A-LevelBiologyThe mitotic cell cycle9700/22 · May/June 2021 · Q18 Marks

(a) Fig. 1.1 is a photomicrograph of a region of eukaryotic tissue. Some of the cells are in stages of mitosis. E F Fig. 1.1

(a)(i)Identify which stage of mitosis is shown in cell E and in cell F in Fig. 1.1. E F[2]
(a)(ii)Microtubules are present within the cells that are in stages of mitosis, but these are not visible in Fig. 1.1. State the function of microtubules in mitosis.[1]
(a)(iii)State, with a reason, whether Fig. 1.1 shows a region of animal or plant tissue.[1]
(b)Semi-conservative replication of DNA occurs during interphase, before mitosis begins. Write the correct term in the spaces provided to complete each of statements A to D. A The DNA double helix unwinds and is separated into two template strands when bonds holding the two strands together are broken. B One of the template strands of DNA is copied in fragments. The enzyme is required to join the fragments together to form a continuous strand of DNA. C Complementary DNA nucleotides are added to the template strands, catalysed by the enzyme D are regions of repeating nucleotide sequences at the ends of chromosomes that allow the continued replication of DNA, without the loss of genes.[4]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

[2] E = metaphase ; F = anaphase; I early / mid / late R more than one stage given for either E or F
[1] any one from (assemble) to form / become part of / AW, spindle fibres / spindle; attach to, centromere; A kinetochore for centromere A form (part of) kinetochore A to connect, chromatid / chromosome, to, spindle / spindle fibres I to connect, chromosome / centromere, to centrosome example of allowing movement of, chromosomes / chromatids ; e.g. A to, pull chromosomes / orientate chromosomes, at equator A to pull (sister) chromatids apart (at anaphase) A to move, (sister) chromatids / daughter chromosomes, to poles
[1] must state 'plant' to gain mark I vacuoles / large permanent vacuole / vague ref. to shape any one from cell walls present; uniform / regular, shape of cells ; no, cleavage furrow / pinching in of cytoplasm (in cells at cytokinesis) ; cell plate present (in late telophase / cytokinesis, stages);
[4] R any answers where a choice is given A hydrogen; B (DNA) ligase ; C DNA polymerase ; R RNA polymerase I roman numerals, e.g. DNA polymerase I D telomeres ;

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.