CBSE Class 10 Biology How do Organisms Reproduce MCQs Set 10

Answer: (d) any

Explanation:
1. Amoeba has an irregular shape with no fixed axis.
2. Hence binary fission can take place in any plane, unlike Leishmania.

Teacher's Note:
1. Leishmania divides along a fixed plane.
2. Amoeba divides in any plane.

Answer: (c) cutting

Explanation:
1. Rose plants are commonly propagated by stem cuttings that are planted in moist soil.
2. The cut stem develops roots and grows into a new plant.

Teacher's Note:
1. Jasmine is propagated by layering.
2. Cutting is the easiest vegetative method.

Answer: (c) sowing

Explanation:
1. Micropropagation, budding and layering produce new plants from a single parent.
2. Sowing means planting seeds, which come from sexual reproduction.

Teacher's Note:
1. Seeds come from fertilisation.
2. Asexual methods do not use seeds.

Answer: (b) by budding

Explanation:
1. Yeast is a unicellular fungus.
2. A small outgrowth called a bud forms on the parent cell, receives a nucleus, and then separates as a new yeast cell.

Teacher's Note:
1. Budding is seen in yeast and Hydra.
2. Spore formation is shown by Rhizopus.

Answer: (d) seed

Explanation:
1. Vegetative propagules are the vegetative parts, namely root, stem and leaf, that give rise to new plants.
2. A seed is formed by sexual reproduction.

Teacher's Note:
1. Seeds are the product of fertilisation.
2. Vegetative parts do not involve gametes.

Answer: (b) yeast and Hydra

Explanation:
1. Yeast and Hydra both form buds on the parent body that detach as new individuals.
2. Rhizopus forms spores and Spirogyra reproduces by fragmentation.

Teacher's Note:
1. Budding: yeast and Hydra; spores: Rhizopus; fragmentation: Spirogyra.
2. Match each organism to its method.

Answer: (c) Planaria

Explanation:
1. Planaria is a flatworm with specialised cells that can form all the missing parts.
2. If it is cut, each piece can grow into a complete worm.

Teacher's Note:
1. Regeneration is shown by Planaria and Hydra.
2. Amoeba divides by fission.

Answer: (d) any one of (a), (b), (c)

Explanation:
1. Cutting, layering and grafting are all methods of artificial vegetative propagation.
2. They give plants genetically identical to the parent, so the desired qualities are retained. Hence any one of them can be used.

Teacher's Note:
1. Vegetative propagation produces clones of the parent plant.
2. It is the preferred way to keep the good qualities of fruits and flowers.

Answer: (b) potato, ginger, onion, sugarcane

Explanation:
1. Potato (tuber), ginger (rhizome), onion (bulb) and sugarcane (stem cutting) all propagate vegetatively.
2. Tomato, okra and cauliflower are grown from seeds.

Teacher's Note:
1. Each correct plant uses a different vegetative part.
2. Check every plant in the option.

Answer: (b) pollen grain on upper surface of stigma and ovule

Explanation:
1. After landing on the stigma, the pollen grain grows a tube through the style to reach the ovule.
2. So the length of the tube depends on the distance between the stigma surface and the ovule.

Teacher's Note:
1. The pollen tube carries the male gamete to the ovule.
2. It grows from the stigma to the ovary.

Answer: (b) gram, pea and groundnut

Explanation:
1. Gram, pea and groundnut seeds split into two cotyledons, so they are dicots.
2. Wheat, maize and barley have one cotyledon and are monocots.

Teacher's Note:
1. Dicot seeds split into two halves.
2. Cereals are monocots.

Answer: (b) sepals, petals, stamen, carpel

Explanation:
1. The outermost whorl is made of sepals, followed by petals, then the stamens.
2. The carpel lies at the centre of the flower.

Teacher's Note:
1. Outer to inner: sepals, petals, stamens, carpel.
2. Carpel is in the centre.

Answer: (a) stigma

Explanation:
1. The stigma is the sticky top of the carpel and receives the pollen grains.
2. The pollen tube then grows through the style.

Teacher's Note:
1. Pollen lands on the stigma.
2. Pollen tube grows only after landing.

Answer: (c) uterus

Explanation:
1. The zygote divides while moving through the oviduct and then settles in the thick lining of the uterus.
2. This is implantation.

Teacher's Note:
1. Fertilisation: oviduct. Implantation: uterus.
2. The embryo develops in the uterus.

Answer: (c) (A) and (C)

Explanation:
1. The testes produce sperms and also secrete testosterone, so A is correct and B is wrong.
2. Fertilisation is the fusion of the sperm and the ovum, so C is correct.

Teacher's Note:
1. The testes have two functions.
2. Fertilisation = fusion of gametes.

Answer: (c) uterus: provides nutrition from mother's blood to the embryo

Explanation:
1. The prostate gland and seminal vesicles add fluid, the testes secrete testosterone, and the fallopian tube carries the egg to the uterus.
2. Nutrition from the mother's blood is provided by the placenta, not by the uterus itself, so the third row is incorrect.

Teacher's Note:
1. The placenta is the organ for exchange of nutrients and wastes.
2. Check each row separately.

Answer: (b) P-(iii), Q-(v), R-(i), S-(ii), T-(iv)

Explanation:
1. External fertilisation occurs in the frog, the female gamete is the ovum, and fusion of gametes is fertilisation.
2. The ovary is the main female organ and the testis is the main male organ.

Teacher's Note:
1. Ovary makes ovum; testis makes sperm.
2. External fertilisation occurs in water.

Answer: (d) requirement of low temperature for formation of sperms

Explanation:
1. The formation of sperms needs a temperature lower than the normal body temperature.
2. The scrotum lies outside the abdominal cavity and keeps the testes cooler, so sperm formation can take place.

Teacher's Note:
1. The scrotum is a temperature regulator for the testes.
2. Remember: sperm formation needs a temperature lower than body temperature.

Answer: (b) A-(i), B-(iii), C-(iv), D-(ii)

Explanation:
1. Parturition is the expulsion of the full-grown foetus, so A matches (i).
2. Menopause is when menstruation stops (iii), gestation is the development of the foetus in the womb (iv), and ovulation is the monthly release of an ovum (ii).

Teacher's Note:
1. Parturition = birth; gestation = pregnancy period.
2. Menopause = end of menstruation.

Answer: (d) all of the above

Explanation:
1. STDs spread by sexual contact, vasectomy is the cutting and tying of a small portion of the vas deferens, and oral pills stop the release of eggs.
2. All three statements are correct, so the answer is (d).

Teacher's Note:
1. Know the meaning of each term.
2. Pills prevent ovulation.

Answer: (c) human immunodeficiency virus

Explanation:
1. AIDS is caused by the human immunodeficiency virus (HIV).
2. Trypanosoma causes sleeping sickness and bacteria do not cause AIDS.

Teacher's Note:
1. HIV damages the body's immune system.
2. AIDS is not curable but can be prevented.

Answer: (c) Copper-T

Explanation:
1. Vasectomy and tubectomy are surgical and permanent.
2. Copper-T can be removed and fertility returns, so it is temporary.

Teacher's Note:
1. Surgical methods are permanent.
2. Pills, condoms and IUDs are temporary.

Answer: (a) (i) and (iv)

Explanation:
1. Tubectomy and vasectomy are surgical methods.
2. Copper-T is an intra-uterine device and a condom is a barrier method, so (i) and (iv) are not surgical.

Teacher's Note:
1. Surgical = tubectomy and vasectomy.
2. Barrier = condom; IUCD = Copper-T.

Answer: (a) fertilisation

Explanation:
1. Multiple fission, micropropagation and fragmentation are asexual methods that produce genetically identical clones.
2. Fertilisation combines the gametes of two parents, so the offspring are not clones.

Teacher's Note:
1. Clones come from one parent.
2. Fertilisation brings variation.

Answer: (b) fertilisation

Explanation:
1. Gametes have half the number of chromosomes.
2. When the male and female gametes fuse in fertilisation, the normal (diploid) number is restored in the zygote.

Teacher's Note:
1. Gametes: half. Zygote: full.
2. Meiosis reduces the number and fertilisation restores it.

Answer: (a) ovulation

Explanation:
1. Ovulation is the monthly release of a mature egg from the ovary.
2. It occurs near the middle of the menstrual cycle.

Teacher's Note:
1. Ovulation → egg in oviduct → fertilisation if sperm present.
2. Menstruation follows if not fertilised.

Answer: (a) I, II and IV

Explanation:
1. DNA copying is the basic event in reproduction and gives two copies in the dividing cell, along with extra cellular apparatus.
2. The copies are similar but not always identical, so statement III is wrong.

Teacher's Note:
1. DNA copying is not perfectly accurate.
2. This inaccuracy produces variation.

Answer: (d) all of these

Explanation:
1. In a seed the cotyledons store food, the plumule is the future shoot and the radicle is the future root.
2. All three matches are correct.

Teacher's Note:
1. Embryo parts: plumule, radicle and cotyledons.
2. Cotyledons nourish the seedling.

Answer: (c) A is true, but R is false.

Explanation:
1. Normally one egg is released every month from one of the ovaries, so A is true.
2. The uterine lining thickens only when it prepares for a possible pregnancy and breaks down during menstruation, so R is false.

Teacher's Note:
1. The lining changes with the menstrual cycle.
2. If the egg is not fertilised, the lining is shed.

Answer: (c) A is true, but R is false.

Explanation:
1. A papaya flower has either stamens or carpels, so it is unisexual and A is true.
2. A unisexual flower contains only one kind of sex organ; the statement 'stamens only' is not true for all papaya flowers, as female flowers have carpels, so R is false.

Teacher's Note:
1. Unisexual flowers have either stamens or carpel.
2. Papaya and watermelon are unisexual.

Answer: (a) Both A and R are true, and R is the correct explanation of A.

Explanation:
1. The secretions of the prostate gland and the seminal vesicles form the seminal fluid.
2. This fluid makes the transport of sperms easier and provides nutrition, so R explains A.

Teacher's Note:
1. Semen = sperms + fluid from accessory glands.
2. The fluid also gives nourishment to sperms.

Answer: (c) A is true, but R is false.

Explanation:
1. Plants like banana and jasmine can be raised from stems and roots even if they do not form seeds, so A is true.
2. In vegetative propagation new plants come from vegetative parts, not seeds, so R is false.

Teacher's Note:
1. Vegetative propagation does not use seeds.
2. It is useful for seedless plants.

Answer: (d) A is false, but R is true.

Explanation:
1. The pistil (carpel) is the female reproductive part, so A is false.
2. Pollen grains do land on the stigma and germinate, so R is true.

Teacher's Note:
1. Stamen is male; pistil is female.
2. Pollen germinates on the stigma.

Answer: (a) Both A and R are true, and R is the correct explanation of A.

Explanation:
1. Pills and Copper-T do not form a barrier between the partners, so infection can pass on.
2. STDs spread through contact of mucous membranes, and only barrier methods like condoms reduce this risk.

Teacher's Note:
1. Only condoms protect against STDs.
2. Use of contraceptives for birth control is not the same as protection from infection.

Answer: (d) A is false, but R is true.

Explanation:
1. The vagina receives the semen during copulation (insemination), so R is true.
2. Fertilisation takes place in the oviduct, not in the vagina, so A is false.

Teacher's Note:
1. Vagina = copulation and birth canal.
2. Fertilisation = oviduct.