(a) (i) Where are testes located in the human males and why? State two function of the testes. (ii) In the human female, one of the ovaries releases an egg every month. State the changes that take place if (1) the egg is fertilized, and (2) the egg is not fertilized. (iii) What is done during the surgical method in males and females to prevent pregnancy? OR (b) (i) What happens when : (1) Leaves of Bryophyllum fall on the soil ? (2) Planaria is cut into many pieces ? (3) Sporangia of Rhizopus on maturation liberate spores ? Mention the modes of reproduction in each of the above three cases. (ii) Write the changes that occur in a flower once the fertilisation has taken place.

Option (a)

(i) Location and Functions of Testes:

• Location: Testes are located outside the abdominal cavity in a pouch-like structure called the scrotum.
• Reason: Sperm formation (spermatogenesis) requires a temperature that is $2^\circ\text{C}$ to $2.5^\circ\text{C}$ lower than the normal internal body temperature. The scrotum hangs outside the body cavity to maintain this lower temperature.
• Two Functions of Testes:

1. Production of male gametes (sperms): Testes produce millions of sperms which carry genetic information.
2. Secretion of testosterone: Testes secrete the male sex hormone, testosterone, which regulates sperm production and stimulates the development of secondary sexual characteristics in boys during puberty.

(ii) Changes in the Human Female:

• (1) If the egg is fertilized:
• The fertilized egg (zygote) starts dividing to form an embryo, which travels down the fallopian tube and gets implanted in the thick, spongy inner lining of the uterus.
• The uterine wall thickens further and becomes richly supplied with blood vessels to nourish the growing embryo.
• A specialized disc-like tissue called the placenta develops between the uterine wall and the embryo. It allows the transfer of glucose, oxygen, and other essential nutrients from the mother's blood to the embryo, and also helps in removing metabolic wastes from the embryo into the mother's blood.
• (2) If the egg is not fertilized:
• The released egg survives for about one day.
• Since fertilization did not occur, the thick, spongy inner lining of the uterus (which was prepared to receive a zygote) is no longer needed.
• This lining slowly breaks down and is expelled from the body through the vagina along with blood and mucus. This monthly discharge is known as menstruation, which typically lasts for $2$ to $8$ days.

(iii) Surgical Methods to Prevent Pregnancy:

• In Males (Vasectomy): A small portion of the sperm duct (vas deferens) is surgically cut or tied up. This blocks the passage of sperms from the testes, preventing them from being ejaculated.
• In Females (Tubectomy): A small portion of the oviduct (fallopian tube) is surgically cut or tied up. This prevents the egg released by the ovary from meeting the sperm, thereby preventing fertilization.

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Option (b) (OR)

(i) Observations and Modes of Reproduction:

1. Leaves of Bryophyllum fall on the soil:

• Observation: The vegetative buds present in the notches along the leaf margins of Bryophyllum fall onto moist soil and grow into new, independent plants with roots and shoots.
• Mode of Reproduction: Vegetative Propagation (Asexual reproduction).

1. Planaria is cut into many pieces:

• Observation: Each cut piece of Planaria proliferates and differentiates through specialized cells to regenerate all the missing body parts, eventually growing into a complete, fully functional individual.
• Mode of Reproduction: Regeneration.

1. Sporangia of Rhizopus on maturation liberate spores:

• Observation: The mature sporangia (blobs-on-a-stick) burst open, releasing tiny, light spores into the air. These spores are protected by thick walls and germinate into new thread-like hyphae when they land on a moist, nutrient-rich surface (like wet bread).
• Mode of Reproduction: Spore Formation (Asexual reproduction).

(ii) Post-fertilisation changes in a flower:

• Zygote development: The zygote inside the ovule divides repeatedly to form an embryo.
• Seed formation: The ovule develops a tough protective outer coat and gradually transforms into a seed.
• Fruit formation: The ovary grows rapidly, accumulates nutrients, and ripens to become a fruit.
• Degeneration of other parts: Other floral parts like the petals, sepals, stamens, style, and stigma shrivel up and fall off.