Mitosis
One cell splits into two cells that are exact copies of it. Your body does this millions of times a minute, and exams love asking how.
By the end of this page you can
- Say why cells divide by mitosis, with an example
- Describe what the cell does before mitosis starts
- Describe and draw the four stages, in order
- Use the key terms correctly
- Answer exam-style questions on mitosis
Goals tick themselves off as you try the activities below.
One parent cell with 4 chromosomes becomes two daughter cells with 4 each. Humans have 46, but 4 is easier to draw, so this page uses 4 (written 2n = 4).
How often it shows up in past papers
Paper 1 counts come from our past-paper bank of CSEC Biology Paper 1s. Paper 2 is not included yet.
Cells divide because bodies need more cells
Cells wear out, get damaged, and organisms need to grow. Mitosis makes the replacement cells, and every new cell is a copy with the same instructions. Tap each card to see a real example.
A cell prepares long before it divides
Mitosis is only the short last part of the cell cycle. Most of a cell’s life is interphase, and that is where the DNA gets copied.
What is the cell doing?
Tap a stage on the list. G1, S and G2 together are interphase. M is mitosis.
Your syllabus may only name “interphase”. G1, S and G2 are the detail inside it. The slice sizes are for drawing, not to scale.
Four stages, one after another
Press Play it through, tap a stage, or drag the slider to scrub. Watch the chromosomes and the cell edge.
CSEC doesn’t require the names of the stages, but they help you describe what happens, in order.
long chromosome pairshort chromosome paircentromere
Prophase
Stage 1 of 4The chromosomes become visible.
- The DNA coils up into chromosomes you can see.
- Each chromosome is two identical sister chromatids joined at the centromere, because the DNA was copied in interphase.
- The nuclear membrane starts to break down and spindle fibres begin to form.
If you have to draw it: X-shaped chromosomes scattered in the cell, with the nucleus fading.
4 chromosomes, each made of 2 chromatids
Put the stages in order
Drag each stage into its slot, or tap a slot then a stage. Use the clue on each card, not the name alone.
Which stage comes first?
Seven terms to know cold
Say what each term means before you flip the card. If you were close, flip it anyway and check the wording.
Six quick questions, then a real one
Pick an answer and you’ll see straight away why it’s right or wrong.
In which part of the cell cycle is the DNA copied?
A human body cell has 46 chromosomes and divides by mitosis. How many chromosomes does each daughter cell have?
What marks the start of anaphase?
Which of these is NOT done by mitosis in the human body?
A student wants to see cells dividing by mitosis in a bean seedling. Where should they look?
Mitosis makes identical cells. Which event, found only in meiosis, would make the new cells differ from each other?
exam style · 2 marks
Describe what happens to the chromosomes during anaphase of mitosis.
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Practice questions are written by My V.I.P. Academy. They are not official CXC papers.