PAPER 2 - practice questions

Question 1

describe how an organism is able to respond to a sharp pin touching the skin

Answer 1

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

Question 2

describe and explain how gravity effects the grwoth of plants

Answer 2

• 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

Question 3

explain how phototropism in a plant shoot helps rhe plant survive

Answer 3

• grow towards light bc more auxin on shaded side so enlonagtes and grow up
• more light abrovbed for phtosynthesis
• more glucose for grwoth

Question 4

explain how gravotropism in pkant roots helps a plant survive

Answer 4

• towards gravity so grow into earth
• so provide anchorage and absorb more minerals and water

Question 5

P17 - LOOK AT DIAGRAM

Question 6

what happens when blood glucose levels rise

Answer 6

• 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

Question 7

hormones are used in IVF treatment. explain how dif hormones are used to help a women become pregnant

Answer 7

FSH stimulates the maturation of egg
LH stimulates ovulation
this causes more eggs to be relesed which increases the chance of fertilisation

Question 8

describe the process of ivf

Answer 8

• 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

Question 9

adrenaline causes a change in the body to prep for a fight or flight response. what changes does this cause in the body

Answer 9

• increases the supply of oxygen and glucose to brain and kuscles
• and increases heart rate blood pressure and breathing rate

Question 10

what happens when blood plasma becomes too concentrated (low water)

Answer 10

• 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

Question 11

what is sweat not as effective in humid conditions

Answer 11

• bc it doesnt evaporate due to the high water concentration in the air

Question 12

describe the role of blood vessels in controlling a constant body temp

Answer 12

• 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

Question 13

describe structure of a nucleotide

Answer 13

• phosphate attactched to a sugar
• sugar attactched to a base - ATGC

Question 14

how are proteins made

Answer 14

• 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

Question 15

describe how butterflies with warning signals have evolved over time

Answer 15

• 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

Question 16

describe the evidence of evolution

Answer 16

• 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

Question 17

describe how fossils may form

Answer 17

• 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

Question 18

describe how animals are adapted to survive in dry conditions such as deserts

Answer 18

• 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

Question 19

explain how carbon is cycled in the environment

Answer 19

• 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

Question 20

gardeners put waste in bins with holes in. explain why

Answer 20

• holes allow oxygen to enter. this is for decomposers such as bacteria to respire
• also for heat produced to be released into surroundings

Question 21

ideal conditions for decay

Answer 21

• warm
• moist
• rich supply of oxygen

Question 22

an airtight compost heap causes anaerobic decay. explain why a gardener may not wish to compost like this

Answer 22

• during anaerobic decay methane is produced
• this can cause global w`nring - climate change

Question 23

explain why when fertilisers go into rivers the concentration of oxygen dissolved in the water decreases

Answer 23

• 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

Question 24

how can a rise in co2 in atmosphere decrease biodiversity

Answer 24

• 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

Question 25

how does organic matter and bacteria entering a river, cause fish to die

Answer 25

• bacteria decay organic matter by digestion
• they do this by repsiring aerobically
• this uses up oxygen in the river which lows the pxygen concentration
• then there is not enough water left for the fish
• so the fish cant get enough oxygen and so dont have enough energy and so die

Question 26

why a short sighted person has dificulty seeing close objects

Answer 26

• too much light refracted
• light focuses infront of retina

Question 27

how do wearing lasses help long sitedness

Answer 27

• convex lense
• which refracts light more
• which focuses rays onto the retina