6.3 DNA and the genome
6 exam questions worth 12 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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What is a gene?
Mark scheme
- a (small) section of DNA (on a chromosome) (1)
- that codes for a particular sequence of amino acids / a specific protein (1)
Model answer
A gene is a small section of DNA that codes for a particular sequence of amino acids, to make a specific protein.
Describe the structure of a DNA molecule.
Mark scheme
- two strands (1)
- twisted into a double helix (1)
- strands joined by (complementary) base pairs / A-T and C-G (1)
- polymer of nucleotides (1)
Maximum 3 marks
Model answer
DNA is a polymer made of two strands twisted into a double helix. The strands are joined by complementary base pairs: A with T and C with G.
One strand of DNA has the base sequence ATTGCA.
Write the sequence of bases on the complementary strand.
Mark scheme
TAACGT
Model answer
TAACGT
Which word describes all the genetic material of an organism?
Choose one answer.
Correct Not quite: the answer is Genome
Mark scheme
B: genome
Model answer
B: genome.
Name the three parts of a nucleotide.
Mark scheme
- sugar (1)
- phosphate (group) (1)
- base (1)
Model answer
A sugar, a phosphate group and a base.
Give two ways that understanding the human genome is useful.
Mark scheme
Any two from:
- finding genes linked to diseases (1)
- understanding / treating inherited disorders (1)
- tracing human migration patterns (1)
Model answer
It helps scientists find genes linked to diseases and understand how to treat inherited disorders.
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