QUESTION 2 (3 marks)
a) Explain the difference between exons and introns.
[2 marks]
b) State a function of telomeres.
[1 mark]
QCAA guide · typeset solution
QCAA sample response and mark allocation
2a) | Exons are sequences of coding DNA, which is transcribed into mRNA and then translated into proteins. Introns are sequences of non-coding DNA and have a variety of other functions. They are spliced out of the mRNA prior to translation. | • states that exons are coding DNA and introns are non-coding DNA [1 mark] • explains that exons are transcribed into mRNA and then translated into proteins, whereas introns are spliced out of mRNA and have other functions [1 mark] |
2b) | Telomeres protect the ends of chromosomes from being degraded, prolonging their life. | • states a function of telomeres [1 mark] |
QCAA sample response and marking criteria reproduced from the official guide.
Compare your working with the guide above.