Asexual Reproduction and Sexual Reproduction.
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TYPE 1: ASEXUAL REPRODUCTION
Only ONE parent is involved. No gametes (sex cells) are needed. Offspring are genetically identical to the parent (called clones)
🔑Modes of Asexual Reproduction
• Binary Fission — Parent splits into TWO equal parts
✏️Example
Amoeba, Bacteria (like Leishmania splits lengthwise)
• Multiple Fission — Parent splits into MANY parts
✏️Example
Plasmodium (malaria parasite)
• Budding — Small bud grows on parent, detaches and forms new organism
✏️Example
Hydra, Yeast
• Fragmentation — Body breaks into pieces, each piece grows into new organism
✏️Example
Spirogyra (algae)
• Regeneration — If an organism is cut, each part can grow into a full organism
✏️Example
Planaria, Starfish
• Spore Formation — Organisms produce spores that germinate into new plants
✏️Example
Rhizopus (bread mould), Ferns, Mosses
• Vegetative Propagation — New plants grow from roots, stems, or leaves
✏️Example
Potato (eyes/buds), Rose (stem cutting), Bryophyllum (leaf margin buds)
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TYPE 2: SEXUAL REPRODUCTION
TWO parents are involved (male and female). Gametes are formed — male gamete (sperm) and female gamete (egg/ovum). Fertilisation joins them to form a zygote. The zygote develops into offspring
💡Key Terms
• Gamete = Sex cell (sperm or egg)
• Fertilisation = Fusion of male and female gametes
• Zygote = Cell formed after fertilisation
• Internal Fertilisation — inside female body
✏️Example
Humans, Cow, Dog
• External Fertilisation — outside female body, in water
✏️Example
Frog, Fish
In Humans:
• Puberty in girls: Around 10–12 years. Menstruation starts.
• Puberty in boys: Around 13–14 years.
• Menstrual cycle = 28 days
• Gestation period (pregnancy) = 9 months (approximately 280 days)
• Fertilisation occurs in the Fallopian tube
• Implantation occurs in the Uterus
In Plants (Flowers):
• Stamen = Male part (produces pollen = male gamete)
• Pistil/Carpel = Female part (contains ovule = female gamete)
• Pollination = Transfer of pollen from stamen to pistil
• Self-pollination = Same flower or same plant
• Cross-pollination = Different plant of same species
• Fertilisation in plants forms SEED. Ovary becomes FRUIT.
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FORMULA BLOCK (Memory Aid):
Zygote = Male Gamete + Female Gamete
Fruit = Fertilised Ovary | Seed = Fertilised Ovule
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📊
Exam Patterns
What examiners ask — read before attempting PYQs
RRB Group D asks: Which organism reproduces by budding? / Where does fertilisation occur in humans? / What is the gestation period? / Vegetative propagation examples.
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SHORTCUT/TRICK:
Trick 1 — Remember Budding: 'HY-dra and Yeast = HY-5 = Budding Brothers'
Trick 2 — For plant parts: 'SiPF' = Stamen is Pollen (male), Pistil is Female
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✏️
Worked Example
Solve this step-by-step before moving on
1
Step 1
Bread mould = Rhizopus fungus
2
Step 2
Rhizopus produces tiny spore sacs called sporangia
3
Step 3
These sporangia burst and release spores into air
4
Step 4
Spores germinate in suitable conditions to form new mould
Answer: Spore Formation
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COMMON MISTAKE:
Students confuse Regeneration with Fragmentation. Remember — Fragmentation means the organism naturally BREAKS apart (like Spirogyra). Regeneration means an organism can REGROW from a cut piece (like Planaria). Also, many students think Yeast uses Binary Fission — it does NOT. Yeast uses BUDDING.
Test Reproduction under exam conditions
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Which of the following statements correctly describes the role of the placenta during human pregnancy?
Practice 2medium
During human reproduction, the fertilised egg (zygote) undergoes repeated cell divisions and develops into a blastocyst. At what stage does the blastocyst implant into the uterine wall?
Practice 3medium
During human reproduction, after fertilisation occurs in the fallopian tube, the zygote undergoes multiple mitotic divisions to form a ball of cells called a blastocyst. This blastocyst then travels to the uterus and gets implanted in the endometrium. After implantation, which of the following structures develops from the tissue that surrounds the embryo and helps in nutrient exchange between mother and fetus?
Practice 4hard
During human reproduction, the secondary oocyte completes meiosis II and forms a mature ovum only after which event occurs?
60-Second Revision — Reproduction
Remember: Asexual = 1 parent, no gametes, clones produced; Sexual = 2 parents, gametes fuse to form zygote.
Budding Duo: Hydra (animal) + Yeast (fungus) — do NOT confuse Yeast with Binary Fission.
Trap: Fertilisation in humans = Fallopian tube; Implantation = Uterus — exams swap these two locations.
Formula: Fruit = Ripened Ovary | Seed = Fertilised Ovule — direct MCQ answers in plant reproduction.