AQA A-level Biology - Topic 4 Exam
Questions And Answers
Define variation - Answer>> Differences that exist between
individuals
In what ways can variation be caused? - Answer>> It can be
caused by genetic factors, such as alleles from mutations.
It can also be caused by the environment, such as climate.
Most variation is caused by a combination of genetic factors and
environmental factors
Why is it impossible to study a whole population? - Answer>>
Because it is too large and would take too long. Instead, scientists
use a sample that is representative of the species' population
Why should the sample taken be random? - Answer>> So you
can make sure that the sample isn't biased in any way.
What could you calculate to look at variation between species? -
Answer>> The mean (average)
What is standard deviation? - Answer>> It tells you how much
values in a single sample vary, by measuring the spread of values
about the mean
What does a large standard deviation mean? - Answer>> That
the values in the sample vary a lot
What does a small standard deviation mean? - Answer>> That
the values in the sample varies little
,What can you use standard deviation to draw on a bar chart of
mean values? - Answer>> An error bar. You would draw it one
standard deviation either side of the mean value.
How is DNA stored in eukaryotic cells? - Answer>> 1) The DNA
is linear and exists as chromosomes
2)It is stored in the nucleus, and has to be wound up because it is
so long
3) It is wound around proteins called histones which help to
support the DNA
4)The DNA is coiled very tightly to make a compact chromosome
How is DNA stored in prokaryotic cells? - Answer>>
1)Prokaryotic cells carry DNA as chromosomes, but the DNA is
shorter and circular
2)It isn't wrapped around histones, so condenses into the cell by
supercoiling
What organelles in eukaryotic cells have their own DNA apart
from the nucleus? - Answer>> The mitochondria and
chloroplasts have their own DNA. It is similar to prokaryotic DNA
as it is shorter, circular and isn't wrapped around histones.
What is a gene? - Answer>> A gene is a sequence of DNA
bases that codes for a polypeptide or functional RNA
What forms the primary structure of proteins? - Answer>> The
sequence of amino acids.
What determines the order of amino acids in a polypeptide? -
Answer>> The order of the bases
, How is each amino acid coded for? - Answer>> By a sequence
of three bases in a gene called a triplet
What is functional RNA? - Answer>> It is RNA molecules other
than mRNA that perform special tasks during protein synthesis.
tRNA and rRNA
What is a cell's genome? - Answer>> The complete set of
genes in a cell
What is a cell's proteome? - Answer>> The full range of
proteins that the cell is able to produce
If a gene doesn't code for polypeptides, what does it code for? -
Answer>> Functional RNA such as tRNA and rRNA
What are introns? - Answer>> Sections of a gene that codes for
polypeptides, that doesn't actually code for amino acids
What are exons? - Answer>> The sections of a gene that
actually code for amino acids
When are introns removed, and why? - Answer>> They are
removed during protein synthesis so it doesn't affect the amino
acid order
Which type of DNA does not have introns? - Answer>>
Prokaryotic DNA does not have introns
What is an allele? - Answer>> The same gene, but a different
version of it
Questions And Answers
Define variation - Answer>> Differences that exist between
individuals
In what ways can variation be caused? - Answer>> It can be
caused by genetic factors, such as alleles from mutations.
It can also be caused by the environment, such as climate.
Most variation is caused by a combination of genetic factors and
environmental factors
Why is it impossible to study a whole population? - Answer>>
Because it is too large and would take too long. Instead, scientists
use a sample that is representative of the species' population
Why should the sample taken be random? - Answer>> So you
can make sure that the sample isn't biased in any way.
What could you calculate to look at variation between species? -
Answer>> The mean (average)
What is standard deviation? - Answer>> It tells you how much
values in a single sample vary, by measuring the spread of values
about the mean
What does a large standard deviation mean? - Answer>> That
the values in the sample vary a lot
What does a small standard deviation mean? - Answer>> That
the values in the sample varies little
,What can you use standard deviation to draw on a bar chart of
mean values? - Answer>> An error bar. You would draw it one
standard deviation either side of the mean value.
How is DNA stored in eukaryotic cells? - Answer>> 1) The DNA
is linear and exists as chromosomes
2)It is stored in the nucleus, and has to be wound up because it is
so long
3) It is wound around proteins called histones which help to
support the DNA
4)The DNA is coiled very tightly to make a compact chromosome
How is DNA stored in prokaryotic cells? - Answer>>
1)Prokaryotic cells carry DNA as chromosomes, but the DNA is
shorter and circular
2)It isn't wrapped around histones, so condenses into the cell by
supercoiling
What organelles in eukaryotic cells have their own DNA apart
from the nucleus? - Answer>> The mitochondria and
chloroplasts have their own DNA. It is similar to prokaryotic DNA
as it is shorter, circular and isn't wrapped around histones.
What is a gene? - Answer>> A gene is a sequence of DNA
bases that codes for a polypeptide or functional RNA
What forms the primary structure of proteins? - Answer>> The
sequence of amino acids.
What determines the order of amino acids in a polypeptide? -
Answer>> The order of the bases
, How is each amino acid coded for? - Answer>> By a sequence
of three bases in a gene called a triplet
What is functional RNA? - Answer>> It is RNA molecules other
than mRNA that perform special tasks during protein synthesis.
tRNA and rRNA
What is a cell's genome? - Answer>> The complete set of
genes in a cell
What is a cell's proteome? - Answer>> The full range of
proteins that the cell is able to produce
If a gene doesn't code for polypeptides, what does it code for? -
Answer>> Functional RNA such as tRNA and rRNA
What are introns? - Answer>> Sections of a gene that codes for
polypeptides, that doesn't actually code for amino acids
What are exons? - Answer>> The sections of a gene that
actually code for amino acids
When are introns removed, and why? - Answer>> They are
removed during protein synthesis so it doesn't affect the amino
acid order
Which type of DNA does not have introns? - Answer>>
Prokaryotic DNA does not have introns
What is an allele? - Answer>> The same gene, but a different
version of it
