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how do organisms reproduce class 10 notes

How do organisms reproduce class 10 notes

Organisms reproduce in two ways to continue the chain of their population. The two modes of reproduction in organisms are Asexual and Sexual. Here, How do organisms reproduce class 10 notes provides you with proper notes that you can follow to achieve good marks in your CBSE examination.

How do Organisms Reproduce?

The organisms reproduce in two modes –

  1. Asexual reproduction – It is the mode in which only a single parent is involved without forming gametes.
  2. Sexual Reproduction – It is the mode in which two parents are involved with the formation of gametes.

Asexual reproduction

  • Single Parent is involved.
  • No formation of gametes takes place.
  • It is a faster method than sexual reproduction.
  • Offsprings are identical to each other as well as to the parent.
  • It can be performed only in favorable conditions.

Types Of Asexual Reproduction -

  1. Fission
  2. Budding
  3. Vegetative Propagation
  4. Regeneration
  5. Spore Formation
  1. Fission – This is the method that is performed in most unicellular organisms. it is of two types:
  • Binary Fission: In this process, the mother cell gets divided into two daughter cells, each containing a nucleus. This process is only performed when a favorable amount of moisture and food is available. Example – Amoeba
  • Multiple Fission: In this process, a cist is formed around the organism that allows the nucleus to divide into daughter cells, each surrounded by a membrane. When the favorable condition is achieved the daughter cells are released which later develop into an individual. example – Entamoeba and plasmodium

2. Budding: In this process, the nucleus of the mother cell divides and one of them moves into the outgrowth which grows bigger and finally separates from the parent cell to lead an independent existence. Example – Yeast.

3. Vegetative Propagation:  In this process, a new plant grows from the fragments of the parent. The offspring are the exact clones of the original plant.

Common methods of vegetative propagation are cutting, grafting, layering, tissue culture(artificial), etc.

4. Regeneration:  It is basically the ability of an organism to redevelop its lost body parts. Organisms having a high capability of regeneration performs this for the reproduction process. Example – Planaria.

5. Spore Formation: In this process, a knob-like structure called sporangium is formed by an organism. This happens when a sufficient amount of food and moisture is present in unfavorable conditions. when the conditions become favorable, they begin to grow. Example – Rhizopus ( a fungus)

Sexual Reproduction

It is the mode of reproduction which requires the involvement of two parents of opposite sexes (male & female).

During the process, the male produces male gametes called sperm and the female produces female gametes called ova. These gametes fuse together to form a zygote that later on develops into an individual.

What is the significance of sexual reproduction?

  • It involves DNA as well as the cellular apparatus of two different organisms which promotes the diversity of characters in the offspring.
  • Since gametes are derived from two different organisms, it results in a new combination of genes which increases the chances of genetic variations.
  • It results in the origin of. new species.
  • It involves division in the sex organs that reduces the DNA matter to half so that the zygote formed after fusion has the same amount of DNA as the parents it maintains DNA in a species.

What is the limitation of sexual reproduction?

This mode of reproduction involves the combining of the DNA of two different individuals which can sometimes result in undesirable outcomes.

Sexual reproduction in flowering plants

The Stamen is the male reproductive part of the flower. It has 2 parts,  Anther produces pollen grains containing male gametes, and Filament a swollen top part that contains a large number of pollen grains.

The carpel is the female reproductive part. It has three parts—Stigma which is the top sticky part that receives pollen grains during pollination,  The style is the middle long part and the ovary which is the swollen part that contains ovules. Each ovule has an egg cell i.e. female gamete.

The Sepals are green structures that protect the inner parts of the flower when it is bud.

The Petals are colorful and attract insects for pollination.

Note: A flower can be unisexual or bisexual.

Pollination

It is the process that involves the transfer of pollen grains from the anther to the stigma. It is of two types –

  • Self-pollination: The transfer of pollen grains from the anther to the stigma of the same flower or another flower of the same plant.
  • Cross-pollination: The transfer of pollen grains from the anther to the stigma of another flower or another flower of a different plant of the same species. It generally takes place with the help of some agents like insects, birds, wind, and water.

Fertilization

It is the process of formation of a zygote by the fusion of male and female gametes. This is the next stop after pollination in flowering plants.

Post-fertilization changes: After fertilization, the following changes take place in the flower.
The zygote divides several times and forms an embryo inside the ovule.

  • The ovule develops a tough coat and changes into a seed.
  • The ovary grows rapidly and ripens to form a fruit.
  • Petals, sepals, stamens, style, and stigma shrivel and fall off.

The embryo has two parts: the plumule and the radicle. Plumule develops into the shoot and the radicle develops into a root.
The process of development of a seedling from the embryo under appropriate conditions is known as germination.

Reproduction in Human Beings

Human beings show sexual reproduction. The male parent produces sperm. Female parent produces ova. Sperms have tails and are, therefore, motile. They are produced in large numbers in the testes. The ovum is bigger and non-motile and only one ovary produces one ovum in one month. There is no food stored in the sperms whereas ova contain stored food. Both the gametes are microscopic unicellular and have half the number of chromosomes as compared to the body cells.

Male Reproductive system

The male reproductive system consists of the following-

  • 1 pair of testes
  • A system of ducts
    • Epididymis
    • Vas deferens or the sperm duct
    • Urethra
  • A system of glands
    • Seminal vesicles
    • Prostrate gland
    • Cowper’s gland
  • A copulatory organ is called a penis.

What is the function of Testis?

Ans- The Functions of Testis are:

  1. It produces sperm.
  2. It produces the male reproductive hormone called testosterone.

What is the function of vas-deferens?

Ans- It provides passage for sperm in the human male body.

What is the function of urethra?

Ans- It provides common passage to sperm and urine in the human male body.

Penis

Ans- It is a special organ in males that are used to introduce semen into the female body.

Female Reproductive System

 It consists of the following:

  • 1 pair of ovaries
  • 1 pair of fallopian tubes or oviducts
  • A uterus/womb
  • A vagina/birth canal.

What is the function of the ovary?

Ans- It is used to –

  1. produce egg or ova.
  2. Produce the female reproductive hormones: Estrogen and progesterone.

Note: There are two fallopian tubes in the female body. The end lying close to the ovary has finger-like structures called fimbriae. The two fallopian tubes unite to form an elastic bag-like structure called the uterus. The inner lining of the uterus is richly supplied with blood vessels and is known as the endometrium. The narrow end of the uterus is called the cervix.

What is the function of fallopian tubes?

Ans- It provides the site for fertilization of the formation of the zygote.

What is the function of the Uterus?

Ans- The embryo formed in the fallopian tube after fertilization, comes down and gets attached to the endometrium (implantation) and develops for the next nine months till the baby is delivered.

Vagina

It is a muscular tube through which the baby is delivered at the end of nine months after fertilization.

It also serves as a canal for receiving semen during copulation.

What is Foetus?

Ans- When the embryo develops and starts resembling, a human structure is formed, it is termed  foetus.

Menstruation

Ans It is basically the loss of blood, and mucous along with the unfertilized ovum and the ruptured cells and tissues of the endometrium through the vagina of the female

The flow of blood continues for 2 to 8 days. If the ovum does not get fertilized, then the endometrium starts sloughing off and there is loss of blood and mucous, etc. through the vagina. In case the ovum gets fertilized, then the endometrium becomes thick and spongy for nourishing the embryo and hence menstruation does not occur.

Note:  The beginning of menstruation at puberty is known as menarche. The stoppage of menstruation when the woman is 45-55 yrs of age is called menopause.

Reproductive Health

Everyone must take care of some important health measures while having intercourse. A number of diseases occur as a result of sexual intercourse if one of the partners is infected. These are known as sexually transmitted diseases (STDs)

They can be caused by bacteria for example; syphilis, gonorrhea; or caused by a virus for example; HIV-AIDS, warts, etc

Birth control measures

These are processes or methods to stop unwanted pregnancy. They can be mechanical, chemical, and surgical.

Mechanical methods: 

  • using Condoms
  • Using Diaphragm
  • Using Intra Uterine Contraceptive Device (IUCD)

Chemical methods:

  • Use of spermicides: These are strong sperm-killing chemicals available in the form of creams, jellies, etc. which are injected into the vagina just before copulation.
  • Oral contraceptive pills: These are hormonal pills that prevent ovulation but do not stop menstruation. eg – i-pill

Surgical methods:

  • Vasectomy: It involves cutting and ligating the vas deferens in males.
  • Tubectomy: It involves cutting and ligating Reproductive organs the fallopian tubes in females.
  • Medical termination of pregnancy (MTP) or abortion is carried out to eliminate the developing embryo. This practice can, however, be misused to carry out female foeticide which involves the killing of the female foetus. It should be avoided at all costs as it disturbs the male-female ratio in a population.

QUESTIONS?

How do organisms reproduce?

Ans- Organisms reproduce in two ways to continue the chain of their population. The two modes of reproduction in organisms are Asexual and Sexual Reproduction.

What is Budding?

Ans- This is a type of asexual reproduction in which the nucleus of the mother cell divides and one of them moves into the outgrowth which grows bigger and finally separates from the parent cell to lead an independent existence. Example – Yeast.

What are the different modes of asexual reproduction?

Ans-

  1. Fission
  2. Budding
  3. Vegetative Propagation
  4. Regeneration
  5. Spore Formation

Define sexual reproduction.

Ans- It is the mode of reproduction which requires the involvement of two parents of opposite sexes (male & female).

What is Pollination?

Ans- It is the process that involves the transfer of pollen grains from the anther to the stigma. It is of two types – self-pollination and cross-pollination.

What is Contraception?

Ans- It is the process of avoidance of pregnancy through different methods—Natural methods, Barrier methods, Oral contraceptives, and Surgical methods.

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Class 10 Science Important Questions

Class 10 Science Notes

Chapter 1
Chemical reaction And Equation
Chapter 2
Acid, Bases, And Salt
Chapter 3
Metals And Non- Metals
Chapter 4
Carbon And Its Compounds
Chapter 5
Periodic Classification Of Elements
Chapter 6
Life Processes
Chapter 7
Control And Coordination 
Chapter 8
How do organisms reproduce?
Chapter 9
Heredity and Evolution
Chapter 10
Light Reflection and Refraction
Chapter 11
Human eye And Colourful World
Chapter 12
Electricity
Chapter 13
Magnetic Effects And Electric Current
Chapter 14
Sources of Energy
Chapter 15
Our Environment
Chapter 16
Sustainable Management of Natural Resources

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