Questions Corrections Flashcards
Name one stimulus that would cause a smaller pupil size
Bright light
Describe how the iris causes the change in size of the pupil
Muscle contraction
Describe how a reflex is coordinated
Receptor detects stimulus and generates impulses
The sensory neurone conducts impulses to spinal cord
There is a synapse between neurones and a neurotransmitter/ chemical crosses synapse stimulating an impulse in the relay neurone.
Motor neurone receives impulse and is conducted to effector
Effector carries out response e.g muscle contract or gland secretes chemicals
One human activity that could cause the higher concentration of CO2 in winter
Burning of fossil fuels
One biological process that lowers the CO2 concentration in summer
Photosynthesis
2 side effects on an increase in global air temperature on living organisms
1) Loss of habitat
2) Migration
Explain why more water was lost through the skin during the race
1) more sweating
2) as exercise releases heat
Explain why more water was lost by breathing during the race
1) More energy needed
So more aerobic respiration
So increased breathing rate to supply oxygen
Why did the students place quadrants at random positions
There is an uneven distribution of dandelions
Plan an investigation to test the hypothesis ‘Light intensity affects the number of dandelion plants that grow in an area’
1) place 10 (1m by 1m )quadrants
2) Place them randomly using a table of random numbers
3) Quadrants placed at coordinates
in each of two areas of different light intensity’s
4) Count number of dandelions in each quadrant and measure light intensity of each quadrant
5) Compare data from different light intensity
Explain why sexual reproduction in an advantage for bluebells
1) Genetic variation in offspring of the bluebell
2) So better adapted to survive
3) and colonise new areas by seed dispersal
4) Many offspring so higher probability some will survive
Why did the students surround the seedlings with damp blotting paper when investigating geotropism in the roots of bean seedlings
To prevent water affection the direction of root growth
How does apparatus B (that is rotating act as control) in the experiment to investigate geotropism
Gravity acts evenly on all sides (as it is rotating)
Explain how the hormone causes the appearance of the seedlings in figure 7 to be different (A is tilted downwards and B is still straight)
Uneven distribution of auxin in root of seedling A
Even distribution of hormone in B
So top grows faster than bottom in root of A and there is equal growth in B
A large amount of untreated sewage (containing organic matter and bacteria) entered the river. Explain why many fish died
1) Bacteria decay organic matter
2) By digestion
3) And bacteria respire aerobically (using oxygen)
4) This lowers oxygen concentration in water (so fish have less oxygen)
5) Reduced energy supply causes death of fish
Explain how a change in one amino acid in an enzyme molecule could stop the enzyme working
1)Different protein made (as change in shape of enzyme)
2) Active site changed
3) So substrate does not fit
2 reasons why IVF is used to breed animals as opposed to natural mating
1) Takes less time
2) More offspring at the same time
Describe how scientist would selectively breed cows to produce a type of cattle that makes large volumes of low fat milk
1) Find female with lowest fat in milk and highest milk yield
2) Find male whose offspring have highest milk yield and lowest fat in milk
3)Cross the best female with best male
4) Select best offspring from each generation and repeat for several generations
Describe how the ancestors of modern lemurs may have evolved into the species
1) Isolation of different populations
2) Habitat variation between lemur populations
3) Genetic variation of mutation in each population
4)Better adapted to survive and reproduce and pass on favourable alleles to offspring
5) Eventually cannot produce fertile offspring with other populations
