Exam-useful questions from this chapter, grouped by marks, each with a full model answer. Try writing the answer yourself first, then check it against this one.
1 1-Mark Questions
Q. What is variation?
Answer: Variation is the small, inheritable difference between a DNA copy and the original, caused because no copying reaction is ever perfectly accurate.
Q. Define asexual reproduction.
Answer: Asexual reproduction is the creation of a new generation from a single individual, without the fusion of male and female germ-cells (e.g. fission, budding, vegetative propagation).
Q. What is the function of the sporangia in Rhizopus?
Answer: Sporangia are the blob-on-a-stick structures that contain the spores, which can develop into new Rhizopus individuals. Each spore is covered by a thick wall that protects it until it comes into contact with a moist surface and can begin to grow.
Q. Name the male and female reproductive parts of a flower.
Answer: The stamen is the male reproductive part and the pistil is the female reproductive part.
Q. What is meant by self-pollination?
Answer: Self-pollination is the transfer of pollen from the stamen to the stigma of the same flower.
Q. Where are sperm formed in the human body?
Answer: Sperm are formed in the testes.
Q. What is menstruation?
Answer: Menstruation is the monthly shedding of the thickened uterine lining, as blood and mucus, when the egg released that month is not fertilised.
Q. Name one hormonal method of contraception.
Answer: Oral contraceptive pills, which work by changing the body’s hormonal balance so eggs are not released.
2 2-Mark Questions
Q. Differentiate between binary fission and multiple fission, with one example of each.
Answer: In binary fission a cell splits into two equal halves – e.g. Amoeba (in any plane) or Leishmania (in a fixed orientation). In multiple fission, one cell divides into many daughter cells at the same time – e.g. Plasmodium, the malarial parasite.
Q. Why does fragmentation not work as a mode of reproduction for complex multicellular organisms?
Answer: In complex multicellular organisms, cells are organised into tissues, and tissues into organs, all placed at fixed positions in the body. Cutting such an organism into random pieces would not produce a working individual, so simple fragmentation does not work; only simple-bodied organisms like Spirogyra can reproduce this way.
Q. Explain why regeneration is not considered the same as reproduction.
Answer: Regeneration lets organisms like Hydra and Planaria regrow a complete individual from a cut piece, using specialised cells that proliferate and differentiate. But most organisms do not normally depend on being cut into pieces in order to reproduce, so the book treats regeneration as a separate ability, not as reproduction itself.
Q. What is the difference between pollination and fertilisation?
Answer: Pollination is only the transfer of pollen from the stamen to the stigma (self- or cross-pollination). Fertilisation is a later, separate step: a pollen tube grows through the style to the ovary, and the male germ-cell fuses with the egg cell in an ovule to form a zygote.
Q. Why are the testes located outside the abdominal cavity, in the scrotum?
Answer: Sperm formation requires a temperature lower than normal body temperature, so the testes are kept outside the abdomen, in the scrotum, where they stay cooler.
Q. What is the function of the placenta?
Answer: The placenta is a disc embedded in the uterine wall. It carries villi on the embryo’s side, surrounded by maternal blood spaces, giving a large surface area for glucose and oxygen to pass from the mother to the embryo, and for waste substances to pass from the embryo back into the mother’s blood.
Q. Why does the uterus lining thicken every month, even when fertilisation has not occurred?
Answer: Since an egg is released every month, the uterus prepares itself every month to receive and nourish a possible fertilised egg by thickening its lining and increasing its blood supply. If fertilisation does not happen, this preparation is not needed, so the thickened lining breaks down and is shed as menstruation.
Q. Why can surgical methods of contraception cause complications if not performed properly?
Answer: Surgical methods block the vas deferens (in males) or the fallopian tube (in females) to prevent fertilisation. While safe in the long run, the surgery itself carries a risk of infection and other problems if it is not carried out properly.
3 4-Mark Questions
Q. Describe four modes of asexual reproduction found in simple organisms, with one example of each.
Answer: (1) Binary fission – a cell splits into two, e.g. Amoeba. (2) Fragmentation – a simple multicellular body breaks into pieces that each grow into a new individual, e.g. Spirogyra. (3) Regeneration – a cut piece regrows an entire organism, e.g. Planaria. (4) Budding – a new individual grows as an outgrowth at one site and later detaches, e.g. Hydra. All four create a new generation from a single parent, with no fusion of germ-cells.
Q. Describe vegetative propagation, and explain two of its advantages over reproduction from seeds.
Answer: Vegetative propagation is reproduction in which a new plant develops from a root, stem or leaf, rather than from a seed – e.g. potato pieces with a bud, or Bryophyllum leaves with buds along the margin, and by layering or grafting for sugarcane, rose or grapes. Two advantages: (i) plants raised this way flower and bear fruit earlier than seed-grown plants; (ii) it makes it possible to propagate plants such as banana, orange, rose and jasmine that have lost the capacity to produce seeds at all, and every plant produced is genetically similar enough to the parent to carry all its characteristics.
Q. Describe the parts of a flower involved in sexual reproduction, and the function of each.
Answer: The stamen is the male part: it has a filament topped by an anther, which produces pollen grains. The pistil is the female part, in the centre of the flower, with three parts: the stigma (sticky tip, receives pollen), the style (connects stigma to ovary) and the ovary (swollen base, contains ovules; each ovule has an egg cell). Together, the stamen produces the male germ-cells and the pistil receives them and houses the female germ-cells for fertilisation.
Q. Describe the sequence of events in a flowering plant after fertilisation, ending in seed and fruit formation.
Answer: After fertilisation the zygote divides repeatedly to form an embryo inside the ovule. The ovule develops a tough coat and gradually becomes the seed. Meanwhile the ovary grows rapidly and ripens into the fruit, while the petals, sepals, stamens, style and stigma may shrivel and fall off. The seed contains the future plant (embryo), which develops into a seedling under the right conditions – this final step is called germination.
Q. Describe the male reproductive system in human beings and the function of each organ.
Answer: The testes, kept in the scrotum outside the abdomen for a lower temperature, produce sperm and the hormone testosterone. Sperm travel through the vas deferens, which joins a tube from the urinary bladder; the urethra is the shared passage for both sperm and urine. Along the way, the seminal vesicles and the prostate gland add secretions that form a fluid, easing the sperm’s transport and providing them nutrition. The sperm themselves are tiny, mainly genetic material with a long tail for movement.
Q. Describe the female reproductive system in human beings and the function of each organ.
Answer: The ovaries make eggs and hormones; a girl is born with thousands of immature eggs, and one matures and is released every month. The egg travels through the fallopian tube (oviduct) toward the uterus, an elastic bag-like structure formed by the two oviducts uniting. The uterus opens into the vagina through the cervix. The vagina receives sperm during intercourse; if fertilisation occurs, the resulting embryo implants and develops in the uterus.
Q. Explain why some degree of sexual maturity does not necessarily mean the body or mind is ready for sexual acts or parenthood.
Answer: Sexual maturation is a gradual process that takes place while general body growth is still going on, so reaching some degree of it does not automatically mean the body or mind is ready for the major responsibility of sexual acts or of having and raising children. Many kinds of pressure – from friends, from families wanting marriage and children, or even from government agencies wanting fewer children – can make these choices difficult, which is why they need to be made carefully rather than under pressure.
4 6-Mark Questions
Q. Explain, with reasons, why sexual reproduction produces more variation in a population than asexual reproduction, and why this variation matters for the survival of a species.
Answer: DNA copying on its own is never perfectly accurate, so it does generate some variation – but slowly, since copying has to stay accurate enough that most copies still work. Sexual reproduction speeds this up by combining the DNA of two different individuals, each already carrying its own accumulated variations; every such combination is new, since it involves two different individuals. This is why meiosis exists – it halves the chromosome number in germ-cells so that, when two germ-cells fuse, the normal number is restored rather than doubling every generation. This extra variation matters because a population’s niche (its place in the ecosystem) can change for reasons beyond its control – temperature shifts, changing water levels, even a meteorite hit. A population with no variation at all could lose every one of its members to such a change. A population with variation has some individuals suited to the new conditions (e.g. heat-resistant bacteria surviving a temperature rise), so the species as a whole survives even though many individuals do not.
Q. Trace the journey of an egg from its release by the ovary to either fertilisation or menstruation, describing what happens at each stage.
Answer: One of the ovaries releases one egg each month. The egg travels through the fallopian tube (oviduct) toward the uterus. Meanwhile, the uterus lining thickens and gains a rich blood supply in preparation. If sperm (entering through the vagina during intercourse) reach the egg in the oviduct, fertilisation occurs, producing a zygote; this divides repeatedly to form a ball of cells, the embryo, which implants in the thickened uterine lining and develops there, nourished through the placenta, for about nine months, ending in birth. If the egg is NOT fertilised, it survives only about a day; the thickened, unused uterine lining then breaks down and is shed through the vagina as blood and mucus – menstruation – lasting about 2 to 8 days, after which the cycle repeats the following month.
Q. Explain the four broad categories of contraceptive methods described in the chapter, giving one example of each and, where the chapter mentions one, a possible drawback.
Answer: (1) Mechanical barrier – a condom on the penis, or a similar covering worn in the vagina, stops sperm from reaching the egg; the chapter mentions no side effect for this method, and a condom also helps to prevent the transmission of many sexually transmitted infections to some extent. (2) Hormonal – oral pills change the body’s hormone balance so eggs are not released; drawback: altering hormones this way can cause side effects. (3) Intrauterine device (IUD) – the loop or copper-T is placed inside the uterus; drawback: it can cause side effects from irritating the uterus. (4) Surgical – blocking the vas deferens (male) or the fallopian tube (female) prevents fertilisation; while safe long-term, the surgery itself carries a risk of infection or other complications if not performed properly.
Q. Discuss the reproductive health issues covered in the chapter – sexually transmitted infections, contraception, and sex-selective abortion – and explain why each matters for a healthy society.
Answer: Since the sexual act is a very intimate connection between two bodies, several infections can pass between partners this way – bacterial (gonorrhoea, syphilis) and viral (warts, HIV-AIDS); a condom helps prevent transmission of many of these, to some extent, though not completely. The sexual act always carries a chance of pregnancy, which makes major demands on a woman’s body and mind, so contraceptive methods (barrier, hormonal, IUD, surgical) exist to let people choose when to have children. Surgery can also be used to remove unwanted pregnancies, and this can be misused to end a pregnancy specifically because of the foetus’s sex – illegal sex-selective (female) foeticide – which skews the female-male sex ratio; the book states that a healthy society must keep this ratio balanced, and that prenatal sex determination has been prohibited by law for this reason. Together, these three issues show that reproductive health is not only about the biology of reproduction, but about making informed, unpressured choices that protect both individual health and the wider population’s balance.
5 Case Studies
(A) 1 mark What is this method of reproduction called?
Answer: Vegetative propagation.
(B) 1 mark Name one other plant part (besides a stem like the potato) that can also be used for vegetative propagation.
Answer: A leaf – for example, buds growing along the leaf margin of Bryophyllum fall onto soil and grow into new plants.
(C) 2 marks Why did the potato pieces without a notch fail to grow?
Answer: The notch (or “eye”) on a potato is the bud, the growing point that can produce fresh shoots and roots. A piece without a notch has no such growing point, so it cannot regenerate a new plant.
(A) 1 mark Name the four broad categories of contraceptive methods described in the chapter.
Answer: Mechanical barrier, hormonal, intrauterine device (IUD), and surgical methods.
(B) 2 marks Which of these methods, besides preventing pregnancy, also helps reduce the transmission of some sexually transmitted infections, and why?
Answer: The mechanical barrier method (a condom). Because it physically covers the penis, it can also reduce, to some extent, the transmission of infections that pass between partners during the sexual act.
(C) 2 marks Give one possible side effect of a hormonal contraceptive method, according to the chapter.
Answer: Oral contraceptive pills work by changing the body’s hormonal balance, and since they alter hormones, they can cause side effects.