1. What is Sound? Sound is a form of energy which produces a sensation of hearing in our ears. Sound is produced by vibrating objects. Examples include vibrating tuning fork, vocal cords in humans, bells, musical instruments, etc. Vibration: Rapid to-and-fro (back and forth) motion of an object. Short Question: Can sound be produced without vibration? Answer: No, sound cannot be produced without vibration. 2. Medium of Sound The substance through which sound travels is called a medium . Sound can travel through solids, liquids, and gases but cannot travel through vacuum . Process of Sound Propagation: When an object vibrates, it makes the air particles around it vibrate. These air particles move back and forth from their original (rest) position. The vibrating air particles push nearby air particles. This causes the nearby particles to also start vibrating. In this way, vibrations pass from one particle to another. This process continues through the medi...
How Do Organisms Reproduce? — Topic-wise Question Bank
Topics covered:
Topic 1 — DNA Copying & Variation
Key idea: DNA is copied during reproduction. Copies are mostly accurate but small changes (variations) occur — these cause differences between individuals and drive evolution.
MCQs
Q1.DNA is the molecule which (a) stores hereditary information (b) helps in copying proteins (c) stores energy (d) gives structural support
Answer: (a)
DNA stores hereditary information (blueprint). Proteins are made using the information in DNA but DNA itself doesn't "copy proteins".
Q2.When DNA copying makes small changes, these changes are called:
Options: (a) errors (b) mutations/variations (c) proteins (d) enzymes
Answer: (b)
Small changes are called mutations or variations. Some are harmful, some neutral, some helpful for survival.
Q3.Why are variations useful for a species?
Options: (a) Make individuals identical (b) Help some survive changes in environment (c) Reduce reproduction rate (d) Stop evolution
Answer: (b)
Variations allow a few individuals to be better suited when environment changes — helps species survival.
Q4.Which of these statements is true about DNA copying?
Options: (a) DNA copying is always perfect (b) DNA copying never happens (c) DNA copying can have small mistakes (d) DNA copying destroys chromosomes
Answer: (c)
Biochemical copying has a small error rate; these cause variation.
Q5.Which process produces rapid useful variations by combining DNA from two individuals?
Options: (a) Asexual reproduction (b) Sexual reproduction (c) Binary fission (d) Fragmentation
Answer: (b)
Sexual reproduction mixes DNA from two parents creating new combinations of variations.
Assertion & Reason
AR1.Assertion (A): Variations occur during DNA copying.
Reason (R): Variation always reduces survival of individuals.
Reason (R): Variation always reduces survival of individuals.
Answer: A is true, R is false.
Variations occur, but they do not always reduce survival — some help survival.
AR2.Assertion (A): DNA copying is needed for reproduction.
Reason (R): Without copying DNA, new cells cannot get genetic information.
Reason (R): Without copying DNA, new cells cannot get genetic information.
Answer: A and R are true; R explains A.
Reproduction must pass DNA to next generation; copying is essential.
Case Study
Passage: A pond has bacteria A. After a pollutant increased temperature, most bacteria died but a few survived and multiplied. Over time, the pond population was mostly the survivors.
Q: Explain in simple words how variation helped bacteria survive. What is the role of DNA copying?
Solution:
Among bacteria, small DNA variations made a few heat-resistant. When temperature rose, only these survived and reproduced. DNA copying had created such variations earlier.
HOTS / Board-style
Q.Explain why perfect DNA copying is not ideal for evolution.
If copying were perfect, no variation would arise → no raw material for evolution. Variations allow adaptation to changing environment.
Q.Write two examples showing advantage of variation in nature.
(1) Some bacteria resist antibiotics and survive; (2) Plants with drought-tolerant traits survive in dry climate and reproduce.
Topic 2 — Asexual Reproduction (Fission, Fragmentation, Regeneration, Budding, Vegetative Propagation, Spore Formation)
Key idea: One parent produces offspring without gamete fusion. Offspring are genetically similar to parent.
MCQs
Q1.Binary fission is seen in:
Options: (a) Amoeba (b) Hydra (c) Rhizopus (d) Bryophyllum
Answer: (a)
Amoeba divides into two similar daughter cells — binary fission.
Q2.Regeneration is best illustrated by:
Options: (a) Spirogyra fragments (b) Planaria cut pieces regrow (c) Yeast budding (d) Seed germination
Answer: (b)
Planaria pieces can grow into whole animals — regeneration.
Q3.Vegetative propagation gives plants which are:
Options: (a) Genetically different (b) Genetically identical (c) Longer gestation (d) Always seedless
Answer: (b)
Vegetative propagation makes clones of parent plant (genetically similar).
Q4.Spore formation helps survival because:
Options: (a) Spores are motile (b) Spores have thick walls (c) Spores need light to grow (d) Spores are multicellular
Answer: (b)
Thick walls protect spores in harsh conditions until environment is suitable.
Q5.Which is true for budding?
Options: (a) Parent disappears (b) Bud grows out and detaches (c) Only plants show budding (d) Budding produces spores
Answer: (b)
A bud forms on parent (Hydra, yeast), matures and detaches as new individual.
Assertion & Reason
AR1.Assertion: In fragmentation, each fragment can grow into a new individual.
Reason: Fragmentation is possible only in unicellular organisms.
Reason: Fragmentation is possible only in unicellular organisms.
Answer: A is true; R is false.
Fragmentation occurs in multicellular simple organisms like Spirogyra, not only unicellular ones.
AR2.Assertion: Vegetative propagation gives early flowering plants.
Reason: Plants produced vegetatively are genetically same as parent.
Reason: Plants produced vegetatively are genetically same as parent.
Answer: A and R true; R explains A.
Clonal plants are already mature in body design, so they flower earlier than seed-grown ones.
Case Study
Passage: A gardener grows many rose plants by grafting and notices they bear flowers earlier than seed-grown roses. He also uses tissue culture to grow disease-free ornamentals.
Q1: Why do grafted plants flower earlier? Q2: How does tissue culture help produce disease-free plants?
Solution:
1. Grafted plants get tissue from mature parent so they have ready structures and flower earlier. 2. Tissue culture grows plants from selected healthy cells in sterile medium, preventing disease transfer.
HOTS / Board-style
Q.Explain why most complex animals cannot reproduce by regeneration like Planaria.
Complex animals have highly specialised tissues and organs placed at fixed positions — piece removal would lack the right organising cells to re-form entire body. Regeneration requires pluripotent regenerative cells and simple body plan.
Q.List two advantages and two disadvantages of vegetative propagation.
Advantages: (1) Quick multiplication (2) Offspring inherit desired traits. Disadvantages: (1) No genetic variation → susceptible to disease (2) Requires human effort/tools.
Topic 3 — Sexual Reproduction
Key idea: Gametes from two parents fuse (fertilisation) to form zygote. Sexual reproduction increases variation.
MCQs
Q1.Sexual reproduction increases variation because:
Options: (a) single parent gives offspring (b) DNA from two individuals combine (c) copying is perfect (d) no mutation occurs
Answer: (b)
Combining DNA creates new combinations of traits — increases variation.
Q2.Meiosis is important because it:
Options: (a) doubles chromosome number (b) halves chromosome number (c) creates identical cells (d) stops variation
Answer: (b)
Meiosis reduces chromosome number in gametes so that fertilisation restores correct number in zygote.
Q3.Which is true about male and female gametes in many animals?
Options: (a) Both identical in size (b) Male motile, female larger with food store (c) Female motile, male larger (d) Neither has food store
Answer: (b)
Typical pattern: small motile sperm; large egg carrying food reserves.
Q4.Cross-pollination increases:
Options: (a) variation (b) selfing (c) cloned offspring (d) seedless plants
Answer: (a)
Cross-pollination mixes genes from different individuals → more variation.
Q5.Which of these is required to prevent chromosome doubling across generations?
Options: (a) Mitosis (b) Meiosis (c) Budding (d) Fission
Answer: (b)
Meiosis halves the chromosome number in gametes; fertilisation restores it.
Assertion & Reason
AR1.Assertion: Sexual reproduction is slower than asexual reproduction.
Reason: Sexual reproduction requires formation and fusion of gametes.
Reason: Sexual reproduction requires formation and fusion of gametes.
Answer: A and R true; R explains A.
Sexual reproduction involves more steps and mates, so slower.
AR2.Assertion: Sexual reproduction always produces fitter offspring.
Reason: Sexual reproduction creates variations in offspring.
Reason: Sexual reproduction creates variations in offspring.
Answer: A false, R true.
Variation is produced, but not always better — some combinations may be harmful.
Case Study (Sexual)
Passage: Two flowers of the same plant: one self-pollinated, another cross-pollinated. The cross-pollinated plant's seeds gave healthier seedlings in next generation.
Q: Suggest reasons for healthier seedlings from cross-pollination.
Solution:
Cross-pollination mixes genes from different individuals → may combine beneficial traits and reduce harmful recessive effects → healthier seedlings.
HOTS / Board-style
Q.Explain how meiosis and fertilisation together maintain chromosome number across generations.
Meiosis halves chromosome number in gametes (n). Fertilisation fuses two gametes to make zygote with 2n chromosomes. Thus the diploid number is restored each generation.
Q.Why might large food-rich eggs evolve in animals where embryo develops inside mother?
Large eggs provide nutrients to developing embryo before/while placenta is established; helps early growth in species with internal development or delayed placental support.
Topic 4 — Reproduction in Flowering Plants
Key idea: Flower organs (stamen, pistil) produce male and female gametes. Pollination → fertilisation → seed & fruit formation.
MCQs
Q1.The male part of a flower is called:
Options: (a) Pistil (b) Stamen (c) Ovary (d) Stigma
Answer: (b)
Stamen produces pollen (male gametes).
Q2.Which is example of self-pollination?
Options: (a) Wind carries pollen to another plant (b) Pollen from anther to stigma of same flower (c) Animal transfers pollen between plants (d) Water carries pollen
Answer: (b)
Self-pollination occurs within same flower.
Q3.Pollen tube grows through the:
Options: (a) Style (b) Ovary wall (c) Seed coat (d) Petal
Answer: (a)
Pollen forms a tube that grows down style to reach ovary.
Q4.After fertilisation, ovule develops into:
Options: (a) Fruit (b) Seed (c) Petal (d) Stamen
Answer: (b)
Ovule develops into seed; ovary develops into fruit.
Q5.Which agent can cause cross-pollination?
Options: (a) Wind (b) Water (c) Insects/Animals (d) Any of these
Answer: (d)
Cross-pollination can be by wind, water or animals.
Assertion & Reason
AR1.Assertion: Fruit formation helps seed dispersal.
Reason: Fruits are often attractive to animals which eat and disperse seeds.
Reason: Fruits are often attractive to animals which eat and disperse seeds.
Answer: A and R true; R explains A.
Animals carry seeds away from parent plant, aiding dispersal.
AR2.Assertion: Pollination always leads to fertilisation.
Reason: Pollination means pollen reaches stigma.
Reason: Pollination means pollen reaches stigma.
Answer: A false, R true.
Pollination is pollen arrival; fertilisation needs pollen tube and compatible gametes.
Case Study
Passage: Farmer observes some seeds fail to germinate even though they were produced. He suspects poor pollination or faulty fertilisation.
Q: List two reasons why seeds may be produced but not germinate.
Solution:
(1) Pollination without compatible pollen → no fertilisation, seed immature. (2) Environmental factors: seed damage, lack of stored food, or seed dormancy conditions not met.
HOTS / Board-style
Q.Explain advantages of seed formation for survival of plant species.
Seeds protect embryo, have food stores, allow dispersal, and can survive unfavorable periods — increasing survival chances.
Q.Differentiate between pollination and fertilisation (one-line each).
Pollination: Transfer of pollen to stigma. Fertilisation: Fusion of male gamete with egg cell to form zygote.
Topic 5 — Reproduction in Human Beings
Key idea: Human reproduction is sexual. Male and female reproductive systems produce gametes; fertilisation → embryo → foetus (in uterus) → birth.
MCQs
Q1.Testes are kept outside the abdominal cavity because:
Options: (a) Easier to reach (b) Sperm production requires lower temperature (c) To protect testes (d) To attach to scrotum
Answer: (b)
Spermatogenesis needs temperature slightly lower than body temperature.
Q2.Fertilisation in humans usually occurs in the:
Options: (a) Uterus (b) Vagina (c) Fallopian tube (oviduct) (d) Cervix
Answer: (c)
Sperm meets egg in the fallopian tube and fertilisation occurs there.
Q3.Placenta functions to:
Options: (a) Provide oxygen & nutrients to embryo (b) Produce sperm (c) Produce eggs (d) Break uterus lining
Answer: (a)
Placenta transfers nutrients and oxygen from mother to embryo and removes waste.
Q4.Menstruation occurs because:
Options: (a) Egg is produced (b) Egg is fertilised (c) Lining of uterus sheds when no fertilisation (d) Sperm is produced
Answer: (c)
If no fertilisation, uterus lining breaks down and comes out as menstrual flow.
Q5.Which structure carries sperms out of male body?
Options: (a) Ureter (b) Urethra (c) Vas deferens (d) Seminal vesicle
Answer: (b)
Urethra is common passage for urine and semen during ejaculation.
Assertion & Reason
AR1.Assertion: Ovaries contain many immature eggs at birth.
Reason: Females can release many eggs every month from birth.
Reason: Females can release many eggs every month from birth.
Answer: A true, R false.
Ovaries have many immature eggs but only about one egg matures and is released each month after puberty.
AR2.Assertion: Breastfeeding helps in immunity of baby.
Reason: Mother's milk contains antibodies.
Reason: Mother's milk contains antibodies.
Answer: A and R true; R explains A.
Breast milk contains antibodies and nutrients that support baby’s immunity and growth.
Case Study
Passage: A girl notices monthly bleeding, breast changes and mood swings. She is worried this means illness.
Q: Explain these changes and suggest simple advice for her.
Solution:
These are normal signs of puberty and menstruation. Advice: maintain hygiene during periods, balanced diet, rest, and speak to a trusted adult or school nurse for guidance.
HOTS / Board-style
Q.Describe the role of placenta in embryo development in two points.
(1) Transfers oxygen & nutrients from mother to embryo through villi. (2) Removes waste products from embryo to mother's blood for disposal.
Q.Why are condoms recommended to prevent STDs? Give two reasons.
Condoms act as barrier preventing exchange of body fluids and reduce risk of transmitting infections like HIV, gonorrhoea and syphilis.
Topic 6 — Reproductive Health & Contraceptives
Key idea: Contraception prevents unwanted pregnancy; some methods also reduce STD transmission.
MCQs
Q1.Which contraceptive method also protects against STI transmission?
Options: (a) Oral pill (b) Copper-T (IUD) (c) Condom (d) Tubectomy
Answer: (c)
Condoms act as barrier preventing contact and fluid exchange that transmit many STIs.
Q2.Copper-T is placed in the:
Options: (a) Vagina (b) Uterus (c) Ovary (d) Cervix
Answer: (b)
Copper-T (IUD) is placed inside uterus to prevent implantation or fertilisation.
Q3.Which method is permanent and surgical?
Options: (a) Condom (b) Oral pill (c) Vasectomy/Tubectomy (d) Copper-T
Answer: (c)
Vasectomy (male) and tubectomy (female) surgically block gamete transport and are permanent.
Assertion & Reason
AR1.Assertion: Oral contraceptive pills may have side effects.
Reason: They change hormonal balance in the body.
Reason: They change hormonal balance in the body.
Answer: A and R true; R explains A.
Hormonal pills affect cycles and may cause side effects like nausea or mood changes.
Case Study
Passage: A couple wants to avoid pregnancy but also protect from STIs. They are deciding between pill, copper-T, and condoms.
Q: Recommend the best method and why. Mention any limitations.
Solution:
Condoms are best to both prevent pregnancy (when used correctly) and protect against many STIs. Limitations: not 100% effective for pregnancy; user must use correctly every time. Pills/IUD protect against pregnancy but not STIs.
HOTS / Board-style
Q.List three social reasons for adopting contraceptive methods.
(1) Control family size for better standard of living; (2) Health of mother; (3) Economic planning & resource management.
Topic 7 — Practice & Revision
Mixed practice covering entire chapter. Good for last-minute revision.
MCQs
Q1.Which one is NOT an asexual method?
Options: (a) Budding (b) Binary fission (c) Fertilisation (d) Vegetative propagation
Answer: (c)
Fertilisation is fusion of gametes in sexual reproduction.
Q2.Which diagram should you draw to show human female reproductive system?
Options: (a) L.S. of flower (b) Binary fission (c) Female reproductive organs (ovary, fallopian tube, uterus, vagina) (d) Spirogyra filament
Answer: (c)
Labelled diagram of ovaries, fallopian tubes, uterus and vagina is required.
Some important questions
Q.Write a short note on 'spore formation' (3–4 lines).
Spore formation: Many fungi and some plants form spores inside sporangia. Spores are single cells with thick walls that can survive harsh conditions and grow into new organisms when conditions improve.
Q.Explain the difference between pollination and fertilisation in two lines.
Pollination is the transfer of pollen to stigma; fertilisation is the fusion of male gamete with egg cell to form zygote.
Q.List 4 differences between asexual and sexual reproduction (point-wise).
1. Asexual — one parent; Sexual — two parents. 2. Asexual — less variation; Sexual — more variation. 3. Asexual — faster and simpler; Sexual — slower and complex. 4. Asexual — common in unicellular organisms and some plants; Sexual — common in higher animals and flowering plants.
Case Study
Passage: A student writes: "All asexual offspring are identical so they are always resistant to disease." He asks you to correct his statement.
Q: Provide a short correction and one example that supports your correction.
Solution:
Correction: Asexual offspring are genetically very similar but minor variations and mutations may occur; they are not always resistant. Example: A crop grown clonally can be wiped out by a disease if all plants are susceptible.
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