1Compare sexual and asexual reproduction in terms of genetic variation, processes and advantages.
Sexual reproduction involves the fusion of gametes from two parents and produces genetically varied offspring due to recombination.
Asexual reproduction involves a single parent and produces genetically identical offspring (clones) via mitosis.
Sexual reproduction increases genetic variation, while asexual reproduction allows rapid reproduction without the need for a mate.
2Outline the roles of meiosis and fertilization in the sexual life cycle.
Meiosis produces haploid gametes by reducing the chromosome number and generates genetic variation through crossing over and independent assortment. Fertilization is the fusion of two haploid gametes to restore the diploid chromosome number and produces genetically unique offspring.
3State how meiosis and fertilization generate genetic variation.
Crossing over (prophase 1) and independent assortment (metaphse 1) during meiosis produce genetically different gametes, and random fertilization further increases genetic variation.
4Compare male and female gametes in terms of size, motility, energy reserves and production rate.
Male gametes (sperm) are small, motile, produced in large numbers, and contain few energy reserves.
Female gametes (ova) are large, non-motile, produced in smaller numbers, and contain substantial energy reserves to support early development.
5Reconstruct and label the male reproductive system.
See slide 26
6Outline the functions of the male reproductive structures.
Testes: produce sperm and testosterone
Scrotum: maintains testes at a temperature below core body temperature
Epididymis: stores and matures sperm
Sperm ducts (vas deferens): transport sperm to the urethra
Seminal vesicles & prostate gland: secrete seminal fluid containing nutrients (e.g., fructose) and alkaline substances
Urethra: conducts semen during ejaculation
Penis: delivers sperm into the female reproductive tract
7Reconstruct and label the female reproductive system.
See slide 27
8Outline the functions of the female reproductive structures.
Ovaries: produce ova and hormones (oestrogen and progesterone)
Oviducts (fallopian tubes): transport ova to the uterus; site of fertilization
Uterus: site of implantation and development; endometrium supports embryo
Cervix: regulates passage between uterus and vagina; remains closed during pregnancy
Vagina: receives penis and acts as birth canal
Vulva: external structures that protect the reproductive system
9Define ovarian cycle, uterine cycle and menstrual cycle.
Ovarian cycle: sequence of events in the ovary involving follicle development, ovulation, and corpus luteum formation
Uterine cycle: changes in the endometrium, including menstruation, proliferation, and maintenance
Menstrual cycle: the overall cycle combining ovarian and uterine cycles, regulated by FSH, LH, oestrogen, and progesterone
10Explain hormonal control of the ovarian cycle, including roles of FSH, LH, estrogen and progesterone.
FSH stimulates the development of ovarian follicles. Developing follicles secrete oestrogen, which initially inhibits FSH and LH (negative feedback).
High levels of oestrogen trigger a switch to positive feedback, causing an LH surge that induces ovulation.
After ovulation, LH promotes formation of the corpus luteum, which secretes progesterone to maintain the endometrium. If fertilization does not occur, progesterone levels fall, leading to menstruation.
11Explain negative and positive feedback in regulation of FSH and LH.
Negative feedback: Moderate levels of oestrogen and progesterone inhibit FSH and LH secretion from the pituitary.
Positive feedback: High levels of oestrogen stimulate the release of LH, causing the LH surge and ovulation.
12Outline events of the uterine cycle.
Menstruation (days 1–5): shedding of the endometrium
Proliferative phase (days 6–14): oestrogen stimulates repair and thickening of the endometrium
Secretory phase (days 15–28): progesterone maintains the thickened endometrium for possible implantation
If no implantation occurs, hormone levels fall and menstruation begins
13Interpret or reconstruct a menstrual cycle hormone graph and relate it to ovulation, corpus luteum and endometrium changes.
See slide 28
14Describe the process of fertilization in humans.
A sperm penetrates the outer layers of the ovum using enzymes from the acrosome. The sperm membrane fuses with the egg membrane, and the sperm nucleus enters the egg. The haploid nuclei fuse to form a diploid zygote. This is followed by mitotic divisions.
15Compare in vivo and in vitro fertilization
In vivo fertilization occurs within the female reproductive tract, whereas in vitro fertilization (IVF) occurs outside the body under controlled laboratory conditions.
16 outline the IVF process.
1. Downregulation: Hormones (e.g., GnRH agonists/antagonists) are used to suppress the natural menstrual cycle and prevent premature ovulation.
2. Superovulation: FSH is administered to stimulate the development of multiple ovarian follicles.
3. Egg collection: Mature oocytes are collected from the ovaries using a needle guided by ultrasound.
4. Sperm collection and preparation: A semen sample is collected and sperm are processed to select motile, viable cells.
5. Fertilization: Eggs and sperm are combined in vitro (in a culture dish), or a single sperm is injected into an egg (ICSI).
6. Embryo culture: Fertilized eggs develop into embryos and are monitored for several days (typically to the blastocyst stage).
7. Embryo transfer: One or more embryos are transferred into the uterus.
8. Implantation and pregnancy: If successful, the embryo implants in the endometrium; progesterone is often given to support the uterine lining.
17Explain the roles of FSH, oestradiol and progesterone in IVF.
FSH stimulates the development of multiple ovarian follicles. Oestradiol promotes thickening of the endometrium and reflects follicle development. Progesterone maintains the endometrium to support implantation after embryo transfer.
18Outline the life cycle of flowering plants and identify where gametogenesis occurs.
Flowering plants alternate between growth and reproduction: germination → vegetative growth → flowering → pollination → fertilization → seed and fruit formation → seed dispersal.
Gametogenesis occurs in the flower:
Male gametes are produced in the anthers (pollen grains)
Female gametes are produced in the ovules within the ovary
19Distinguish between pollination and fertilization.
Pollination is the transfer of pollen from the anther to the stigma of a flower (of the same species).
Fertilization is the fusion of the male gamete (from pollen) with the female gamete in the ovule to form a diploid zygote.
20Reconstruct and label an insect-pollinated flower.
See slide 29
21Outline functions of the main parts of an insect-pollinated flower.
Petals: large, brightly coloured and scented to attract insects; may provide a landing platform and guide insects towards reproductive structures
Nectaries: secrete nectar (sugar solution) as an energy reward; often positioned deep in the flower to ensure contact with anthers and stigma
Sepals: protect the flower in bud stage
Anther: produces pollen grains (male gametes)
Filament: positions anther to maximise contact with pollinators
Pollen grains: large, sticky or spiky to attach to insects; may be protein-rich as a food source
Stigma: large and sticky to collect pollen from insects
Style: allows growth of pollen tube to the ovary
Ovary: contains ovules; develops into fruit after fertilization
Ovule: contains female gamete; develops into seed
22Explain adaptations of insect-pollinated flowers for attracting insects and transferring pollen.
Insect-pollinated flowers have adaptations to attract pollinators and ensure pollen transfer. Petals are brightly coloured and scented to attract insects. Nectaries produce nectar as a reward. The anthers are positioned so pollen attaches to the insect’s body, while the stigma is sticky to receive pollen. Flower shapes may provide landing platforms or fit specific pollinators, increasing the likelihood of pollen transfer between flowers.
23State the meaning of homologous structures in flowers.
Homologous structures are structures that share a common evolutionary origin but may have different functions.
24Define cross-pollination.
Cross-pollination is the transfer of pollen from the anther of one plant to the stigma of a different plant of the same species.
25Explain advantages of cross-pollination and self-incompatibility.
Cross-pollination increases genetic variation, which enhances adaptability and reduces the risk of inbreeding depression. Self-incompatibility prevents self-fertilization by rejecting genetically similar pollen, ensuring cross-pollination and promoting genetic diversity.
26Outline methods that promote cross-pollination.
Self-incompatibility: prevents fertilization by genetically similar pollen
Dioecy: male and female flowers occur on separate plants
Temporal separation: male and female reproductive organs mature at different times
Spatial separation: anthers and stigma are positioned apart
Pollinator attraction: flowers attract animals to transfer pollen between plants
Wind pollination: pollen carried between plants by wind
27Explain why self-pollination is generally avoided.
Self-pollination is generally avoided because it reduces genetic variation and can lead to inbreeding depression, increasing the expression of harmful recessive alleles and reducing adaptability
28Explain mechanisms of self-incompatibility in flowering plants.
Self-incompatibility is controlled by S-alleles. If pollen has the same S-allele as the stigma, recognition proteins prevent pollen tube growth. This blocks fertilization and ensures only genetically different pollen can fertilize the ovule.
29Distinguish between seed dispersal and pollination and state the function of a seed.
Pollination is the transfer of pollen to the stigma to enable fertilization. Seed dispersal is the movement of seeds away from the parent plant to reduce competition and increase survival.
A seed contains an embryo, a food store, and a protective coat, allowing survival and germination under suitable conditions.
30List mechanisms of seed dispersal.
Wind dispersal
Water dispersal
Animal dispersal (ingestion or attachment)
Mechanical (explosive) dispersal
31Define germination.
Germination is the process by which a seed resumes growth and develops into a seedling.
32Explain why water, oxygen and warmth are required for germination and outline the role of gibberellin.
Water is required to rehydrate the seed and activate metabolic processes. Oxygen is needed for aerobic respiration to provide energy for growth. Suitable temperature (warmth) ensures optimal enzyme activity.
Gibberellin stimulates the production of hydrolytic enzymes (e.g., amylase), which break down stored food reserves into usable nutrients, promoting growth of the embryo and germination.