Practise DNA and the genome. 13 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
DNA is a polymer made of two strands. What name is given to the shape of a DNA molecule?
Double helix
The whole human genome has now been studied. What is meant by the genome of an organism?
The entire genetic material of that organism
Name the structures in a cell's nucleus that contain most of an organism's DNA.
Chromosomes
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
The genetic material in the nucleus of a cell is found in chromosomes.
(a) What chemical is the genetic material in the nucleus made of? Tick (✓) one box.[1]
DNA
Glucose
Lipid
Starch
(b) DNA is a polymer made of two strands. What name is given to the shape of a DNA molecule?[1]
(c) Write the words chromosome, gene and genome in order of size, starting with the smallest.[1]
(d) What is a gene?[2]
Show the answer and mark scheme
(a)Answer: DNA
(b)Answer: Double helix
double helix
(c)Answer: Gene, chromosome, genome
gene, chromosome, genome
(d)Answer: A small section of DNA on a chromosome that codes for a particular sequence of amino acids, to make a specific protein
a (small) section of DNA (on a chromosome)
that codes for a particular sequence of amino acids / a specific protein
Question 2Medium7 marks
The whole human genome has now been studied.
(a) What is meant by the genome of an organism?[1]
(b) Give three reasons why studying the human genome is important.[3]
(c) Scientists found that women with a particular allele of one gene have a much higher risk of developing breast cancer. Suggest how this discovery could be used to help people.[2]
(d) Suggest one concern that people may have about genetic testing.[1]
Show the answer and mark scheme
(a)Answer: The entire genetic material of that organism
the entire / all the genetic material of the organism
(b)Answer: To search for genes linked to different types of disease; to understand and treat inherited disorders; to trace human migration patterns from the past
searching for genes linked to (different types of) disease
understanding and treatment of inherited disorders
tracing human migration patterns from the past
(c)Answer: Women could be tested for the allele; those with it could have more frequent check-ups or preventive treatment so any cancer is found early; drugs could be developed that target the faulty protein
people can be tested / screened for the allele
people with the allele can have regular check-ups / screening so cancer is detected early
people with the allele could choose preventive treatment / make lifestyle changes
new treatments / drugs could be developed that target the effects of the allele
(d)Answer: Insurance companies or employers might discriminate against people with a high-risk allele
discrimination by insurers / employers / anxiety about a result for a disease that may never develop / privacy of genetic data
Question 3Hard8 marks
Scientists compared the same section of DNA, 1000 bases long, in people from four populations, W, X, Y and Z. {table} shows the number of bases that were different between each pair of populations.
[object Object]
(a) Which two populations are most closely related? Give a reason for your answer.[2]
(b) Differences in DNA build up over time because mutations happen continuously. Explain how comparing DNA can show how long ago two populations separated.[2]
(c) Scientists think that populations X, Y and Z are all descended from people who migrated away from population W. Explain how the data support this idea.[2]
(d) Tracing human migration is one reason why the human genome is studied. Give two other reasons.[2]
Show the answer and mark scheme
(a)Answer: Y and Z: they have the fewest differences (3 bases)
Y and Z
fewest differences in their DNA (3)
(b)Answer: After populations separate, each collects different mutations; the more differences there are, the longer ago they shared a common ancestor
after separating, different mutations build up in each population
more differences means they separated longer ago / shared a common ancestor longer ago
(c)Answer: W is the most different from each of the other populations (12 or 13 differences), while X, Y and Z differ from each other by only 3 to 8 bases, so X, Y and Z share a more recent common ancestor
W has the most differences from each of the other populations (12–13)
X, Y and Z are more similar to each other (3–8 differences) so they share a more recent common ancestor (the migrants)
(d)Answer: Searching for genes linked to diseases; understanding and treating inherited disorders
searching for genes linked to (different types of) disease