Describe the importance of mitosis in growth, repair and asexual…

The idea

Mitosis is a type of cell division that produces two genetically identical diploid daughter cells from one parent cell. Before division the DNA is replicated, so each daughter cell receives a full set of chromosomes. This makes mitosis the basis of three processes. In growth, it increases the number of identical cells so a multicellular organism can develop and enlarge. In repair, it replaces damaged or worn-out cells, for example healing a cut skin surface or replacing lining cells of the gut. In asexual reproduction, it lets a single parent produce offspring that are genetically identical clones, as in many plants grown from cuttings or runners. Because the daughter cells are identical, no genetic variation is introduced, which is why asexual reproduction keeps the parent's characteristics.

What earns the marks

• Mitosis produces two genetically identical diploid daughter cells from one parent cell.
• DNA is replicated before mitosis so each daughter cell receives a complete set of chromosomes.
• Growth: mitosis increases cell number so a multicellular organism can develop and increase in size.
• Repair: mitosis replaces damaged or worn-out cells, for example healing skin or replacing gut lining cells.
• Asexual reproduction: mitosis allows a single parent to produce genetically identical offspring (clones).
• Because daughter cells are identical, mitosis introduces no genetic variation.

Common mistakes and how to put them right

• Thinking mitosis produces gametes with half the chromosome number.

  Put it right: Mitosis produces diploid cells identical to the parent, whereas meiosis forms gametes.

• Believing mitosis creates genetic variation.

  Put it right: Mitosis gives identical daughter cells, so variation is not produced.

• Confusing growth with repair.

  Put it right: Growth increases cell number to enlarge the organism, while repair replaces damaged cells.

• Assuming asexual reproduction needs two parents.

  Put it right: Asexual reproduction involves one parent and relies on mitosis.

Exam tips

• Read the question stem to identify which of the three processes (growth, repair or asexual reproduction) is being tested before choosing an option.
• Eliminate options that describe meiosis or gamete formation, since these do not match mitosis.
• Check that the chosen option states daughter cells are genetically identical to the parent cell.
• For each option, ask whether it correctly links mitosis to one named process rather than mixing processes.