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The Vault
RowQ
The Vault
CBSE Class 10 Biology · 11 questions · 26 marks
Reproduction is the one life process not essential for an individual organism's own survival, yet without it no species would continue to exist. This chapter compares the many ways organisms create copies of themselves — from a single Amoeba splitting in two, to flowers exchanging pollen, to the elaborate human reproductive system — and explains why sexual reproduction, despite being more complex, generates the variation that helps species survive over time.
Amoeba reproduces asexually mainly by which method?
Answer
Binary fission is correct — the single-celled Amoeba simply divides its nucleus and cytoplasm to form two independent daughter cells.
In the human male reproductive system, sperm are produced in the:
Answer
Testes is correct — the testes contain seminiferous tubules where sperm are produced, and they also secrete the hormone testosterone.
In a flower, the stamen is the reproductive part that:
Answer
Produces pollen grains (the male part) is correct — the stamen consists of the anther (which produces pollen) and the filament; the female part is the pistil.
The fusion of a male gamete and a female gamete to form a zygote is called:
Answer
Fertilisation is correct — this fusion combines genetic material from both parents to form a new individual.
Assertion (A): Contraceptive methods such as condoms, oral pills, and copper-T help in preventing pregnancy. Reason (R): These methods work by either physically preventing the meeting of sperm and egg or by disrupting hormonal conditions needed for fertilisation or implantation.
Answer
Both A and R are true and R is the correct explanation of A — different contraceptive methods act at different stages, but all ultimately prevent successful fertilisation or implantation.
Differentiate between self-pollination and cross-pollination.
Answer
In self-pollination, pollen grains from the anther are transferred to the stigma of the same flower or another flower on the same plant, so offspring closely resemble the parent. In cross-pollination, pollen grains are transferred from the anther of one plant to the stigma of a flower on a genetically different plant (often with the help of agents like wind, water, or insects), which introduces greater genetic variation in the offspring.
What is regeneration? Give one example of an organism that reproduces by this method.
Answer
Regeneration is the ability of a fully differentiated organism to regrow a lost or damaged body part, and in some organisms a fragment can even regrow into a complete new individual, effectively acting as a mode of asexual reproduction. Planaria (a flatworm) is a classic example — if it is cut into pieces, each piece can regenerate into a whole new organism.
Briefly describe the menstrual cycle in human females.
Answer
The menstrual cycle is a roughly 28-day cycle in which the uterus lining (endometrium) thickens with blood vessels each month to prepare for a possible pregnancy, while one ovary usually releases a mature egg (ovulation) around the middle of the cycle. If the released egg is not fertilised within about a day, hormone levels fall, the thickened uterine lining breaks down, and it is shed along with some blood through the vagina over about 3 to 5 days — this shedding is called menstruation, after which the cycle begins again.
Describe the human male reproductive system, naming its main parts and the function of each.
Answer
The male reproductive system includes a pair of testes located inside the scrotum, outside the abdominal cavity, which keeps them at a slightly lower temperature needed for sperm production; the testes contain seminiferous tubules that produce sperm and also secrete the hormone testosterone, which brings about changes at puberty. Sperm travel from each testis through a long tube called the vas deferens. Along the way, glands including the seminal vesicles and the prostate gland add nutrient-rich fluids that nourish and help transport the sperm, together forming semen. This semen passes through the urethra, which serves as a common passage for both semen and urine (though not at the same time), and is released from the body during ejaculation.
Explain the process of sexual reproduction in flowering plants, from pollination to seed and fruit formation.
Answer
A flower contains the male part (stamen, with anther producing pollen grains) and the female part (pistil, made of stigma, style, and ovary containing ovules). Pollination is the transfer of pollen grains from the anther to the stigma of the same flower (self-pollination) or a different flower (cross-pollination), often carried out by wind, water, or insects. After pollination, a pollen grain on the stigma develops a pollen tube that grows down through the style to reach the ovule inside the ovary; the male germ cell travels down this tube and fuses with the egg cell in the ovule — this fusion is fertilisation, producing a zygote. The zygote develops into an embryo, the ovule develops into a seed containing the embryo and stored food, and the ovary develops into a fruit that encloses and protects the seed or seeds, often aiding in their dispersal.
A gardener notices that a small piece cut from a mature rose stem, when planted in soil, develops roots and grows into a complete new rose plant identical to the parent. Explain the name and nature of this method of reproduction, and state one advantage and one disadvantage of this method compared to reproduction using seeds.
Answer
This method is called vegetative propagation, a form of asexual reproduction in which a vegetative part of the plant (here, a stem cutting) develops into a new, independent plant that is genetically identical to the parent. One advantage is that it allows farmers and gardeners to quickly produce many plants with reliably desirable characteristics (such as flower colour or fruit quality) without waiting for seed germination or flowering. One disadvantage is that, since offspring are genetically identical to the parent, little to no genetic variation is produced, which makes the population more vulnerable to being wiped out entirely by a disease or environmental change that the parent plant is susceptible to.
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