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How do Organisms Reproduce? · Class 10 Science: 162 MCQs with answers

All 162 multiple-choice questions from this kit, free and with no sign-up.

Full kit · everything Flashcards · 66 Quick Revision · 45

Warm-up · 18 questions

Q1. Banana must be propagated vegetatively because it:

Beginner
A grows too tall B has thorns C is seedless D hates soil
Show answer & explanation

is seedless

No viable seeds — no other route.

Q2. Why is DNA copying an essential part of reproduction?

Beginner
Show answer & explanation

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Q3. Distinguish between binary and multiple fission with one example each.

Beginner
Show answer & explanation

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Q4. Why is regeneration not the same as reproduction?

Beginner
Show answer & explanation

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Q5. Describe budding in Hydra.

Beginner
Show answer & explanation

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Q6. What is vegetative propagation? Describe two natural examples.

Beginner
Show answer & explanation

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Q7. How does Rhizopus reproduce? Why does mould appear so easily on moist bread?

Beginner
Show answer & explanation

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Q8. Why is sexual reproduction considered advantageous over asexual reproduction?

Beginner
Show answer & explanation

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Q9. Draw up the parts of a flower whorl by whorl with functions.

Beginner
Show answer & explanation

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Q10. Distinguish between self-pollination and cross-pollination.

Beginner
Show answer & explanation

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Q11. What changes occur in the flower after fertilisation?

Beginner
Show answer & explanation

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Q12. What is germination? What conditions does it need?

Beginner
Show answer & explanation

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Q13. What changes occur at puberty in boys and in girls?

Beginner
Show answer & explanation

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Q14. Why are the testes located outside the abdominal cavity? What two things do they produce?

Beginner
Show answer & explanation

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Q15. What is the placenta? State its functions.

Beginner
Show answer & explanation

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Q16. What happens when the egg is not fertilised?

Beginner
Show answer & explanation

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Q17. Name common STIs and state the method that helps prevent their transmission.

Beginner
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Q18. Why is prenatal sex determination legally banned?

Beginner
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Building up · 48 questions

Q19. Consider these asexual methods and the organisms that use them. I. Binary fission in Amoeba. II. Budding in yeast and Hydra. III. Fragmentation in Spirogyra. IV. Spore formation in Rhizopus. Which statements are correct?

Intermediate
A All four B I and II only C I, II and III only D II and IV only
Show answer & explanation

All four

All four are correct, and all four share one feature — a single parent, so the offspring are genetically identical to it and to one another.

Q20. Tiny complete plantlets growing along the notched edges of a leaf are characteristic of:

Intermediate
A Bryophyllum B Rhizopus C Spirogyra D Planaria
Show answer & explanation

Bryophyllum

Each plantlet falls off and roots where it lands. It is vegetative propagation from a leaf, which is unusual enough to make the plant a standard example.

Q21. A drastic DNA-copying error usually:

Intermediate
A improves the cell B makes spores C makes the cell glow D kills the new cell
Show answer & explanation

kills the new cell

The blueprint no longer fits the machinery.

Q22. Leishmania divides in a definite plane because of its:

Intermediate
A nucleus B whip-like flagellum C cell wall D colour
Show answer & explanation

whip-like flagellum

The structural landmark fixes the axis.

Q23. Malaria's periodic fevers relate to:

Intermediate
A binary fission of Amoeba B yeast budding C spore walls D synchronised multiple fission bursts of Plasmodium
Show answer & explanation

synchronised multiple fission bursts of Plasmodium

Waves of parasite release from blood cells.

Q24. Regeneration proceeds by:

Intermediate
A single giant cell growth B proliferation of specialised cells then re-differentiation C swallowing nutrients D photosynthesis
Show answer & explanation

proliferation of specialised cells then re-differentiation

Mass first, order second.

Q25. Regeneration is NOT reproduction because:

Intermediate
A it is too fast B it needs light C it uses seeds D organisms don't normally depend on being cut to multiply
Show answer & explanation

organisms don't normally depend on being cut to multiply

A capability, not the strategy.

Q26. Fragmentation is possible in Spirogyra because its body has:

Intermediate
A complex organs B minimal cell specialisation C bones D flowers
Show answer & explanation

minimal cell specialisation

Any piece contains all it needs.

Q27. Which is an ARTIFICIAL vegetative method?

Intermediate
A spore release B fission C budding in Hydra D grafting
Show answer & explanation

grafting

The farmer's join-two-plants technique.

Q28. Grafting joins a chosen shoot onto another plant's:

Intermediate
A rootstock B flower C leaf D fruit
Show answer & explanation

rootstock

Combining shoot quality with root hardiness.

Q29. Plants raised by vegetative propagation bear fruit:

Intermediate
A later than seed plants B never C earlier than seed-grown plants D only once
Show answer & explanation

earlier than seed-grown plants

One of the method's three advantages.

Q30. Genetic identity of vegetatively propagated offspring is an advantage because:

Intermediate
A variety is boring B clones grow taller C seeds are heavy D the proven parent's qualities are preserved exactly
Show answer & explanation

the proven parent's qualities are preserved exactly

The prized mango stays prized.

Q31. Mould appears on ANY moist bread because spores:

Intermediate
A grow from bread itself B come from water pipes C form from crumbs D are already floating in the air everywhere
Show answer & explanation

are already floating in the air everywhere

Ubiquitous airborne armoured dust.

Q32. In budding, the bud arises due to:

Intermediate
A water swelling B repeated cell division at one site C cutting D gravity
Show answer & explanation

repeated cell division at one site

Localised proliferation builds the mini-me.

Q33. Which mode produces the LEAST variation among offspring?

Intermediate
A sexual reproduction B cross-pollination C asexual cloning modes D fertilisation
Show answer & explanation

asexual cloning modes

One parent's copy = near-uniformity.

Q34. Variation is most valuable to a species when:

Intermediate
A nothing changes B the environment changes drastically C food is abundant D all individuals are strong
Show answer & explanation

the environment changes drastically

Insurance pays out at disasters.

Q35. Variation helps a species even where it does no good to the single organism. Why is that?

Intermediate
Show answer & explanation

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Q36. How does regeneration occur in Planaria?

Intermediate
Show answer & explanation

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Q37. State the advantages of practising vegetative propagation in agriculture.

Intermediate
Show answer & explanation

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Q38. Compare asexual reproduction's strengths and weaknesses.

Intermediate
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Q39. The male and female parts of a flower are respectively the:

Intermediate
A carpel, made of anther and filament, and the stamen, made of stigma, style and ovary B petal and the sepal C anther and the filament D stamen, made of anther and filament, and the carpel, made of stigma, style and ovary
Show answer & explanation

stamen, made of anther and filament, and the carpel, made of stigma, style and ovary

The anther makes pollen and the ovary holds the ovules. Knowing which sub-part belongs to which whorl is what makes the fertilisation story followable.

Q40. Consider these statements about what happens after fertilisation. I. The zygote develops into the embryo. II. The ovule becomes the seed. III. The ovary becomes the fruit. IV. The petals and stamens usually wither and fall. Which statements are correct?

Intermediate
A All four B I and II only C I, II and III only D II and IV only
Show answer & explanation

All four

All four hold. The petals have done their advertising job and are dropped, which is why a fruit rarely has the flower still attached.

Q41. Pollen reaching the stigma of the same flower, and pollen carried to the stigma of a different plant of the same kind, are called respectively:

Intermediate
A cross-pollination and self-pollination B fertilisation and pollination C chemotropism and geotropism D self-pollination and cross-pollination
Show answer & explanation

self-pollination and cross-pollination

Only the second brings together two different sets of genes, which is why so many flowers have arrangements that make the first difficult.

Q42. Consider these statements about flowers. I. A unisexual flower has either stamens or carpels, not both. II. Papaya and watermelon bear unisexual flowers. III. A bisexual flower has both stamens and carpels. IV. Hibiscus and mustard bear unisexual flowers. Which statements are correct?

Intermediate
A I, II and III only B I and IV only C II and IV only D All four
Show answer & explanation

I, II and III only

Hibiscus and mustard are the standard bisexual examples. Whether a flower carries one set of parts or both decides whether it can pollinate itself at all.

Q43. Gametes contain ______ the DNA of body cells.

Intermediate
A half B double C equal to D triple
Show answer & explanation

half

So fusion restores the normal amount.

Q44. Without DNA halving in gametes, each generation's DNA would:

Intermediate
A halve B double C stay equal D vanish
Show answer & explanation

double

The arithmetic sex had to solve.

Q45. Cross-pollination differs from self-pollination in that pollen:

Intermediate
A never moves B reaches another plant's stigma C stays in the anther D becomes seed directly
Show answer & explanation

reaches another plant's stigma

Two plants' genes mix — more variation.

Q46. The pollen tube grows down through the:

Intermediate
A filament B style C sepal D petal
Show answer & explanation

style

From stigma toward the ovary's ovule.

Q47. The pollen tube's directional growth is an example of:

Intermediate
A phototropism B chemotropism C geotropism D thigmotropism
Show answer & explanation

chemotropism

Chemically guided — the classic case.

Q48. What travels down the pollen tube?

Intermediate
A the whole flower B the ovule C the male germ-cell D nectar
Show answer & explanation

the male germ-cell

Delivered to fuse with the egg cell.

Q49. After fertilisation, petals and stamens usually:

Intermediate
A become seeds B shrivel and fall off C turn into roots D grow larger forever
Show answer & explanation

shrivel and fall off

Their advertising and supply jobs are done.

Q50. Which flower part list is entirely FEMALE?

Intermediate
A anther, filament B stigma, style, ovary C petal, sepal D pollen, anther
Show answer & explanation

stigma, style, ovary

The carpel's three storeys.

Q51. Wind-pollinated flowers typically have:

Intermediate
A small dull flowers with abundant light pollen B huge bright petals C heavy sticky pollen only D no stigma
Show answer & explanation

small dull flowers with abundant light pollen

No insect to attract — quantity over advertising.

Q52. A flower with only a carpel is called:

Intermediate
A bisexual B male unisexual C female unisexual D sterile
Show answer & explanation

female unisexual

Carpel = female organ.

Q53. Vanilla farmers hand-pollinate because:

Intermediate
A it's traditional B pollen is toxic C natural pollinators are absent where it's farmed D flowers are too big
Show answer & explanation

natural pollinators are absent where it's farmed

No native courier, so humans do the transfer.

Q54. Why do germ cells carry only half the DNA, and what restores the full amount?

Intermediate
Show answer & explanation

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Q55. Describe fertilisation in a flowering plant.

Intermediate
Show answer & explanation

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Q56. Explain how flowers ensure pollination despite plants being immobile.

Intermediate
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Q57. A farmer's lone papaya tree flowers every year but never fruits. Explain.

Intermediate
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Q58. Trace what each part of a pea pod meal once was, botanically.

Intermediate
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Q59. Which sequence correctly traces the path of a sperm from where it is made to where it leaves the male body?

Intermediate
A testis, urethra, vas deferens B scrotum, oviduct, urethra C testis, vas deferens, urethra D testis, oviduct, uterus
Show answer & explanation

testis, vas deferens, urethra

The vas deferens is the tube that a vasectomy interrupts. The urethra in the male carries both urine and semen, though never at the same time.

Q60. How many eggs normally mature in a woman's body each month, and from where?

Intermediate
A one from each ovary, so two in all B several from each ovary C one from the uterus D one, from one of the two ovaries
Show answer & explanation

one, from one of the two ovaries

The two ovaries generally take turns. Releasing one at a time is why a single pregnancy is the usual outcome and twins the exception.

Q61. The embryo's wastes are ultimately excreted by:

Intermediate
A its own kidneys externally B the mother's body after transfer via placenta C the uterus wall D the oviduct
Show answer & explanation

the mother's body after transfer via placenta

Mother's kidneys serve both.

Q62. The sperm's long tail functions for:

Intermediate
A storing DNA B digestion C swimming toward the egg D anchoring
Show answer & explanation

swimming toward the egg

The flagellum outboard motor.

Q63. Describe the male reproductive system's organs in the order sperm travels them.

Intermediate
Show answer & explanation

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Q64. Describe the female reproductive system's organs in the order the egg travels.

Intermediate
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Q65. List the four contraception families with an example and note of each.

Intermediate
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Q66. Why do surgical contraception methods not harm general health?

Intermediate
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Topper level · 96 questions

Q67. Consider these statements about reproduction. I. An individual organism can survive perfectly well without reproducing. II. Reproduction costs the organism energy. III. Reproduction is essential for the survival of the species. IV. Reproduction is one of the life processes an individual needs to stay alive. Which statements are correct?

Advanced
A I, II and III only B I and IV only C II and IV only D All four
Show answer & explanation

I, II and III only

Nutrition and respiration keep an individual alive; reproduction does nothing for it and a great deal for its kind. That is what sets it apart from the other life processes.

Q68. Why is the copying of DNA described as the central event of reproduction?

Advanced
A DNA is the largest molecule in the cell and takes the longest to make B DNA supplies the energy that cell division requires C DNA carries the information for building the body, so a new individual can only be made by first making a copy of it D DNA is the only part of the cell that the offspring inherits
Show answer & explanation

DNA carries the information for building the body, so a new individual can only be made by first making a copy of it

Cells also copy their other machinery, but the blueprint is what makes the offspring the same kind of organism. Everything else in reproduction serves that copy.

Q69. Assertion (A): The copying of DNA is never perfectly accurate. Reason (R): The small errors that survive are variations, and they are what allow a species to withstand a change in its surroundings.

Advanced
A Both A and R are true, and R is the correct explanation of A B Both A and R are true, but R is not the correct explanation of A C A is true but R is false D A is false but R is true
Show answer & explanation

Both A and R are true, and R is the correct explanation of A

A drastic error kills the cell and goes no further. It is the small ones that accumulate, and a population with no variation at all has no answer to a new disease or a rising temperature.

Q70. Amoeba divides in any plane while Leishmania divides along a definite axis. The reason for the difference is that Leishmania:

Advanced
A is a larger organism and needs a fixed plane for balance B divides more slowly and so needs greater accuracy C has a whip-like flagellum at one end, which gives its body a definite orientation D reproduces sexually while Amoeba reproduces asexually
Show answer & explanation

has a whip-like flagellum at one end, which gives its body a definite orientation

A cell with no particular shape can split anywhere. Once the body has a recognisable front and back, the split has to respect it.

Q71. Plasmodium divides into many daughter cells at once rather than into two. Which statement best explains the advantage of this?

Advanced
A producing a large number of offspring from one cell at one stroke lets the parasite multiply inside a host far faster than splitting in two would B dividing into many cells uses less energy than dividing into two C the many daughter cells are genetically different from one another D multiple fission allows the parasite to reproduce sexually
Show answer & explanation

producing a large number of offspring from one cell at one stroke lets the parasite multiply inside a host far faster than splitting in two would

Binary fission doubles; multiple fission multiplies many times over in the same step. The simultaneous release of a whole generation is also what produces malaria's periodic fevers.

Q72. Which statement explains why Spirogyra can reproduce simply by breaking into pieces while a Hydra cannot?

Advanced
A Spirogyra is a plant and plants can always be cut up and regrown B Spirogyra's body is a simple filament of similar cells, so any piece has everything it needs, whereas a Hydra's cells are specialised for different jobs C Spirogyra's pieces are carried by water to new places and Hydra's are not D Spirogyra reproduces faster and so has more opportunities to break
Show answer & explanation

Spirogyra's body is a simple filament of similar cells, so any piece has everything it needs, whereas a Hydra's cells are specialised for different jobs

Fragmentation works where there is little division of labour. The more specialised the body, the more a fragment is missing — which is why Hydra needs regeneration instead.

Q73. Which sequence correctly describes what happens when a Planaria is cut in two?

Advanced
A specialised cells in each piece divide, and the new cells then change into the various tissues and organs needed to complete the body B each piece simply grows larger until it reaches the original size C the two pieces rejoin and heal into one animal again D each piece produces spores from which new animals grow
Show answer & explanation

specialised cells in each piece divide, and the new cells then change into the various tissues and organs needed to complete the body

Regeneration is division followed by differentiation. It is a remarkable ability and still not the same as reproduction — the animal did not set out to make a copy of itself.

Q74. Which statement correctly distinguishes budding in Hydra from regeneration in Hydra?

Advanced
A budding produces a genetically different individual while regeneration produces an identical one B budding is the animal's normal way of reproducing, while regeneration is a repair of damage that happens to produce a new individual C budding happens only in water and regeneration only on land D budding requires two parents and regeneration only one
Show answer & explanation

budding is the animal's normal way of reproducing, while regeneration is a repair of damage that happens to produce a new individual

One is planned and routine, the other a response to injury. Both give offspring identical to the parent, which is true of asexual reproduction generally.

Q75. Which statement explains why a potato can be grown from a piece of tuber but not from a piece of its leaf?

Advanced
A the tuber stores the food that a new plant needs and the leaf does not B the leaf dies as soon as it is cut from the plant C the tuber is underground and only underground parts can sprout D the eyes on the tuber are buds — groups of cells that have kept the ability to grow into a whole plant
Show answer & explanation

the eyes on the tuber are buds — groups of cells that have kept the ability to grow into a whole plant

Not every part of a plant can start a new one. It takes tissue that has kept the power to divide and form all the organs, which is what a bud is.

Q76. Which statement best explains why a farmer would choose vegetative propagation over growing a crop from seed?

Advanced
A plants grown vegetatively are always larger than plants grown from seed B vegetative propagation needs no water or soil preparation C every plant will be genetically identical to the chosen parent, so the desirable qualities are preserved exactly and the crop fruits sooner D plants grown vegetatively are immune to disease
Show answer & explanation

every plant will be genetically identical to the chosen parent, so the desirable qualities are preserved exactly and the crop fruits sooner

A seed carries a new mixture and may disappoint. A cutting is the same plant continued, which is why oranges, roses, sugarcane and bananas are grown this way.

Q77. Which statement best explains why mould appears on almost any piece of bread left moist and uncovered?

Advanced
A bread contains mould in a dormant state from the time it is baked B moisture itself turns the bread's own material into mould C flies carry mould from one loaf to another D spores are present everywhere in the air, and any one landing on a suitable surface can grow
Show answer & explanation

spores are present everywhere in the air, and any one landing on a suitable surface can grow

Producing enormous numbers of light, tough-walled spores is the strategy. Almost all of them die; the few that land somewhere suitable are enough.

Q78. The thick wall of a fungal spore serves chiefly to:

Advanced
A make it heavy enough to fall on the food below B supply food to the growing fungus once it germinates C protect it from drying out and from unfavourable conditions until it reaches a suitable place D stop other spores from settling in the same place
Show answer & explanation

protect it from drying out and from unfavourable conditions until it reaches a suitable place

A spore may drift for a long time before it lands anywhere useful. Survival in transit is exactly what the wall buys.

Q79. Which comparison of asexual and sexual reproduction is correct?

Advanced
A asexual reproduction is slower and produces varied offspring, while sexual reproduction is faster and produces identical ones B asexual reproduction is faster and produces identical offspring, while sexual reproduction is slower and produces varied offspring C both produce identical offspring but sexual reproduction is faster D both produce varied offspring but asexual reproduction needs two parents
Show answer & explanation

asexual reproduction is faster and produces identical offspring, while sexual reproduction is slower and produces varied offspring

Speed against variety is the whole trade. In a stable pond, speed wins; when the surroundings change, the varied population is the one that has an answer.

Q80. A gardener wants a mango tree with tasty fruit on drought-hardy roots. The best method is:

Advanced
A sowing seeds from the tasty variety in dry soil B cutting a stem of the hardy variety and planting it C crossing the two varieties and sowing the resulting seed D grafting — joining a shoot of the tasty variety onto the root stock of the hardy one
Show answer & explanation

grafting — joining a shoot of the tasty variety onto the root stock of the hardy one

Grafting keeps two chosen sets of qualities and joins them in one plant. A seed would mix everything and the result could not be predicted.

Q81. Consider these statements about variation. I. Variation arises from small inaccuracies in DNA copying. II. Asexual reproduction produces very little of it. III. It is most valuable to a species when the environment changes. IV. A population with no variation is the safest kind of population. Which statements are correct?

Advanced
A I, II and III only B I and IV only C II and IV only D All four
Show answer & explanation

I, II and III only

Uniformity is safe only while nothing changes. A new disease that can kill one member of an identical population can kill all of them, which is the standing risk in a plantation of cloned bananas.

Q82. Assertion: Asexual reproduction is faster for colonising a stable pond. Reason: It needs no partner and multiplies clones rapidly.

Advanced
A Both true, reason explains assertion B Both true, reason irrelevant C Assertion false D Both false
Show answer & explanation

Both true, reason explains assertion

Speed and simplicity win in stable niches.

Q83. Assertion: A disease could wipe out an entire banana plantation. Reason: Vegetatively propagated crops are genetically identical.

Advanced
A Both true, reason explains assertion B Both true, reason irrelevant C Assertion false D Both false
Show answer & explanation

Both true, reason explains assertion

Uniform strengths mean uniform weaknesses.

Q84. A scientist finds an organism dividing into two along a fixed axis, bearing a flagellum. It is most like:

Advanced
A Amoeba B Plasmodium C Leishmania D Spirogyra
Show answer & explanation

Leishmania

Definite-plane binary fission's signature.

Q85. Which sequence correctly orders regeneration's events?

Advanced
A differentiate→cut→divide B cut→cells proliferate→cells re-differentiate→body restored C spore→bud→cut D graft→root→shoot
Show answer & explanation

cut→cells proliferate→cells re-differentiate→body restored

Mass before order.

Q86. Seedless oranges across an orchard were produced by:

Advanced
A improved seeds B spores C fission D vegetative propagation from a parent stock
Show answer & explanation

vegetative propagation from a parent stock

No seeds — cloning is the only route.

Q87. The DEEP reason evolution requires imperfect DNA copying is that perfect copying would:

Advanced
A be too slow B use more energy C freeze species unchanged, unable to adapt D make bigger cells
Show answer & explanation

freeze species unchanged, unable to adapt

No errors, no variants, no adaptation.

Q88. Seedless oranges of exactly the same variety are found across an entire orchard. They must have been produced by:

Advanced
A sowing seed collected from a particularly good tree B cross-pollination between two chosen parent trees C vegetative propagation, since a seedless plant has no seed to grow from and every tree is a copy of one original D allowing the trees to self-pollinate for several generations
Show answer & explanation

vegetative propagation, since a seedless plant has no seed to grow from and every tree is a copy of one original

A seedless variety is a dead end sexually and can only be continued by cuttings or grafts. Every seedless orange tree in the world is, in a sense, one tree.

Q89. Why is a pond colonised faster by an organism reproducing asexually than by one reproducing sexually?

Advanced
A asexual offspring grow to full size more quickly B a single individual can begin a population at once, without needing to find a partner or produce gametes C asexual offspring are larger and so survive better D sexual reproduction can only take place on land
Show answer & explanation

a single individual can begin a population at once, without needing to find a partner or produce gametes

Speed and independence are what asexual reproduction buys. What it cannot buy is the variety that would help if the pond were to change.

Q90. Explain the importance of DNA copying in reproduction, why its built-in inaccuracy is essential rather than a defect, and how variation connects reproduction to evolution and species survival — with a concrete scenario.

Advanced
Show answer & explanation

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DNA's informational role + copying mechanics (1.5), inaccuracy as feature with fatal-vs-survivable distinction (1.5), bacteria scenario (1.5), evolution linkage (0.5).

Q91. Describe all the modes of asexual reproduction with one organism each, and arrange them to show how the method used relates to the complexity of the organism's body plan.

Advanced
Show answer & explanation

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All six modes with organisms (3), complexity-gradient argument woven through (1.5), shared asexual signature (0.5).

Q92. Write a detailed note on vegetative propagation: natural methods with examples, artificial methods used by farmers, its three advantages, and its one great risk — illustrated with the banana story.

Advanced
Show answer & explanation

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Natural methods with examples (1.5), three artificial methods (1.5), three advantages (1), uniformity risk + banana illustration (1).

Q93. A student examines three samples: pond water with a shapeless cell splitting in two, a damp bread slice growing grey fuzz with black dots, and a garden Bryophyllum leaf edged with tiny plantlets. For each: identify the organism and reproductive mode, describe the mechanism, and state what all three share at the molecular level.

Advanced
Show answer & explanation

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Each sample: organism + mode + mechanism (1.3 × 3 ≈ 4), shared DNA-copying core with variation note (1).

Q94. If two parents simply fused whole cells to make an offspring, the amount of DNA would double in every generation. Living things avoid this by:

Advanced
A discarding half the DNA of the offspring after it is formed B producing special cells, the gametes, that carry only half the usual amount of DNA C having only one parent contribute DNA to the offspring D making the offspring's cells half the size of the parents' cells
Show answer & explanation

producing special cells, the gametes, that carry only half the usual amount of DNA

Halving before fusing is the elegant answer. Two halves make one whole, and the amount stays constant generation after generation.

Q95. Consider these statements about the four whorls of a flower. I. Sepals are green and protect the bud. II. Petals are brightly coloured and attract pollinators. III. Stamens are the male parts and carpels the female parts. IV. All four whorls are present in every flower. Which statements are correct?

Advanced
A I, II and III only B I and IV only C II and IV only D All four
Show answer & explanation

I, II and III only

Unisexual flowers such as papaya carry only stamens or only carpels. Wind-pollinated flowers often have no showy petals at all, since there is nobody to attract.

Q96. Which statement best explains why wind-pollinated flowers are usually small, dull and without scent, while insect-pollinated ones are showy and often fragrant?

Advanced
A wind-pollinated plants grow in poorer soil and cannot afford large flowers B bright petals would be torn off by the wind C scent is destroyed by moving air and so would be wasted D colour and scent are advertisements for insects, and a plant relying on the wind gains nothing by paying for them
Show answer & explanation

colour and scent are advertisements for insects, and a plant relying on the wind gains nothing by paying for them

Each flower is built for its carrier. Wind-pollinated flowers instead invest in enormous quantities of light pollen and large feathery stigmas to catch it.

Q97. Which sequence correctly orders the events from pollination to seed?

Advanced
A pollen lands on the stigma, the ovule becomes a seed, a pollen tube grows, and the zygote forms B pollen lands on the stigma, a pollen tube grows down the style, the male gamete fuses with the egg, the zygote forms an embryo, and the ovule becomes a seed C the ovary becomes a fruit, a pollen tube grows down the style, and the zygote forms an embryo D a pollen tube grows from the ovule up to the stigma and collects the pollen
Show answer & explanation

pollen lands on the stigma, a pollen tube grows down the style, the male gamete fuses with the egg, the zygote forms an embryo, and the ovule becomes a seed

The tube always grows downward from the stigma, carrying the male gamete to the pauseing egg. Everything else follows the fusion.

Q98. Assertion (A): The pollen tube grows towards the ovule rather than in a random direction. Reason (R): Chemicals released near the ovule guide its growth, which makes this an example of chemotropism.

Advanced
A Both A and R are true, and R is the correct explanation of A B Both A and R are true, but R is not the correct explanation of A C A is true but R is false D A is false but R is true
Show answer & explanation

Both A and R are true, and R is the correct explanation of A

The tube is growing, not swimming, so the direction has to be built into where it adds new cells. A chemical gradient is what tells it which way that is.

Q99. A flower has its stigma cut off before any pollen can reach it. The flower will:

Advanced
A set seed normally, since pollen can reach the ovary directly B set seed but produce fruit without any seeds inside C produce more pollen to compensate for the loss D fail to set seed, because pollen has nowhere to land and germinate
Show answer & explanation

fail to set seed, because pollen has nowhere to land and germinate

The stigma is the landing platform and the start of the tube's journey. Removing it breaks the chain at its first link.

Q100. Which statement correctly distinguishes POLLINATION from FERTILISATION?

Advanced
A pollination is the fusion of gametes and fertilisation is the transfer of pollen B pollination happens in insect-pollinated flowers and fertilisation in wind-pollinated ones C pollination is the transfer of pollen to the stigma, while fertilisation is the fusion of the male gamete with the egg inside the ovule D the two words describe the same event at different stages of the flower's life
Show answer & explanation

pollination is the transfer of pollen to the stigma, while fertilisation is the fusion of the male gamete with the egg inside the ovule

Pollination is delivery; fertilisation is the union itself. Pollen can be delivered and still fail to fertilise, which is why the two are counted as separate steps.

Q101. Many bisexual flowers have arrangements — such as the anthers ripening before the stigma is receptive — that make self-pollination difficult. The advantage to the plant is that:

Advanced
A pollen from another plant is larger and produces stronger seedlings B self-pollination would damage the flower's own ovules C pollen from another plant brings a different set of genes, so the offspring are more varied D cross-pollination produces seeds more quickly than self-pollination
Show answer & explanation

pollen from another plant brings a different set of genes, so the offspring are more varied

A bisexual flower could easily pollinate itself, and some do. Those that go to trouble to avoid it are paying for variation — the same thing the flower itself is for.

Q102. Which statement best explains why the ovary of a flower develops into a fleshy, often sweet fruit?

Advanced
A an animal that eats the fruit carries the seeds away and deposits them elsewhere, spreading the plant to new ground B the flesh supplies food to the seedling after it germinates C the flesh protects the seeds from drying out during germination D the flesh is what the seed grows from once it is planted
Show answer & explanation

an animal that eats the fruit carries the seeds away and deposits them elsewhere, spreading the plant to new ground

The fruit is a payment to a courier. Seeds that fall under the parent compete with it; seeds carried away have a place of their own.

Q103. Which statement explains why a seed needs a tough coat as well as an embryo and a food store?

Advanced
A the coat supplies the embryo with minerals B a seed may have to survive drying, cold and rough handling for a long time before conditions allow it to germinate C the coat keeps the food store from being digested too early D the coat helps the seed photosynthesise before it germinates
Show answer & explanation

a seed may have to survive drying, cold and rough handling for a long time before conditions allow it to germinate

The seed is a plant packed for a journey of unknown length. Embryo, packed lunch and suitcase is a fair description of what is inside.

Q104. Which statement explains where a germinating seedling gets its food before its first leaves open?

Advanced
A from the soil, through the root that emerges first B from sunlight, which the seed coat absorbs C from the water it takes in as it swells D from the food stored in the cotyledons of the seed itself
Show answer & explanation

from the food stored in the cotyledons of the seed itself

Until a green leaf is out in the light the seedling cannot feed itself. The cotyledons carry it through exactly that gap.

Q105. In a germinating bean, the first structure to emerge from the seed is the:

Advanced
A plumule, the baby shoot B cotyledon, the food store C radicle, the baby root D first green leaf
Show answer & explanation

radicle, the baby root

The root goes down first and anchors the seedling and finds water. Only then is it worth sending a shoot upward.

Q106. Germination of a seed requires:

Advanced
A water, light and a suitable temperature B air, light and soil C soil, light and warmth only D water, air and a suitable temperature
Show answer & explanation

water, air and a suitable temperature

Light is not on the list — many seeds germinate perfectly well buried in the dark. Air is, because the germinating seed is respiring hard on its stored food.

Q107. What is the deepest reason a flowering plant invests so much in a structure as elaborate as a flower?

Advanced
A a flower makes the plant more attractive to human beings, who then cultivate it B a flower is where most of the plant's photosynthesis takes place C a flower is the plant's means of combining DNA with another individual, which produces the variation the species depends on D a flower stores the food the plant will need through the winter
Show answer & explanation

a flower is the plant's means of combining DNA with another individual, which produces the variation the species depends on

Petals, nectar and scent are all expenditure on getting pollen from one plant to another. The plant is paying for variation, and it is worth the price.

Q108. Which statement best explains why a germinating seed needs AIR as well as water?

Advanced
A the air carries the pollen that the seed still needs B the air dries the seed coat so that it can split open C the seed is respiring hard on its stored food to power its growth, and that respiration needs oxygen D the air supplies the carbon dioxide the seed uses to photosynthesise
Show answer & explanation

the seed is respiring hard on its stored food to power its growth, and that respiration needs oxygen

Nothing green has appeared yet, so nothing is being made — only spent. That is also why seeds sown in waterlogged soil rot instead of sprouting.

Q109. A pea pod is found to contain four peas, although its ovary held six ovules. The best explanation is that:

Advanced
A two of the seeds were absorbed by the pod as it grew B the pod can only hold four seeds however many ovules were fertilised C two ovules fused together to make a single larger pea D two of the ovules were never fertilised, and only a fertilised ovule becomes a seed
Show answer & explanation

two of the ovules were never fertilised, and only a fertilised ovule becomes a seed

One pollen tube, one ovule, one seed. An ovule that no tube reached simply shrivels, which is why pods are often not quite full.

Q110. Which statement best explains why a seed can lie in dry storage for months and still germinate when it is sown?

Advanced
A the seed is not alive at all until it is planted in soil B the seed coat slowly grows a new embryo while in storage C the embryo inside is alive but dormant, its activity almost stopped until water and warmth reach it D the stored food keeps the embryo growing steadily throughout
Show answer & explanation

the embryo inside is alive but dormant, its activity almost stopped until water and warmth reach it

Dormancy is suspended life, not death. Taking in water is the signal that starts everything again, which is why soaking seeds speeds germination.

Q111. The number of pollen grains far exceeds ovules because:

Advanced
A pollen is decorative B ovules are large C anthers overwork D transport is chancy — most grains never reach a stigma
Show answer & explanation

transport is chancy — most grains never reach a stigma

Lottery economics of pollination.

Q112. Assertion: A lone papaya tree may never bear fruit. Reason: Papaya's unisexual flowers may require pollen from a male tree elsewhere.

Advanced
A Both true, reason explains assertion B Both true, reason irrelevant C Assertion false D Both false
Show answer & explanation

Both true, reason explains assertion

Separate sexes need cross-transfer.

Q113. Assertion: Every fruit contains at least the memory of a flower. Reason: Fruits develop from the flower's ovary after fertilisation.

Advanced
A Both true, reason explains assertion B Both true, reason irrelevant C Assertion false D Both false
Show answer & explanation

Both true, reason explains assertion

Fruit = ovary, matured.

Q114. Assertion (A): Every fruit was once a flower. Reason (R): A fruit is the ripened ovary of a flower, and an ovary exists only within a flower.

Advanced
A Both A and R are true, and R is the correct explanation of A B Both A and R are true, but R is not the correct explanation of A C A is true but R is false D A is false but R is true
Show answer & explanation

Both A and R are true, and R is the correct explanation of A

Wheat grains, peas in a pod, a coconut and a tomato are all fruits by this definition. Following the ovary forward is what makes the claim testable rather than poetic.

Q115. A seed's tough coat primarily provides:

Advanced
A food B colour C protection for the dormant embryo D photosynthesis
Show answer & explanation

protection for the dormant embryo

Armour for the pause and the journey.

Q116. Which sequence is correct?

Advanced
A fertilisation→pollination→germination B pollination→fertilisation→seed formation→germination C germination→pollination→zygote D seed→zygote→pollen
Show answer & explanation

pollination→fertilisation→seed formation→germination

Transport, fusion, packaging, awakening.

Q117. Seeds inside a tomato are many because the ovary contained:

Advanced
A one ovule B no ovules C many stigmas D many ovules, each becoming a seed
Show answer & explanation

many ovules, each becoming a seed

Each fertilised ovule ripens into one seed.

Q118. The deepest reason flowering plants invest in flowers at all is:

Advanced
A decoration B shade C storing water D achieving two-parent DNA mixing while rooted in place
Show answer & explanation

achieving two-parent DNA mixing while rooted in place

The flower solves sex-without-motion.

Q119. Explain the significance of sexual reproduction: the variation argument, the DNA-halving necessity, gamete specialisation, and why cross-pollination extends the advantage — closing with the contrast against asexual reproduction's trade-offs.

Advanced
Show answer & explanation

—

Variation argument (1.25), DNA-halving logic (1.25), gamete specialisation (0.75), cross-pollination extension (0.75), trade-off contrast (1).

Q120. Describe the complete structure of a flower and classify flowers by sex, then follow pollen from its formation to fertilisation — naming every structure it touches and every process involved.

Advanced
Show answer & explanation

—

Four whorls with sub-parts (1.5), bisexual/unisexual with examples (1), seven-step pollen journey with structures + chemotropism (2.5).

Q121. Narrate the events from fertilisation to a growing seedling: the fates of zygote, ovule and ovary; the fate of the other floral parts; the anatomy of the finished seed; the conditions and sequence of germination; and how the young plant finances its growth before photosynthesis.

Advanced
Show answer & explanation

—

Three fates (1.5), other parts' fall (0.5), seed anatomy (1), germination conditions + sequence (1.5), cotyledon financing (0.5).

Q122. Design a comparative account: wind-pollinated versus insect-pollinated flowers (features and reasons), self- versus cross-pollination (genetic consequences), and unisexual versus bisexual arrangements (with the papaya farmer's problem) — ending with what all these variations are 'for' in evolutionary terms.

Advanced
Show answer & explanation

—

Wind/insect features + reasons (1.5), self/cross genetic consequences (1.25), unisexual/bisexual + papaya problem (1.25), evolutionary synthesis (1).

Q123. Consider these statements about puberty. I. It is the age at which the reproductive tissues begin to mature. II. It usually begins earlier in girls than in boys. III. It comes only after most of the body's basic growth is done. IV. It begins at exactly the same age in everyone. Which statements are correct?

Advanced
A I, II and III only B I and IV only C II and IV only D All four
Show answer & explanation

I, II and III only

The age varies from person to person and with nutrition and health. What is consistent is the order — the body finishes most of its building before it invests in reproduction.

Q124. Which statement best explains why the deepening of a boy's voice, the growth of body hair and the widening of the shoulders all happen at about the same time?

Advanced
A all are caused by the body growing rapidly taller at that age B all are responses of different tissues to the same hormone, testosterone, released from puberty onwards C all are controlled by separate nerves that mature together D all are caused by the change of diet that usually happens in the teens
Show answer & explanation

all are responses of different tissues to the same hormone, testosterone, released from puberty onwards

One chemical message, many tissues answering it in their own way. This is what sustained hormonal control looks like, in contrast with the brief precision of a nerve.

Q125. Which statement best explains why the testes lie in the scrotum, outside the main body cavity?

Advanced
A sperm formation needs a temperature one to three degrees below the body's own, which the scrotum provides B the scrotum protects the testes from injury better than the abdomen would C the scrotum allows the sperm to be released more quickly D the abdomen has no room for the testes alongside the other organs
Show answer & explanation

sperm formation needs a temperature one to three degrees below the body's own, which the scrotum provides

It is a temperature requirement and nothing else. An organ placed outside the body for the sake of a couple of degrees is a striking piece of evidence for how particular the process is.

Q126. A human sperm is little more than a nucleus with a long tail, while an egg is a large cell well stocked with food. The reason for the difference is that:

Advanced
A the egg is older than the sperm and has had time to grow B the sperm's only task is to travel and deliver its DNA, while the egg must supply the food the early embryo will live on C the sperm loses its food store while swimming D the egg must be large enough to be seen without a microscope
Show answer & explanation

the sperm's only task is to travel and deliver its DNA, while the egg must supply the food the early embryo will live on

Each gamete is built for its job. The same division — small and mobile against large and provisioned — appears throughout the living world, plants included.

Q127. Semen is more than sperm alone. The additional secretions serve to:

Advanced
A dissolve the wall of the egg when the sperm arrives B carry the sperm's own food store into the egg C protect the sperm from the male body's own immune system only D nourish the sperm and provide a fluid in which they can move
Show answer & explanation

nourish the sperm and provide a fluid in which they can move

Sperm cannot swim in nothing and carry almost no supplies of their own. The glands along the tract supply both the medium and the fuel.

Q128. A girl is born with all the immature eggs she will ever have, while sperm are produced continuously from puberty onwards. This difference means that:

Advanced
A eggs are produced monthly in the ovary from birth onwards B the number of eggs increases each year until puberty C eggs and sperm are both replaced every month D the egg store is fixed from birth and is drawn on one at a time from puberty until it is exhausted
Show answer & explanation

the egg store is fixed from birth and is drawn on one at a time from puberty until it is exhausted

Thousands are present at birth and roughly one ripens each month thereafter. The store is finite, which is why the reproductive years come to an end.

Q129. Which statement best explains why fertilisation normally takes place in the oviduct rather than in the uterus?

Advanced
A the uterus is too large for a sperm to find the egg in it B the egg is released into the oviduct and survives only about a day, so it must meet a sperm there if it is to be fertilised at all C the egg cannot travel as far as the uterus without being fertilised first D the uterus is occupied by its thickened lining and has no room
Show answer & explanation

the egg is released into the oviduct and survives only about a day, so it must meet a sperm there if it is to be fertilised at all

The sperm swim up and the egg comes down, and they meet in the tube. The fertilised egg then continues to the uterus to implant, which takes several days.

Q130. Consider these roles of the oviduct. I. It receives the egg released from the ovary. II. It is where fertilisation normally occurs. III. It carries the developing embryo to the uterus. IV. It is where the embryo grows for nine months. Which statements are correct?

Advanced
A I, II and III only B I and IV only C II and IV only D All four
Show answer & explanation

I, II and III only

The oviduct is a meeting place and a corridor, not a home. Development happens in the uterus, which is the organ built for it.

Q131. Which statement best explains why the lining of the uterus thickens every month whether or not an egg is fertilised?

Advanced
A the lining must be ready in advance, since an embryo arriving several days after fertilisation cannot pause for it to be built B the thickening is what causes the egg to be released C the lining supplies the egg with food while it is still in the ovary D the thickening protects the ovary from infection
Show answer & explanation

the lining must be ready in advance, since an embryo arriving several days after fertilisation cannot pause for it to be built

Preparation must come before the event, so it happens on a schedule rather than on demand. When no embryo arrives, the preparation is dismantled — which is menstruation.

Q132. Which statement best explains how the placenta allows an embryo to be fed and its wastes removed, when its blood and the mother's never actually mix?

Advanced
A the mother's blood enters the embryo through the umbilical cord and returns B villi on the embryo's side project into blood spaces on the mother's side, giving a large surface across which substances diffuse C the embryo swallows the mother's blood and digests it D the placenta manufactures the food the embryo needs from the mother's tissue
Show answer & explanation

villi on the embryo's side project into blood spaces on the mother's side, giving a large surface across which substances diffuse

Diffusion across a large thin surface is the same design as the villi of the intestine and the alveoli of the lung. Keeping the two blood supplies separate is essential, since they may differ in group.

Q133. Glucose and oxygen pass from mother to embryo while carbon dioxide and nitrogenous wastes pass the other way. The wastes are ultimately removed from the mother's body by:

Advanced
A the embryo's own lungs and kidneys B the placenta, which stores them until birth C the amniotic fluid, which is replaced regularly D her own lungs and kidneys
Show answer & explanation

her own lungs and kidneys

The embryo's kidneys and lungs are not yet working in any useful way. Its mother's organs are doing the work for two, which is part of why pregnancy is demanding.

Q134. Which statement correctly describes menstruation?

Advanced
A the unfertilised egg is shed from the ovary along with blood B the uterus sheds its muscular wall each month and grows a new one C the thickened uterine lining, no longer needed because no embryo implanted, is shed along with blood over a few days D the body removes surplus blood that has accumulated during the month
Show answer & explanation

the thickened uterine lining, no longer needed because no embryo implanted, is shed along with blood over a few days

What is shed is the preparation, not the organ and not the egg. The cycle then begins again, building a fresh lining for the following month.

Q135. An unfertilised egg survives about a day after release, while the uterine lining takes about two weeks to build. This tells us that:

Advanced
A the egg is released before the lining begins to form B the lining is built only after fertilisation has occurred C the egg can pause in the uterus until the lining is ready D the body prepares well in advance for an event that may or may not happen, and dismantles the preparation quickly when it does not
Show answer & explanation

the body prepares well in advance for an event that may or may not happen, and dismantles the preparation quickly when it does not

Reading the two timescales against each other is what makes sense of the whole cycle. Preparation is slow and speculative; the window of opportunity is brief.

Q136. Contraceptive methods fall into families. A condom, an oral pill, a copper-T and a vasectomy work respectively by:

Advanced
A changing hormone levels, creating a barrier, blocking a tube, and preventing implantation B blocking a tube, preventing implantation, creating a barrier, and changing hormone levels C creating a barrier, blocking a tube, changing hormone levels, and preventing implantation D creating a barrier, changing hormone levels, preventing implantation in the uterus, and blocking the tube that carries sperm
Show answer & explanation

creating a barrier, changing hormone levels, preventing implantation in the uterus, and blocking the tube that carries sperm

Four families, four points of interruption along the same chain of events. Knowing which point each acts at is what explains their different side effects and reliability.

Q137. Which statement best explains why oral contraceptive pills can have side effects while a condom does not?

Advanced
A the pill is swallowed and so irritates the stomach B the pill is taken daily and a condom only occasionally C the pill is made of chemicals and a condom is not D the pill works by changing the body's hormone balance, which affects the whole body, while a condom acts only as a physical barrier
Show answer & explanation

the pill works by changing the body's hormone balance, which affects the whole body, while a condom acts only as a physical barrier

Anything that alters a hormone alters everything that hormone touches. A barrier changes nothing in the body's chemistry, which is why it has no such effects.

Q138. Assertion (A): A copper-T is fitted by a doctor and then needs no further action for years. Reason (R): Condoms also lower the risk of passing on a sexually transmitted infection.

Advanced
A Both A and R are true, and R is the correct explanation of A B Both A and R are true, but R is not the correct explanation of A C A is true but R is false D A is false but R is true
Show answer & explanation

Both A and R are true, but R is not the correct explanation of A

Both are true, but what condoms additionally do is not why a copper-T needs no daily attention.

Q139. Which statement about the surgical methods of contraception is correct?

Advanced
A in a vasectomy the testes are removed and in a tubectomy the ovaries are removed B both methods stop the production of sex hormones C in a vasectomy the vas deferens is cut so that sperm cannot leave, and in a tubectomy the oviducts are blocked so that the egg cannot meet a sperm D both methods can be reversed easily at any time
Show answer & explanation

in a vasectomy the vas deferens is cut so that sperm cannot leave, and in a tubectomy the oviducts are blocked so that the egg cannot meet a sperm

Both block a tube and neither removes a gland, so hormone production and the changes it drives continue unaffected. That is the point most often misunderstood about them.

Q140. Consider these statements about sexually transmitted infections. I. Gonorrhoea and syphilis are caused by bacteria. II. HIV-AIDS and warts are caused by viruses. III. A condom reduces the risk of transmission. IV. A copper-T and an oral pill also protect against them. Which statements are correct?

Advanced
A I, II and III only B I and IV only C II and IV only D All four
Show answer & explanation

I, II and III only

Only the barrier method does both jobs. A device or a hormone that prevents pregnancy does nothing at all about an infection, which is why the two needs are considered separately.

Q141. Which statement best explains why reproductive health is described as covering more than the prevention of pregnancy?

Advanced
A it covers only the treatment of infections and nothing else B it also covers protection from sexually transmitted infections, and the physical and social well-being of the people concerned C it refers only to the health of the reproductive organs themselves D it is another name for the study of contraception
Show answer & explanation

it also covers protection from sexually transmitted infections, and the physical and social well-being of the people concerned

Health here is the broader word. Infection, informed choice and well-being all sit inside it, which is why the chapter treats contraception and infection together.

Q142. Which statement best explains why prenatal sex determination is prohibited by law in India?

Advanced
A the test is unreliable and often gives the wrong result B it was being used to abort female foetuses, which distorted the child sex ratio in several regions C the test is dangerous to the mother's health D knowing the sex in advance has no medical value of any kind
Show answer & explanation

it was being used to abort female foetuses, which distorted the child sex ratio in several regions

The biology is settled — the father's sperm decides the sex, and nobody chooses it. The law exists because a technology with legitimate medical uses was being turned to a harmful one.

Q143. Which statement best explains why a developing baby is surrounded by a fluid inside the uterus?

Advanced
A the fluid supplies it with the oxygen it needs B the fluid cushions it against knocks and jolts and lets it move and grow freely C the fluid keeps the uterus from contracting too early D the fluid carries away its waste products directly
Show answer & explanation

the fluid cushions it against knocks and jolts and lets it move and grow freely

It is the same protective trick as the fluid around the brain. Oxygen and waste removal are the placenta's work, not the fluid's.

Q144. Millions of sperm are released although only one can fertilise the egg. The best reason is that:

Advanced
A several sperm are needed to carry one another along B the journey to the oviduct is long and hazardous and the vast majority never complete it C the extra sperm supply food to the one that succeeds D the egg selects the best sperm from among the millions
Show answer & explanation

the journey to the oviduct is long and hazardous and the vast majority never complete it

The same logic as a plant producing far more pollen than ovules. Where delivery is chancy, overproduction is how living things make success likely.

Q145. Which statement best explains why a pregnant woman is advised to avoid tobacco, alcohol and unprescribed medicines?

Advanced
A substances in her blood can cross the placenta into the embryo's blood and affect its development B these substances make the placenta detach from the uterine wall C the embryo cannot excrete anything at all and so stores everything it receives D these substances stop the uterine lining from thickening
Show answer & explanation

substances in her blood can cross the placenta into the embryo's blood and affect its development

The placenta is a surface for exchange, not a filter that recognises what is good for the embryo. Whatever is small enough to diffuse across, crosses.

Q146. Consider these statements about birth. I. The developing baby spends about nine months in the uterus. II. Birth is brought about by rhythmic contractions of the muscular wall of the uterus. III. The umbilical cord connects the baby to the placenta. IV. The baby breathes through the placenta for several days after birth. Which statements are correct?

Advanced
A I, II and III only B I and IV only C II and IV only D All four
Show answer & explanation

I, II and III only

The placenta is delivered shortly after the baby and the cord is cut. From the first breath the newborn's own lungs take over entirely.

Q147. Which statement best explains why early marriage and early motherhood are discouraged on health grounds?

Advanced
A the reproductive organs are not yet formed at that age B the sex hormones have not yet begun to be produced C a girl's body is still completing its own growth in the early teens, and pregnancy at that stage carries greater risk to both mother and child D early pregnancies always result in twins
Show answer & explanation

a girl's body is still completing its own growth in the early teens, and pregnancy at that stage carries greater risk to both mother and child

Puberty makes reproduction possible some years before the body has finished growing. That gap is exactly why the legal ages for marriage were set where they are.

Q148. Which statement best explains why the decision to use contraception is described as one for both partners rather than one?

Advanced
A only one partner is able to use any method at a given time B the methods available to women are all unreliable C the consequences — a pregnancy, an infection, or the side effects of a method — fall on both, and methods exist that either partner can use D the law requires both partners to agree before any method is used
Show answer & explanation

the consequences — a pregnancy, an infection, or the side effects of a method — fall on both, and methods exist that either partner can use

Barrier, hormonal, device and surgical methods between them give both partners options. Treating it as one person's responsibility is how the choice tends to go wrong.

Q149. Which statement best explains why a sexually transmitted infection should be treated early rather than pauseed out?

Advanced
A these infections always clear up by themselves if left alone B treatment is only effective in the first day after infection C an untreated infection becomes a different disease altogether D untreated infections can cause lasting damage, including infertility, and can be passed on to others in the meantime
Show answer & explanation

untreated infections can cause lasting damage, including infertility, and can be passed on to others in the meantime

Bacterial infections such as gonorrhoea and syphilis respond well to treatment and do real harm if ignored. Delay is what turns a curable infection into a permanent consequence.

Q150. Assertion (A): A person who has contracted HIV falls ill within days and can be identified at once. Reason (R): The virus weakens the immune system slowly, so symptoms appear long after the infection itself.

Advanced
A Both A and R are true, and R is the correct explanation of A B Both A and R are true, but R is not the correct explanation of A C A is true but R is false D A is false but R is true
Show answer & explanation

A is false but R is true

Years may pass without symptoms, so the assertion is false. The reason explains why.

Q151. Why is only ONE sperm's fusion with the egg normal?

Advanced
A others get lost B sperm dislike company C the egg blocks further entries after the first fusion D the uterus forbids it
Show answer & explanation

the egg blocks further entries after the first fusion

Multiple fusion would wreck the DNA arithmetic.

Q152. Assertion: The scrotum holds testes outside the abdomen. Reason: Sperm formation needs a temperature slightly below body temperature.

Advanced
A Both true, reason explains assertion B Both true, reason irrelevant C Assertion false D Both false
Show answer & explanation

Both true, reason explains assertion

Anatomy serving thermodynamics.

Q153. Assertion: Menstruation indicates the egg was not fertilised that cycle. Reason: The thickened uterine lining is shed when no embryo implants.

Advanced
A Both true, reason explains assertion B Both true, reason irrelevant C Assertion false D Both false
Show answer & explanation

Both true, reason explains assertion

The reset follows the non-event.

Q154. A couple wants effective contraception PLUS STI protection. The advice is:

Advanced
A pills alone B copper-T alone C condoms (possibly combined with another method) D tubectomy alone
Show answer & explanation

condoms (possibly combined with another method)

Only the barrier covers both goals.

Q155. The placenta and the intestine's villi share which design idea?

Advanced
A muscle layers B bone support C large thin-walled surface for efficient exchange D acid secretion
Show answer & explanation

large thin-walled surface for efficient exchange

Nature's recurring exchange architecture.

Q156. If both oviducts are blocked (tubectomy), eggs:

Advanced
A exit the body monthly B stop forming C become sperm D cannot meet sperm — no fertilisation; menstrual physiology continues
Show answer & explanation

cannot meet sperm — no fertilisation; menstrual physiology continues

The transport is cut; hormones and cycles continue.

Q157. Identical twins result from:

Advanced
A two eggs, two sperm B two months' eggs C one zygote splitting early into two embryos D the placenta dividing
Show answer & explanation

one zygote splitting early into two embryos

One fertilisation, two identical individuals.

Q158. Which statement best explains why the size of a country's population continues to rise for some years even after families begin having fewer children?

Advanced
A a large number of people are already young and have yet to reach the age of having children themselves B people begin living to a greater age as soon as birth rates fall C the number of children per family rises again after a few years D fewer children means each child survives longer and so the total grows
Show answer & explanation

a large number of people are already young and have yet to reach the age of having children themselves

A young age structure carries its own momentum. This is why population policy is discussed in terms of decades rather than years.

Q159. Describe the human male reproductive system in full: each organ with its function, the temperature logic of the scrotum, the composition and purpose of semen, and the sperm cell's design — closing with what happens at and after puberty.

Advanced
Show answer & explanation

—

Five organs with functions (2), scrotum temperature logic (1), semen composition + dual purpose (1), sperm design (0.5), puberty onset + continuous production (0.5).

Q160. Describe the female reproductive system and the two alternative monthly outcomes: the organs with functions; the egg's journey; fertilisation, implantation, placenta and birth on one path; menstruation on the other — and why both outcomes begin with the same uterine preparation.

Advanced
Show answer & explanation

—

Organs with functions (1.5), shared monthly preparation (0.5), fertilisation→implantation→placenta→birth path (2), menstruation path (0.5), one-preparation-two-outcomes synthesis (0.5).

Q161. Write a complete note on contraception: why family planning matters, all four method families with mechanisms, effectiveness and limitations, the unique dual role of barriers, surgical methods' misconceptions, and the ethical-legal boundary regarding sex selection.

Advanced
Show answer & explanation

—

Family-planning rationale (0.5), four families with mechanism+limitation (2), barrier's dual role + STI list (1), surgical misconception corrected (0.75), sex-selection law + ethics (0.75).

Q162. Compare reproduction in flowering plants and human beings across: gamete production, gamete transfer, fertilisation site, embryo nourishment, and development environment — then state the design principle every difference serves.

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Five comparison axes (0.9 × 5 = 4.5), unifying lifestyle-strategy principle (0.5).

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