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CAIE A-Level Biology A2 16.1 Passage of Information From Parents to Offspring Questions

Practise 16.1 inheritance by interpreting meiosis diagrams, tracking chromosome sets and explaining how gamete formation and fertilisation create variation.

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Calculate haploid and diploid chromosome numbers in gametes, zygotes and hybrid offspring.
  • Identify homologous pairs from shared loci, chromosome length, centromere position or banding.
  • Explain how meiosis halves chromosome number so fertilisation restores the diploid number.
  • Trace meiosis I and II through chromosome separation, spindle movement and nuclear/cell division changes.
  • Identify meiosis stages from diagrams or photomicrographs and infer chromosome or ploidy state.
  • Link prophase I crossing over and random assortment of homologues and chromatids to varied gamete alleles.
  • Explain how random gamete fusion combines different alleles to produce genetically varied offspring.

Covered syllabus points

16.1.1—Haploid (n) and diploid (2n)16.1.2—Homologous pairs of chromosomes16.1.3—Reduction division16.1.4—Chromosome behaviour during meiosis16.1.5—Meiosis I and II stages16.1.6—Meiosis image interpretation16.1.7—Genetic variation in meiosis16.1.8—Random fertilisation and variation

Question 1

[Maximum number: 6]

Question (a)

(a)

In sexual reproduction, meiosis occurs to produce haploid gametes from a diploid cell.
Explain the meaning of the terms haploid and diploid.

[ 2 ]

Question (b)

(b)

Describe the behaviour of chromosomes during the main stages of meiosis I in animal cells. prophase I
metaphase I
anaphase I
telophase I

[ 4 ]

Question 2

[Maximum number: 1]

Many different genes are involved in the production of pigments in mammals. One example is the TYR gene.

In humans the TYR gene is located on chromosome 11.

Fig. 6.1 shows the homologous pair for chromosome 11.

Fig. 6.1

Fig. 6.1

Homologous chromosomes have the same genes located at the same loci. State one other feature shared by homologous chromosomes.

Question 3

[Maximum number: 8]

Meiosis is described as a reduction division because the number of chromosomes in the daughter cells is reduced by half.

Question (a)

(a)

Table 5.1 describes some of the events that take place during four of the different stages of meiosis in an animal cell.

Table 5.1

Table 5.1

Figure for Question (a) — CAIE A-Level Biology A2
Figure for Question (a) — CAIE A-Level Biology A2
Figure for Question (a) — CAIE A-Level Biology A2

Complete Table 5.1 by:
- outlining the behaviour of the spindle fibres during anaphase I
- identifying the stage of meiosis in which spindle fibres re-form the spindle in daughter cells
- drawing a diagram to show telophase II.

You do not need to add labels to your diagram showing telophase II.

[ 4 ]

Question (b)

(b)

Explain the need for a reduction division during meiosis.

[ 4 ]
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