Class 9 Science: Reproduction – Practice Extra Questions

Ans: C

Explanation: During reproduction, offspring inherit genetic material from both parents. This genetic material carries traits that determine their characteristics. While offspring generally resemble their parents due to shared genes (similarities), they also exhibit unique combinations of these genes and occasional mutations, leading to differences (variations). Therefore, both similarities and variations are passed down.
Correct Option: C

Ans: C

Explanation: The uterus is a muscular organ where a fertilized egg implants and develops into a fetus. The ovaries produce eggs, the fallopian tubes are where fertilization typically occurs, and the cervix is the lower, narrow part of the uterus that opens into the vagina.
Correct Option: C

Ans: C

Explanation: The vas deferens, also known as the ductus deferens, is a muscular tube that transports sperm from the epididymis to the ejaculatory duct in the male reproductive system. The ovary, uterus, and oviducts (also called fallopian tubes) are all essential components of the human female reproductive system.
Correct Option: C

Ans: C

Explanation: Grafting is a horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion while the lower part is called the rootstock. The scion is the detached stem piece that is used to graft onto another plant.
Correct Option: C

Ans: D

Explanation: Complete regeneration from severed body parts is a remarkable ability possessed by certain organisms. Hydra are known for their ability to regenerate an entire new organism from small fragments of their body. Planaria, a type of flatworm, also exhibit impressive regenerative capabilities, where a small piece of the worm can grow into a whole new individual. Paramecium and Amoeba are single-celled organisms and do not regenerate from severed body parts in the same way multicellular organisms do. Leishmania is a parasitic protozoan and also does not exhibit complete regeneration from severed body parts. Therefore, Hydra and Planaria are the two organisms listed that are capable of complete regeneration from severed body parts.
Correct Option: D

Ans: C

Explanation: The test tube baby technique, also known as in vitro fertilization (IVF), was pioneered by Patrick Steptoe and Robert Edwards. They successfully achieved the first human pregnancy and birth through IVF in 1978.
Correct Option: C

Ans: C

Explanation: Adolescence is a period of rapid physical changes leading to sexual maturity. In girls, common secondary sexual characteristics include the development of breasts, widening of the hips, and the onset of menstruation. Deepening of the voice, growth of facial hair, and broadening of shoulders are typically associated with sexual maturation in boys. Therefore, the development of breasts is a characteristic of sexual maturation in girls.
Correct Option: C

Ans: B

Explanation: The blastopore is a key structure formed during gastrulation in embryonic development. It is the initial opening of the archenteron (primitive gut) that forms as the cells of the blastula invaginate. This opening later contributes to the formation of the anus in deuterostomes and the mouth in protostomes. Option A is incorrect because the neural tube forms from the ectoderm and is unrelated to the blastopore. Option C is incorrect as the blastopore’s fate depends on the organism’s developmental plan. Option D is incorrect because the blastula is a stage *before* the blastopore is prominent; the blastopore is characteristic of the gastrula stage.
Correct Option: B

Ans: B

Explanation: Barrier methods of contraception physically block sperm from reaching the egg. A diaphragm, cervical cap, and vault (which refers to a vaginal pouch or diaphragm-like device) all serve this purpose. Lippe’s loop, however, is a type of intrauterine device (IUD), which is a hormonal or copper device inserted into the uterus, not a barrier method.
Correct Option: B

Ans: A

Explanation: A microspore mother cell undergoes meiosis to produce four microspores. Each microspore then develops into a male gametophyte (pollen grain). Inside each pollen grain, mitosis of the generative nucleus produces two male gametes. Therefore, one microspore mother cell ultimately gives rise to 4 microspores, and each of these 4 microspores develops into a pollen grain containing 2 male gametes. Thus, 1 microspore mother cell leads to 4 microspores x 2 male gametes/microspore = 8 male gametes. If there are 16 microspore mother cells, the total number of male gametes produced will be 16 microspore mother cells * 8 male gametes/microspore mother cell = 128 male gametes.
Correct Option: A

Ans: A

Explanation: Genetic variation refers to the differences in DNA among individuals within a population. When the environment changes, some individuals may have genetic traits that are advantageous for survival and reproduction in the new conditions, while others may not. This increased likelihood of survival for some individuals is the most significant advantage of genetic variation in the face of environmental changes. Option B is incorrect because genetic variation doesn’t ensure perfect adaptation to the current environment, and environments are constantly changing. Option C is incorrect because individual organisms do not rapidly change their genes; evolution acts on populations over generations through natural selection. Option D is incorrect because inheritance of “strongest possible traits” is not guaranteed and depends on the specific traits and the environmental pressures.
Correct Option: A

Ans: C

Explanation: Grafting is a horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion while the lower part is called the rootstock. This method is used to propagate plants that do not reproduce true from seed or that are difficult to propagate by other means. Tissue culture involves growing plant cells or tissues in a sterile laboratory environment. Layering involves inducing roots to form on a stem while it is still attached to the parent plant. Cuttings involve taking a piece of stem or leaf and inducing it to form roots and shoots. Therefore, grafting is the technique that uses a stock and a scion.
Correct Option: C

Ans: A

Explanation: The scientific study of pollen grains and spores is called palynology. Xenology is the study of foreign or alien things. Parthenocarpy is the natural or artificial induction of fruit development without fertilization. Ornithology is the study of birds.
Correct Option: A

Ans: D

Explanation: The testis (plural: testes) are the primary male reproductive organs responsible for producing sperm through a process called spermatogenesis. The epididymis is a coiled tube located on the back of the testis where sperm mature and are stored. The vas deferens is a tube that transports sperm from the epididymis to the ejaculatory duct. The seminal vesicles are glands that produce a fluid that contributes to semen.
Correct Option: D

Ans: D

Explanation: Budding is a form of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. Sponges, yeast, and hydra all reproduce asexually through budding. Planaria, however, reproduce asexually primarily through fission (where the organism splits into two or more pieces, each regenerating into a complete individual) and also through regeneration. While some forms of regeneration might resemble budding in a broad sense, it’s not the primary or defining mode of asexual reproduction for planaria.
Correct Option: D

Ans: C

Explanation: Fission is a form of asexual reproduction where a parent organism divides into two or more equal parts. Amoeba, Leishmania, and Plasmodium are all single-celled organisms that primarily reproduce through binary fission or multiple fission. Planaria, however, are multicellular flatworms that reproduce both asexually and sexually. While they can reproduce asexually through fragmentation (where a piece of the worm breaks off and regenerates into a new individual), this is distinct from fission. Sexual reproduction in Planaria involves the exchange of gametes. Therefore, Planaria does not reproduce through fission in the same manner as the single-celled organisms listed.
Correct Option: C

Ans: D

Explanation: A flagellum is a whip-like appendage that helps in locomotion. Amoeba moves using pseudopodia, which are temporary extensions of the cytoplasm. Paramecium moves using cilia, which are short, hair-like projections. Hydra is a multicellular organism and its locomotion is achieved by other means. Leishmania is a protozoan that possesses a single flagellum, typically arising from the anterior end, which it uses for movement.
Correct Option: D

Ans: C

Explanation: Dichogamy refers to the temporal separation of male and female reproductive functions within the same organism or flower. This means that either the male parts mature before the female parts (protandry) or the female parts mature before the male parts (protogyny). This temporal separation is a strategy to prevent self-fertilization and promote cross-pollination. Monogamy refers to mating with a single partner. Dicliny refers to plants that have separate male and female flowers on the same or different plants. Heterostyly is a mechanism of cross-pollination found in some flowering plants, where the styles and stamens of flowers are of different lengths, reducing the likelihood of self-pollination.
Correct Option: C

Ans: B

Explanation: Parthenogenesis is a type of asexual reproduction in which an egg cell develops into an embryo without fertilization. Vivipary refers to the development of an embryo inside the body of the mother, leading to birth of live young. Apomixis and Apogamy are terms related to asexual reproduction in plants, specifically the development of a new sporophyte from a gametophyte without sexual fusion. Therefore, parthenogenesis is the correct term for the development of an organism without fertilization.
Correct Option: B

Ans: C

Explanation: Meiosis is a two-stage cell division process that reduces the chromosome number by half. In Anaphase I, homologous chromosomes separate and move to opposite poles of the cell. This separation of homologous pairs is what reduces the chromosome number from diploid (2n) to haploid (n) in the resulting daughter cells after meiosis I. Prophase I is involved in crossing over and homologous chromosome pairing. Metaphase II and Telophase II occur after meiosis I and do not directly contribute to the reduction of chromosome number from diploid to haploid; they are involved in separating sister chromatids.
Correct Option: C