CAIE IGCSE Biology 16 Reproduction
Review asexual and sexual reproduction, flowering plants, human reproduction, sex hormones and sexually transmitted infections.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Review asexual and sexual reproduction, flowering plants, human reproduction, sex hormones and sexually transmitted infections.
Fig. 2.1 shows a dwarf sunflower and a tall sunflower, Helianthus annuus. The height of the dwarf sunflower is 0.45 m and the height of the tall sunflower is 4.5 m .

not to scale
Dwarf plants like the one in Fig. 2.1 have mutant alleles.
Fig. 2.3 shows how several strawberry plants can be formed from one parent plant.

Fig. 2.3
Explain the type of reproduction that produces plants by the method shown in Fig. 2.3.
ref. to asexual reproduction ;
(plantlets / cells / offspring grow by) mitosis ; all cells / new plants, are genetically identical ;
AVP ;
Explain the disadvantages of the type of reproduction shown in Fig. 2.3.
competition for resources as all individuals are close together ;
increased risk of inheriting harmful, alleles / features / trait ; no / little, (genetic) variation ; no new adaptive features ; no evolution / no (natural) selection / no artificial selection / AW ; no / little, ability to respond to (named) environmental change ; all individuals are susceptible to the same, diseases / pests ; higher risk of extinction ;
A scientist investigated sexual reproduction in flowering plants.

Fig. 2.1 shows the procedure for crossing two plants of the same species.
The scientist collected the seeds and germinated them. The leaves and flowers of the offspring plants showed phenotypic variation as they were not all identical to the parent plants.
The scientist then investigated the chromosomes of all the offspring plants and found that they had exactly the same number of chromosomes as the parent plants.
Suggest why the scientist placed a bag around flower 1.
prevent pollination (from another flower or plant)/ to prevent (other) pollen
landing on stigma ;
Explain how sexual reproduction results in the variation that the scientist discovered in the offspring plants.
any two from:
reference to meiosis ;
gametes contain different alleles ;
idea of new / different, combinations of, maternal and paternal chromosomes / alleles ;
idea of random fertilisation / fusion of gametes with different, genotypes or alleles ;
AVP ;
The chromosome number of the offspring plants is the same as the chromosome number of the parent plants in this investigation.
Explain how the chromosome number is maintained from one generation to the next.
either:
1 meiosis halves the number of chromosomes
or
gametes are haploid
or
gametes, have one of each type of chromosome / have one set of chromosomes ;
and
2 idea that parental / diploid, number is restored at fertilisation or
cells have 23 chromosomes and fuse together form a cell with 23 pairs ;
A diploid to haploid in meiosis
A sperm and eggs / ova / pollen
A haploid gametes fuse to form diploid, zygote / offspring = 2 marks
Fig. 6.1 is a half-flower drawing of pride of Barbados, Caesalpinia pulcherrima.

Fig. 6.1
Complete Table 6.1 by stating the letter from Fig. 6.1 that indicates the organ where each function occurs and the name of the organ.

Table 6.1
process / event | letter from Fig. 6.1 | name of the
organ
meiosis to produce pollen grains
C
anther
pollination
D
stigma
development of seeds
E
ovary
protection of flower in the bud
A
sepal
one mark per row
Fig. 6.2 is a scanning electron micrograph of some pollen grains from wind-pollinated flowers and insect-pollinated flowers.

Fig. 6.2
Explain how the pollen grain labelled J is adapted for insect pollination.
(covered in) spikes / sticky ; (pollen) sticks to, insect / animal (bodies / legs / AW) ;
large(r) size (in comparison with wind) ; AVP ;
Pollen grains grow tubes, which contain haploid male gamete nuclei.
One of these male gamete nuclei fuses with the female gamete.
State the part of the flower that contains the female gamete.
ovule ;
Explain why it is important for gametes to be haploid.
so that chromosome number does not double (at fertilisation) ; so that chromosome number remains constant from generation to generation ;
Fig. 4.1 is a photograph of a bee on a flower. One of the bee's legs is covered with pollen.

Fig. 4.1
State one way that pollen grains are adapted for pollination by bees.
Any one from: large; sticky; spiky; or equivalent wording.
Fig. 4.2 is a diagram of a cross-section of an insect-pollinated flower.

Fig. 4.2
On Fig. 4.2, name and draw label lines to:
- the structure that supports an anther
- a structure that protects the flower bud
- an ovule.
filament labelled ;
sepal labelled ;
an ovule labelled ;
Describe sexual reproduction in a flower, from the release of pollen to the formation of a zygote.
any five from:
1 pollen (released) from the anther ;
2 pollen transferred to stigma ;
3 pollen tube, grows ;
4 (pollen tube goes) down / through, the style ;
5 ref. to ovule / ovary ;
6 pollen / male, nucleus travels down the (pollen) tube / style ;
7 pollen / male, and, ovule / female, nuclei fuse ;
8 fertilisation ;
9 AVP ;
e.g. ref. to haploid nuclei or diploid zygote ;
Sexual reproduction also occurs in humans.
State the name of the male gamete in a human.
sperm (cell)
State where gametes are formed in the human male reproductive system.
testis / testes
Describe the function of the prostate gland in the male reproductive system.
Produces fluid / semen for sperm (male gametes) to swim.
Accept reference to providing nutrients.