CBSE Class 10 Biology How do Organisms Reproduce MCQs Set 13

Answer: (a) reproduction in earthworms

Explanation:
1. Spore formation, binary fission and budding are asexual methods.
2. Earthworms are bisexual animals that reproduce sexually.

Teacher's Note:
1. Earthworms are hermaphrodites but still reproduce sexually.
2. Asexual methods involve one parent.

Answer: (b) vegetative reproduction

Explanation:
1. These plants are propagated by stem cuttings, layering or grafting, which are vegetative methods.
2. They give plants identical to the parent.

Teacher's Note:
1. Many fruit and flower plants are raised vegetatively.
2. It gives uniform plants and early flowering.

Answer: (b) Leishmania

Explanation:
1. Leishmania has a whip-like flagellum at one end of its body.
2. It therefore divides by binary fission along a definite plane.

Teacher's Note:
1. Leishmania causes kala-azar.
2. Amoeba has no fixed shape.

Answer: (b) gametes, fertilisation, zygote, embryo

Explanation:
1. Gametes are formed first, and they fuse during fertilisation.
2. The fertilised egg is the zygote, which divides to form the embryo.

Teacher's Note:
1. Fertilisation is the fusion of gametes, so gametes must come before it.
2. The embryo is formed last from the zygote.

Answer: (c) reproduction

Explanation:
1. Reproduction is the production of new individuals of the same kind by the parent organisms.
2. Budding is only one method of reproduction and flowering is a stage in plants.

Teacher's Note:
1. Reproduction is the process by which organisms produce new individuals of their own kind.
2. It maintains the continuity of the species.

Answer: (a) Mucor

Explanation:
1. Mucor is a fungus related to Rhizopus and reproduces by spores.
2. Planaria regenerates, Spirogyra fragments and potato propagates vegetatively.

Teacher's Note:
1. Fungi reproduce by spores.
2. Mucor, Rhizopus and Penicillium are examples.

Answer: (c) vegetative propagation

Explanation:
1. Vegetative propagation uses a part of the parent plant, so the new plants are genetically identical to it.
2. Banana is propagated this way because it rarely forms viable seeds.

Teacher's Note:
1. Vegetative propagation gives uniform plants with the parent's characters.
2. Sexual reproduction gives variation instead.

Answer: (c) callus

Explanation:
1. In tissue culture the plant tissue first grows into an undifferentiated mass of cells called callus.
2. The callus is later transferred to a medium to form plantlets.

Teacher's Note:
1. Callus → plantlets → mature plants.
2. Tissue culture produces disease-free plants.

Answer: (d) embryo

Explanation:
1. Inside a seed, the embryo is the young plant that will grow into the seedling.
2. The cotyledons store food and the seed coat protects.

Teacher's Note:
1. Embryo = plumule + radicle + cotyledons.
2. Seed = embryo + food + coat.

Answer: (c) coloured and scented

Explanation:
1. Bright colours and fragrance attract insects to the flowers.
2. The insects carry pollen from one flower to another.

Teacher's Note:
1. Wind-pollinated flowers are small and unscented.
2. Insect-pollinated flowers advertise themselves.

Answer: (a) P-(ii), Q-(i), R-(iv), S-(iii)

Explanation:
1. Germination is the development of the embryo into a seedling (ii) and pollination is the transfer of pollen (i).
2. Menstruation occurs when the egg is not fertilised (iv) and the zygote is implanted in the uterus (iii).

Teacher's Note:
1. Match each term with its definition.
2. Keep the sexual reproduction events in order.

Answer: (c) zygote

Explanation:
1. In fertilisation a male gamete fuses with a female gamete.
2. The cell formed by this fusion is the zygote.

Teacher's Note:
1. Zygote → embryo → new individual.
2. A gamete is a haploid cell that takes part in fertilisation.

Answer: (c) both (a) and (b)

Explanation:
1. At puberty the reproductive tissues mature, so sexual maturation takes place.
2. At the same time the rate of general body growth begins to slow down.

Teacher's Note:
1. Both events occur together at puberty.
2. Sex hormones bring about the changes.

Answer: (a) the prostate gland also synthesises sperm

Explanation:
1. Sperms are made only in the testes.
2. The prostate gland and seminal vesicles are outside the testes and add fluid that makes sperm transport easier and provides nutrition.

Teacher's Note:
1. Testes make sperms; accessory glands make fluid.
2. The statement that the prostate makes sperm is false.

Answer: (c) menstruation stops and reproductive capacity is arrested

Explanation:
1. Menopause occurs around the age of 45 to 50 years.
2. The ovary stops releasing eggs, menstruation ceases and the woman can no longer reproduce.

Teacher's Note:
1. Menarche = start of menstruation; menopause = end.
2. It marks the end of reproductive life.

Answer: (d) menstruation

Explanation:
1. The first menstruation (menarche) shows that the ovaries have started releasing eggs.
2. Growth, hair pattern and voice changes occur but do not by themselves show that reproduction has become possible.

Teacher's Note:
1. Menarche marks the start of reproductive life in girls.
2. Menopause marks its end.

Answer: (b) prostate gland, penis and vas deferens

Explanation:
1. Prostate gland, penis and vas deferens all belong to the male reproductive system.
2. Uterus, vagina and cervix are female organs.

Teacher's Note:
1. Separate the male and female organs in two lists.
2. Scrotum, testis, penis, vas deferens are male.

Answer: (c) endometrium

Explanation:
1. The endometrium is the thick, spongy inner lining of the uterus.
2. If the egg is not fertilised, this lining breaks and leaves the body as blood and mucus.

Teacher's Note:
1. Menstrual flow is the broken uterine lining.
2. The lining is rebuilt every month.

Answer: (a) 40 weeks

Explanation:
1. Gestation is the period from fertilisation to the birth of the baby.
2. In humans it lasts about 280 days, that is 40 weeks.

Teacher's Note:
1. 280 days = 40 weeks.
2. Parturition is the birth itself.

Answer: (c) menopause

Explanation:
1. In women the ovaries stop releasing eggs at around 45 to 50 years and menstruation ceases.
2. This stage is menopause.

Teacher's Note:
1. Menopause ends the reproductive life.
2. Menarche begins it.

Answer: (a) mechanical method

Explanation:
1. A condom is a barrier that stops the sperms from reaching the egg.
2. Barrier methods are mechanical methods.

Teacher's Note:
1. Surgical: vasectomy and tubectomy. Hormonal: pills.
2. Condoms also reduce the spread of STDs.

Answer: (a) (A) and (B)

Explanation:
1. Copper-T is used by women, and condoms prevent STDs, so A and B are correct.
2. Ovulation occurs around the middle of the cycle (about the 14th day), and males produce sperms throughout adult life, so C and D are wrong.

Teacher's Note:
1. Ovulation is in the middle of the cycle.
2. Males keep producing sperms in later life.

Answer: (b) femidom

Explanation:
1. A femidom (female condom) forms a physical barrier that stops sperms from reaching the egg.
2. Oral pills are hormonal, Copper-T is an IUD and vasectomy is surgical.

Teacher's Note:
1. Barrier methods also protect against STDs.
2. Condoms and diaphragms are barrier methods.

Answer: (b) DNA copying is not error free

Explanation:
1. DNA copying during reproduction is not perfectly accurate, so small changes occur.
2. These changes produce variations that pass on to the next generation.

Teacher's Note:
1. Errors in DNA copying create variation.
2. Single-parent reproduction gives less variation.

Answer: (c) (i), (ii) and (iii)

Explanation:
1. Sexual reproduction needs male and female gametes, whose fusion (fertilisation) always forms a zygote.
2. The offspring are not clones because the genes come from two parents, so (iv) is false.

Teacher's Note:
1. Clones are produced only by asexual reproduction.
2. Sexual reproduction brings variation.

Answer: (d) maintenance of body design features

Explanation:
1. Variations help bacteria to resist heat, produce different eye colours and help a species to survive over time.
2. The body design features are maintained by the consistency of DNA copying, not by variations.

Teacher's Note:
1. Variation brings difference; DNA copying keeps the body design constant.
2. Both are needed.

Answer: (d) (i), (ii) and (iii)

Explanation:
1. Sexual reproduction needs two gametes and combines the DNA of two individuals, which gives more variation.
2. It does not produce genetically identical offspring; that is a feature of asexual reproduction.

Teacher's Note:
1. Identical offspring = clones = asexual.
2. Sexual reproduction brings variation.

Answer: (b) Both A and R are true, but R is not the correct explanation of A.

Explanation:
1. Variation helps some members survive when the environment changes, so A is true.
2. Populations do occupy niches using reproduction, so R is true, but it does not explain why variation is useful.

Teacher's Note:
1. Both statements are correct but unconnected.
2. Check whether R answers the question why for A.

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

Explanation:
1. These changes are secondary sexual characters of boys, so A is true.
2. They are caused by an increase, not a decrease, in testosterone secretion, so R is false.

Teacher's Note:
1. Testosterone brings the changes of puberty in boys.
2. Look for the words increased and decreased in R.

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

Explanation:
1. The common passage for sperms and urine in males is the urethra, so A is false.
2. The ureter carries only urine from the kidney to the bladder and never carries sperms, so R is true.

Teacher's Note:
1. Ureter ≠ urethra.
2. Do not confuse the two words.

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

Explanation:
1. HIV-AIDS is a viral disease, so A is false.
2. It does spread through infected needles, so R is true.

Teacher's Note:
1. HIV is a virus.
2. Do not share needles or blades.

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

Explanation:
1. The shedding of blood and mucus from the thick uterine lining is menstruation, so A is true.
2. It occurs when the egg is not fertilised, so R is false.

Teacher's Note:
1. No fertilisation means menstruation.
2. Fertilisation leads to pregnancy.

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

Explanation:
1. Sexual reproduction produces variations, and some variants can survive when the environment changes.
2. So the greater survival chance of sexually produced organisms is explained by R.

Teacher's Note:
1. Variation is the key to survival of a species.
2. Clones all suffer if conditions change.

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

Explanation:
1. In males the urethra serves both as the passage for urine and for sperms (semen), so the assertion is true.
2. The reason is false because the urethra also carries sperms; the vas deferens joins it.

Teacher's Note:
1. The male urethra is a common passage for urine and sperms.
2. Hence A is true but R is false.

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

Explanation:
1. Male gametes (sperms) have tails and swim, so A is true.
2. They are haploid cells and are not free-living, so R is false.

Teacher's Note:
1. Gametes are haploid.
2. The zygote is diploid.