5. Asexual reproduction
In asexual reproduction there is only one parent
All the offsprings are identical to the parents. They
have the same genes.
They are called clones.
Example: Bacteria, amoeba, potato,Hydra
8. Sexual reproduction
In sexual reproduction there are two parents.
The parents have sex organs that produce sex cells or
gametes.
In male animals gametes or sex cells are called sperms. They
are made in male sex organs called testes.
In female animals female gametes or sex cells are called
eggs or ova. The eggs are made in sex organs called
ovaries.
9. Sexual reproduction involves the joining together of
male gamete and female gametes (sex cells).
The offsprings are not identical to the parents. They
show much more genetic variation than asexual
reproduction.
Half of the genes come from the father and half
from the mother.
10. Differences between asexual and sexual
reproduction:
Sexual reproduction Asexual reproduction
1. Results from fusion of male and female
gametes
1. Does not involve fusion of male and
female gametes
2. It requires two different parents 2. Requires only one parent
3. The offsprings produced are not
identical to the parents
3. Offsprings produced are identical to
the parents- both genetically and
morphologically
4. Causes genetic variation and leads to
genetic diversity
4. Do not cause genetic variation and
hence does not lead to any genetic
diversity
5. Most animals reproduce sexually 5. Algae,fungi and bacteria reproduce
asexually
12. The main function of the testes is producing and
storing the sperm. They're also important for
producing testosterone hormone.
Location of testes: The testes are contained in the
scrotum.
14. Male reproductive organs
Epididymis: a duct behind the testis which transports sperm to the
vas deferens.
Vas deferens/ Spermatic duct: the duct which transports sperm
from the testicle to the urethra.
Seminal vesicles: A pair of glands that secrete seminal fluid present
in the semen.
Prostate: Gland that secretes prostatic fluid that nourishes the
sperm.
Scrotum: a pouch of skin containing the testicles.
Cowper’s gland: Secretes fluid that adds to the semen.
15. Cowper’s gland
Seminal vesicles Forms fluid that nourishes the sperms
Prostate gland
Composition of semen : Sperm and fluid from these three glands
16. Female reproductive organs
Female reproductive organs are called
1. Ovaries
2. Uterus
3. Fallopian tubes/ Ovi ducts
4. Vagina
17. Ovaries: The ovaries produce and release eggs into
the fallopian tube at the mid-point of each
menstrual cycle. They also produce the hormones
oestrogen and progesterone. Location: lower
abdomen
Fallopian tube: A pair of tubes along which eggs
travel from the ovaries to the uterus. Fertilization
takes place here.
18. Uterus: The uterus is a hollow muscular organ that
holds the developing baby or fetus during
pregnancy.
Vagina: The vagina is the elastic muscular canal that
connects the uterus to the outside world.
20. Sex cells or gametes:
Male sex cells or gametes are called sperm.
Sperms are produced in the testes (singular testis).
Semen is the male reproductive fluid that contain up to 10 per cent of
sperm. The rest consists of enzymes, vitamin C, calcium, protein, sodium,
zinc and fructose sugar.
21.
22. Structure of a sperm
Structure of a sperm: Contains head, mid-piece
and tail.
Head: contains the nucleus with the genetic
material from the father , surrounded in front by a
thin sac called the acrosome, which contains
enzymes used for penetrating the female egg.
Middle-piece contains mitochondria.
Tail helps the sperm to move.
23. Structure of egg
The egg or ovum (pl. ova) is circular in shape. Larger
in size than sperms
Inside the cell there are nucleus containing genetic
information from the mother.
It contains yolk as food store.
It has jelly coat that also protects the ovum.
24. Differences between sperm and egg
Sperm Egg
Small Large
Swim using tail Can not move much
No food store have a food store
Millions produced much fewer made
25. Fertilisation
Fertilisation happens when the nucleus of
sperm joins with the nucleus of the egg.
A fertilized egg or zygote is produced.
The fertilized egg then divides into a ball
of cells called embryo.
26.
27. Types of fertilization:
1. External fertilization: Fertilization
taking place outside the body. Eg. fishes
2. Internal fertilization: Fertilization taking
place inside the female body.
Eg. Human,lion
28.
29.
30.
31.
32.
33.
34. Adolescence
Adolescence - the period of life when a
child develops into an adult.
Age: 10-14 years
You become an adolescent on the onset of
puberty.
Adolescence finishes when you stop
growing at 18.
Why does this changes occur? – Due to
hormones.
35. Puberty
Puberty - the period during which
adolescents reach sexual maturity and
become capable of reproduction.
36. The pituitary glands produces hormones that
make the sex organs active.
Secondary sexual characteristics in male:
Testes produces testosterone which causes-
1. the testes start to make sperm
2. hair starts to grow on the face and body
3.the voice deepens
4. the muscles develop
37. Secondary sexual characteristics in female:
The ovaries start making oestrogen.
1. the ovaries start to release eggs.
2. hair starts to grow on parts of the body.
3. the breast develops.
4. the hips widen.
5. period starts.
38. Menstrual cycle
Menstruation- Monthly periodic shedding
of the lining of the uterus is called
menstruation. Also known as period.
Ovulation- Release of mature egg from the
ovary into the oviduct is called ovulation.
39.
40.
41. Menstrual Cycle
Starting at the puberty, the female reproductive system
undergoes a regular sequence of events, repeated every 28
days. This is known as the menstrual cycle.
Sequence of events during one menstrual cycle-
From day 1 to 5 of the menstrual cycle , the endometrial
lining of the uterus breaks down. This is known as
menstruation.
The pituitary gland secretes follicle stimulating hormone
(FSH) ,which stimulates the development of the follicles in
the ovaries. Usually one follicle ripens to become Graafian
Follicle in one of the ovaries during each cycle.
42. Menstrual Cycle
FSH also stimulates the follicles in the ovary to secrete
oestrogen.
3. Oestrogen thickens the endometrial wall of the uterus. The
level of oestrogen peaks between 7-14 day of the menstrual
cycle.
4.A high level of oestrogen in the blood inhibits FSH production,
preventing the ripening and growth of more follicles.
5.Oestrogen also stimulates the pituitary gland to secrete
Luteinising hormone (LH).
6.LH causes the release of the egg cell from a matured follicle,
this is known as ovulation.
43. Menstrual cycle
7.LH also causes the formation of corpus luteum, the
remaining part of the follicle (yellow body).
8. Corpus luteum secretes progesterone.
9. Progesterone keeps the uterine lining thick and well
supplied with blood, preparing it for the implantation of the
embryo. It inhibits both FSH and LH. Progesterone level
peaks between day 14-21 of the cycle.
10. Around the last few days of the cycle, the corpus
luteum starts to degenerate. It stops releasing
progesterone. This leads to the breakdown of the
endometrial wall, starting another cycle.
44. summary
Day 1 – Menstruation begins (bleeding)
Day 5 – Menstruation is usually ended
Day 14 – Ovum has matured and bursts out of
the ovary
Day 15 – After 24 hours the egg is gone
Day 26 – In the absence of fertilization,
estrogen/progesterone levels drop
and the endometrium lining breaks
down
Day 28 – Menstruation begins again.
45.
46. Menstrual cycle
FSH (Follicle Stimulating Hormone): Secreted
from pituitary gland
Function: Causes development of the follicle and
egg. Stimulates ovary to produce oestrogen.
Oestrogen: Secreted from ovary.
Function: Causes thickening of the lining of the
uterus and prevents more eggs from developing.
Stops pituitary to make more FSH.
47. Menstrual cycle
Luteinising hormone: Secreted from pituitary
gland.
Function: Makes the ovary to release egg (ovulation).
Converts empty follicle into yellow body.
Progesterone: Secreted by corpus luteum (yellow
body).
Function: Makes the uterus lining thicker.
48. Menopause
When period permanently stops in female
it is called menopause and it usually
occurs at the age of 45-55 years of age.
49. Corpus luteum/ yellow body
After ovulation, the Graafian follicle develops into
a corpus luteum. The corpus luteum produces
hormones that prepare the body for pregnancy.
It secretes progesterone, a hormone that causes
thickening of the uterus. Progesterone also
inhibits the secretion of FSH and LH – thus
prevents development of any further follicles.
50.
51. Fertile period
During this period, sperms in vagina are likely to
cause fertilization.
Day 11-16 of the menstrual cycle
After its release from an ovary, an egg can
survive for 1-2 days in the reproductive system.
For a 28 day cycle, ovulation occurs around day
14. Hence an egg can survive from day 14 till day
16.
52. Fertile period
During this time, it travels along the oviduct.
Sperms can live for 3-4 days in the female
reproductive system. This means that sperm
released into the vagina on around day 11 can
fertilise the ovum and bring about pregnancy.
Hence, fertilization is possible from around day
11 to day 16. This period is known as the fertile
period.
The rest of the days make up the infertile period
of the menstrual cycle.During this time,sperms
released into the vagina are less likely to fertilise
the ovum.
