Class 10 – Science Extra Questions – Ch. 7 – How do Organisms Reproduce

Ans: C

Explanation: Asexual reproduction is a mode of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring arise from a single organism and inherit the genes of that parent only. This means that the offspring are genetically identical to the parent. Option A describes sexual reproduction. Option B is incorrect because not all organisms reproduce asexually. Option D describes sexual reproduction.
Correct Option: C

Ans: C

Explanation: The nucleus is the organelle within eukaryotic cells that contains the genetic material (DNA). DNA carries the instructions for all the cell’s activities, including its structure, function, and reproduction. Therefore, the nucleus is considered the blueprint for building and operating a cell. Mitochondria are responsible for energy production. The endoplasmic reticulum is involved in protein and lipid synthesis and transport. Vacuoles are storage organelles.
Correct Option: C

Ans: C

Explanation: Asexual reproduction is a mode of reproduction that does not involve meiosis or fertilization, and the offspring are identical to the parent organism. Option A describes sexual reproduction. Option B is incorrect because not all organisms reproduce asexually. Option D describes sexual reproduction. Option C accurately describes asexual reproduction as producing genetically identical offspring.
Correct Option: C

Ans: A

Explanation: While all options can be associated with puberty, the deepening of the voice is a direct and primary indicator of the hormonal changes, specifically the increased production of testosterone, which affects the vocal cords. Growth of body hair, increased height and weight, and acne are also signs of puberty, but the vocal changes are more directly linked to the hormonal surge that drives these developments.
Correct Option: A

Ans: D

Explanation: AIDS (Acquired Immunodeficiency Syndrome) is a disease caused by the Human Immunodeficiency Virus (HIV). Viruses are microscopic infectious agents that replicate only inside the living cells of other organisms. Protozoans are single-celled eukaryotic organisms, fungi are eukaryotic organisms like yeasts and molds, and bacteria are single-celled prokaryotic microorganisms. None of these are the causative agents of AIDS.
Correct Option: D

Ans: A

Explanation: Ferns are vascular plants that reproduce through spores. They have a life cycle that alternates between a sporophyte generation, which produces spores, and a gametophyte generation. Planaria reproduce asexually by fission or sexually. Spirogyra is a type of filamentous green algae that reproduces asexually by fragmentation and sexually by conjugation. Potatoes reproduce vegetatively from tubers (which are modified stems) or sexually from seeds.
Correct Option: A

Ans: C

Explanation: Sexual reproduction in flowering plants begins with pollination, where pollen is transferred from the anther to the stigma. Following pollination, fertilization occurs when the male gamete from the pollen fuses with the female gamete in the ovule, forming an embryo. The embryo develops within the seed, and once the seed germinates under suitable conditions, it grows into a seedling. Therefore, the correct order is pollination, fertilization, embryo, and seedling.
Correct Option: C

Ans: A

Explanation: Fetal development is a complex process with specific milestones occurring at different stages. The formation of fetal membranes, such as the amnion and chorion, which protect and nourish the developing fetus, typically begins in the early weeks of pregnancy. However, the question asks about the formation of fetal membranes *and* the start of hair growth on the head. Significant development of hair follicles and the actual appearance of hair on the scalp are generally noted around the fourth to fifth month of gestation. The fifth month is a commonly cited period for these developments to be well underway.
Correct Option: A

Ans: D

Explanation: Meiosis is a type of cell division that reduces the number of chromosomes in a parent cell by half to produce four gamete cells. This reduction is essential for sexual reproduction, as it ensures that when two gametes (one from each parent) fuse during fertilization, the resulting offspring will have the correct diploid number of chromosomes. Mitosis produces identical daughter cells, fertilization is the fusion of gametes, and cytokinesis is the division of the cytoplasm.
Correct Option: D

Ans: A

Explanation: The question asks for the scientific term for insect pollination. Let’s break down the options:
A. Entomophily is derived from the Greek words “entomon” (insect) and “philos” (loving), and it specifically refers to pollination by insects.
B. Chiropterophily refers to pollination by bats.
C. Anemophily refers to pollination by wind.
D. Zoophily is a general term for pollination by animals, but entomophily is the more specific and commonly used term for insect pollination.
Therefore, entomophily is the correct scientific term for insect pollination.
Correct Option: A