NCERT Formulas Class 10 Science Chapter 7 How do Organisms Reproduce

🧬 Modes of Asexual Reproduction

Single parent involvement without gamete fusion. Key methods follow this logic:

1. Fission (Amoeba): 1 Parent $\rightarrow$ 2 Daughter Cells (Binary)

2. Fragmentation (Spirogyra): Body part $\rightarrow$ New Organism

3. Regeneration (Planaria): Cut pieces $\rightarrow$ Complete Organism

4. Budding (Hydra): Outgrowth $\rightarrow$ Detachment $\rightarrow$ New Life

🌸 Sexual Reproduction in Plants

The journey from a pollen grain to a seed involves specific biological steps.

↔ Swipe to view fertilization pathway

$$\text{Pollen (Stigma)} \rightarrow \text{Pollen Tube (Style)} \rightarrow \text{Male Gamete + Female Gamete (Ovule)} \rightarrow \text{Zygote} \rightarrow \text{Embryo} \rightarrow \text{Seed}$$

🩸 The Menstrual Cycle

A monthly cycle involving the thickening of the uterine lining and its subsequent shedding if fertilization does not occur.

Cycle Duration: ~28 Days

Ovulation Phase: Mid-cycle (Release of egg)

If No Fertilization: Lining breaks $\rightarrow$ Blood/Mucus flow (2–8 days)

[Image of the phases of the menstrual cycle]

🔢 Chromosome Math

Biological “halving” ensures the constant chromosome number across generations.

$$\text{Male Gamete (n)} + \text{Female Gamete (n)} \xrightarrow{\text{Fertilization}} \text{Zygote (2n)}$$

(Where ‘n’ is the haploid number of chromosomes)

🛡️ Population Control Mechanisms

Methods to prevent unwanted pregnancies, categorized by their mechanism of action:

1. Mechanical Barrier: Condoms, Diaphragms (Prevent Sperm-Egg contact)

2. Chemical: Oral Pills (Hormonal balance change – prevent egg release)

3. IUCDs: Copper-T (Placed in Uterus to prevent implantation)

4. Surgical: Vasectomy (Males) and Tubectomy (Females)