Notes of Chap 8
How Do Organisms Reproduce?
Covered Topics
- Introduction
- Modes of Reproduction
- Asexual Reproduction
- Sexual Reproduction
- Types of Asexual Reproduction
- Fission
- Fragmentation
- Regeneration
- Budding
- Vegetative Propagation
- Spore Formation
- Sexual Reproduction
- Sexual Reproduction in Plants
- Structure and Type of Flowers
- Reproduction in Human Beings
- Puberty Changes in Male and Female
- Male Reproductive System
- Female Reproductive System
- Fertilization of Eggs
- Reproductive Health
- Female Foeticide
- Why the Sexual Mode of Reproduction?
- Reproduction: The biological process in which new individuals "Offsprings" are produced from their parents called reproduction.
- Why do We Need to reproduce: It is important for the survival of all living beings on the earth. Without it, no one living things will exist longer on the earth.
- DNA(Deoxyribose Nucleic Acid): It is the heredity material that is found inside the nucleus of living things cells.
- Variation: Any difference between the two cells or two individuals due to replicating DNA materials is called variation. It is important for the survival of organisms as well as evolution.
- Methods by which organisms or individuals can reproduce is known as a mode of reproduction.
- Reproduction can be made through two modes
- (i) Asexual Reproduction (ii) Sexual Reproduction
- (i) Asexual Reproduction: Mode of reproduction in which a single individual or organism take participate in the formation of offspring or new individual is called asexual reproduction. It is useful for the rapid multiplication of organisms.
- > This mode of reproduction occurs in lower-class organisms.
- > In this mode of reproduction gametes are not formed.
- > Newly formed individuals are identical to their parents.
- The mode of reproduction in which two individuals( male and female) are required for the formation of new individuals or offspring is called sexual reproduction.
- > In this mode of reproduction gametes are form.
- > Newly formed individuals or organisms are similar but not identical to their parents.
- > This mode of reproduction adopted by higher class organisms.
- There are six types of asexual reproduction which is followings:
- 1. Fission
- 2. Fragmentation
- 3. Regeneration
- 4. Budding
- 5. Vegetative Propagation
- 6. Spore Formation
- The type of asexual reproduction in which the parent cell simply divides into daughter cells is called Fission.
- Types of Fission: There are two types of fission-
- (i) Binary Fission: Fission in which the parent cell divide into two daughter cells is called binary fission.
- Examples: Amoeba, Bacteria, Euglena
- (ii) Multiple Fission: Fission in which the parent cell divides into many cells is called multiple fission.
- Examples: Plasmodium, Chlamydomonas, Algae
- Asexual reproduction in which multicellular organisms splits into many pieces and each piece developed into a matured organism that is fully identical to their parents is known as Fragmentation.
- Examples: Spirogyra, Moulds, Lichens
- Asexual reproduction in which organisms replace or restore their lost body parts or if the organisms split into many pieces accidentally then it developed whole body part from each piece is called regeneration.
- Examples: Planaria, Leopard, Starfish
- Asexual reproduction in which a bud-like structure formed in the parent cell and detached from the parent cell after its maturation and living as an independent body is called budding.
- Examples: Hydra, Yeast, Jellyfish
- Asexual reproduction in which organisms reproduce through their stems, roots, and leaves under appropriate conditions is called vegetative propagation.
- Examples: Ginger, Onion, and Gladioli Reproduce through stems | Carrot, Radish and Turnip Reproduce through roots | Bryophyllum, Begonias and Piggyback Reproduce through leaves
- The Artificial Technique in Vegetative Propagation: Here are some technique which is used in vegetative propagation:
- Cutting: A technique of vegetative propagation in which portion of the stem, leaf, and root detached from the parent plant and induced to rooting and shooting in a proper medium is called Cutting. Examples: Rose, China Rose, etc.
- Grafting: A technique of vegetative propagation in which two different plants stem cutting portion attache to each other for most fruit production is called grafting. Example: Mangoes, Litchi, etc
- Layering: A technique of vegetative propagation in which plants stem buried into the soil layer and remain attached to the parent plant until the stem completely grows into the roots, this technique is known as layering. Examples: Climbing Rose, Myrtle, etc.
- Tissue Culture: A technique of vegetative propagation in which tiny fragments of plants are treated with plant hormones in a sterile growing medium. The hormones stimulate the growth of a callus, from which a new seedling can grow, such a technique is known as tissue culture or micropropagation. Examples: Pine, Banana, Date, etc.
- Asexual reproduction in which parents produce a large number of small units like spore(bulb-like structure) in non-flowering plants is known as spore formation. Examples: Moulds, Protozoa, Rhizopus, etc.
- Reproduction in which male and female two individuals are required to produce a new individual, during the reproduction, male and female gametes fused in the female reproductive organs is known as sexual reproduction.
- Examples: Bulls alone can't produce calves nor hens alone produce chicks. In such a case, both males and females are needed to produce a new generation.
- Gamete: It is a germ cell that is responsible for the formation of zygote. It has two types one is male gamete and another is female gamete.
- Male Gametes: Germ cell produced by male individuals is known as male gametes or sperm.
- Female Gametes: Germ cell produced by female individuals is known as female gametes or eggs or ova.
- Fertilization: During the reproduction process fusion of male gametes/sperm and female gametes/egg in the ovary to forming zygote is called fertilization.
- Zygote: The fertilized product of reproduction is known as a zygote.
- Sexual Reproduction in plant takes place in flower because it has a reproductive organ which is responsible for reproduction.
- Structure of Flower: A flower has mainly four whorls which are Sepal, Petal, Stamen, and Pistil.
- Flower: Reproductive organ of plants that is responsible for the bearing of seed and consists of reproductive organs (stamens and carpels) that are generally surrounded by a brightly coloured corolla (petals) and a green calyx (sepals) is known as the flower.
- Types of flower: There are two types of flower: (i) Bisexual Flower, (ii) Unisexual Flower
- (i) Bisexual Flower: The flower in which both male and female reproductive organ is present is known as a bisexual flower.
- (ii) Unisexual Flower: The flower in which either male or female reproductive organ is present is known as a unisexual flower.
- Pollination: The process of transferring pollen grains from anther to stigma by itself or by the help of wind, water and air is called pollination.
- Fertilisation Process in Plant's Flower: Pollen grains, produced in the anther, are transferred to the stigma of the same flower by self-pollination or stigma of another flower by cross-pollination through agents like animals, air or water. Pollen grains germinate and form pollen tubes that pass through style to reach up to the ovules present in the ovary. The fusion of male and female gametes is called fertilisation. The zygote is produced inside the ovary. The zygote divides to form the embryo. Ovule develops a thick coat and changes into seed gradually. Ovary changes into fruit and other parts of the flower fall off. Hence produced seed can used for germination again and again.
- Humans reproduce through the sexual mode of reproduction that's causes variation in human beings.
- Puberty: Sexual maturation period of life in which production of germs cell-like sperm in male and egg in the female start that period of maturation is known as puberty. Puberty usually occurs in girls between the ages of 10 to 14 years, while in boys it generally occurs between the ages of 12 to 16 years.
- Common Puberty Changes in Both Male and Female Changes like hair grow on your face, armpits and genital area. Your chest and shoulders get broader. You may have to swell around your nipples during puberty. Some smells are also coming out of your body.
- Puberty Changes in Male: Beard comes out on the face. Penis and testes become large. Voice begins to deeper.
- Puberty Changes in Female: Brest size starts to increase. Vagina, Uterus and Fallopian tubes will develop. Girls begin to menstruate.
- These changes usually occur between the ages of 10 to 21 years.
- The system which consists of many male reproductive organs like- Penis, Testes, Scrotum, etc is called the male reproductive system.
- Parts of The Male Reproductive System: These are the parts of the male reproductive system:-
- Seminal vesicle: The two small glands that associated with urethra and responsible for store and secrete semen and mix them with sperm through the urethra during the ejaculation of sperm is known as the seminal vesicles.
- Prostate gland: The gland that lies below the bladder and responsible for releasing the fluid components of semen and help to control urination.
- Penis: Erectile organ of the male reproductive system/copulation by which sperm and urine discharged from the body is known as the penis.
- Urethra: A Tube-like structure inside the penis that is responsible for the discharging of urine and sperm to the exterior side is called the urethra.
- Vas deferens: A thick tube-like structure that connects testis with urethra and responsible for the transferred sperm from the epididymis to ejaculatory duct and urethra, known as the Vas Deferens.
- Testis: The male sex organ located below the penis in oval-shaped in a pouch of skin and responsible for the production and storing of sperm is known as the Testis.
- Scrotum: A pouch of the skin or the muscular sac that contains and protects testicles, blood vessels, and spermatic cord parts is known as the scrotum.
- The system which consists of many female reproductive organs like- Ovary, Vagina, Uterus, etc is called the female reproductive system.
- Parts of The Female Reproductive System: These are the parts of the female reproductive system:-
- Oviduct or Fallopian Tube: A pair of slender ducts that are responsible for the transportation of ova from the ovary to the uterus for fertilization is known as the oviduct or fallopian tube.
- Ovary: The female reproductive organ that produces female gametes or eggs/ovals and also contains some sex hormones for the development of the female body to have a baby. After reaching the age of puberty one egg produced every month by one of the ovaries.
- Uterus/Womb: A hallow and inverted pear-shaped muscular structure in the female reproductive system located between the abdomen and the rectum is called the uterus. It is the place where all the development of the fetus takes place until the fetus becomes deliverable.
- Cervix: It is the narrow part of the uterus which enables sperm to enter into the uterus and getting out of waste material during the menstrual cycle, this narrow part is known as the cervix.
- Vagina: The elastic muscular canal with the mucous lined wall stretching from the cervix to the outer side is called the vagina. It is responsible for the recieve penis inside it and collect sperm for fertilization.
- The process of combining the eggs with the sperm in the uterus is known as fertilisation of eggs.
- When The Eggs Are Fertilised: When the sperms enter through the vaginal passage during sexual intercourse. Then they travel upwards and reach the oviduct where they encounter the egg. The fertilised eggs or zygote get implanted in the lining of the uterus and start dividing. After dividing the zygote get converted into the embryo. The embryo gets nutrition from the mother's blood by the help of placenta. This is a disc embedded in the uterine wall. The development of the child inside the mother's body takes approximately nine months to give out the childbirth.
- When The Eggs Are Not Fertilised(Menstruation/Period): When the eggs are not fertilised then it comes in the uterus. Due to the unfertilised eggs, the lining of the uterus becomes thick and spongy. But it does not survive any longer. So, the lining slowly breaks and comes out through the vagina as blood and mucus. This cycle roughly takes place every month that's why it is known as menstruation or Monthly Cycle(MC). It is also known as the period.
- When our body is ready for sex Physically, Mentally, Socially and Behaviourally then is said to be reproductive health.
- Diseases That Can Transmit Through Sex: Many diseases can be transmitted through sex that is:-
- (i) Bacterial Infection: Disease like Gonorrhoea and Syphilis can be transmitted from one person to another person through sex.
- (ii) Viral Disease: Disease like warts and HIV-AIDS can be transmitted from one person to another person through sex.
- Precaution To Protect Yourself From These Diseases: To protect from such types of disease use the condom or coper-T.
- Contraception: The process of preventing pregnancy through the artificial method or other methods by preventing ovulation, fertilisation, implantation is known as contraception. Following methods can be used for contraception:-
- (i) Barrier Methods: The Method of contraception in which we prevent sperm to reach the eggs by condoms or diaphragm is known as a barrier method.
- (ii) Medicinal Method: The method of contraception in which we used pills or drugs to avoid fertilisation by unbalancing realising of eggs is known as a medicinal method.
- (iii) Intrauterine Contraceptive Device Method(IUCD): The method contraceptive in which we blocked the uterine by the Copper-T is known as IUCD.
- (iv) Surgical Methods: The method of contraception in which we blocked Vas Deferens in the male by vasectomy to prevent the releasing of sperm and in female, blocking the oviduct or fallopian tube by tubectomy to prevent the releasing of eggs by surgery is called surgical method.
- The act of killing the child inside the mother's womb or uterus is called female foeticide. It is illegal in India. We should avoid female foeticide for the balanced sex ratio in our country.
- The creation of two new cells from one involves copying of the DNA as well as of the cellular apparatus. The DNA copying mechanism cannot be absolutely accurate and the resultant errors are a source of variations in the population of organisms. Every individual organism can not be protected by variations, but in a population, variations are useful for ensuring the survival of the species. It would, therefore, make sense of organisms came up with reproductive modes that allowed more and more variation to be generated. That's why Sexual Mode of Reproduction is useful.
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