Class 10 Science Chapter 7 Practice Question Answers - How Do Organisms Reproduce

Ans:
(i) IUCD - Intrauterine Contraceptive Device
(ii) STD - Sexually Transmitted Disease
(iii) HIV - Human Immunodeficiency Virus
(iv) AIDS - Acquired Immunodeficiency Syndrome

Ans: Oral contraceptives function by preventing ovulation, altering the cervical mucus to prevent sperm from reaching an egg, and changing the uterine lining to make it less receptive to a fertilized egg.

Ans: Contraception refers to methods or devices used to prevent pregnancy by interfering with the normal process of fertilization, implantation, or ovulation.

Ans: A vasectomy is a surgical procedure for male sterilization or permanent contraception. It involves cutting and sealing the vas deferens, preventing sperm from entering the semen.Vasectomy

Ans: Fertilization is the process in which a sperm cell and an ovum (egg cell) fuse to form a zygote, initiating the development of a new individual.

Ans: Fertilization takes place in the fallopian tube of the female reproductive system.

Ans: An embryo is produced when a zygote undergoes several rounds of cell division and begins to develop into a multicellular organism.

Ans: A zygote is the initial cell formed when a sperm fertilizes an ovum, marking the beginning of a new organism’s development.

Ans: Examples of animals with external fertilization include frogs, fish, and some amphibians.

Ans: The primary sex organs are known as gonads.

Ans: The male reproductive system includes the testes, vas deferens, prostate gland, seminal vesicles, penis, and associated ducts.

Ans: Metamorphosis is a biological process in which an animal undergoes significant physical changes during its development after birth or hatching.

Ans: In internal fertilization, fertilization occurs inside the female body, while in external fertilization, it occurs outside the body, usually in water.

Ans: Sperm is a small, motile male gamete with a tail, whereas an ovum is a larger, immobile female gamete with a nutrient-rich cytoplasm.

Ans: Oviparous animals lay eggs, while viviparous animals give birth to live young.

Ans: A zygote divides to form an embryo, which implants in the uterus and continues developing through cell division and differentiation to become a foetus.

Ans: Puberty is the developmental phase in which a human reaches sexual maturity and undergoes physical and hormonal changes.

Ans: If the ovum is not fertilized, it degenerates and is shed along with the uterine lining during menstruation.

Ans: Internal fertilization occurs inside the female body, as seen in humans.

Ans: If the ovum is not fertilized, it degenerates and is shed along with the uterine lining during menstruation.

Ans: Female frogs produce a large number of eggs as part of an adaptive strategy to ensure the survival of their species. Since frog eggs are laid in open water, they face numerous threats, including predation from fish, birds, and other aquatic animals. The aquatic environment exposes the eggs to a high rate of mortality due to predators, harsh weather conditions, and other environmental hazards. By producing hundreds or even thousands of eggs, frogs increase the probability that at least some offspring will survive through the various stages of development—egg, tadpole, and finally adult frog. This strategy of producing large numbers of offspring, often seen in animals with external fertilization, helps compensate for the low survival rate of each individual egg.

Ans: Sexual reproduction is considered more advanced than asexual reproduction because it involves the combination of genetic material from two different individuals, leading to genetic variation within the species. In sexual reproduction, offspring inherit genes from both parents, resulting in a unique combination of traits. This genetic diversity enhances a population's ability to adapt to environmental changes, resist diseases, and survive in a variety of habitats. In contrast, asexual reproduction produces genetically identical offspring, making the species more vulnerable to adverse changes in the environment, as a single threat could impact the entire population uniformly. Thus, sexual reproduction contributes to evolutionary adaptability and resilience, which are essential for long-term survival and success in changing ecosystems.

Ans: A foetus is a more developed form of the embryo that occurs in later stages of prenatal development, typically from the ninth week of pregnancy onwards. During the early stages (embryo stage), the basic structure of the body begins to form, including the development of vital organs, the neural tube (which becomes the spinal cord and brain), and the beginnings of the heart and limbs. By the time the embryo transitions to a foetus, these organs have largely formed and are undergoing refinement and growth. The foetus stage is characterized by significant growth, movement, and the further maturation of body systems. This distinction between the embryo and foetus stages is crucial because it marks the shift from simple cellular differentiation to the detailed development of organs, bones, and tissues that prepare the body for independent life after birth.

Ans: The embryo gets embedded in the uterus, a muscular organ within the female reproductive system. The uterus provides a stable, nutrient-rich environment necessary for the growth and development of the embryo. After fertilization occurs in the fallopian tube, the fertilized egg, now a zygote, travels to the uterus, where it undergoes several rounds of cell division to form a multicellular structure known as a blastocyst. Once in the uterus, the blastocyst attaches to the uterine lining, a process called implantation. This lining, known as the endometrium, thickens each month in preparation for pregnancy and is richly supplied with blood vessels to nourish the developing embryo. The uterus also offers protection from external threats, and its ability to expand allows it to accommodate the growing foetus until birth. Therefore, the uterus is critical for the successful development and sustenance of a pregnancy.

Ans: The transformation from a single cell, the zygote, into a complex multicellular organism involves processes called cell division, differentiation, and growth. Initially, the zygote divides multiple times through a process known as mitosis, producing a large number of identical cells. As these cells multiply, they begin to specialize through a process called differentiation, whereby cells develop specific structures and functions based on their role in the organism (e.g., muscle cells, nerve cells, and blood cells). Differentiation is guided by genetic instructions within each cell and influenced by signals from neighboring cells and the environment. Over time, these specialized cells form tissues and organs, which organize into complex body systems, such as the circulatory, nervous, and digestive systems. This coordinated development allows a single fertilized cell to grow into a fully formed individual capable of independent life. This transformation is a remarkable demonstration of how complex life forms are built through orchestrated cellular processes.