1. 1
   After accidentally cutting her finger while gardening, a woman's skin cells at the wound begin to divide rapidly to repair the damaged tissue. Doctors observe that the lost skin cells are fully replaced within a few days.

   (a)

   Which type of cell division is responsible for repairing the woman's damaged skin?

   [1 mark]

   • AMeiosis
   • BMitosis
   • CFertilisation
   • DDifferentiation

   (b)

   How many daughter cells are produced from one skin cell during this type of division, and are they genetically identical or different from the parent cell?

   [1 mark]

   • AOne cell, genetically different
   • BTwo cells, genetically different
   • CTwo cells, genetically identical
   • DFour cells, genetically different

   (c)

   Describe the stages of the cell cycle that a skin cell undergoes before it divides by mitosis.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A fertility clinic is investigating a patient's egg cells (gametes), which are produced in the ovaries by a type of cell division different from that used for tissue repair. Each egg cell produced contains only half the number of chromosomes found in the patient's other body cells.

   (a)

   Which type of cell division produces the patient's egg cells in the ovaries?

   [1 mark]

   • AMeiosis
   • BMitosis
   • CBinary fission
   • DBudding

   (b)

   How many egg cells are produced from one parent cell during this type of division, and are they genetically identical to each other?

   [1 mark]

   • ATwo cells, genetically identical
   • BTwo cells, genetically different
   • CFour cells, genetically identical
   • DFour cells, genetically different

   (c)

   Explain why it is important that the patient's egg cells contain only half the number of chromosomes found in her other body cells.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A plant breeder crosses two different varieties of pea plant to produce offspring with new combinations of characteristics. The breeder explains that seeds are produced via meiosis in the parent plants followed by fertilisation, and that this process, involving independent assortment and crossing over, results in offspring that are genetically different from both parents and from each other.

   (a)

   Explain how meiosis produces four genetically different haploid cells (gametes).

   [3 marks]

   (b)

   Explain the significance of mitosis and meiosis in terms of chromosome number and genetic variation in the pea plants.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   In the late nineteenth century, scientists studying cell division under early microscopes first identified the two different processes now known as mitosis and meiosis, laying the foundations for our modern understanding of genetics and inheritance.

   (a)

   Describe mitosis as a type of cell division, including its role in growth, repair and asexual reproduction, and describe the stages of the cell cycle leading up to it.

   [6 marks]

   (b)

   Describe meiosis as a type of cell division producing gametes, and explain how independent assortment and crossing over create genetic variation.

   [6 marks]

   Total for question 4: 12 marks

End of questions