used in IVF treatment. explain how dif hormones are used to help a women become pregnant
FSH stimulates the maturation of egg
LH stimulates ovulation
this causes more eggs to be relesed which increases the chance of fertilisation
describe the process of ivf
- woman give FSH and LH
- fsh causes egg to mature and LH stimulates these eggs to be released
- eggs are fertilised in lab and give time to develope into balls of cells
- some eggs are transferred into the womans uterus to be implanted
adrenaline causes a change in the body to prep for a fight or flight response. what changes does this cause in the body
- increases the supply of oxygen and glucose to brain and kuscles
- and increases heart rate blood pressure and breathing rate
what happens when blood plasma becomes too concentrated (low water)
- concentrated plasma detected by the receptor cells in the brain
- in response the pituitary gland releases the hormone ADH
- this causes the kidney tubes to be more permeable so more water is reabsorbed by the body
- this causes small volume of concentraeted urine to be produced so water loss form the body is less
- then blood plasma returns to a normal level
what is sweat not as effective in humid conditions
- bc it doesnt evaporate due to the high water concentration in the air
describe the role of blood vessels in controlling a constant body temp
- when body too hot the skin dialtes in vasodilation where blood flows closer to skin surface and so more energy is lost into the surroundings
- if body is too hot vessels narrow in vasoconstriction and blood doesnt flow as close to the skins surface to reduce energy being lost into the surroundings
describe structure of a nucleotide
- phosphate attactched to a sugar
- sugar attactched to a base - ATGC
how are proteins made
- made at ribosomes
- made up of amino acids in a particular sequence
- bases code and work in triplets so 3 bases make an amino acid
describe how butterflies with warning signals have evolved over time
- there’s genetic variation in the species of butterflys
- some would have warning signals to make them less likely to be eaten by predators
- these woul be more likely to survive and pass on their beneficial genes to their offspring
- this means that the beneficial gene becomes more common within the population
describe the evidence of evolution
- fossils show the gradual changes happening to animals over thousands of years
- antibiotic resistance - bacteria divide very fast and we have seen advantageous genes within bacteria become more common ;loading ti changes in the bacterial population
describe how fossils may form
- preserved traces - footprints, burrows, rootlets
- parts of an organism replaced overtime by minerals as they decayed
- parts of animals who havent decayed as there was no moisture of warmth
describe how animals are adapted to survive in dry conditions such as deserts
- large SA:V through long limbs and long ears
- this increases heat lost to the environment
- long eyelashes to prevent dust getting in their eyes
- wide feet to reduce pressure on sand so they dont sink
explain how carbon is cycled in the environment
- green plants remove co2 from atmosphere by photosynthesis and release it when they respire
- plants eaten by animals carbon transferred and animals respire and release it
- when plants and animals die they get broken down by microoganisms which respire and release
- if plants burned they release
gardeners put waste in bins with holes in. explain why
- holes allow oxygen to enter. this is for decomposers such as bacteria to respire
- also for heat produced to be released into surroundings
ideal conditions for decay
- warm
- moist
- rich supply of oxygen
an airtight compost heap causes anaerobic decay. explain why a gardener may not wish to compost like this
- during anaerobic decay methane is produced
- this can cause global w`nring - climate change
explain why when fertilisers go into rivers the concentration of oxygen dissolved in the water decreases
- fertlisers causes the growth of algae
- algea blocks light which causes death
- microoganisms break down dead matter and respire aerobically
- aerobic respiration uses oxygen so the levels decrease
how can a rise in co2 in atmosphere decrease biodiversity
- a rise in co2 will lead to global warming
- this causes sea level rising, unpredictable weather, droughts, increased freq of tropical storms
- this all damages and disrupts habitats which can lead to extinction
- it can also disrupt food chain bc one animals/plant less adapted to the external change in the environment
