MEIOSIS - LIFE SCIENCES QUESTIONS AND ANSWERS (2024)

Monday, 23 August 2021 13:18

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Activity 1

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

1.1	The structure that joins the two halves of a double-strandedchromosome (1)
1.2	A pair of chromosomes, one inherited from each parent, that have thesame genes at the same locus (1)
1.3	A single-stranded chromosome formed during Anaphase 2 (1)
1.4	The point of contact between two chromosomes of a hom*ologous pairduring crossing over (1)
1.5	One half of a double-stranded chromosome (1)
1.6	The phase in meiosis where crossing over occurs (1) [6]

Answers to question 1
1.1 Centromere✔(1)
1.2 hom*ologous 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. Studythe 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 appearanceimmediately 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 thestrands 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 ismeiosis 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:

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

3.5 State ONE place in a human female where meiosis would takeplace. (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 chromosomesdo 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 theopposite 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 thenumber 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 Mrepresents 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 chromosomenumber 21 and therefore gamete N does not have a copy ofchromosome 21✔ (2)
4.2 Down syndrome✔/Trisomy 21 if gamete M fuses with normalsperm having 1 copy of chromosome 21 ✔ the resulting zygote willhave 3 copies of chromosome 21✔ (3)[5]

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Last modified on Monday, 25 April 2022 11:04

MEIOSIS - LIFE SCIENCES QUESTIONS AND ANSWERS (2024)

Activity 1

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