2014 june

Question 1

give reasons why a shorter food chain passes on the greatest proportion of biomass and energy to humans (3)

Answer 1

✏️ shortest or fewest stages / transfers / (trophic) levels
✏️ less losses in waste / faeces / urine / CO2 / excretion
✏️ less loss in respiration / heat / movement

Question 2

describe how animals and plants are adapted to survive in dry conditions such as deserts. for each adaptation that you give, describe how the adaptation helps the animal or plant to survive in dry conditions. go obtain full marks you should refer to both animals and plants (6)

Answer 2

animals:

✏️ change / decrease in surface area / example - reduces area from which sweat / water may be lost

✏️ hump with fat / fat stores - to convert to water (via respiration)

✏️ long eyelashes - to keep (windblown)
dust out of eyes

✏️ nocturnal / ‘keep out of the sun’ - reduce sweat loss (in heat of the day)

plants:

✏️ decrease in surface area or leaves are spikes - reduces water loss / transpiration / evaporation

✏️ long / wide spread / extensive roots - to absorb (more) water

✏️ fleshy / thick stem - to store water

Question 3

suggest how dead plants decaying in a nest helps to keep the eggs warm for many weeks (3)

Answer 3

✏️ microorganisms
✏️ (microorganisms) respire
✏️ (respiration / decay / microorganisms) releases (thermal) energy / ‘heat’

Question 4

megapode birds open and close the air vents of the nest at different times of the day. suggest reasons why it is necessary to open and close the air vents (3)

Answer 4

✏️ (opening) allows oxygen in
✏️ microorganisms / eggs need oxygen
✏️ oxygen needed for respiration
✏️ (opening) allows release of carbon dioxide (from
microorganisms / respiration / eggs)
✏️ (opening) allows energy / ‘heat’ to escape
✏️ (closing) retains energy / ‘heat’ if too cool / at night
✏️ (closing) retains moisture

Question 5

The sex of a megapode bird that hatches from an egg depends on the temperature at which the egg was kept. use this information to suggest why it is important for megapode birds to control the temperature of their nests (1)

Answer 5

maintains sex balance, (survival of species depends on there being) males and females in population

Question 6

apart from measles, which two other diseases does the MMR vaccine protect against? (1)

Answer 6

mumps & rubella / german measles

Question 7

suggest one advantage to the population as a whole of children having the second MMR vaccination (1)

Answer 7

less chance of epidemic / pandemic OR less chance of spread of disease / measles / mumps / rubella

Question 8

what does a vaccine contain? (1)

Answer 8

dead / inactive pathogens / viruses / bacteria

Question 9

explain how a vaccination prevents infection (3)

Answer 9

✏️ white blood cells produce antibodies
✏️ antibodies produced rapidly (on re-infection) or response rapid (on re-infection)
✏️ these antibodies kill pathogens / viruses / bacteria

Question 10

antibiotics can only be used to treat some infections. explain why antibiotics cannot be used to treat measles (2)

Answer 10

✏️ antibiotics don’t kill viruses

✏️ (because measles) virus / pathogen lives inside cells

Question 11

why do antibiotics become less useful at treating an infection if the antibiotic is overused? (1)

Answer 11

(bacteria / pathogens) develop resistance (to antibiotic)

Question 12

a nerve impulse passing along a relay neurone causes an impulse to be sent along another type of neurone, what is the name of this neuron? (1)

Answer 12

motor neuron

Question 13

describe how information passes from the relay neurone to the motor neuron (3)

Answer 13

✏️ release of chemical (from relay neurone)
✏️ chemical crosses gap / junction / synapse
✏️ chemical attaches to motor neuron / next neurone (causing impulse)

Question 14

what was the drug thalidomide originally developed to treat? (1)

Answer 14

idea of poor sleeping

Question 15

soon after it was developed, thalidomide was found to be useful in treating another condition, what was this other condition? (1)

Answer 15

(for) morning sickness (in pregnant women)

Question 16

describe one harmful effect of thalidomide (1)

Answer 16

limb abnormalities / defects

Question 17

suggest why this harmful effect had not been detected during clinical drug trials on thalidomide (1)

Answer 17

drug not tested / trialled on pregnant animals / women

Question 18

using a recreational drug may cause a person to become dependent on the drug. what happens in the body to make someone dependent on a drug? (1)

Answer 18

changes to chemical processes

Question 19

graph question - some people think that some legal drugs should be made illegal, why (use info from graph)? (2)

Answer 19

✏️ dependency on (some) legal drugs is more than / equal to on (some) illegal drugs
✏️ example of a named legal drug for which dependency is equal to or greater than a named illegal drug

Question 20

suggest one piece of information about legal drugs that would need to be considered before the classification of these drugs was changed (other than dependency on legal/illegal drugs) (1)

Answer 20

the harm it does / harmfulness or effect on health or side effects

Question 21

use Darwin’s theory of natural selection to explain how the elephant’s trunk evolved from the Phiomia to the Elephant (4)

Answer 21

✏️ variation (in population) / mutation
✏️ longer nosed individuals get more food / leaves
✏️ (these) survivors breed (more)
✏️ pass on genes / alleles / DNA (for long nose)

Question 22

use Lamarck’s theory to explain how the elephant’s trunk evolved from the Phiomia to the elephant (2)

Answer 22

✏️ phiomia / ancestor stretched its nose (during its lifetime) to reach food / leaves
✏️ passed on (stretched nose) to offspring

Question 23

in the 1800s, many scientists could not decide whether Lamarck’s theory or Darwin’s theory was the right one. give two reasons why (2)

Answer 23

✏️ insufficient evidence / no proof

✏️ mechanism of inheritance not known (didn’t know about genes)

Question 24

before the 1800s, many people had a different idea to explain where all the living things on earth came from. what idea was this? (1)

Answer 24

god made all living things / them

Question 25

describe how scientists can transfer the gene from bacillus thuringiensis (which killls insects) to maize plants (3)

Answer 25

✏️ (gene) cut out
✏️ (gene / cut out) from (bacterial) chromosome / DNA
✏️ ref to enzymes (at any point)
✏️ (gene spliced) into maize chromosome / DNA
✏️ (gene added) at an early stage of development

Question 26

would you advise farmers to grow GM maize plants?

justify your answer by giving advantages and disadvantages of growing GM maize plants. (4)

Answer 26

advantages:
✏️ less effort for farmer or less likely to harm farmer
✏️ (pesticide) always there or doesn’t wash away
✏️ less insects to eat crop / maize or carry disease
✏️ so greater crop production / yield

disadvantages:
✏️ (toxin) kills other insects
✏️ so (some) crops don’t get pollinated / (sexually) reproduce
✏️ possible harm when eaten by humans / animals
✏️ damage to food chains
✏️ gene may spread to other species