1. How do Organisms
Reproduce?
Class X- Science-Chapter 8 Biology
by Eswari Kumaravel M.Sc., M.Phil., B.Ed.

2. Reproduction
• Living organisms produce new individuals of their
own kind and maintain their existence generation
after generation.
• This process is called as Reproduction.
Importance of Reproduction:
• Continuation of life on Earth
• To maintain the size of the population
• Transfer of variation from one generation to another.

3. Reproduction – Basic Steps
• DNA in the cell nucleus is the
information centre for making
protein
• The first step in reproduction
is replication of DNA followed
by cell division.
• Variations happen during
copying of DNA.
• These variations are the basis
of evolution.
• Variations are useful for the
survival of species over time.

4. Importance of DNA copying in Reproduction
• DNA Copying:
o Organisms pass on their
characteristics to their
offspring.
• Importance of DNA Copying:
o Maintains characteristics
in different generations.
o DNA is the blueprint and it
ensures correct body
design.
o Any change in it causes
change in synthesis of
proteins and in turn body
design. i.e. it will cause
variation.

5. Variation is Beneficial for the Species
• Variation – Change in body design of an individual
• It allows organisms to adapt and exist in diverse habitat
or niches.
• Small variations or variations over time, will help the
species in its survival in different conditions.
• However, drastic variation in a single individual will affect
its chance of survival.
• It is the basis of evolution.

6. Types of Reproduction
• There are two types of reproduction namely (a)
Asexual reproduction and (b) Sexual reproduction
Asexual Reproduction Sexual Reproduction
New individual is produced
from a Single parent
New individual is produced
from two parents
It does not involve union of
gametes
Involves union of gametes.
Younger ones are genetically
identical to the parents
Younger ones are not
genetically identical to the
parents
Variations are absent Variations are present

7. Various Types of Asexual Reproduction
• Types of Asexual Reproduction
o Fission
o Budding
o Fragmentation
o Regeneration
o Vegetative Propagation
o Spore Formation

8. Fission
• Fission is a process of division of
single celled organism into two or
many cells.
a) Binary Fission:
• Fission into two cells.
• Takes place during
favorable conditions.
E.g. Amoeba,
Paramecium
b) Multiple Fission:
 Fission into many cells.
 Takes place during
unfavorable conditions.
• E.g. Plasmodium (which
causes Malaria)

9. Budding
• Budding is a method of reproduction in which a
protuberance develops on the mature organism’s
body, attains full maturity and detaches.
o E.g. Hydra, Yeast

10. Fragmentation
• Fragmentation is a
process in which body
of an individual simply
breaks up into smaller
pieces upon
maturation.
• These pieces or
fragments grow into
new individuals.
o E.g. Spirogyra

11. Regeneration
• Regeneration is the ability of an organism to
replace or repair any lost part.
• Carried out by specialized cells.
E.g. Planaria, Hydra

12. Differences between Fragmentation and
Regeneration

13. Spore Formation
• Spores are special cells
formed within special
structures called
‘sporangia’.
• Sporangia disseminate
and can form the entire
plant
• This is exclusive to
plant kingdom
E.g. Aspergillus, Fungi-
Rhizopus, Mushroom

14. Vegetative Propagation
• Vegetative Propagation is a method of reproduction
where a vegetative plant part produces a new plant.
o Here vegetative part refers to non-reproductive or non-
flowering part of the plant body such as Stem, root,
leaves.
e.g. Bryophyllum, Rose, Jasmine, Sugarcane,
Vegetative
Propagation
Natural Artificial

15. Natural Vegetative Propagation
Stem
Example: Potato, Onion,
Garlic, Mint
Root
Example: Carrot, Grass,
Radish, Tapioca
Leaves
Example: Bryophyllum,
Begonia

16. Artificial Vegetative Propagation
• Artificial Vegetative propagation is done through cutting,
Layering and Grafting.
• Cutting - e.g. Grapes, Bougainvillea, cactus, Pineapple
Grows
into new
Plant
Develops
roots and
shoots
Cutting
of Stem
placed in
moist soil

17. Artificial Vegetative Propagation
Mound Layering – made to
grow as an independent plant and
plant can be cut from main plant
• Layering
Still attached to Parent Plant
Induced to Produce roots
Branch of Plant - Buried in Soil (5 to 6
inches)

18. Artificial Vegetative Propagation
• Grafting
Joining a part of one
plant with other
Root Stock Supporting and
Rooted part (disease
resistant)
Scion Cutting from a
desirable plant (superior
quality)
Cambium of Scion is in
direct contact with
cambium of stock
New Plant with Root
System of Stock + Shoot
system of Scion

19. Importance of Vegetative Propagation
Suitable
for long
periods of
Seed
dormancy
Easy and
Less
Expensive
Desirable
New
Plants
Suitable
for poor
seed
viability
To save a
stock of
preserved
varieties
Earlier
Production
of Flowers
Fruits

20. Sexual Reproduction
• Sexual Reproduction
involves male and female
individuals to produce
new organism.
• It involves the formation
and fusion of male and
female gametes.
• New individuals exhibit
variation, it helps in the
processes of adaptation.
• Cell division involves
meiosis.

21. Importance of Sexual Reproduction
• Variations ensure retaining of a species with in the
community.
• As DNA of two individual organisms of same species
are involved, sexual reproduction results in
variation.
• Sexual reproduction helps in crossing over and it is
essential for variation.
• Variation allows organisms to live in diverse habitat
with the help of adaptation.
• During this type of reproduction fusion of gametes
take place. This helps to maintain constant number
of chromosomes throughout the species.

22. Plant Reproductive System
• Flower is the reproductive part of the plant.
o Male reproductive part is Stamens.
o Female reproductive part is Carpel.

23. Male reproductive part in Plants
Parts of Stamen
Filament • Stalk like Structure
Anther
• Flattened top
• Produces pollen grains
(male gametes or germ
cells)

24. Female reproductive part in Plants
Parts of Carpel
Stigma • Terminal part
Style • Elongated structure
Ovary
• Swollen base
• Produces ovules
(female gametes or
egg cells)

25. Pollination
• Pollination: Transfer of pollen grains from anther to
stigma by agents like wind, water and insects etc.
• Two types of pollination –
o Self Pollination
o Cross pollination

26. Types of Pollination
• Self Pollination: Transfer of pollen grains from
anther to stigma of same flower.
• Cross Pollination: Transfer of pollen grains from
anther to stigma of different flower of same plant or
different plant.
Flower to
Flower
Pollination
Type
A → A Self
A → B Cross
A → C Cross
B → C Cross

27. Fertilisation in Plants
• Fertilisation It is the process of fusion of male gametes
(male germ cells) and female gametes (female germ cells
or egg cells).

28. Fertilisation in Plants
Pollen Grains
(Male germ cells)
from Anther
Enters Stigma
Forms Pollen
tubes
Grows inside the
Style
Reaches Ovary
and then Ovules
(female germ
cells - egg cells)
Fusion takes
place
Zygote
formation!!!

29. Formation of Seed
• Formation of Seed
Ovary → Fruit
Ovule → Seed
Embryo forms within Ovule
Divides Several times
Zygote

30. Human Reproductive System
• Puberty: Reproductive system of young organisms
become functional at a definite age.
• At puberty,
•
 13-14-Years
 Starts production of sperms
 Male Hormone Testosterone
is produced from Testis
 10 – 12 years
 Starts production of ovum
Female hormone Estrogen is
produced from Ovary

31. Importance of Hormones
• Regulates the process of gametogenesis (formation
of gametes)
• Maintains structure and function of accessory sex
organs
• Develops secondary sexual characteristics such as
o facial, axial and pubic hair, change
o pitch of voice
o development of mammary glands.

32. Male Reproductive System
• .
Ureter
Urinary
Bladder
Urethra
Penis –
Opening
(Genital
Part)
Pair of Testis
(inside pouch
like muscular
structure –
Scrotum)
Vas
Deferens
Prostate
Gland
Seminal
Vesicle

33. Functions of Male Reproductive System
Sperms are
produced in
Testis
Requires temperature 1
or 3º less than body
temperature
To maintain less
temperature Testis are
present in Scrotum – a
muscular pouch like
structure
Sperms enter
urethra through
Vas Deferens – a
long tube like
structure
Just before sperms
enter urethra, Sperms
are enriched with
secretions from
Prostrate gland and
Seminal Vesicle
To provide nutrition
and motility for Sperms
Urethra opens
outside to genital
pore.
Urethra is enclosed in
muscular organ - Penis
Urethra and Genital
pore are common for
both Urine and Sperms

34. Female Reproductive System
• .
Pair of
Ovaries
Funnel like
structure leading
to Fallopian Tube
Uterus
Cervix
Vagina

35. Functions of Female Reproductive System
Pair of
Ovaries
produce Ova
Secretes two hormones
Estrogen and
Progesterone
Composed of follicles
that produce Ova at
puberty
Uterus
At end of ovary, funnel
like structure leads to
Fallopian tube.
Fallopian tubes from
both ends open into
elastic bag like
structure - Uterus
Cervix & Vagina
Uterus opens into
vagina through the
cervix
Vagina has a tubular
structure.
Starts producing Ova at
puberty
Vagina is the birth
canal through which
the young ones are
born.
Urethra and Vaginal
openings are separate.

36. Sexual Cycle in Females
Ovulation
(7-14 days)
Preparation of
Uterus
(14-28 days)
Menstruation
(0-7 days)
 If fertilisation
doesn’t occur,
uterine lining
along with blood
vessels break
down.
 Broken down
Uterline lining
moves out of
vagina in the
form of bleeding.
 Ovarian follicles
Mature into Egg or
Ovum
 Released from
respective Ovary.
 Uterine wall
starts to thicken
 Ovum waits for fertilisation to occur.
 Further thickening of Uterine wall
happens.

37. Fertilization
Implantation
Fertilized Ovum  Zygote  Grows
and becomes Embryo
Embryo attaches to uterine wall
which is called Implantation
Fertilisation
In fallopian tube only one sperm
fertilizes Ovum.
Once fertilisation occurs, menstrual
cycle stops.
Movement of Sperms (Sperms are active & motile)
During copulation sperms reach
female genital tract
Millions of sperms  Vagina 
Uterus (through Cervix).

38. Functions of Placenta
• Special tissues called placenta forms between
Uterine wall and foetus.
• Placenta provides nutrition to the developing
embryo.
• Helps in the exchange of CO2 and oxygen.
• Helps in the removal of waste substance formed
in the developing foetus.
• Helps in the attachment of foetus to Uterus wall.
• Development of foetus takes about 9 months.
• Birth of foetus occurs through rhythmic
contraction of muscles in the uterus.

39. Population Control
• Physical methods – Condoms, Diaphragm and
Cervical Caps
• Prevents entry of Sperms / AIDS, STD (Gonorrhea,
Syphilis)
Barrier Method
• Specific Drug (Oral Pills).
• Affects hormonal preparation.
• Prevents formation of Gametes. But can cause side
effects
Chemical Method
• Copper-T
• Prevents implantation on the Uterus
• Causes irritation of Uterus
Intrauterine
Contraceptive Devices
• Vas Deferens Surgical removal or Ligated (called as
Vasectormy).
• Fallopian tubes are ligated (Tubectomy).
Surgical Method

40. Reproductive Health
• Reproductive health includes aspects such as
o Responsible, safe and satisfying reproductive life.
o Awareness regarding fertility regulation methods, the right,
freedom and choice to control birth.
o Ability to prevent and control sexually transmitted diseases.
• Sexually Transmitted diseases (STDs):
o Infectious diseases caused by pathogens such as bacteria,
protozoans virus and fungi that spread through sexual contact.
o e.g. Gonorrhoea, Syphilis, Trichomoniasis, AIDS etc.
o Most STDs causes symptom such as burning sensation in
urination and urethral discharge.
o AIDS (Acquired Immuno Deficiency Syndrome) is caused by
HIV (Human Immuno Deficiency Virus). Its cure has not been
found till now and it may cause death if not treated properly.

41. Activity 8.1 – Budding in Yeast
• Aim: To demonstrate asexual reproduction by budding in
Yeast.
• Materials required: Sugar, water, Test tube, Yeast
Granules, cotton, slide, coverslip.
10g of Sugar
in 100 ml of
water
Take 20 ml of
this solution
in Test tube
Add a pinch
of yeast
Granules
Keep a cotton
plug on test tube
and leave it in a
warm place
Place drop of yeast
from test tube on a
slide and observe
under Microscope

42. Activity 8.1
• Observation: Yeast shows asexual reproduction by
budding.

43. Activity 8.2 – Observation of bread mould
Observe the surface with
magnifying glass
Record your observation
for a week
Wet a Slice of bread
Keep it in a cool and dark
place
• Observation: Bread mould
grows on bread.
• It is initially white in colour,
then it becomes brown to black
on maturity.

44. Activity 8.3 – Binary Fission in Amoeba
Compare the observations
of both the slides
Observe another permanent
slide of Amoeba showing
Binary Fission.
Observe a permanent slide of
Amoeba under a microscope
Observation:
• Slide of Amoeba shows single
Amoeba.
• One with Binary Fission,
appears big sized Amoeba with
construction in the centre.

45. Activity 8.4 – Observing Spirogyra
Observe the slide under
Microscope
Put 1 or 2 filaments on a slide,
add a drop of glycerine and
cover it with Coverslip
Collect Water from lake or Pond
that is dark green and contains
filamentous structures
Observation:
• We can observe Spirogyra
filament under the microscope.

46. Activity 8.5 – Vegetative Propagation in Potato
Observation:
• Potato with notches or buds
show the growth of new
plantation.
• Other slices of potato do not
show growth.
Cut potato
into slices
Potato Slices
with notches
Potato Slices
without
notches
Keep in
moisture
cotton
Observe the
changes for
next few days

47. Activity 8.6 – Vegetative Propagation in Money Plant
Observation:
• Stems of Money plant with
leaves showed the growth.
• Other parts between two leaves
did not show any growth.
Cut Money
plant into small
portions
Portion with
at least one
leaf
Portion
without leaf
Keep one end of
all pieces in
water
Observe which
portions grow
faster

48. Activity 8.7 – Observing Spirogyra
Soak a few seeds of Bengal gram
and keep them overnight.
Drain excess water and cover
the seeds with wet cloth.
Leave them for a day.
Cut open the seed carefully
and observe different parts
Observation:
• The seed consists of two
cotyledons (dicotyledon) when
it starts growing it shows
growth of future shoot called
plumule and root called radicle.