Page 155 - Class 10 Biology Chapter How do Organisms Reproduce Notes

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Chapter : How do Organisms Reproduce

🖊 Reproduction :- The production of new organisms from the existing organisms of the same species is known as reproduction.

There are two types of reproduction

1. Asexual Reproduction : Modes of sexual reproduction used are binary fission, 

multiple fission, Budding, spore formation, regeneration, vegetative propagation, tissue 

culture, fragmentation

2. Sexual Reproduction : In sexual reproduction, a male gamete (germ cells) fuses with a 

female gamete to form a new cell called ‘zygote’. This zygote then grows and develop into a 

new organism in due course of time.

🖊 Fertilization. :- When male gamete and female gamete fuse, they form a zygote and the process is known as fertilization.

There are two types of fertilization :-
1. External fertilization 
2. Internal fertilization.

🖊 Sexual Reproduction in Flowering Plants :

Flower is meant essentially for sexual reproduction.

• Pollination is the process in which pollen grains are transferred from the anther to stigma 

of the carpel. It is of two types self pollination and cross-pollination.

• In the fertilization process primary endospermic nucleus is formed.

• After the fertilization process, ovary developes into the fruit whereas ovules into the 

seed.

🖊 Reproduction in Human Being
The sex organ in males are testes and ova in females.

• Male reproductive organ consist of a pair of testes, vas deferens, a pair of epididymis, a 

pair of ejaculatory duct, urethra, pairs of accessory gland.

• Female reproductive part consist of a pair of ovaries, a pair of fallopian tube, 

uterus, vagina, external genitalia, mammary glands and accessory glands. Ovary 

produces the female gametes (eggs or ova) and female sex hormone (estrogen).

• If sperms are present, fertilization of ovum takes place in the upper end of the 

fallopian tube.

• Bleeding accompanied by discharge of soft tissue lining the reproductive tract 

is menstrual flow. It last for 3-5 days.

• Secretory phase lasts for 12-14 days.

• Fertilization process occurs in fallopian tube. In this process zygote is formed. In this 

process umbilical cord is produced which is attached to foetus. During this

• process two hormones are produced which are estrogen and progesterone.

• Progesterone stops menstruation and prevents ovulation. The placenta protects the body 

against diseases. Due to contraction of uterine muscles young one is expelled and the 

phenomenon is called parturition.

• If the egg is not fertilized, it lives for about one day. Since the ovary releases one 

egg every month, the uterus also prepares it self every month to recieve a fertilized egg.

• After the age of 45-50 years menses stop and process is called menopause.

• Fertility control can be done chemically, mechanically or surgically.

🖊 Reproductive Health Barrier methods

(i) Mechanical barrier method:- They prevent contraception by preventing either sperms from 

entering uterus or preventing implantation if fertilization has occurred.

The instruments are condom, cercival cap, diaphragm & ICDU method.

(ii) Hormonal method: They are used by women for suppressing the production of ovum. i.e. , 

oral pills, Implants morning after pills.

(iii) Chemical contraception: They are creams, jellies and foaming tables which are placed in 

vagina for killing the sperms at the time of coitus.

(iv) Surgical techniques:—

(a) Vasectomy: — The two vasa deferential of the male are blocked by cutting a small piece of 

tying the rest. This prevents the passage of sperms from testes to semen.

(b) Tubectomy:— A portion of both the fallopian tubes is excised to ligated to block the 

passage of ovum

🖊 Sexually Transmitted Diseases (STDs)

It is a group of infections caused by different types of pathogens that are transmitted by sexual 

contact between a healthy person and an infected person. The sexually transmitted diseases are 

also called venereal diseases (VDs). Some 30 different types of STDs are known. Fol example : 

Gonorrhea, Syphilis, Trichomonas, Genital warts, AIDS.

Dear Asif Sir