Activity 1

Question 1
Give the correct word or term for each of the statements or definitions provided below.

Answers to question 1
1.1 Centromere✔(1)
1.2 Homologous chromosomes✔ (1)
1.3 Daughter chromosome/chromatid✔ (1)
1.4 Chiasma✔/chiasmata✔ (1)
1.5 Chromatid✔ (1)
1.6 Prophase 1✔ (1) [6]

Question 2
Figure 2.12 (right) represents a process taking place during meiosis. Study the diagram and answer the questions that follow.

2.1 Provide labels for parts A, B, C and D. (4)
2.2 Name the process in meiosis that is illustrated in Figure 2.12. (1)
2.3 State ONE importance of the process you named in question 2.2. (2)
2.4 Draw a diagram of the structure labelled A to show its appearance immediately after the process you named in question 2.2. (2) [9]

Answers to question 2
2.1

A - Chromosome✔
B - Centromere✔
C - Chromatid✔
D - Chiasma✔/chiasmata (4)

2.2 Crossing over✔ (1)
2.3 It introduces genetic✔ variation✔ (2)
2.4

• A double-stranded chromosome with the strands joined by a centromere✔
• There is evidence of crossing over.✔ (2)
  

Question 3
Figure 2.13 (below) represents an animal cell in a phase of meiosis. Study the diagram and answer the questions that follow.

3.1 State whether the phase of meiosis shown in Figure 2.13 is meiosis I or meiosis II. (1)
3.2 Give ONE visible reason for your answer in question 3.1. (1)
3.3 Identify the parts labelled A and B. (2)
3.4 How many chromosomes:

1. were present in the parent cell before meiosis began? (1)
2. will be present in each cell at the end of meiosis? (1)

3.5 State ONE place in a human female where meiosis would take place. (1)
3.6 Could the cell represented in Figure 2.13 be that of a human? (1)
3.7 Explain your answer to question 3.6. (2)
3.8 Give TWO reasons why meiosis is biologically important. (2)
3.9 Give the term for the situation when some of the chromosomes do not separate correctly during the phase shown in Figure 2.13. (1) [13]

Answers to question 3
3.1 Meiosis II✔ (1)
3.2 Daughter chromosomes/chromatids are being pulled to the opposite poles✔ (1)
3.3

A - Spindle fibre✔
B - Cell membrane✔ (2)

3.4

a) 8✔
b) 4✔ (2)

3.5 Ovaries✔ (1)
3.6 No✔ (1)
3.7 There are only 4 chromosomes present3 instead of 23.✔ (2)
3.8

• It introduces genetic variation.✔
• It balances the doubling effect of fertilisation as it halves the number of chromosomes in the sex cells.✔ (2)

3.9 Non-disjunction✔ (1) [13]

Question 4
The diagram below shows the nuclei of the four cells that resulted from meiosis of chromosome pair 21 in a woman.

Figure 2.14: Diagram that shows the nuclei of four cells resulted from meiosis
4.1 Explain why nucleus N does NOT have a chromosome pair 21. (2)
4.2 Name and explain the disorder that will result if diagram M represents an egg cell that fuses with a normal sperm cell. (3) [5]

Answers to question 4
4.1 During Anaphase 1 the chromosome pair 21 does not separate✔/ non-disjunction. Gamete M will have an extra copy of chromosome number 21 and therefore gamete N does not have a copy of chromosome 21✔ (2)
4.2 Down syndrome✔/Trisomy 21 if gamete M fuses with normal sperm having 1 copy of chromosome 21 ✔ the resulting zygote will have 3 copies of chromosome 21✔ (3) [5]

For more papers on Meiosis visit https://www.elimuza.com/