Diversity in living Organisms
1. The production o
f new organisms from the
existing organisms ofthe same species is
known
as reproduction.
2. Asexual Reproduction :
Modes of sexual
reproduction used are binary fission,
multiple
fission, Budding, spore formation, regeneration,
vegetative propagation, tissu
e
culture,
fragmentation
3. 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.
When male game
te and female gamete fuse,
they form a zygote and the process is known
as
fertilization.
Fertilization is of two types :
-
External
fertilization and Internal fertilization.
4. 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.
5. Reproduction in Human Being :
The sex organ
in males are testes and ova in females.
Male reproductive organ consist of a pair
of testes, vasdeferens, 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 l
ast 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 mensturation 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 i
s 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 contro
l can be done chemically,
mechanically or surgically.
6. Reproductive Health
Barrier methods
(i) Mechanical barrier method:
-
They prevent
contraception by preventing either sperms
from
entering uterus or preventing
implantation if fertilization has occurre
d.
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, jelli
es 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
passag
e 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
7. Sexually Transmitted Diseases (STDs)
It is a group of infections caused by different
types of pathogens that are t
ransmitted 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 :
Gonorrhoea, Syphilis, Trichomonas,
Genital war
ts, AIDS.
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