Class 10 Science · Original EZT practice
How do Organisms Reproduce (Class 10 Chapter 7): summary and practice
Reproduction copies life, but never perfectly - and the chapter opens with why that small difference matters. It then tours the asexual modes single organisms use, and finishes with sexual reproduction in flowering plants and in humans. All questions are original EZT tutor practice following the chapter's own section order.
8 original worked examples, 8 fresh self-check questions and 4 mixed questions, with explained answers. These are not copied textbook exercises, an official chapter index or a full answer key. No affiliation with NCERT is claimed.
Official sources for topic and edition context, checked 20 October 2026:
1. Exact copies and why variation matters
Reproduction makes copies that are similar but not identical. Variation comes from copying errors and, far more, from sexual reproduction. It matters because a population with variation can survive changing conditions.
2. Asexual modes in single organisms
One parent is enough: fission (binary in Amoeba, multiple in Plasmodium), fragmentation in Spirogyra, regeneration in Planaria, budding in Hydra, vegetative propagation in plants, and spore formation in Rhizopus.
3. Sexual reproduction in flowering plants
The flower carries the reproductive parts: stamens (male) and pistil (female). Pollination moves pollen to the stigma - self or cross - and fertilisation fuses the gametes to form a zygote, which grows into the seed's embryo.
4. Reproduction in human beings
The chapter outlines the male and female reproductive systems, puberty, fertilisation and development, keeping to what sections 7.3.3 (a) and (b) describe.
Choose, solve, check, then try a fresh question.
Before calculating, read the method prompt and name the condition that makes it useful. Write your own attempt. Open the steps only when you need them, and use the check to catch a wrong sign, unit or interpretation. Finish with the fresh question before reading its answer.
Why variation matters
Choose the method: Variation buffers a population against change.
EZT practice question
Reproduction aims to copy, yet the chapter says variation is important. Why?
Show the worked solution
- Copies are never perfectly exact; some variation always appears.
- If conditions change, some variants may survive where identical copies would all fail.
Answer: Variation lets at least some individuals survive changing conditions, so the population endures.
Check: Sexual reproduction produces the most variation - consistent with its success across species.
Watch for this: Do not call variation a defect; it is what natural selection works on.
Now try it yourself
Which produces more variation, asexual or sexual reproduction?
Check your answer
Sexual reproduction.
It combines DNA from two parents, multiplying the combinations.
Tell binary from multiple fission
Choose the method: Count the daughters: two versus many.
EZT practice question
Name the two kinds of fission and give the chapter's example for each.
Show the worked solution
- Binary fission splits one cell into two - Amoeba.
- Multiple fission splits one cell into many - Plasmodium.
Answer: Binary fission (Amoeba) and multiple fission (Plasmodium).
Check: Both need only one parent - they are asexual modes.
Watch for this: Do not swap the examples; Amoeba divides in two, Plasmodium into many.
Now try it yourself
Which mode of reproduction does Amoeba use?
Check your answer
Binary fission.
The parent cell splits into two daughter cells.
Separate fragmentation from regeneration
Choose the method: Fragmentation is splitting to reproduce; regeneration is regrowing lost parts - which some organisms use to reproduce.
EZT practice question
Spirogyra breaks into pieces that each grow into a new filament. Is this regeneration?
Show the worked solution
- The body simply breaks and each fragment grows - that is fragmentation.
- Regeneration is a different process: specialised cells regrow a whole organism from a part, as in Planaria.
Answer: No - it is fragmentation. Regeneration, as in Planaria, uses specialised cells to regrow the full body.
Check: The chapter itself warns that the two are not the same.
Watch for this: Do not use the two words interchangeably; the chapter keeps them distinct.
Now try it yourself
Which organism does the chapter give for regeneration?
Check your answer
Planaria.
A cut Planaria can regrow complete individuals from its parts.
Match organism to mode: budding and spores
Choose the method: Hydra buds; Rhizopus makes spores.
EZT practice question
Identify the mode: (a) Hydra grows a small outgrowth that detaches; (b) Rhizopus releases tiny round structures that grow into new fungi.
Show the worked solution
- An outgrowth that detaches is a bud - budding.
- Tiny dispersal structures are spores - spore formation.
Answer: (a) Budding; (b) spore formation.
Check: Both are asexual: one parent, no gametes.
Watch for this: A bud is not a spore; buds grow on the parent's body, spores are released.
Now try it yourself
Which mode does Hydra use?
Check your answer
Budding.
The new individual develops as an outgrowth of the parent.
Use vegetative propagation
Choose the method: New plants from stems, roots or leaves - no seeds.
EZT practice question
What is vegetative propagation, and which two methods does the chapter name that use it?
Show the worked solution
- New plants grow from vegetative parts like stems, roots or leaves.
- The chapter names layering and grafting, used for plants like sugarcane, roses and grapes.
Answer: Growing new plants from vegetative parts; the chapter names layering and grafting.
Check: Such plants are genetically uniform - like the sugarcane field in the chapter's opening.
Watch for this: Do not list seed formation here; vegetative propagation needs no seeds or flowers.
Now try it yourself
Give one plant the chapter names for propagation by layering or grafting.
Check your answer
Sugarcane, roses or grapes (any one).
These are the chapter's own examples of such methods.
Name the flower parts and pollination types
Choose the method: Stamens are male, pistil is female; pollen must reach the stigma.
EZT practice question
Name the male and female parts of a flower, and the two kinds of pollination.
Show the worked solution
- Stamens are the male parts; the pistil is the female part.
- Self-pollination moves pollen within the same flower or plant; cross-pollination moves it to another plant.
Answer: Stamens (male) and pistil (female); self-pollination and cross-pollination.
Check: A bisexual flower carries both; a unisexual flower carries only one.
Watch for this: Do not confuse pollination with fertilisation; pollination only delivers the pollen.
Now try it yourself
What is a bisexual flower?
Check your answer
A flower that has both stamens and a pistil.
It carries both the male and female reproductive parts.
Distinguish pollination from fertilisation
Choose the method: Pollination delivers pollen; fertilisation fuses gametes.
EZT practice question
After pollen lands on the stigma, what happens next in a flowering plant?
Show the worked solution
- The pollen grows a tube down to the ovule.
- The male gamete fuses with the egg - fertilisation - forming a zygote.
Answer: Fertilisation: the male gamete fuses with the egg to form a zygote, which develops into the embryo inside the seed.
Check: The ovary then ripens into fruit and the ovules become seeds.
Watch for this: Landing on the stigma is pollination, not fertilisation; fusion is fertilisation.
Now try it yourself
What does the zygote develop into?
Check your answer
The embryo of the seed.
The zygote divides and grows into the new plant's embryo.
Outline human reproduction
Choose the method: Keep to what the chapter covers: systems, puberty, fertilisation.
EZT practice question
What changes mark puberty, and why do they matter for reproduction?
Show the worked solution
- Puberty brings the maturation of the reproductive systems.
- Only after it can the body produce gametes.
Answer: Puberty readies the male and female reproductive systems to produce gametes, making sexual reproduction possible.
Check: The chapter then describes fertilisation and development inside the mother's body.
Watch for this: Do not add detail beyond the chapter; the exam asks for what the text covers.
Now try it yourself
Where does fertilisation take place in human beings?
Check your answer
Inside the female reproductive tract (the fallopian tube region, as the chapter describes).
The chapter places internal fertilisation in the female body.
Try a mixed set
Choose a method or explanation before opening each answer.
1. Binary fission example?
Show answer and reason
Amoeba.
One cell splits into two daughters.
2. How does Hydra reproduce?
Show answer and reason
By budding.
A bud grows on the parent and detaches.
3. How does Rhizopus reproduce?
Show answer and reason
By spore formation.
Released spores grow into new fungi.
4. Pollination versus fertilisation?
Show answer and reason
Pollination delivers pollen to the stigma; fertilisation is the fusion of gametes forming the zygote.
Mixing the two is the classic error in this chapter.
Try it yourself
Work these on paper before checking any notes. Answers are deliberately not shown here.
- Identify the mode: an Amoeba cell splits into two.
- Identify the mode: a Planaria fragment regrows a complete worm.
- Name the male and female reproductive parts of a flower.
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Questions about this practice page
- Why is variation important?
- Variation lets at least some individuals survive when conditions change, so the population can endure. Sexual reproduction creates the most variation.
- What is the difference between binary and multiple fission?
- Binary fission splits one parent into two daughters (Amoeba); multiple fission splits it into many (Plasmodium).
- Self-pollination versus cross-pollination?
- Self-pollination moves pollen to the stigma of the same flower or plant; cross-pollination carries it to a different plant.
- Is regeneration the same as budding?
- No. The chapter keeps them distinct: budding grows an outgrowth on the parent (Hydra), while regeneration regrows a whole organism from a part using specialised cells (Planaria).
- Are these the NCERT exercise questions for How do Organisms Reproduce (Class 10)?
- No. EZT pages are original practice following the chapter's section order - use them to prepare for the textbook exercises, not as a substitute for your book.