Sexual Reproduction In Animals

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – BIOLOGY

SEXUAL REPRODUCTION IN ANIMALS Gamete: – Sex Cells The cells involved in sexual reproduction are called gametes. Gametes are of 2 types n = no. of chromosomes

(i) Male Gamete / Sperm (ii) Female gamete/Ovum/Egg

Zygote: – The cell which is formed by fusion of male gamete & female gamete is called zygote 2n = no. of chromosemes. Fertilization: – The fusion of a male gamete with a female gamete to form a zygote during sexual reproduction is called fertilization. It gives rise to an embryo It is of 2 types Internal fertilization: -

(occurs inside the female body – mammals, reptitis, birds)

External fertilization: -

(occurs outside the female body – fish – amphibians)

Unisexual organisms: – The organisms which posses only one kind of reproductive organs (male/female) in its body is called unisexual organisms. e.g. Human beings, Frogs,

Birds

Bisexual Organisms: – The organisms which posses both male & female sex organs in the body are called Bisexual organisms/Hermaphrodites e.g. Earthworm, Tapeworm, Leech, Starfish They can behave both as a male & female. Advantages of Sexual Reproduction:– 1.

Because of combination of the characters of 2 parents all the offspring’s have genetic variation.

2.

It leads to variety in population.

3.

It also leads to individuality.

4.

Sexual reproduction promotes Diversity of characters by providing genetic variation.

5.

It play imp. Role in orgin of new species

6.

Genetic variation leads to evolution.

STEPS____________________________________________________________ 1 Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T C Y P r og r am _______________________________________________________________________________________ LECTURE NOTES – BIOLOGY

MODE OF SEXUAL REPRODUCTION ↑ O Male body

O female body +

gonads

Primary sex organs / gonads

meiosis

meiotic division

Ovaries

Testes

Ovum (n)

(gamete) Sperm (n)

Fertilization

Zygotic formation

embryo

foetus

newborn baby HUMAN REPRODUCTIVE SYSTEM Puberty The age at which the sex hormones begin to be produced and the person becomes sexually active/nature (gonad production starts) is able to reproduce is called puberty. Puberty starts earlier in famels (10 – 12 yrs) than in males (13 – 14 yrs) The tests produce male sex hormone Testosterone ovaries produce female sex hormone Estrogen & Progestrone.

2 STEPS____________________________________________________________ Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – BIOLOGY

Functions of sex hormones 2.

Control the process of gametogeneis Maintains the structure & function of accessory sex organs. Primary sex organs

=

Accessory sex organs = 3.

Testes & ovaries. Penis, Seminal vesicles, Vagina, uterus, Fallopian tubes

Develop the secondary sex characteristics e.g. Low pitch voice Growth of hair on chest Growth of mostaches, beard

in males

Growth of public hair Development of muscles High pitch voice Growth of hair in armpits

in females

Growth of public hair Development of Mammory glands

FEMALE REPRODUCTIVE SYSTEM

Sperm

SITE FOR FERTILIZATION Fallopian Tube (oviduct) •

UTERUS

Implantation

1.

Released Egg Ovary (ovum) Cervix

vagina

STEPS____________________________________________________________ 3 Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T C Y P r og r am _______________________________________________________________________________________ LECTURE NOTES – BIOLOGY

Female reproductive system (Humans)

Seminal vesical Urinary bladder

VASDEFERENS (Sperm Duct.) URETHRA

EPIDIDYMIS TESTIS Outside the body

Made Reproductive Organ System Menstruation/Mentrual Cycle 1.

When a girl reaches puberty, the sex hormones released into blood cause some ova in her ovaries to become mature.

2.

Usually one mature egg is released from ovary into the fallopian tube once every 28 days. This is called ovulation

3.

Before ovulation the inner living of uterus becomes thick & full of blood vessels to prepare itself to receive fertilized egg.

4.

But if the ovum does not get fertilized then the thick & soft inner lining breaks. So the thick, soft inner lining of uterus & blood vessels & dead ovum comes one of vagina in the form of blading called neutruation.

5.

Menstruation occurs 14 days after ovulation & lasts for 3-5 days The menstrual cycle is controlled by hormones if menstruation stopes (ovum gets fertilizes), the woman gets pregnant.

Menarche: The beginning of menstruation at puberty is called menarche it sets in at the age of puberty. It marks the beginning of reproductive life of a woman. Menopause: The age at which the menstrucation stops & woman becomes intertile is called menopause it occurs in woman at the age 45 – 50. Fertilization in Humans In humans, INTERNAL fertilization takes place. The sperms made in the tests of man are introduced into the vagina of woman thru penis during copulation. Millions of sperms are released into the vagina at one time. The sperms move up thru cervix into the uterus & from there to the fallopian tubes.

4 STEPS____________________________________________________________ Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – BIOLOGY

One of the fallopian tubes contains an ovum released by the ovary during ovulation. Only one sperm fuses with the ovum in the fallopian tube to form a ZYGOTE. After the fertilization the woman it called pregnant. As soon as pregnancy begins, the menstruation stops. The Zygote (formed in the fallopian tubes), starts dividing rapidly & is called an EMBRYO which gets embedded in the thick lining of uterus. This called IMPLANTATION. The time period from the fertilization upto the birth of the body is called gestation. The gestation period in humans is 280 day = 40 wks. The process of the birth/moving out of baby thru birth canal is called PARTURITION/LABOUR. POPULATION / BIRTH CONTROL Birth Control Methods/Contraceptives 1.

Barrier Methods •

Condoms

•

Diaphragm (Femals)

2.

Chemical Methods

3.

Surgical Methods

Oral pills (OC) Æ (For females) oral contraceptives Vaginal pills Tubectomy ( O ) +

↑

Vasectomy ( O ) 4.

IUCDs (Intra uterine Contraceptive Devices) Copper – T

STD (Sexually Transmitted Diseases) 1.

Genorrhoea

2.

Syphilis

3.

Trichomonaisis

4.

AIDS

AIDS A sexually Transmitted Disease. Acquired Immuno Deficiency Syndrome Consative Agent:

HIV

Symptoms:

(i)

Body becomes weak

(ii)

Immune system of body weakens to defend itself from other

A virus Æ Human Immunodeficency Virus

diseases. (iii)

Weak memory with severe headaches

(iv)

Vomiting, Bodyache.

STEPS____________________________________________________________ 5 Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T C Y P r og r am _______________________________________________________________________________________ LECTURE NOTES – BIOLOGY

Prevention: Preventive Measure include 1.

Using contraceptives

2.

Safe sex

3.

Using fresh, disposable syringes

Cure: No Definite cure has been found.

6 STEPS____________________________________________________________ Get free chapterwise tests for Class Xth on www.tcyonline.com