Reproductive system of mammals and flowering plants

(A) Reproductive System of Mammals

(i) Structure and Function of Male and Female Reproductive Systems

Male Reproductive System

• Structure: Includes testes, scrotum, epididymis, vas deferens, seminal vesicles, prostate gland, and penis.
• Functions:
  1. Testes: Produce sperm and testosterone.
  2. Epididymis: Stores and matures sperm.
  3. Vas Deferens: Transports sperm to the urethra.
  4. Accessory Glands: Provide seminal fluid for sperm mobility and nutrition.

Female Reproductive System

• Structure: Comprises ovaries, fallopian tubes, uterus, cervix, and vagina.
• Functions:
  1. Ovaries: Produce ova (eggs) and hormones (estrogen and progesterone).
  2. Fallopian Tubes: Site of fertilization; transport zygote to uterus.
  3. Uterus: Supports fetal development.
  4. Vagina: Receives sperm and acts as a birth canal.

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(ii) Differences Between Male and Female Reproductive Organs

Feature	Male	Female
Primary Organ	Testes	Ovaries
Gametes	Sperm	Ovum
Location	External (in scrotum)	Internal (pelvic cavity)
Duct System	Epididymis, vas deferens	Fallopian tubes

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(iii) Structure of Gametes (Sperm and Ovum)

Sperm

• Structure: Head (contains nucleus and acrosome), midpiece (mitochondria), tail (flagellum for movement).
• Function: Delivers genetic material to the ovum.

Ovum

• Structure: Large, spherical, with cytoplasm, nucleus, and zona pellucida.
• Function: Provides nutrients and genetic material for embryo development.

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(iv) Fertilization, Embryo Development, and Birth

• Fertilization: Sperm fuses with ovum in the fallopian tube, forming a zygote.
• Embryo Development: Zygote undergoes cell division (cleavage) and forms a blastocyst that implants in the uterus.
• Birth: Hormonal signals initiate labor, leading to the delivery of the baby through the birth canal.

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(v) Birth Control

Methods include:

1. Barrier Methods: Condoms, diaphragms.
2. Hormonal Methods: Pills, implants, IUDs.
3. Surgical Methods: Vasectomy, tubal ligation.
4. Natural Methods: Abstinence, rhythm method.

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(B) Metamorphosis in Insects

Life Histories of Butterfly and Cockroach

Butterfly

• Stages: Egg → Larva (caterpillar) → Pupa (chrysalis) → Adult.
• Type: Complete metamorphosis.
• Duration: Varies by species, typically weeks to months.

Cockroach

• Stages: Egg → Nymph → Adult.
• Type: Incomplete metamorphosis.
• Duration: 3-4 months to adulthood.

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(C) Comparison of Reproduction in Vertebrates

Group	Fertilization	Eggs Produced	Parental Care
Fish	External	Many	Minimal
Amphibians	External	Many	Some
Reptiles	Internal	Moderate	Some
Birds	Internal	Few	Extensive
Mammals	Internal	Few	Extensive (lactation)

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(D) Reproduction in Flowering Plants

(i) Floral Parts in Insect and Wind-Pollinated Flowers

Insect-Pollinated Flower (e.g., Hibiscus):

• Bright petals, nectar, sticky pollen.

Wind-Pollinated Flower (e.g., Maize):

• Small petals, no nectar, light pollen.

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(ii) Structure and Function of Male and Female Parts

• Male: Stamens (anther and filament); produce pollen.
• Female: Carpels (stigma, style, ovary); site for fertilization.

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(E) Pollination in Plants

(i) Types

1. Self-Pollination: Same flower/plant.
2. Cross-Pollination: Between flowers on different plants.

(ii) Features

• Self: Less genetic diversity.
• Cross: Higher genetic diversity.

(iii) Agents of Pollination

1. Insects: Bees, butterflies.
2. Wind: Grasses.
3. Water: Aquatic plants.

(iv) Types of Placentation

• Axile: Ovules in central column (e.g., tomato).
• Marginal: Along one margin (e.g., pea).
• Parietal: Attached to ovary wall (e.g., mustard).

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(F) Development of Zygote in Plants

• Fertilization: Fusion of male and female gametes in the ovule.
• Embryo Formation: Zygote develops into an embryo; ovule becomes a seed.

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(G) Types and Structure of Fruits

(i) Types

1. Dry Fruits: Dehiscent (split open, e.g., pea) or indehiscent (do not split, e.g., sunflower).
2. Fleshy Fruits: Berry (e.g., tomato), drupe (e.g., mango).

(ii) Structure

• Seed, pericarp (exocarp, mesocarp, endocarp).

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(H) Dispersal of Fruits and Seeds

• Agents:
  1. Wind: Light seeds (e.g., dandelion).
  2. Water: Buoyant fruits (e.g., coconut).
  3. Animals: Fleshy fruits (e.g., berries).

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Illustrations

• Draw diagrams of male and female reproductive systems, gametes (sperm and ovum), and stages of embryo development in mammals and plants.

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• Label floral parts, fruits, and seed dispersal mechanisms.

 

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Real-World Applications

• Understanding human reproduction aids in healthcare, fertility treatments, and family planning.
• Plant reproduction knowledge is crucial in agriculture and biodiversity conservation.