Ch 08: Reproduction | Exam Fusion Prep

🔀 Asexual vs Sexual Reproduction

Feature	Asexual Reproduction	Sexual Reproduction
Parents needed	Single parent	Fusion of male and female gametes, from different or sometimes the same individual
Organisms	Unicellular and multicellular organisms	Many unicellular and multicellular organisms
Gametes	Absent (no gamete formation or fusion)	Present (gamete formation + fertilisation)
Offspring	Clone of parent (very similar genetically; mutations may introduce variation)	Different from parents (Variations present)

Fission

Unicellular organisms

Fragmentation

Simple multicellular

Regeneration

Broken part → new organism

Budding

Bud on body

Spore Formation

Thick-walled spores

Vegetative Repro.

Root/Stem/Leaf

🦠 Types of Asexual Reproduction

1. Fission

Reproduction in unicellular organisms by cell division; not universally described as amitotic
Binary fission: 2 progenies formed
e.g. Amoeba, Bacteria, Leishmania, Paramecium
Multiple fission: Many progenies formed
e.g. Plasmodium (Malarial parasite)

2. Fragmentation

Simple multicellular organism breaks into 2+ segments
Each segment grows into complete organism
e.g. Spirogyra and Ulothrix

3. Regeneration

In some organisms, a suitable body fragment can regenerate a complete individual
e.g. Hydra, Planaria

4. Budding

Bud forms on body → develops into new organism
e.g. Hydra, Yeast

5. Spore Formation

Spores aid multiplication and dispersal; many resistant spores survive unfavourable conditions
Germinate under favorable conditions
e.g. Chlamydomonas (motile zoospores), Rhizopus, Mucor, Puccinia

Tissue Culture

Disease-free plants from plant tissue/parts in suitable culture medium in lab
Also called: In-vitro propagation / Micropropagation
Used for decorative and disease-free plants in less time

⚠ Exam Trap

Plasmodium = Multiple fission (malarial parasite). Hydra = Both budding AND regeneration. Yeast = Budding only. Leishmania = Binary fission (causes Kala-azar).

⚡ Quick Recall

Tissue culture = Micropropagation / In-vitro propagation. Disease-free plants are produced in the laboratory.

🌿 Vegetative Reproduction

New offspring from vegetative parts: Roots, Stems and Leaves

Natural Vegetative Propagation

Part used	Examples
Stem	Potato, Sugarcane
Roots	Rosewood, Sweet potato
Leaf	Begonia, Bryophyllum

Artificial Vegetative Propagation

Cutting:
- Shoot cutting: Rose, Sugarcane, Bougainvillea; banana is commercially multiplied by tissue culture
- Grafting / budding: Mango, Apple, Citrus
Layering: Jasmine, Litchi, Guava (layering / air-layering)

⚠ Exam Trap

Potato = vegetative reproduction by Stem (not root!). Sweet potato = by Root. Bryophyllum = by Leaf. These three examples should not be confused.

🌸 Flower Structure

Flower = Condensed shoot, sexual organ of plant
Parts of flower:
- Calyx (green)
- Corolla (coloured)
- Androecium: Stamens = Male reproductive organ
- Gynoecium: Pistil/Carpel = Female reproductive organ

Bisexual Flowers

Both male & female organs in same flower
e.g. Hibiscus, Mustard, Pea, Rose, Tomato, Lily
Note: Maize has unisexual flowers

Dioecious Plants

Male and female flowers on separate plants
e.g. Papaya and date palm

⚠ Exam Trap

Maize is a monoecious plant with unisexual flowers: separate male and female flowers occur on the same plant. Papaya is dioecious, with male and female flowers on separate plants. This is an important distinction.

🔬 Double Fertilisation

Gametogenesis: Microsporogenesis forms haploid microspores by meiosis in anthers; these develop into pollen grains. Megasporogenesis forms haploid megaspores by meiosis in ovules; a functional megaspore develops into the embryo sac

Male gamete (n) + Female gamete (n) = Zygote (2n) → Embryo

Male gamete (n) + Polar/Secondary nuclei (2n) = Endosperm (3n)

Ovule becomes:Seed Ovary becomes:Fruit

⚡ Quick Recall

Double fertilisation = unique to Angiosperms. One fertilisation produces the embryo (2n); the other produces the endosperm (3n = triploid). The endosperm stores food in the seed.

🌼 Pollination

Transfer of pollen grain from anther to stigma of pistil

Self-Pollination

Autogamy: Within same bisexual flower
Geitonogamy: Between different flowers of same plant

Cross-Pollination

Between two different plants
Anemophily: By wind
e.g. Maize, Bamboo, Sugarcane
Hydrophily: By water
e.g. Vallisneria, Hydrilla
Entomophily: By insects
e.g. Salvia, Fig, Rose

⚠ Exam Trap

Anemophily = Wind pollination (Maize, Bamboo). Entomophily = Insect pollination (Rose, Fig). Hydrophily = Water pollination (Vallisneria). Remember these three “-phily” terms.

⚡ Quick Recall

Autogamy = same flower | Geitonogamy = same plant different flower | Cross pollination = different plant. Genetically, geitonogamy is equivalent to self-pollination.

👨 Male Reproductive System

Testes: A pair of primary reproductive organs located in scrotum (outside abdominal cavity)
Produce male sex hormone Testosterone by Leydig cells
Produce haploid sperms through Spermatogenesis
Nutrition of sperms by Sertoli cells
Epididymis: Maturation of sperms
Vas deferens: A pair — transport sperm from the epididymis toward the ejaculatory ducts
Vas deferens + seminal-vesicle duct → Ejaculatory duct → Urethra → Penis
Accessory glands: Seminal vesicles, Prostate and Cowper's (bulbourethral) glands

⚠ Exam Trap

The testes are located in the scrotum, outside the abdomen, for temperature regulation. Leydig cells produce testosterone, whereas Sertoli cells nourish sperm. These are different cell types.

👩 Female Reproductive System

Ovaries: A pair of primary reproductive organs located in pelvic cavity, one on each side of the uterus
Ovarian follicles secrete mainly oestrogens; after ovulation, the corpus luteum secretes mainly progesterone
Produce haploid eggs through Oogenesis
Oviducts: A pair — connect ovaries to uterus
Uterus: Site of embryo development
Accessory glands: Bartholin's (greater vestibular) glands — mucus secretion for lubrication

⚖️ Male vs Female — Quick Compare

Feature	Male	Female
Primary organ	Testes (in scrotum)	Ovaries (in pelvic cavity)
Hormone-producing cells	Leydig cells → Testosterone	Follicles → mainly Oestrogen; Corpus luteum → mainly Progesterone
Gamete production	Spermatogenesis (haploid sperms)	Oogenesis (haploid eggs)
Nutrition support cells	Sertoli cells (for sperms)	—
Sperm maturation / Egg transport	Epididymis	Oviduct (carries egg)
Accessory glands	Seminal vesicles, Prostate, Cowper's	Bartholin's (greater vestibular)

⚡ Quick Recall

Spermatogenesis = Male gamete formation | Oogenesis = Female gamete formation | Both produce haploid gametes via Meiosis. Fertilisation = Zygote (2n) formation.

🌱 Chapter 08 — Reproduction