REPRODUCTION
Q. What is reproduction?
REPRODUCTION
The
process by which living organisms produce offspring of their own kind is called
reproduction.
Q. How vegetative propagation does occur in
plants via Stem?
The
plants that can reproduce via stem are recognized as runners, bulbs, rhizome,
tubers and suckers.
In
many plants including strawberries, daffodils, onion, stem starts to grow in
offspring.
Q. How vegetative propagation does occur in
plants via Leaves?
Some
leaves have bud on their margin. These buds give rise adventitious roots when
fall on ground or contact with the soil.
After
some time, these parts grow into an independent plant.
For
instance; Bryophyllum
Q. How vegetative propagation does occur in
plants via Suckers?
Suckers
are known as root sprouts. Basically the part of root or stem
Q. Describe the methods of artificial
vegetative propagation?
Following
are the ways of vegetative propagation.
·
Cutting
·
Grafting
·
Cloning
CUTTING
The
short part of stem having 2-3 nodes and buds are called cutting.
GRAFTING
This
is a technique in which a branch of desired variety of plant is joined together
to another plant with well established root system. The plant from which the
branch is taken is known as scion and the plant where it is joined is called
stock.
For
instance; oranges, lime, mango etc.
CLONING
In
this method, tissues of plants are cultured in test tube by asseuxal
reproduction. To speed up the reaction, hormone rich solutions are added.
When
the baby plant is developed, it is transferred to field for large commercial
scale production.
Q. What is mean by Apomixes {parthenogenesis}?
APOMIXES
{Parthenogenesis}
Apomixes
is a type of asexual reproduction in which egg develops into a complete diploid
or haploid individual without being fertilized.
Q. Which part of the plant is responsible for
sexual reproduction in Angiosperms?
Angiosperms
are flowering plants so for the sexual reproduction they have flower. Flower is
responsible for reproduction by producing seeds within the fruits.
Q. What are the four whorls of flower?
The
four whorls of flower are:
·
Calyx which consists of sepals,
·
Corolla which
consists of petals,
·
Androecium
(Stamen) which produce pollen
grains
·
Gynoecium
(Carpels) which produce
ovule
Q. Describe the structure of Ovule.
STRUCTURE OF OVULE
·
Ovule
has a central cellular body called nucleus.
·
Nucleus
is surrounded by two coats i.e. outer and inner integuments.
·
A
large oval cell is embedded in nucleus which forms female gametophyte (Embryo
sacs).
·
The
mature embryo sacs consist of 7 cells i.e.
o
One
ovum
o
Two
synergids
o
Three
antipodal cells
o
One
secondary nucleus
·
Micropyle
is the opening at the apex of the ovule.
·
Ovule
has funicle which helps in to attach to the ovary wall.
·
The
tissues between the nucleus and funicle are called chalaza.
Q. Describe the structure of Pollen grain.
STRUCTURE OF POLLEN
GRAIN
Pollen
grains develop in pollen sac of anther into micro spore in the form of loose,
dusty powder. Each pollen grain is 4 celled structures, bounded by exine and
intine.
Q. What are the parts of a plant?
PARTS OF PLANT
In
angiospermic plant, the main plant is Sporophyte which consists of vegetative
and reproductive parts.
·
Vegetative
parts are Root, stem and leaves
·
Reproductive
parts are fruits, seeds and flowers
Q. What is the mechanism of Stamen?
In
flower, stamen has 2-4 pollen sacs in its anther. These pollen sacs are filled
with microspore mother cell which produces microspore by meiosis. The
microspore divides to produce 2-4 cells via mitosis.
This
is how, unicellular microspore become haploid cells called pollen grains. These
pollen grains disperse in the nature via various methods.
Q. What is the mechanism of Carpel?
Carpel
has one more ovules in its ovary. Each ovule has single megaspore mother cell.
This megaspore mother cell divided by meiosis to produce 4 haploid megaspores.
Only one survives and develops into embryo sac (female gametophyte) inside ovule,
which consists of 7 cells.
Q. Define pollination. Describe its types.
POLLINATION
The
process by which pollen grains are transferred from anther of stamen to stigma
of carpel is called Pollination.
TYPES OF POLLINATION
There
are two types of Pollination.
·
Self
Pollination
·
Cross
Pollination
Self pollination
The
process by which pollen grains are transferred from anther of stamen to stigma
of carpel of same flower is called Self Pollination.
Cross pollination
The
process by which pollen grains are transferred from anther of stamen to stigma
of carpel of same flower is called Cross Pollination.
It
is more common than self pollination.
Q. Describe the methods of transfer of pollen
grains.
This
transfer of pollen grains can be done by:
·
Wind
·
Water
·
Insects
·
Animals
Q. How does fertilization take place?
When
pollen grain drops at stigma, it starts to develop into pollen tube (male
gametophyte), which consists of 6 haploid cells, among them:
·
Two
are prothallial cells,
·
Two
are male gametes,
·
One
stalk nucleus and
·
One
tube nucleus.
The pollen tube grows from stigma to ovule through style and transfers two male gametes in ovule through micropyle which ultimately reach to embryo sac.
One
sperm nucleus fuses with ovum to produce diploid (2N) zygote. The 2N zygote
develops into an embryo within the embryo sac. While other gamete fuses with
secondary nucleus to form 3N (Triploid) cell which develops into endosperm.
Endosperm provides nourishment to develop embryo.
This
type of fertilization is called double fertilization which is the
characteristic feature of angiospermic plant.
During this development the ovule develops into seed, the integument develops into seed coat whereas zygote form small embryo and cotyledon. During this, the ovary outside ovule become swollen due to mitotic cell division and become fruit.
Q. How does the fruit formation take place?
FRUIT FORMATION
The
ovary enlarges to form a fruit, containing seed or seeds.
The
stigma and style disappear. The stamens and petals are usually lost after
pollination. In some cases, sepals remain attached with fruit e.g. brinjal.
The
endosperm provides nourishment to develop embryo.
It
also stores energy in grains like wheat, rice, gram etc. which can be utilized
by us or other animals.
Q. What is mean by fruit formation without
fertilization?
Fruit
and seed formation usually occur after fertilization but some fruit may formed
without fertilization. This mechanism is called parthenocarpy i.e. formation of
seedless fruit, like banana.
Q. What are the adaptive characteristics of
wind & Water pollinated plants?
ADAPTIVE CHARACTERISTICS
OF WIND & WATER POLLINATED PLANTS
·
Flowers
are non attractive.
·
Flowers
are small in size.
·
They
don’t have any odor.
·
They
produce pollen grains in high quantity.
·
Pollen
grains are light in weight.
·
They
don’t produce high quantity of nectar.
Q. What are the adaptive characteristics of
Insect pollinated plants?
ADAPTIVE CHARACTERISTICS
OF INSECT POLLINATED PLANTS
·
Flowers
are large in size
·
Flowers
are bright in colors
·
They
have pleasuring odors.
·
Pollen
grains are sticky and light.
·
They
produce high quantity of nectar.
Q. Describe seed and its structure.
SEED
The
unit of reproductive in flowering plant which is capable to develop into
another plant is called Seed.
The
seed consists of following parts:
·
Seed
coat
·
Embryo
·
Cotyledon
·
Endosperm
(rarely)
The outermost wall of the seed is called seed coat. It consists of two layers i.e. outer thick layer is called testa and inner thinner layer is called tegmen.
Embryo
develops from diploid zygote. It lies between the two cotyledons. It has two
parts the upper end is known as plumule which develops into shoot and lower end
is radicle which develops into root, after fertilization.
Leaf
life structure of seed is known as cotyledon. It is responsible for the storage
of food in the absence of endosperm (in some cases).
Q. Describe the structure of maize seed.
STRUCTURE OF MAIZE SEED
In
maize seed, the seed coat (testa) is fused with the fruit wall (pericarp).
Externally, it is yellow in color and somewhat triangular in shape with the
following features:
·
Seed coat: Seed coat is made up of seed coat and pericarp i.e. fruit
wall.
·
Endosperm: Maize grain consists of
two unequal portions which are divided by a layer called epithelium. The large
portion is the endosperm and the smaller is called embryo.
·
Embryo: It consists of large and shield shaped cotyledon/
scutellum. The axis of the embryo is embedded in the scutellum.
The axis consists of a plumule at the upper portion and
radicle at the lower end. Both radicle and plumule are enclosed in a sheath
called coleoptiles and that covering the radicle are known as coleorhizae.
Q. What is micropyle?
Micropyle
is the opening on the seed coat which is responsible for the movement of water
in and out of the seed.
Q. What is mean by germination of seed?
GERMINATION OF SEED
Breaking
of seed dormancy is called germination of seed.
OR
The
development of seed into the young plant is called germination of seed.
Q. What are the conditions necessary for seed germination?
CONDITIONS NECESSARY FOR
SEED GERMINATION
Conditions
which are needed for germination of seeds are discussed below:
ROLE OF WATER
Cotyledons
and endosperm absorb water by imbibitions become swollen and exert pressure on
seed coat to break. So the embryo comes out to grow, enzymes become activated
by water and solid reserve food change into solution.
ROLE OF OXYGEN
Oxygen
has a key role in germination of seed. It helps in the production of energy by
the process of respiration.
TEMPERATURE
Most
of the seeds require the temperature range between 250C to 37o
C. Seeds do not germinate at temperature below 0o C or above 45oC.
Q. Differentiate between Epigeal Germination OR
Hypogeal Germination.
|
Epigeal Germination |
Hypogeal Germination |
|
The
type of germination where seeds come above the soil during germination is
called Epigeal germination. |
The
type of germination where seeds remain in the soil during germination is
called Hypogeal germination. |
|
Growth
rate of hypocotyls is higher than epicotyls. |
Growth
rate of epicotyls is higher than hypocotyls. |
|
Hypocotyls
grow in the form of arch. |
Hypocotyls
doesn’t grow in the form of arch. |
|
Cotyledons
become green when come above the soil. |
Cotyledon
doesn’t become green when come above the soil. |
Q. Describe the methods of asexual reproduction
in animals.
ASEXUAL REPRODUCTION IN
ANIMALS
Following
are the methods of asexual reproduction in animals.
·
Fission
o
Binary
fission
o
Multiple
fission
·
Budding
·
Fragmentation
SPLITTING
The
division of a cell into two or more cells or organism is called splitting.
It
is of two types:
·
Binary
fission
·
Multiple
fission
Binary
fission
In
this type of reproduction, cell divides into two cell or organisms.
For
instance; Bacteria.
Multiple fission
The
type of division in which cell divides into more than two cells or organisms is
called multiple fission.
For
instance; Plasmodium.
BUDDING
The
type of reproduction in which one or more outgrowths develop on the buds is called
budding.
After
maturation, buds detach from parent plant and develop into a complete new
organism.
For
instance; Hydra.
FRAGMENTATION
Fragmentation
is the type of reproduction in which organism divides into fragments.
Q. What is fertilization?
The
fusion of male and female gamete is called Fertilization.
Q. What are the processes involved in reproduction?
Following
are the steps involved in sexual reproduction.
·
Gametogenesis [Formation of gametes]
·
Mating [Union of male
& female organism]
·
Fertilization [Fusion of male and
female gametes to form zygote]
Q. What is mean by gametogenesis?
GAMETOGENESIS
The
process of formation of gamete by meiosis is called gametogenesis.
As
gametogenesis undergoes meiosis, so number of chromosomes reduces to half in gametes.
It
is of two types:
·
Spermatogenesis
[Formation of testes]
·
Oogenesis [Formation of ovaries]
Q. Describe the male and female reproductive
organs in rabbit.
|
Organs |
Male |
Female |
|
Gonads (Gamete
producing organs) |
· Testes (01 pair) · Testes lies in scrotum · Testes contain
seminiferous tubules · Testes have epididymis
to collect sperm.
|
·
Ovaries (01 pair) ·
Lies in abdominal cavity ·
Produce ovum
|
|
Duct (Gametes
collecting ducts) |
· Vas deferens (01 Pair) |
·
Oviduct or fallopian tube collect ovum from ovary. ·
01 (Pair) |
|
Genitals ((Gametes
depositing or receiving organs) |
· Penis |
·
Vagina |
|
Glands |
· Prostate gland · Cowper’s gland · Seminal vesicle |
·
Ovary |
Q. How many types of fertilization are there?
Distinguish them.
|
External fertilization |
Internal fertilization |
|
It
takes place outside the body. |
It
takes place inside the body. |
|
It
takes place in water. |
It
takes place inside female body. |
|
Both
gametes get mature at same time. |
Gametes
mature after each other |
|
Large
numbers of gametes are produced. |
Limited
numbers of gametes are produced. |
|
It
occurs in fishes, amphibians etc. |
It
occurs in reptiles, aves and mammals. |
Q. What is mean by population and population
planning?
POPULATION
The
total number of organisms living in a particular habitat is called population
POPULATION PLANNING
Population
planning is the policy to limit the growth in number of population especially
in those countries which has limited resources or located in densely populated
part of the earth.
Q. What are the benefits of human population?
The
human population helps in estimating the birth and death rates, the number of
resources that will be required i.e. food, houses, health, electricity,
transport, drinking water, garbage disposal etc.
Q. Why is there need of population planning?
Population
planning is essential to establish and maintain the quality of human life and
environmental conditions.
The
birth rate should be planned according to available resources of the area.
Birth
and death rate should be balanced to maintain sustainable population growth.
Q. What is mean by sexually transmitted
diseases?
SEXUALLY TRANSMITTED
DISEASES (STDS)
The
diseases or infections which are passed from one organism to other organism
through genital organs and genital fluids are called STDs.
Some
common STDs are:
·
Herpes
·
Gonorrhea
·
AIDS
·
Syphilis,
·
Genital
herpes
Q. What do you know about AIDS?
ACQUIRED
IMMUNO-DEFICIENCY SYNDROME (AIDS)
AIDS
is one of the serious threat came into light in the year 1980.
AIDS
is caused by HIV Virus which may transfer from one organism to another organism
via:
·
Sharing
of Surgical instruments
·
Transfusion
of blood
·
Sexual
contact
·
Placenta
·
Mother’s
milk
Q. What are the roles of national AIDS Control
Program?
·
The
first role is the study of AIDS patients,
·
Second
is to analyze the reasons of AIDS,
·
Third
is to educate people about its prevention,
