Core ConceptRead this first — the foundation of the topic
There are two main types
Asexual Reproduction and Sexual Reproduction.
---
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)
---
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.
---
Formula BlockMemorise — at least one formula appears in every paper
(
Memory HookRemember this — never confuse the two again
):
Zygote = Male Gamete + Female Gamete
Fruit = Fertilised Ovary | Seed = Fertilised Ovule
---
Exam PatternsWhat 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.
---
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
---
Worked ExampleSolve this step-by-step before moving on
Question: Bread mould reproduces by
When to UseQuickly decide which method to apply in the exam
?
Step 1: Bread mould = Rhizopus fungus
Step 2: Rhizopus produces tiny spore sacs called sporangia
Step 3: These sporangia burst and release spores into air
Step 4: Spores germinate in suitable conditions to form new mould
Answer: Spore Formation
---
Exam TrapsCommon mistakes students make — avoid these
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.
Key Points to Remember
Asexual reproduction involves ONE parent; offspring are genetically identical (clones) to the parent.
Binary fission = splitting into 2 equal halves — Amoeba and Bacteria; Multiple fission = many parts — Plasmodium.
Budding occurs in Hydra (animal) and Yeast (fungus) — a small bud forms and detaches.
Spore formation occurs in Rhizopus (bread mould), Ferns, and Mosses.
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.