How Do Organisms Reproduce?
REPRODUCTION: - THE PROCESS OF PRODUCING A NEW INDIVIDUAL OR
ORGANISM FROM THE EXISTING ONES (OF THE SAME SPECIES) IS CALLED
REPRODUCTION.
Q. IS REPRODUCTION NECESSARY FOR AN INDIVIDUAL?
ANS - NO, IT IS NOT NECESSARY FOR AN INDIVIDUAL BUT IT IS ESSENTIAL FOR
THE PERPETUATION (=CONTINUATION) OF THE SPECIES.
*TYPES OF REPRODUCTION
1- ASEXUAL REPRODUCTION
2- SEXUAL REPRODUCTION
1. ASEXUAL REPRODUCTION: - THE TYPE OF REPRODUCTION IN WHICH
ONLY ONE INDIVIDUAL(SINGLE PARENT) IS REQUIRED TO PRODUCE A NEW
INDIVIDUAL IS CALLED ASEXUAL REPRODUCTION.
IN THIS NO NEED OF TWO INDIVIDUAL OF OPPOSITE SEX IS REQUIRED.
2. SEXUAL REPRODUCTION:- THE TYPE OF REPRODUCTION IN WHICH TWO
INDIVIDUAL OF OPPOSITE SEX (MALE AND FEMALE) ARE REQUIRED TO
PRODUCE NEW OFF- SPRINGS (CHILD) IS CALLED SEXUAL REPRODUCTION.
*ALL LIVING BEING IS MADE UP OF CELLS.
*A VERY IMPORTANT CELL COMPONENT IS CHROMOSOME
*CHROMOSOME:- IT IS THE CARRIER OF CHARACTERS FROM ONE GENERATION
TO ANOTHER.
•
TRANSFER OF CHARACTER FROM ONE GENERATION TO ANOTHER IS
CALLED HEREDITY.
•
CHROMOSOMES ARE OF TWO TYPES
1. AUTO SOME: - IT DECIDES THE SOMATIC (SOMA=BODY) CHARACTERS.
2. SEX CHROMOSOME: - IT DECIDES THE SEX OF THE CHILD.
THE NUMBER OF CHROMOSOMES IN A NORMAL HUMAN CELL = 46 (23 PAIRS)
1. MALE (MAN) = 44 AUTOSOME S+ 2 SEX CHROMOSOMES (XY)
2. FEMALE (WOMAN) = 44 AUTOSOMES + 2 SEX CHROMOSOMES (XX)
MALE = 44 + XY {BOY}
FEMALE = 44 + XX {GIRL}

CHROMOSOMES ARE MADE UP OF “ DNA” AND PROTEINS
DNA = DEOXY RIBONUCLEIC ACID.
DNA = IT IS THE UNIT OF HEREDITY.
DNA COPYING:- A PROCESS IN WHICH CELLS USE CHEMICAL REACTION TO BUILD
COPIES OF THEIR DNA IN A REPRODUCING CELL IS CALLED DNA COPYING.
IT IS NECESSARY FOR THE MAINTENANCE OF BODY DESIGN
FEATURES IN DIFFERENT GENERATIONS OF THE SAME SPECIES. BUT DNA
COPYING ALSO PRODUCE VARIATIONS DUE TO LINKAGE AND CROSSING OVER.
THESE VARIATIONS ARE BENEFICIAL FOR THE SURVIVAL OF SPECIES FOR A
LONG PERIOD OF TIME.
TYPES OF ASEXUAL REPRODUCTION
1. FISSION :-(A).BINARY FISSION
(B). MULTIPLE FISSION
2. FRAGMENTATION
3. REGENERATION
4. BUDDING
5. SPORE FORMATION
6. VEGETATIVE PROPAGATION
1. FISSION: - (fission = to break)
A. BINARY FISSION: - THE TYPE OF ASEXUAL REPRODUCTION IN WHICH
AN ORGANISM DIVIDE INTO TWO PART AND BOTH PART DEVELOP INTO
A NEW INDIVIDUAL IS CALLED BINARY FISSION.e.g. AMOEBA, YEAST
B. MULTIPLE FISSION:- THE TYPE OF ASEXUAL REPRODUCTION IN
WHICH NUCLEUS OF THE CELL DIVIDES INTO MANY NUCLEI ALONG WITH
CELLULAR COMPONENT AND FORMS A CELL OR INDIVIDUAL.
THIS PROCESS IS CALLED MULTIPLE FISSION.
2. FRAGMENTATION: - THE TYPE OF ASEXUAL REPRODUCTION IN WHICH A
MATURE CELL SIMPLY BREAKS INTO SMALL PIECES AND EACH PIECE GROW
INTO A NEW INDIVIDUAL OR CELL, THIS IS CALLED FRAGMENTATION.
3. REGENERATION: - THE TYPE OF REPRODUCTION IN WHICH ANY
BROKEN PART OF THE CELL OR INDIVIDUAL CAN PRODUCE A NEW
INDIVIDUAL IS CALLED REGENERATION.
4. BUDDING: - THE TYPE OF ASEXUAL REPRODUCTION IN WHICH A BULDGE
COMES OUT ON THE SURFACE OF THE BODY OF ORGANISM. THIS BULDGE
IS CALLED BUD.
THIS BUD DEVELOP AND THEN DETACHED FROM THE
PARENT BODY AND DEVELOP INTO A NEW INDIVIDUAL.
5. SPORE FORMATION: - SPORE FORMATION IS ALSO A TECHNIQUE
OF ASEXUAL REPRODUCTION IN WHICH SOME SPECIFIC STRUCTURE
CALLED ‘SPORES’ FORMED.
THESE SPORES GIVE RISE TO A NEW INDIVIDUAL(DIRECTLY OR
INDIRECTLY).
THIS REPRODUCTION GENERALLY OCCUR IN NON-GREEN
MULTICELLULER ORGANISM LIKE FUNGI.
FUNGI HAVE THREAD LIKE STRUCTURE CALLED HYPHAE.
SPORANGIUM CONTAINS SPORES. THE SPORES DEVELOP A NEW INDIVIDUAL
WHEN MOIST ATMOSHERE AVAILABLE TO IT. THAT IS IN FAVOURABLE
CONDITION SPORES GROW & FORM A NEW INDIVIDUAL.
6. VEGETATIVE PROPAGATION: - WHEN VEGETATIVE PART LIKE ROOTS,
STEMS OR LEAVES ARE USED TO DEVELOP A NEW PLANT. THE PROCESS IS
CALLED VEGETATIVE PROPAGATION.
{1}NATURAL: -(i) BY ROOT :- SWEET POTATO
(ii) BY STEM:- GINGER, COLOCASIA
(iii) BY LEAVES: - BRYOPHYLLUM
{2}ARTIFICIAL: - A. CUTTING
B. LAYERING
C. GRAFTING
SEXUAL REPRODUCTION IN FLOWERING PLANTS
• The reproductive part of a plant – Flower
• Stalk of a flower is called Pedicel.
Flower with pedicel is called Pedicellate flower.
Flower without pedicel is called Sessile flower.
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2}
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A flower has four parts –
1)
Calyx – Generally green.
2)
Corolla – Colorful – to attract insects.
3)
Androecium – Male reproductive part.
4)
Gynoecium – Female reproductive part.
Sepal – unit of calyx
Petal – unit of corolla
Stamen – unit of androecium
Carpel or Pistil – unit of gynoecium
Unisexual flower: - If a flower contains either male or female reproductive part(stamen or
carpel), the flower is called unisexual flower. e.g. Watermelon, Papaya, cucurbits etc.
Bisexual flower: - If a flower contains both the reproductive parts (stamen and carpel), the
flower is called bisexual flower(Hermaphrodite). e.g. – Hibiscus, Mustard, Gram etc.
•
Plant contains germ cells. The germ cells are capable to produce
male gamete and female gamete with half number of chromosomes.
Male reproductive part of a flower – STAMEN
• Stamen has three parts: –
1) Filament: - Thread like thin structure.
2) Anther: - It is a box type structure which contains pollen chamber and Pollen
grains(yellowish in colour).
3)
Connective: - A connective tissue which joints filament to anther.
Female reproductive part of a flower – PISTIL or CARPEL
• Carpel or pistil also have three parts:–
1)
Ovary: - It is the lowermost swollen part which contains ovule. Egg
is present inside the ovule.
2)
Stigma: - It is the uppermost (terminal) sticky part which helps in receiving
the pollen grains.
3)
Style: - It is a long tubular structure between stigma and ovary.
Ovule: -It contains 7 cells and 8 nuclei. (generally).
nuclei(=central nuclei), 1-egg cell,2-synergid cells].
[3-antipodal cells, 1-Polar
Pollination: - Transfer of pollen grain from anther to stigma is called pollination.
A) Self-pollination.
B) Cross Pollination.
(A)Self-Pollination: - If the transfer of pollen grain occur from anther to stigma of the same
flower, or another flower of the same plant the process is called self-pollination. e.g. Pea,
wheat, rice etc.
(B)Cross Pollination: - If the transfer of Pollen grain occur from the anther of one flower to
the stigma of another flower of a different plant, the process is called cross pollination.
Pollen grain:- It has two layers -Exine and Intine. Pollen tube develops from pollen grains.
Pollen tube releases two male gamete in embryosac of the ovule.
Fertilization : - The fusion of male gamete with female gamete (egg) is called fertilization.
The product of fertilization is zygote. Zygote divides continuously to form embryo within the
ovule.
•Explanation:When pollen grain falls on stigma. Pollen tube grows and moves
towards ovule (inside the style) due to chemotropism.
Double fertilization
a)
Syngamy:b)
Triple fusion
Male gamete(n) + Egg(n)

Zygote(2n)
Male gamete(n) + Polar nuclei (2n)  Endosperm(3n)
Ovary develops and then mature and ripend ovary is called fruit.i.e. Ovary becomes fruit.
Meanwhile ,the petals, sepals, stamens, style, and stigma may shrievel or fall off.
Ovule becomes seed in future. A seed have an outer covering called seed coat. e.g. Gram, pea.
Germination: - The development of a new plant(seedlings) from seed is called germination.
•
•
Plumule form shoots in future.
Radical forms root in future.
SEXUAL REPRODUCTION IN HUMAN BEINGS
SEXUAL CHARACTERS1. PRIMARY SEXUAL CHARACTERS
2. SECONDARY SEXUAL CHARACTERS
 PRIMARY SEXUAL CHARACTERS:- THE CHARACTER WHICH IS PRESENT IN CHILD AT THE
TIME OF BIRTH AND DECIDE THE SEX OF THE CHILD IS CALLED PRIMARY SEXUAL
CHARACTERS. e.g. PRESENCE OF GONADS(TESTES AND OVARY).
 SECONDARY SEXUAL CHARACTERS:- THOSE CHARACTER WHICH APPEARS AT THE TIME
OF REPRODUCTIVE MATURITY(=PUBERTY) IN HUMAN BEINGS ARE CALLED SECONDARY
SEXUAL CHARACTERS.
*SECONDARY SEXUAL CHARACTERS IN MALE
1. GROWTH OF FACIAL HAIR: - a) MOUSTACHE
b) BEARD
2. GROWTH OF BODY HAIR:-a) ON CHEST
b) ON HANDS & LEGS
3.GROWTH OF HAIR IN ARM PITS AND NEAR THE GENITAL ORGAN BETWEEN THE THIGHS (PUBIC REGION).
4. HEAVENING OF VOICE DUE TO INCREASE IN LENGTH OF VOCAL CORD (i.e. ADAMS APPLE)
(VOICE OF MALE IS LOUDER THAN FEMALE)
5. SKIN BECOMES OILY AND PIMPLES MAY APPEAR.
6. INCREASE IN HEIGHT.
7. CHEST SIZE INCREASE, WIDENING OF SHOULDERS, MALE LIKE PHYSIQUE.
8. DAY DREAMING.
9. ENLARGEMENT OF PENIS AND SCROTUM.
10. ERECTION OF PENIS DUE TO THE BLOOD FILLED IN BLOOD VESSELS PRESENT IN IT.
*SECONDARY SEXUAL CHARACTER IN FEMALE
1. GROWTH OF BODY HAIR:-a) IN ARM PITS
b) NEAR THE GENITAL ORGAN IN BETWEEN THE THIGHS (PUBIC REGION).
2. GROWTH OF MAMMARY GLAND(BREAST SIZE BEGINS TO INCREASE,WITH DARKENING OF THE SKIN OF
THE NIPPLES AT THE TIP OF THE BREASTS).
3. SKIN BECOMES OILY, PIMPLES MAY APPEAR.
4. SWEETENING OF VOICE.
5. INCREASE IN HEIGHT.
6. BROADENING OF PELVIS.
7. DAY DREAMING.
8. PROPER DISTRIBUTION OF FAT ALL OVER THE BODY (PARTICULARLY IN THIGHS, SHOULDERS,
BUTTOCKS AND FACE).
9. COMMENCEMENT OF MENSTRUATION AND OVULATION AT PUBERTY.
PUBERTY:-THE AGE AT WHICH THE REPRODUCTIVE ORGANS BECOME FUNCTIONAL (i.e. PRODUCES
GAMETES) IN HUMAN BEINGS IS CALLED PUBERTY.
i)
ii)
MALES ATTAIN PUBERTY AT THE AGE OF 13 TO 14 YEARS.
FEMALES ATTAIN PUBERTY AT THE AGE OF 10 TO 12 YEARS.
*MALE REPRODUCTIVE SYSTEM
MALE GONAD = TESTIS (2 IN NUMBER)
1. TESTIS:-i) IT IS THE MALE REPRODUCTIVE ORGAN (PRESENT OUTSIDE THE ABDOMINAL CAVITY).
ii) IT IS THE PRIMARY SEXUAL CHARACTER OF A MALE.
iii) IT HAS DUAL FUNCTION.
a)PRODUCTION OF SPERMS
b)SECRETION OF MALE SEX HORMONE- TESTOSTERONE(THIS HORMONE
REGULATE THE DEVELOPMENT OF SECONDARY SEXUAL CHARACTERS).
2. SCROTUM: - IT IS A POUCH OF SKIN WHICH HOLDS TESTIS OUTSIDE THE OBDOMINAL CAVITY. IT
PROVIDES AN OPTIMAL TEMPERATURE FOR FORMATION OF SPERMS. THAT IS 1-30 LOWER THAN THE
NORMAL TEMPRATURE OF THE BODY.
3. VAS DEFERENS:- IT IS A TUBE LIKE STRUCTURE WHICH HELP IN TRANSFERRING OF SPERM FROM
TESTIS TO URETHRA.
4. SEMINAL VESICLES:- IT PROVIDES SEMEN, A FLUID LIKE MATERIAL WHICH HELP THE SPERM TO
MOVE. THIS FLUID ALSO PROVIDES SOME NUTRITION TO SPERMS.
5. PROSTATE GLAND:- IT PREVENT/ PROTECT THE SPERM FROM URINE AT THE TIME OF EJACULATION. IT
GIVES SOME ALKALINE MATERIAL.
6. URETHRA:-IT IS A COMMON TUBE (=PASSAGE) WHICH RECEIVES BOTH SPERM(FROM VAS DEFERENS)
AND URINE(FROM URETER).
7. PENIS:-IT IS A THICK LONG MUSCULAR COPULATORY ORGAN WHICH HELPS IN INSERTING OF SPERM
INTO VAGINA DURING SEXUAL INTERCOURSE.
SPERM- TINY BODIES WHICH HAVE A LONG TAIL(FOR MOVEMENT) BUT CARRIES GENETIC MATERIAL.
*TESTIS IS PRESENT OUTSIDE THE ABDOMINAL CAVITY BECAUSE DEVELOPMENT OF SPERM REQUIRE 1-30
LOWER TEMPARATURE THAN NORMAL TEMPARATURE OFTHE BODY.
*THERE IS ONLY ONE OPENING IN MALE FOR THE EXCRETION OF URINE AND EJACULATION OF SPERM.
BUT, IN FEMALE THERE ARE TWO SEPARATE OPENINGS i) URINARY OPENING & ii) VAGINAL OPENING.
FEMALE REPRODUCTIVE SYSTEM
FEMALE GONAD = OVARY (TWO IN NUMBER)
1. OVARY:- i)IT IS THE FEMALE REPRODUCTIVE ORGAN LOCATED IN THE ABDOMINAL CAVITY NEAR THE
KIDNEY. OVARY ALREADY CONTAIN THOUSANDS OF IMMATURE EGGS(AT THE TIME OF BIRTH).
ii) IT IS GENERALLY ALMOND SHAPED.
iii) IT ALSO HAS DUAL FUNCTION
a) PRODUCTION OF FEMALE GAMETE (OVUM).
b) SECRETION OF FEMALE SEX HORMONE (ESTROGEN AND PROGESTERONE)
2. FALLOPIAN TUBE OR OVIDUCT:-IT IS A LONG CONVOLUTED TUBE WHICH IS THE MAIN SITE OF
FERTILISATION.
3. UTERUS:-IT IS A PEAR SHAPED ELASTIC BAG LIKE STRUCTURE IN WHICH THE FALLOPIAN TUBE OPEN
FROM BOTH SIDES. IT OPENS INTO THE VAGINA THROUGH CERVIX. IT IS THE SITE OF DEVELOPMENT OF
EMBRYO INTO A BABY. IT IS A MUSCULAR CAVITY WHICH HAS A VERY RICH VASCULAR SUPPLY (RICH WITH
BLOOD VESSELS).
•
CERVIX:- IT IS THE ENTRY GATE FOR SPERMS.
4. VAGINA:- i)IT HELPS IN RECEIVING SPERMS FROM MALE.
ii) IT IS ALSO CALLED “BIRTH CANAL”.
SEXUAL CYCLE IN FEMALES
*OVULATION:-THE RELEASE OF OVUM FROM OVARY IS CALLED OVULATION. ONE OVUM(EGG) IS
RELEASED EVERY MONTHFROM THE OVARIES. IT IS CONTROLLED BY ESTROGEN .
MENSTRUATION OR MENSTRUAL FLOW:-WHEN THE EGG IS NOT FERTILISED, IT LIVES
ABOUT ONE DAY. SINCE THE OVARY RELEASES ONE EGG EVERY MONTH, THE UTERUS PREPARES
ITSELF TO RECEIVE A FERTILISED EGG. THUS ITS LINING BECOMEES THICK AND SPONGY. IN CASE
FERTILISATION DOES NOT TAKE PLACE THE THICKENED INNERWALL OF THE UTERUS BREAKS
DOWN ALONGWITH ITS BLOOD VESSELS, AND MOVES OUT OF THE VAGINA (WITH A OVUM) IN
THE FORM OF BLEEDING, CALLED MENSTRUATION OR MENSTRUAL FLOW.
MENSTRUAL CYCLE(MC):-THE CYCLE OF EVENTS TAKING PLACE IN THE OVARIES AND UTERUS
EVERY TWENTY EIGHT DAYS AND MARKED BY THE MENSTRUAL FLOW, IS CALLED MENSTRUAL
CYCLE.
MENARCHE:-THE COMMENCEMENT OF MENSTRUATION AT PUBERTY IN HUMAN FEMALE IS
CALLED MENARCHE. IT OCCURS AT THE AGE OF 10 TO 12 YEARS GENERALLY.
MENOPAUSE:-THE PERMANENT STOPPAGE OF MENSTRUAL FLOW IN HUMAN FEMALE (AT
THE AGE OF 45-55 YEARS) IS CALLED MENOPAUSE.
IT MEANS THE NORMAL REPRODUCTIVE LIFE IN HUMAN FEMALE IS 12 TO 50 YEARS.
* COPULATION:-THE PROCESS IN WHICH THE HUMAN MALE INSERT HIS PENIS INTO THE VAGINA IS CALLED
MATING OR COPULATION.
*EJACULATION :-DURING COPULATION RELEASE OF SPERM IN THE GENITAL TRACT OF FEMALE IS CALLED
EJACULATION.
•
FERTILISATION:- THE FUSIONS OF MALE GAMETE (SPERM) WITH FEMALE GAMETE
(OVUM OR EGG) TO FORM A ZYGOTE IS CALLED FERTILISATION.
•
ZYGOTE UNDERGOSE SEVERAL DIVISIONS AND FROM EMBRYO.
•
IMPLANTATION:- THE ATTACHMENT OF EMBRYO WITH THE UTERINE WALL IS CALLED IMPLANTATION.
•
Placenta: - A disc like nutritive tissue through which foetus receives nutrition from the mother
body and also removes wastes is called placenta.
•
Foetus: - A developing embryo in which all the body parts can be identified in mother womb
(uterus) is called Foetus.
•
Umbilical Cord: - A tube like structure which connects foetus to the mother body. It contains a
set of blood vessels which help in getting nutrition, oxygen by the foetus from the mother body
and removes toxic wastes from the foetus by mother body.
•
Gestation Period:- The time period of complete development of a foetus till birth inside the
mother womb is called Gestation.
The time period for gestation in human beings is 270-280 days (9
months). It is called Gestation period.
•
Parturition:- The process of child birth is called parturition.
first sign of pregnancy.
•
The temporary stoppage of menstruation (after fertilization) is the
Ovulation occurs in the mid of menstrual cycle. I.e., 14th day.
Population control
1.Natural method:- By avoiding physical contact or intercourse during the days of ovulation.
2.Barrier method.
A)Physical barrier(Mechanical barrier).
i) Condoms for male.
ii) Cervical cap or Diaphragm or covering for female.
B)Chemical barrier:- By creating hormonal imbalance..
i) Oral contraceptives(OC) – e.g. Mala-D or oral contraceptive pill (I-Pill).
[CEPTION:- FUSION OF MALE GAMETE (SPERM) WITH FEMALE GAMETE (OVUM)]
ii)Vagina pills (i.e. Spermicidal).
3. IUCD(=Intra Uterine Contraceptive Device).
e.g. -> Copper-T [It must be inserted by a doctor or a skilled nurse].
4. Surgical method
i) Vasectomy in male.
ii) Tubectomy in female.
•
Vasectomy :- In vasectomy, vas difference is cut and both ends are tied with a thread.
•
Tubectomy:- The Fallopian tube is cut and both ends are tied with a thread is called
tubectomy.
NOTE:-Prenatal Sex Determination has been Prohibited by LAW.
REPRODUCTIVE HEALTH
STD (= Sexually Transmitted Disease):-Those disease which can spread one person to another
through physical contact (sexually intercourse) are called STD.
STD
•
Bacterial :- Infected by bacteria.
i) Gonorrhoea.
ii)Syphilis.
•
Viral
i)Wart disease
ii)AIDS (Acquired Immuno Deficiency Syndrome)--Caused by a virus HIV(=Human
Immunodeficiency Virus) .
•
Prevention is better than cure.
HIV can be transferred from one person to another by following means:•
Through blood transfer.
•
From mother to their foetus.
•
By infected needle and syringes.
•
By unsafe sexual intercourse.
•
By shaving razors.