This free quiz has 12 real AQA A-level Biology exam questions on mitosis and the cell cycle (22 marks, about 30 minutes). It marks itself: tick-box, table and calculation questions are marked for you, and for written answers you check your work against the real AQA mark scheme.
What the quiz covers (AQA 3.2.2)
what happens to chromosomes in each stage of mitosis
identifying a stage of mitosis from a photograph
the division of the cytoplasm at the end of the cell cycle
how prokaryotic cells divide, and how this compares with mitosis
preparing a root tip squash: the acid step and pressing the coverslip
why drugs that stop spindle fibres forming stop the cell cycle
using a mitotic index to calculate the number of cells in mitosis
how viruses are replicated, and evaluating a cancer drug from data (4 marks each)
How to use it
Write each written answer in full before you open the mark scheme, then tick only the points you really made. Say what happens to chromatids and centromeres rather than just chromosomes, and for the calculation convert the units before you divide and show your working.
Where students lose marks (from AQA examiners’ reports and mark schemes)
Each point below is followed by wording that gained marks.
Mitotic index is a proportion. Some students multiplied by 100 to give a percentage, which was rejected. Others counted the number of visible chromosomes rather than the number of cells with visible chromosomes.
✔ Gains credit: the mitotic index is the number of cells in mitosis divided by the total number of cells in the field of view.
A reliable mitotic index. Many students missed the word “reliable” and didn't say they would repeat their counts, or wrote “repeat” without saying how many times. “Several” wasn't credited.
✔ Gains credit: count the cells in many fields of view (at least 5), selected at random, and count only whole cells.
Root tip squash steps. Only about a third of students knew why the root is put in acid; wrong ideas included speeding up mitosis, killing bacteria and neutralising the root. Pressing the coverslip “to remove air bubbles” or “to spread the stain” was ignored.
✔ Gains credit: acid breaks down the links between cells (the cell walls) so the cells separate and the stain can get in; pressing makes a single thin layer of cells so light can pass through.
Chromatids, not homologous chromosomes. Some students described meiosis, writing about homologous pairs or crossing over in mitosis. Few mentioned that the centromere divides in anaphase.
✔ Gains credit: in anaphase the centromeres divide and the spindle fibres shorten, pulling the sister chromatids to opposite poles of the cell.
Uncontrolled, not faster. A common error was saying cancer cells divide faster rather than uncontrollably. Many knew a tumour involves uncontrolled mitosis but didn't say it is a mass of cells, and “growth” on its own was ignored.
✔ Gains credit: a tumour is a mass of abnormal cells produced by uncontrolled mitosis (cell division).
Interphase is part of the cycle. Many students didn't appreciate that the cell cycle has two stages, interphase and mitosis, and some described mitosis as the whole cell cycle. Describing a trend in mitotic index without linking it to the proportion of cells in mitosis or interphase gained no marks.
✔ Gains credit: the cell cycle is interphase (G1, S and G2) followed by mitosis, so more cells in mitosis means a smaller proportion of cells in interphase.
Viral replication. Answers such as “the virus replicates” or “a new virus is produced” were too vague, and some wrongly gave a role to binary fission or mitosis. Many left out assembly before the new viruses are released.
✔ Gains credit: the attachment protein binds to receptors on the host cell, the viral nucleic acid enters and is replicated, viral proteins are made, and the components are assembled and released.
Keep practising
The other AQA 3.2 self-marking quizzes: Cell structure · Membrane transport · Immune system
Topic 3.1 quizzes start with carbohydrates
The AQA topic index
weekly AQA group classes: Year 12 on Tuesdays at 5.15pm, Year 13 on Wednesdays or Thursdays at 6.30pm
Questions © AQA, from past A-level and AS Biology papers, with their mark schemes and examiners’ reports.