biology paper 1 Flashcards
how does the order of amino acids in a protein is determined by gene sequence
a single strand of messenger rna is transcribed from the gene in the nucleus
messenger rna molecules binds to the ribosome
the triplet code from the MRNA is matched by a complementry + rna anticodon at the ribosome
tRNa transfers amino acids to the polypeptide chair in a specific order
describe how monoclonal antibodies are deloped to detect STI in a urine test
isolate an antigen from the pathogen which is the sti
inject the antigen into a rodewnt
collect lymphocytes producing an antibodies to the STI antigen
fuse the b- lymphocytes with a melanoma cell. production of a hybridoma which produces a monoclonal antibody against the antigen of the STI
attach the monoclonal antibody to coloured bead and incorporate into a test strip
how to produce genetically modified bacteria that bmakes penicillin
use of restriction enzymes to remove the gene and cut the plasmid
use of ligase to join the DNA molecules togeth
cut the gene from the genome of the fungus and extract a plasmid from the bacteria insert the recombinant plasmid back into the bacteria
why does phenolphthalein turn colourless when lipase breaks down lipids
fatty acids are formed when the lipds are broken down by lipase
and fatty acids are acidic so the ph decreases
effect of penicillin on bacteria and human cells (3)
prevents the bacteria from dividing as they cannot make a new cell wall
human cells do not have a cell wall so they are not affected by penicillin
how to grow drought resistant plants
genetic variation = some plants will be tolerant to droughts
cross - pollinate these plants
select offspring and repeat over several generations
evidence to date how old species is
fossil structure
older fossils are deeper down in the rocks
how embryonic stem cells are used to treat disease
embryonic stem cells are stimulated to produce cells of the retina
which can be transplanted into the patients eye to replace the damaged cells
benefits of asexual reproduction (3)
rapid reproduction technique allowing the production of more plants
as there is no requirement of cross pollination
higher crop yield
-> increased profit
why is reproduction via seed/pollination good
introduces variation into the population
which allows for natural selection
Describe the advantages of producing plants by tissue culture .
- many plants produced (1)
- quicker than sexual
reproduction (1)
genetically identical/ clones
produced (1)
with the desired
characteristics (1) - plants from
{endangered/rare} plants (1)
Describe the possible benefits of this research on stem cells
have the potential to produce any
cell type (1)
* no need to use embryonic stem cells
less chance of patient rejecting their
own cells (1)
used to treat conditions which are
currently incurable / used for cell
transplants /used to replace faulty
cells (1)
the role of ethanol in DNA extraction
to percipitate the DNA
explain how bacteria become resistant to antibiotics
patients to not finish course of antibiotics
natural selection/evolution occurs
some bacteria have a mutation/genetic mutation
resistant bacteria survive//resistant bacteria reproduce
give reasons why the three domain methods of classification are used
improved genetic analysis
DNA/RNA [sequencing/screening]
domain theory is based on genetics
differences between coding and non-coding DNA
explain how gonorrhoea is transmitted and how it can be prevented
gonorrhoea is spread through exchange of bodily fluids/sexual contact
from mother to child through child birth
barrier contraception methods
abstinence prevents infection
screening for infection
contact tracing partners of infected individuals
education on ways to prevent it and reduce its spread
treating infection with antibiotics
explain how a mutation in an allele can change/allele the function of a protein
Codon codes for a different amino acid
protein structure is different/it folds (in enzymes shape of active site changes…)
–> affects protein function.
describe role of the sensory neurons
transmit electrical impules
from receptors (skin cells) to CNS(spinal chord)
Describe how the specific immune system defends the body against disease
- (pathogens have) antigens
(1) - (that trigger) antibodies to
be produced (1) - by lymphocytes (1)
- (leads to the) destruction/engulfing of
the pathogen (1) - memory {cells/
lymphocytes} produced (1) - cause a secondary response
(in the event of infection by
the same pathogen) (1)
Give one reason why the number of people per million diagnosed with
measles is different in these countries
vaccination (1)
* {reporting/diagnosis}
systems (1)
* {access to/quality of}
healthcare (1)
* environmental factors (1)
Describe the function of a meristem in the growth of a plant
(meristem cells) are
undifferentiated
* (meristem cells) divide /
produce more cells (1)
* by mitosis (1)
Describe how a prokaryotic cell is different from the plant cell
- no nucleus/
chromosomal DNA (in
the cytoplasm) (1) - no membrane-bound
organelles (1) - circular/plasmid DNA
(1) - no mitochondria (1)
- no chloroplasts (1)
- no vacuole (1)
) Scientists think that great tits living now have longer beaks because of the
increased use of bird feeders during the last 50 years.
Explain how natural selection could have caused an increase in beak length
because of the use of bird feeders.
- the population of great tits
shows variation (1) - bird feeders provide a selection
pressure (1) - birds with longer beaks {can
feed from bird feeders/get more
food} (1) - these birds are more likely to
{survive/ reproduce} / survival
of the fittest (1) - pass the {allele/gene
/characteristic} for long beaks to
their offspring (1) - over many generations the beak
length of the bird population
increases (1)
Amylase has an optimum pH of 6.8.
Devise a method the students could use to confirm the optimum pH for amylase
- mix starch solution with
amylase (1) - use different pH values (1)
- using buffers / test at pH
solutions between pH 6.5 and
7.5 (1) - control named variables (1)
- a method of testing for
glucose/a method of testing for
starch - the sample that produces
glucose in the shortest time is
closest to the optimum
Amylase is produced by salivary glands and the pancreas.
Explain why amylase is not produced in the stomach.
- the stomach is {acidic/low pH/pH 2}(1)
- which will denature the {amylase/enzyme} (1)
- changes the shape of the active site/substrate will not
{bind/fit} into the active site (1)
Discuss the advantages and disadvantages of growing crop plants that
produce a toxin that can kill insects.
Advantages
* less damage to crops
* increased yield/more food
* more profit
* that the toxin only affects target insects
* less use of chemical insecticides
* no need to buy chemicals
Disadvantages
* insects develop resistance to the toxin
* plants are more expensive to produce initially
* risk of cross fertilisation with wild plants/other
crops
* reduces biodiversity
* detrimental impact on the food web in the area
* possibility of bioaccumulation
* reliance on seed companies
* consumer concerns with eating GM crops
Some painkillers prevent neurotransmitters binding to receptors in a synapse.
Explain how a signal is transmitted at a synapse and how the painkillers reduce the pain
felt by the person
neurones transmit electrical impulses
* the synapse is a gap between 2 neurones
* triggering the release of neurotransmitters
* which diffuse across the synapse
* as a chemical signal
* neurotransmitters bind to receptors on the next
neurone
* triggering an electrical impulse in the next
neurone
Painkillers
* prevent neurotransmitters binding to receptors in
the next neurone
* electrical impulse is not triggered
* signal is not received by the central nervous
system
* person does not feel pain
Cancer Research UK found that many people do not realise that obesity is linked to an
increased risk of developing cancer.
In the body, fat tissue sends signals that cause other cells to divide.
(a) (i) Describe how this could cause cancer to develop
- (cells are triggered to divide)
by mitosis (1) - this division is uncontrolled (1)
- creates a mass/large number
of cells /tumour (1)
Obesity is linked to 1 in 20 cases of all types of cancer.
Approximately 13% of cases of bowel cancer are caused by obesity.
Determine how the impact of obesity on bowel cancer compares to the
impact of obesity on all types of cancer.
- 1 in 20 is a rate of 5% (1)
- obesity increases the risk of
bowel cancer more (than
other types of cancer) (1)
Obesity can also cause cardiovascular disease to develop.
Describe the different treatments available for cardiovascular disease
surgery to treat narrow or
blocked arteries (1)
* lifestyle changes including
{healthy diet/more
exercise} (1)
* (life-long) medication to
{prevent blood clots/reduce
blood pressure/thin the
blood} (1)
Explain how a diverging lens corrects short-sightedness
(a diverging lens)
{bends/refracts} light rays
outwards (1)
* so the light rays
{meet/converge/focus} on
the retina (1)
Colour blindness is a sex-linked genetic disorder caused by a recessive allele.
Colour blindness only affects 1 in 200 women.
Explain why more men than women are colour blind.
- allele is located on the X
chromosome (1) - men are XY/have one X
chromosome (1) - if they have one
{recessive/affected} allele
they are colour blind (1)
