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2024 AQA A LEVEL BIOLOGY UNIT 4 EXAM WITH CORRECT ANSWERS
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2024 AQA A LEVEL BIOLOGY UNIT 4 EXAM WITH CORRECT ANSWERS
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2024 AQA A LEVEL BIOLOGY UNIT4 EXAM WITH CORRECT ANSWERS
What is a gene? - CORRECT-ANSWERSA section of DNA that codes for a
protein and functional RNA
What is a section of DNA with a particular portion called? - CORRECT-
ANSWERSLocus
How do they know three bases code for one amino acid? - CORRECT-
ANSWERSOnly 20 different amino acids regularly occur in proteins
Each amino acid must have its own code of bases for the DNA
Only 4 bases are present in DNA
Three bases produce 64, more than enough to cover 20 amino acids
Features of the genetic code? - CORRECT-ANSWERSDegenerate - most amino
acids are coded for by more than one triplet
Non-overlapping - each base is read once
Universal - each triplet codes for the same amino acids in all organisms
What is species richness? - CORRECT-ANSWERSThe number of different
species in a particular area at a given time
What is the impact of agriculture? - CORRECT-ANSWERSEcosystems have a
high index of diversity
Farmers select species for particular qualities that make them more
productive
The genetic variety of alleles they posses is reduced
They have to compete for what little space and resources are available
Many won't survive this competition
Pesticides reduce species diversity
How does farming reduce diversity? - CORRECT-ANSWERSDiminishes variety
of habitats within ecosystems and reduce diversity
Removal of hedgerows
Creating monoculture
Overgrazing of land
Use of pesticides
What are some conservation methods? - CORRECT-ANSWERSPlant hedges
instead of fences
Use of organic fertilisers
, Nitrogen fixing group of crops instead of fertilisers
Maintain existing ponds
How do you investigate diversity by comparing observable characteristics? -
CORRECT-ANSWERSTraditionally, genetic diversity was measured by
observing the characteristics which is based on the fact that characteristics
are determined by a gene
How do you compare base sequences? - CORRECT-ANSWERSEach nucleotide
can be tagged with a different coloured which produces a series of coloured
bands, each represents one of the four nucleotide bases
We can measure the genetic diversity of a species by sampling the DNA of
its members and sequencing it to produce a pattern of coloured bands
This allows us to compare individuals in the same species to see how diverse
they are
It also helps us determine the evolutionary relationships between species
Mutations means the sequence of the nucleotide bases change, over time
accumulation of more differences in DNA leads to new species
How do you compare the base sequence of mRNA? - CORRECT-ANSWERSThe
base sequences on mRNA are complementary to those on DNA, therefore we
can measure DNA diversity and genetic diversity
How do we compare amino acids sequence of proteins? - CORRECT-
ANSWERSThe sequence of amino acids in proteins is determined by mRNA
which is determined by DNA
The degree of similarity in the amino acid sequence of the same protein in
two sequences will reflect how closely related two species are
What does random sampling include? - CORRECT-ANSWERSTaking
measurements of individuals selected form the population of the organism
being investigated
What are some reasons measurements might not be representative? -
CORRECT-ANSWERSSampling bias - the selection process may be biased
Chance - individuals chosen by chance may not be representative
The best was to prevent sampling bias is to eliminate any human
involvement
How do we minimise chance from the sampling process? - CORRECT-
ANSWERSUse a large sample size - the more individuals are selected the
smaller the probability that chance will influence the result and less influence
anomalies will have
Analysis of the data collected - data analysed to find out how much chance
will have of the results
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