How do organisms reproduce Class 10 Notes: Reproduction is a basic life process. It ensures the continuation of the species from one generation to the next.
These notes provide a clear overview of reproduction. They explain its importance for life on Earth. Students will find these how do organisms reproduce class 10 notes helpful. This chapter is essential for understanding life science.
How do Organisms Reproduce Class 10 Notes
How do organisms reproduce class 10 notes help students in their board exam. Reproduction is the process by which living organisms produce new individuals.
These new individuals are of the same species. It is crucial for species continuity.
Variation
No two individuals are exactly alike because of variation. During reproduction, DNA copying takes place.
This process is not completely accurate, which leads to small changes in the DNA sequence. These changes are called variations.
Importance of Variation
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Survival: Variations help organisms adapt to changing environments (e.g., bacteria developing resistance to heat or antibiotics).
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Evolution: Accumulation of variations over many generations leads to the formation of new species.
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Stability: Variation ensures stability of a species by increasing its chances of survival in adverse conditions.
Asexual Reproduction
A single parent creates new individuals in asexual reproduction. No gametes are involved. No fertilisation occurs. Offspring are usually genetically similar to the parent.
1. Fission
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Binary Fission: A single cell divides into two identical cells.
Examples: Amoeba, Leishmania -
In Leishmania, division occurs in a specific orientation due to its whip-like structure.
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Multiple Fission: A single parent cell divides into many daughter cells at the same time.
Example: Plasmodium (malarial parasite)
2. Fragmentation: In simple multicellular organisms like Spirogyra, the parent body breaks into smaller fragments. Each fragment grows into a complete organism.
3. Regeneration: If an organism is cut into pieces, each piece can grow into a complete organism using specialised cells. Examples: Hydra, Planaria
4. Budding: A small outgrowth called a bud forms due to repeated cell division at a specific site. The bud grows, matures, and eventually detaches.
Examples: Hydra, Yeast
5. Vegetative Propagation
New plants are produced from vegetative parts like roots, stems, or leaves.
Types:
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Natural:
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Leaves (Bryophyllum – buds along leaf margins)
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Roots and stems
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Artificial:
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Layering
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Grafting
Advantages:
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Plants flower and fruit earlier
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Useful for seedless plants like banana and orange
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Produces plants identical to parent
6. Spore Formation: In fungi like Rhizopus (bread mould), thick-walled spores form inside sporangia. When released on moist surfaces, they grow into new hyphae.
Sexual Reproduction
Two parents are involved in sexual reproduction. It includes gamete formation and fertilization. Offspring are genetically dissimilar from parents.
Cell Division:
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Mitosis: Occurs in somatic cells. Maintains chromosome number. Produces two diploid daughter cells. Important for growth and repair.
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Meiosis: Occurs in sexual cells. Halves the chromosome number. Produces four haploid daughter cells. Essential for gamete formation.
Sexual Reproduction in Flowering Plants
Flowers are the reproductive organs of plants.
Flower Parts:
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Stamens (Male Part): Produce pollen grains. Each stamen has an anther and a filament.
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Pistil/Carpel (Female Part): Consists of stigma, style, and ovary. Ovary contains ovules with egg cells.
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Pollination: Transfer of pollen grains from anther to stigma.
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Self-Pollination: Pollen transfers within the same flower.
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Cross-Pollination: Pollen transfers between different flowers.
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Fertilization: Fusion of male and female gametes. Pollen lands on the stigma and grows a tube. Male germ cells travel to the ovule. One male germ cell fuses with the egg cell to form a zygote. The other fuses with polar nuclei.
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Post-Fertilization Changes: The Zygote develops into an embryo. An ovule develops into a seed. The ovary develops into a fruit. Other flower parts wither.
Sexual Reproduction in Human Beings
Humans reproduce sexually.
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Puberty: Reproductive tissues mature. This phase occurs during adolescence.
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Changes During Puberty:
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Common: Hair growth in armpits and genital areas, oily skin, pimples.
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Boys: Thick facial hair, voice deepens, penis enlarges.
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Girls: Breast size increases, menstruation starts.
Male Reproductive System
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Testes: The testes produce sperm and the hormone testosterone, which is responsible for male secondary sexual characteristics such as deep voice and facial hair. They are located in the scrotum outside the body to maintain a lower temperature required for proper sperm production.
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Vas Deferens: The vas deferens is a long muscular tube that transports sperm from the testes to the urethra. It also serves as a temporary storage site for sperms until ejaculation occurs.
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Urethra: The urethra is a common passage for both urine and semen, but they do not pass at the same time. During ejaculation, the flow of urine is temporarily blocked to allow semen to pass.
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Glands (Seminal Vesicles and Prostate Gland): These glands add fluids to semen that provide nutrition (fructose) to sperms and protect them from the acidic environment of the female reproductive tract. The fluid also helps in improving sperm movement.
Female Reproductive System
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Ovaries: Ovaries produce eggs (ova) and release the hormones estrogen and progesterone. These hormones regulate the menstrual cycle, control puberty-related changes, and support pregnancy.
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Oviducts (Fallopian Tubes): The fallopian tubes carry the egg from the ovary to the uterus. Fertilization occurs in the oviduct, where the sperm fuses with the egg.
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Uterus: The uterus is a muscular organ where the fertilized egg implants and develops into an embryo. Its lining thickens every month to prepare for pregnancy and sheds if fertilization does not occur.
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Vagina: The vagina is a muscular canal that receives sperm during sexual intercourse. It also acts as the birth canal and allows menstrual blood to pass out of the body.
Fertilization: Sperm meets egg in the oviduct. The fertilized egg (zygote) implants in the uterus.
Placenta: A disc in the uterine wall. Provides nutrients and oxygen to the embryo. Removes waste.
Menstruation
If the egg is not fertilized, the thick, spongy lining of the uterus (prepared to nourish an embryo) breaks down and is discharged through the vagina as blood and mucus. This cycle occurs roughly every 28 days
Reproductive Health and Contraceptive Methods
Reproductive health involves preventing STDs and unwanted pregnancies.
Physical Barriers: Condoms, diaphragms.
These methods physically block sperm from reaching the egg, thus preventing fertilisation. Condoms are the only contraceptive method that also protects against STDs, including HIV/AIDS. They are easy to use, affordable, and have no hormonal side effects.
Hormonal Barriers: Oral contraceptive pills.
These pills change the hormonal balance in the female body to prevent ovulation (release of an egg). They also make the uterus unsuitable for implantation. Regular intake is necessary for effectiveness, and they do not protect against STDs.
Intrauterine Devices (IUDs): Copper-T.
Copper-T is placed inside the uterus by a doctor and prevents implantation of the embryo. Copper also reduces sperm activity. It provides long-term protection and is a reliable, reversible method but does not prevent STDs.
Surgical Methods: Vasectomy (males), Tubectomy (females).
These are permanent methods of contraception where gamete transfer is blocked surgically. Vasectomy blocks the vas deferens, while tubectomy blocks the fallopian tubes. These methods are highly effective but irreversible and do not protect against STDs.
How Do Organisms Reproduce Class 10 Notes PDF
How do organisms reproduce notes provide a clear and structured explanation of reproduction as an essential life process that ensures the continuity of species.
These notes cover the importance of variation, types of reproduction such as asexual and sexual reproduction, reproduction in plants and humans, reproductive health, and contraceptive methods.
Designed as Class 10 exam-oriented study material, the how do organisms reproduce class 10 notes pdf help students understand concepts easily and revise key topics efficiently for CBSE board preparation.
How Do Organisms Reproduce Class 10 Notes PDF
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