BIOLOGY 2021 Flashcards
What type of substance does a gene code for
protein
How could the student keep the milk at a constant temperature for 5 days
water bath
Give the reason why the person should not move during the investigation.
movement would release
(extra) heat
* movement would increase
body temperature
* movement would increase
sweating
The results show that when the ice-cold water was drunk, the temperature near the
brain decreased.
Explain why the temperature near the brain decreased
blood is cooled at stomach /
mouth
(cooled) blood flows to the brain
The thermoregulatory centre in the brain responds to the decrease in temperature.
How does the thermoregulatory centre send information to sweat glands in the skin?
via nerve(s) / neurones
or
via (nerve) impulse(s)
Describe:
* how microorganisms in the layers of soil help to recycle chemicals in the
dead plants
* how the chemicals are used again by living plants.
in microorganisms
* digestion or large molecules to small molecules
* enzymes or named example
* respiration
* production of carbon dioxide
* release of mineral ions or named example such as nitrate /
phosphate / magnesium
in plants
* carbon dioxide (from air) taken in by leaves
* by diffusion
* via stomata
* carbon dioxide used in photosynthesis
* making glucose / sugar / starch / cellulose or making other
correctly named example
* (named) ions taken in by roots
* by active transport
* nitrate ions for making amino acids / proteins / DNA / chlorophyll
* phosphate for making DNA
For Level 2 processes in microorganisms and in plants should be
considered
Using the mean from this investigation to calculate the number of daisy plants on the
lawn may not be accurate.
Give two reasons why.
too few quadrats
or quadrat too small
sample may not be
representative of the lawn
A woman’s hand accidentally touches a hot object.
The woman moves her hand away rapidly.
Describe how the woman’s nervous system coordinates the reflex action.
receptor (in skin of finger / hand)
detects stimulus / temperature
change
(electrical) impulses pass along
neurones
(impulses pass from) sensory to
relay to motor neurones
synapse between neurones
where chemical crosses gap
(synapses) in spinal cord / CNS
muscle contraction (to pull hand
away)
or effector is a muscle
Describe how hormones control the menstrual cycle.
FSH (release from pituitary)
stimulates maturation of egg /
ovum / follicle
oestrogen (release from ovary)
inhibits FSH production and
stimulates LH production
LH (release from pituitary)
stimulates ovulation
progesterone (release from
ovary) inhibits FSH and LH
production
oestrogen and progesterone
maintain the uterus lining
Give the reason why a mutation in the gene coding for haemoglobin could be harmful
mutation means less oxygen for
(aerobic) respiration
Without medical treatment, people with sickle cell anaemia are frequently ill and have
a reduced life expectancy.
The malarial parasite cannot live in the red blood cells of a person who has
the HS allele.
A scientist stated:
‘It is an advantage for people to have the HS allele in countries where malaria occurs.’
Evaluate the scientist’s statement
any three from:
points for:
* HAHS do not get malaria
* HAHS survive sickle cell
anaemia
points against:
* HAHA may die from malaria
* HSHS may become (severely)
ill with sickle cell anaemia
* Judgement:
if parents HAHS then some
offspring survive both malaria
and sickle cell anaemia
or
if parents HAHS then some
offspring may become
(severely) ill with malaria
and some become (severely)
ill with sickle cell anaemia
Give evidence from Figure 17 that beak depth is an inherited characteristic
offspring have similar beak
depths to parent
Scientists suggested that more than one gene controls beak depth.
Give evidence from Figure 17 to support the scientists’ suggestion
parents of a given beak depth
produce offspring with several
beak depths
The medium ground finch and the small ground finch both feed on seeds. box
The size of seeds eaten by each bird depends on the depth of the bird’s beak.
The range of beak depth of medium ground finches on Isabela Island is different
from the range on Daphne Island.
Explain what might have caused this difference
colonisers of Isabela have a
range of beak depths
due to different combinations of
alleles of several genes
or
due to different alleles of one
gene
or
due to mutation
large range of (sizes / species
of) seeds / food (on Isabela)
or
large(r) seeds (on Isabela)
more competition for seeds /
food (on Isabela)
birds with larger beaks get
enough food to (survive and)
reproduce (on Isabela)
(survivors) pass on (beneficial)
alleles to offspring
Suggest why both species of finch are able to live on Isabela Island
Isabela is a large island with
more species of plants
or
Isabela is a large island with
more variety in seed / food sizes
or
Isabela is a large island with
more plants / seeds / food
less competition for seeds / food
or
enough seeds / food for both
bird species
