CG Board Class 10 Science Chapter 14 Solutions: Life Processes: Reproduction, Growth and Development (जैविक प्रक्रियाएँ: प्रजनन, वृद्धि और परिवर्धन) (2026-27)

(i) The following type of division takes place in most cells of our body:**

• (a) meiosis
• (b) unisexual
• (c) bisexual
• (d) mitosis

(d) mitosis

Explanation: Mitosis occurs in all somatic (body) cells for growth, development, and repair, maintaining the original chromosome number (2n = 46).

Answer: (c) Sperm duct

Explanation: The sperm duct (vas deferens) is part of the male reproductive system. Ovary, uterus, and fallopian tube belong to the female system.

Answer: (d) Both a and b

Explanation: Sexual reproduction involves the fusion of male and female gametes to form a zygote and generates genetic variations in offspring.

Yes, the placenta is absolutely essential** for the developing child in the uterus.

• Reasons:

1. Nutrition: It transports glucose, amino acids, water, and essential nutrients from the mother’s bloodstream to the developing embryo.
2. Respiration: It facilitates gaseous exchange, delivering oxygen from mother to fetus and removing carbon dioxide from fetal blood.
3. Excretion: Fetal metabolic wastes (like urea) pass through the placenta into the mother’s blood for excretion.
4. Endocrine function: It secretes hormones essential for maintaining pregnancy.

Role of Male:**

• Produces microscopic, motile male gametes called sperms in the testes via meiosis.
• Transfers millions of sperms into the female vagina during copulation. Each sperm carries a haploid set of paternal chromosomes (23 chromosomes).
• Role of Female:
• Produces a non-motile female gamete called ovum/egg in the ovary via meiosis once every menstrual cycle.
• Provides the site of fertilization in the fallopian tube (oviduct) and contributes a haploid set of maternal chromosomes (23 chromosomes) along with cytoplasm and resources for embryonic development.

Structure Description for Diagram:**

• Male Reproductive Part (Stamen / Androecium): Composed of Anther (pollen bearing head) and Filament (stalk).
• Female Reproductive Part (Carpel/Pistil / Gynoecium): Composed of Stigma (sticky terminal surface), Style (elongated tube), and Ovary (swollen base containing ovules).
• Non-essential Whorls: Petals (Corolla) and Sepals (Calyx).

Definition:** Menstruation is the monthly cyclic shedding of the inner thickened lining of the uterus (endometrium) along with blood, tissue fluid, and unfertilized ovum through the vagina in human females. It repeats every 28-30 days from puberty to menopause.

• Effects on Female Body:

1. Indicates reproductive maturity and regular ovarian function.
2. Temporary abdominal cramps, backache, and fatigue during blood discharge (3-5 days).
3. Prepares the body every month for potential pregnancy; stops temporarily during pregnancy.

1. Barrier Methods (Physical Barriers):

• Example: Condoms (for males) or Diaphragms/Cervical Caps (for females).
• Working: Condoms are rubber/latex sheaths worn over the penis that trap ejaculated semen, preventing sperms from entering the female vagina.
• Advantage: Prevents unwanted pregnancy AND protects against Sexually Transmitted Diseases (STDs) like AIDS, syphilis, and gonorrhea.

1. Surgical Methods (Permanent Contraception):

• Vasectomy (in males): A minor surgical procedure where a small section of the sperm duct (vas deferens) is cut or tied to block sperm passage.
• Tubectomy (in females): A minor surgery where fallopian tubes are tied or cut to prevent the egg from reaching the uterine cavity.

Unicellular Organisms:**

• Reproduce almost exclusively by asexual methods based on mitosis.
• Fission: A single parent cell divides into two equal daughter cells (binary fission in Amoeba, Paramecium, bacteria).
• Budding: Small outgrowth forms on the parent cell and detaches (Yeast).
• Growth and reproduction are identical processes (cell division directly increases organism count).
• Multicellular Organisms:
• Most complex multicellular organisms (vertebrates, flowering plants) reproduce by sexual reproduction involving meiosis.
• Specialized reproductive organs produce haploid gametes (sperms/ova in animals, pollen/egg in plants).
• Fertilization creates a diploid zygote, which develops into an embryo via repeated mitosis and differentiation.
• Simple multicellular organisms (like Hydra, Planaria, Bryophyllum) can also reproduce asexually by budding, fragmentation, or vegetative propagation.

Organisms die continually due to aging, natural mortality, diseases, predation, and environmental hazards. Reproduction ensures the birth of new individuals of the same species to replace dead organisms. Thus, reproduction balances the birth rate with the death rate, maintaining a stable population size, preventing extinction, and ensuring the long-term survival and continuity of a species on Earth over generations.

Non-seed-producing plants reproduce by Vegetative Propagation or Spore Formation

1. Vegetative Propagation: New plants develop from vegetative parts like stem, root, or leaf.

• Stems: Potato tubers (eyes), sugarcane stem cuttings, rose grafts, runner grass.
• Roots: Sweet potato, Dahlia, Parwal, Kundru.
• Leaves: Bryophyllum and Begonia form plantlets along leaf margins.

1. Spore Formation: Non-flowering plants like mosses, ferns, fungi (Rhizopus, Mucor) produce microscopic thick-walled spores inside sporangia that germinate into new plants under moist favorable conditions.

Growth:** Growth refers to the permanent, irreversible increase in the physical size, mass, height, and volume of an organism over time due to cell division and resource accumulation.

• Example: Increase in height from a 1-meter child to a 1.6-meter adult.
• Development: Development refers to the qualitative structural and functional changes, progressive cellular differentiation, and maturation of organs that lead to complex body organization.
• Example: Formation of specialized hands, fingers, nerve connections, and mature functional reproductive organs during embryonic and adolescent growth.

1. Balanced & Nutritious Diet: High intake of proteins, iron, calcium, folic acid, vitamins, and fluids to support fetal growth and prevent anemia.
2. Regular Medical Check-ups: Periodic antenatal health check-ups, blood pressure monitoring, blood sugar checks, and ultrasound scans.
3. Proper Vaccination: Timely Tetanus Toxoid (TT) vaccinations to protect both mother and newborn.
4. Rest & Mental Well-being: Adequate sleep, avoidance of heavy physical exertion, and stress-free family support.
5. Hygiene & Safe Delivery: Ensuring clean personal hygiene and planning delivery at a recognized hospital/health center under skilled medical staff.

Multiple births (twins, triplets, or quintuplets) occur in two primary biological ways

1. Polyembryony / Division of Zygote (Identical / Monozygotic): After fertilization of a single egg by a single sperm, the resulting early zygote/embryo splits into two or more independent blastomere groups during initial cleavage. Each split group implants separately and develops into an independent fetus carrying identical genetic material (same sex).
2. Multiple Ovulation (Fraternal / Dizygotic / Polyzygotic): Sometimes, due to hormonal spikes, the ovaries release more than one egg (2, 3, or more ova) simultaneously during a single cycle. Each egg gets fertilized by a different sperm, leading to the concurrent development of multiple distinct embryos in the uterus.