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How do organisms reproduce? is a chapter you can revise largely through its diagrams. Board questions often ask you to draw and label a flower, a budding Hydra or a human reproductive system, and long answers are easier when you can see the diagram in your head. This post lists the diagrams to know, explains the ideas behind them, gives a model answer, lists the common slips and ends with a revision routine built around drawing.
What does the syllabus include?
The CBSE Class X Science syllabus for 2026-27 lists reproduction in animals and plants (asexual and sexual), reproductive health, the need for and methods of family planning, safe sex and HIV/AIDS, and child bearing and women's health. Two practicals come from this chapter: studying binary fission in Amoeba and budding in yeast and Hydra on prepared slides, and identifying the parts of a dicot seed embryo. Everything below is from Chapter 7 of the NCERT Class 10 Science textbook.
Why does reproduction involve copying DNA?
NCERT starts with this idea. Reproduction makes a copy of the DNA plus extra cell machinery. The copying is accurate but not perfect, so small variations appear. Sexual reproduction mixes DNA from two parents and makes more variation, which can help a species survive when conditions change. Germ cells carry half the usual amount of DNA, so that when two fuse, the zygote has the normal amount.
Which diagrams should you be able to draw?
NCERT's figures, in order:
Binary fission in Amoeba and Leishmania (Figure 7.1). One cell divides into two. In Leishmania, which has a whip-like structure at one end, the split happens in a definite orientation.
Multiple fission in Plasmodium (Figure 7.2). One cell divides into many daughter cells at once.
Regeneration in Planaria (Figure 7.3). Each piece of the body grows into a whole organism.
Budding in Hydra (Figure 7.4). An outgrowth develops into a small individual and detaches.
Leaf of Bryophyllum (Figure 7.5). Buds on the leaf margin grow into new plants: vegetative propagation.
Spore formation in Rhizopus (Figure 7.6). Sporangia release spores with thick walls that protect them.
Longitudinal section of a flower (Figure 7.7). Sepals, petals, stamens (anther and filament), and pistil (stigma, style, ovary with ovules).
Germination of pollen on stigma (Figure 7.8). The pollen tube grows through the style to the ovule.
Seed germination (Figure 7.9). Plumule, radicle and cotyledon.
Human male and female reproductive systems (Figures 7.10 and 7.11). Testes, vas deferens, seminal vesicle, prostate, urethra; ovaries, oviduct, uterus, cervix, vagina.
A model answer to a common question
Question. How is pollination different from fertilisation?
Answer. Pollination is the transfer of pollen grains from the anther to the stigma. It can happen in the same flower (self-pollination) or between flowers (cross-pollination), helped by wind, water or animals. Fertilisation comes after pollination: a pollen tube grows from the pollen grain through the style to the ovary, and the male germ cell fuses with the egg in the ovule to form a zygote. Pollination moves pollen; fertilisation fuses germ cells.
A labelled sketch of Figure 7.8 beside the answer makes it complete. After fertilisation, NCERT notes, the ovule becomes a seed and the ovary ripens into a fruit.
What does reproductive health cover?
NCERT makes three points worth stating carefully in an answer. First, physical changes at puberty do not mean the body or mind is ready for sex or parenthood. Second, some infections spread through sexual contact, including gonorrhoea, syphilis, warts and HIV-AIDS; a condom reduces the risk of many of them. Third, contraceptive methods fall into groups: barriers such as condoms, hormonal pills, devices placed in the uterus such as the copper-T, and surgical methods. NCERT also notes that prenatal sex determination is prohibited by law, and that female foeticide has lowered the child sex ratio in some sections of society. If you have questions about your own health, a doctor or your school counsellor is the right person to ask.
Which mistakes come up most often?
Calling regeneration and budding the same thing. In budding, a new individual grows from a specific site; in regeneration, a cut piece grows into a whole organism.
Confusing pollination and fertilisation (see the model answer).
Unlabelled or crowded diagrams. Draw large, in pencil, with straight label lines that do not cross.
Saying fertilisation happens in the uterus. In humans, NCERT says it occurs in the fallopian tube (oviduct); the embryo then implants in the uterus.
Why does drawing help you remember?
Drawing is more than decoration. Wammes, Meade and Fernandes (2016) ran seven experiments and found that people recalled words they had drawn better than words they had written out, even with less time to study. Ainsworth, Prain and Tytler (2011) argue in Science that drawing should be recognised as a key part of science education. Our post on drawing the diagram first has more on using this in revision.
A drawing-based revision routine
Day 1: Draw diagrams 1 to 6 from memory. Check each against NCERT and correct in a different colour.
Day 2: Draw the flower, pollen germination and seed diagrams. Write a two-line caption for each.
Day 3: Draw both human systems and write the function of each labelled part.
Day 4: Answer three long questions with a sketch each, including the model question above.
If a structure is hard to picture, look it up on its own before drawing it again. The Fermi Concept Library covers every concept in biology, each with its own lesson.
Start now: draw a budding Hydra and a binary fission sequence from memory, then check them against the book.
