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Q1. Hibiscus and mustard flowers are:
BisexualHibiscus (China rose) and mustard flowers are bisexual (also called hermaphroditic or perfect flowers) because they contain both male reproductive parts (stamens) and female reproductive parts (carpel/pistil) in the same flower. Unisexual flowers have only one sex; sterile flowers produce no gametes; incomplete flowers lack one or more whorls.
Q2. Pollen grains carry:
Male germ-cellsPollen grains are microscopic structures produced in the anthers of stamens. Each pollen grain contains the male germ-cell (male gamete) that is released during pollination and travels through the pollen tube to fuse with the female gamete. Female gametes are in the ovule; seeds and embryos develop after fertilisation.
Q3. Rapid creation of variation can be achieved by:
Combining DNA from two individualsSexual reproduction combines DNA from two different parents, leading to new combinations of genes in the offspring. This reshuffling (recombination) and mixing of genetic material produces far more variation than asexual reproduction (which produces clones) or exact DNA copying. Variation is the raw material for evolution.
Q4. Fusion of two germ-cells restores:
Original chromosome numberGerm-cells (sperm and egg) are haploid (n), meaning they contain half the normal chromosome number. When they fuse during fertilisation, the resulting zygote becomes diploid (2n), restoring the original chromosome number characteristic of the species. This maintains genetic stability across generations while allowing variation from parental combinations.
Q5. The sticky part of the carpel is the:
StigmaThe stigma is the uppermost part of the carpel (female reproductive organ). It is sticky or feathery to trap and hold pollen grains that land on it. The sticky surface secretes a sugary fluid that provides moisture and nutrients for pollen germination. The style is the tube; ovary contains ovules; ovules contain the female gamete.
Q6. Sexual reproduction requires:
Two individualsSexual reproduction typically involves two parents—one male and one female (except in hermaphroditic organisms that can self-fertilise, but even then, two different gametes are involved). The fusion of male and female gametes from two different individuals (or at least two different gamete sources) produces genetically diverse offspring. Asexual reproduction requires only one individual.
Q7. Agents of pollination include:
Wind, water and animalsPollination—the transfer of pollen from anther to stigma—requires external agents. Biotic agents include insects (bees, butterflies), birds, and bats. Abiotic agents include wind (anemophily) for grasses and many trees, and water (hydrophily) for aquatic plants like Vallisneria. Seeds, fruits, soil, minerals, roots, and stems are not pollination agents.
Q8. Pollination within the same flower is:
Self-pollinationSelf-pollination (autogamy) occurs when pollen from the anther of a flower lands on the stigma of the same flower. This is common in plants like pea, wheat, and rice. Cross-pollination involves different flowers (same or different plants); artificial pollination is human-assisted; hybridisation is crossing different species or varieties.
Q9. Variations are important because they:
Ensure species survivalGenetic variation allows populations to adapt to changing environments (climate shifts, new diseases, predators). Individuals with advantageous variations survive and reproduce, ensuring the species does not go extinct. Without variation, a single environmental change could wipe out an entire uniform population. Variations may sometimes harm individuals but benefit the species long-term.
Q10. The ultimate purpose of sexual reproduction is:
Species survival with variationSexual reproduction produces offspring with new combinations of genes, generating genetic diversity. This variation allows species to adapt, evolve, and survive over long periods in changing environments. Asexual reproduction may be faster but produces clones vulnerable to extinction. Individual survival and energy saving are not the ultimate evolutionary purpose—species continuity with adaptability is.
Q11. Sexual reproduction generally results in:
More variationSexual reproduction involves the fusion of two different gametes from two parents. During gamete formation, crossing over (recombination) and independent assortment shuffle genes. The offspring inherits a unique combination of DNA from both parents, producing far more genetic variation than asexual reproduction, where offspring are clones (genetically identical).
Q12. Fertilisation is the fusion of:
Male and female gametesFertilisation is the process where the male gamete (sperm in animals, male germ-cell in plants) fuses with the female gamete (egg or ovum) to form a diploid zygote. Spores are asexual reproductive units; seeds contain embryos; embryos develop from zygotes. Fusion of two gametes defines fertilisation.
Q13. Vegetative propagation is practiced to:
Grow same types of plantsVegetative propagation produces genetically identical offspring (clones). Farmers and gardeners use it to preserve desirable traits—same fruit quality, flower colour, disease resistance, and yield—across generations. It does not increase variation (it reduces it) and is a form of reproduction, not prevention of reproduction. Growing different types requires sexual reproduction or hybridisation.
Q14. Bulls alone cannot produce calves because:
Two sexes are requiredCattle (like most mammals) reproduce sexually, requiring both a male (bull) and a female (cow) to produce offspring. The male produces sperm (male gamete), and the female produces eggs (female gametes). Fusion of both gametes is essential for fertilisation and zygote formation. A bull alone cannot produce calves because both sexes are required for sexual reproduction.
Q15. After fertilisation, the ovule becomes:
SeedIn angiosperms, after fertilisation, the ovule—which contains the female gamete (egg cell)—develops into the seed. The seed contains the embryo (developed from the zygote), stored food (endosperm), and a seed coat (from ovule integuments). The ovary develops into the fruit; the embryo sac is the female gametophyte within the ovule before fertilisation.
Q16. A flower having only stamens or carpels is:
UnisexualA unisexual flower contains either only stamens (male flower, called staminate) or only carpels (female flower, called pistillate), but not both. Examples include papaya, watermelon, and cucumber. Bisexual flowers have both; sterile flowers produce no functional gametes; complete flowers have all four whorls (sepals, petals, stamens, carpels) but may be bisexual.
Q17. DNA copying is essential in reproduction because it:
Transfers hereditary informationDNA contains the genetic blueprint that determines an organism’s traits. During reproduction, DNA is copied and passed to offspring, ensuring that hereditary information is transmitted from one generation to the next. Without DNA copying, offspring would receive no genetic instructions and could not develop. Body temperature, tissue formation, and energy production are not the primary roles of DNA copying.
Q18. Germ-cells have:
Half the chromosomesGerm-cells (sperm and egg) are produced by meiosis, a specialised cell division that reduces the chromosome number by half. They are haploid (n), containing only one set of chromosomes. When two germ-cells fuse during fertilisation, the diploid number (2n) is restored. This prevents the chromosome number from doubling every generation.
Q19. The ovary develops into a:
FruitIn flowering plants, after fertilisation, the ovary (the swollen basal part of the carpel) undergoes development to become the fruit. The fruit protects the developing seeds and aids in their dispersal. The ovules inside the ovary become seeds. Stems, roots, and leaves are vegetative parts, not derived from the ovary.
Q20. Petals and sepals usually:
Shrivel and fall offPetals and sepals are accessory floral parts that protect the reproductive organs and attract pollinators. After fertilisation, they are no longer needed and typically wither, shrivel, and fall off. In some plants, sepals may persist (e.g., in tomato, the calyx remains), but generally, they do not develop into seeds or fruits. Seeds develop from ovules; fruits from the ovary.
Q21. If DNA doubled every generation, it would:
Cause imbalanceIf the entire DNA content doubled with each generation (without reduction), chromosome numbers would increase exponentially, leading to genetic imbalance, abnormal development, and likely death. Organisms avoid this by producing haploid germ-cells through meiosis, which halves the chromosome number. Fertilisation restores the original number, maintaining genetic balance across generations.
Q22. The process by which a seed develops into a seedling is:
GerminationGermination is the process by which a seed, under suitable conditions (water, oxygen, appropriate temperature), resumes growth and develops into a seedling. The embryo inside the seed emerges, the radicle forms the root, and the plumule forms the shoot. Pollination is pollen transfer; fertilisation is gamete fusion; development is the general term for growth, but germination is the specific term for seed to seedling.
Q23. Reproductive parts of angiosperms are found in:
FlowersFlowers are the reproductive structures of angiosperms (flowering plants). They contain the male parts (stamens, which produce pollen) and female parts (carpels, which contain ovules). Roots, leaves, and fruits (which develop after fertilisation) are not reproductive parts; fruits are the result of reproduction.
Q24. To prevent doubling of DNA, organisms form:
Special germ-cellsTo prevent DNA from doubling every generation, organisms produce specialised germ-cells (gametes) through meiosis. Meiosis reduces the chromosome number by half (from diploid to haploid). When two haploid germ-cells fuse at fertilisation, the original diploid number is restored. Somatic cells (muscle, nerve, etc.) are diploid and do not prevent DNA doubling; they are the cells that would double if no reduction occurred.
Q25. The zygote develops into:
EmbryoThe zygote is the diploid cell formed by the fusion of male and female gametes. Through repeated mitotic divisions and cell differentiation, the zygote develops into the embryo (the early stage of the new organism). In plants, the embryo is inside the seed; in animals, it develops into a foetus. The fruit develops from the ovary; the seed coat from the ovule integuments.
Q26. Sexual reproduction involves:
Male and female organismsSexual reproduction requires two parents—one male (producing male gametes) and one female (producing female gametes). In some hermaphroditic organisms, a single individual produces both types of gametes, but the principle remains: fusion of male and female gametes from two different sources. A single male or female alone cannot reproduce sexually.
Q27. A major limitation of asexual reproduction is:
Limited variationAsexual reproduction produces genetically identical offspring (clones). This lack of genetic variation is a major disadvantage when environmental conditions change—if the parent is vulnerable to a disease or temperature shift, all offspring are equally vulnerable, risking population extinction. Asexual reproduction is actually fast, requires only one parent, and produces many offspring, but variation is very limited.
Q28. Sexual reproduction is important because it:
Promotes evolutionSexual reproduction generates genetic variation through recombination, independent assortment, and fusion of gametes from two parents. This variation provides the raw material for natural selection, driving evolutionary change over generations. Without sexual reproduction, populations would be genetically uniform and evolve much more slowly (or not at all) in response to environmental changes.
Q29. Pollination between different flowers is:
Cross-pollinationCross-pollination (allogamy) is the transfer of pollen from the anther of one flower to the stigma of a different flower (either on the same plant, geitonogamy, or on a different plant, xenogamy). This promotes genetic variation. Self-pollination occurs within the same flower; fertilisation happens after pollination; germination is seed sprouting.
Q30. In complex organisms, one germ-cell is:
Large and contains foodIn complex organisms (animals, plants), the female germ-cell (egg/ovum) is large, non-motile, and contains abundant food reserve (cytoplasm, yolk) to nourish the developing embryo after fertilisation. The male germ-cell (sperm) is small and motile. Both contain a nucleus with half the chromosomes. The description in the correct answer applies to the female gamete.
Q31. Germ-cells are formed in:
Reproductive organsGerm-cells (gametes) are produced in specialised reproductive organs. In animals: testes (male, produce sperm) and ovaries (female, produce eggs). In plants: anthers (male, produce pollen containing male gametes) and ovules within the ovary (female, contain female gametes). Leaves, roots, and stems are vegetative parts and do not produce germ-cells.
Q32. The pollen tube grows through the:
StyleAfter a pollen grain lands on the stigma, it germinates and produces a pollen tube. The pollen tube grows downward through the style (the elongated part of the carpel between stigma and ovary), carrying the male gametes. It then enters the ovary and reaches the ovule for fertilisation. Sepals and petals are not involved in pollen tube growth.
Q33. Papaya and watermelon flowers are:
UnisexualPapaya and watermelon plants bear unisexual flowers—male flowers (only stamens) and female flowers (only carpels) are on separate plants (dioecious in papaya) or on the same plant (monoecious in watermelon). They are not bisexual (no flower has both sexes), not sterile (they produce functional gametes), and may be complete (have all four whorls) but still unisexual.
Q34. The non-motile germ-cell with food reserve is:
Female gameteThe female gamete (egg/ovum) is non-motile and contains stored food reserves (yolk, cytoplasm) to support the early embryo after fertilisation. The male gamete (sperm) is typically small and motile (flagellum). Pollen grains contain male gametes but are not themselves gametes; spores are asexual reproductive units, not gametes.
Q35. Combination of DNA from two parents leads to:
Novel variationsWhen DNA from two parents combines during sexual reproduction, offspring inherit a unique mix of genes—not identical to either parent. This produces novel genetic combinations and variations that did not exist before. This increases genetic diversity, which is not uniform, does not reduce variation, and enhances survival potential rather than preventing it.
Q36. Sexual reproduction allows:
New combinations of variationsSexual reproduction allows existing variations from two parents to be reshuffled and combined in new ways. Crossing over during meiosis and random fertilisation produce offspring with unique combinations of traits. This creates new variations, not elimination or slowing of variation. DNA copying still occurs (it is essential), but the combinations are novel.
Q37. Fertilisation results in formation of:
ZygoteFertilisation is the fusion of male and female gametes. The immediate product of this fusion is a single diploid cell called the zygote. The zygote then undergoes cell division and differentiation to form an embryo. The ovule becomes the seed; the ovary becomes the fruit; these occur after fertilisation but are not the direct product of fusion itself.
Q38. Pollen grains are usually:
YellowishPollen grains commonly appear yellowish due to the presence of carotenoid pigments and sporopollenin (a tough polymer). While colour can vary (white, cream, orange, or even purple in some species), yellowish is the most common and typical colour described in textbooks. Many flowers with yellow anthers produce yellowish pollen.
Q39. Transfer of pollen from stamen to stigma is called:
PollinationPollination is defined as the transfer of pollen grains from the anther (part of the stamen) to the stigma (part of the carpel). It is the first step in sexual reproduction in flowering plants. Germination is seed sprouting; fertilisation is gamete fusion; reproduction is the broader process that includes pollination, fertilisation, and seed development.
Q40. Ovules are present inside the:
OvaryOvules are the structures that contain the female gamete (egg cell). They are located inside the ovary, which is the swollen basal part of the carpel. After fertilisation, ovules become seeds. The style is the tube connecting stigma to ovary; the stigma is the receptive surface; petals are accessory floral parts.
Q41. Pollen grains are produced by:
StamenStamens are the male reproductive organs of a flower. Each stamen consists of an anther (which produces pollen grains) and a filament. Pollen grains contain the male germ-cells. The ovary, style, and stigma are parts of the female reproductive organ (carpel) and do not produce pollen.
Q42. The male reproductive part of a flower is:
StamenThe stamen is the male reproductive part of a flower. It consists of the anther (produces pollen containing male gametes) and the filament (supports the anther). Stigma, ovary, and carpel are all parts of the female reproductive organ (pistil/carpel). A flower may have multiple stamens.
Q43. The female reproductive part of a flower is:
CarpelThe carpel (also called pistil) is the female reproductive part of a flower. It consists of the stigma (receptive surface), style (tube), and ovary (contains ovules with female gametes). Petals attract pollinators; sepals protect the bud; stamens are male parts. A flower may have one or multiple carpels.
Q44. After landing on stigma, pollen forms a:
TubeAfter a pollen grain lands on a compatible stigma, it absorbs moisture and nutrients and germinates, producing a pollen tube. The pollen tube grows through the style, carrying the male gametes down to the ovule for fertilisation. Seeds form later after fertilisation; spores are asexual; buds are outgrowths for vegetative reproduction.
Q45. The cell formed after fertilisation is called:
ZygoteThe zygote is the single diploid cell formed immediately after the fusion of male and female gametes during fertilisation. It is the first cell of the new individual. The zygote then divides repeatedly to form an embryo. The seed develops from the ovule after fertilisation; the ovule is the structure containing the female gamete before fertilisation.
Q46. DNA copying is not absolutely accurate because:
Errors occur during copyingDNA replication, despite proofreading mechanisms, is not 100% perfect. Occasional mistakes (mutations) occur due to mispairing of bases, insertion/deletion errors, or damage during replication. These errors are a natural consequence of biochemical reactions. Enzymes do not stop working (they occasionally make mistakes); DNA is chemically stable; cell age may increase error rates but is not the fundamental reason.
Q47. The swollen basal part of the carpel is the:
OvaryThe carpel (female reproductive part) has three main parts: stigma (top, sticky), style (middle, tube-like), and ovary (swollen basal part). The ovary contains one or more ovules, which contain the female gametes. After fertilisation, the ovary develops into a fruit. The ovule is inside the ovary, not the basal part itself.
Q48. The motile germ-cell is called:
Male gameteThe male gamete (sperm in animals, male germ-cell in plants) is typically motile, possessing a flagellum or being capable of movement to reach the female gamete. The female gamete (egg) is non-motile. Ovules contain the female gamete but are not gametes themselves; the zygote is formed after fusion and is non-motile.
Q49. Stamens and carpels contain:
Germ-cellsStamens produce pollen grains, which contain male germ-cells (male gametes). Carpels contain ovules, which contain female germ-cells (female gametes/egg cells). Thus, both stamens and carpels are reproductive structures that house germ-cells. Seeds develop later after fertilisation; petals are separate floral parts; all plant parts contain tissues, but that is not the specific distinction.
Q50. Seed formation is advantageous because:
Seeds protect embryoSeeds provide a protective seed coat (derived from ovule integuments) that shields the embryo from physical damage, desiccation, pathogens, and harsh environmental conditions. Seeds also contain stored food (endosperm or cotyledons) to nourish the embryo during germination. This protection allows seeds to remain dormant until favourable conditions for growth, significantly improving survival compared to spore-based reproduction.