HOW ORGANISM REPRODUCE CLASS 10 FULL CHAPTER

Phases of growth and development in human beings

There are three phases of growth and development in human beings. They are

Infancy: The state of early childhood is infancy.
Childhood: It is the age span ranging from birth to adolescence.
Adulthood: An individual attains full physical growth and a great number of physical stability.

Problems of reproductive health in India

Over population
Early marriage
Health of mothers
Deformities
Maternal mortality rate (MMR) and infant mortality rate (IMR)
Sexually transmitted diseases (STDs)
Career

Strategies for maintaining reproductve health in India

Family planning programme
Awareness about reproduction
Sex education
Knowlegde of growth of reproductive organs and STDs
Birth control devices and care of mother and child
Prevention of sex abuse and sex related crime
Information about reproduction related problems
Research in reproductive health area
Medical facilities
Amniocentesis

Understanding adolescence

Adolescence is a transitional stage of physical and psychological development which generally occurs during the period from childhood to adulthood.

Brief account on Adolescence

Adolescence describes the years between ages 13 to 19. It is a transition stage from childhood to adulthood. It can be a time of both disorientation (mental confusion) and discovery. It involves issues of independence, self-identity, social acceptance etc. Adolescents have to make difficult choices about their interests, sexuality, appearance, drugs, alcohol and social life during their journey towards adulthood.

Puberty

Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction to enable fertilization.
The onset of puberty starts much earlier in girls, between 8 and 13 years of age lasts 2 to 4 years.
Puberty starts at the beginning of adolescence.

Changes at puberty - Increase in height

At this time, the bones of the arms and legs elongate and make a person tall.
Full height (cm) can be calculated by the following formulae:

Changes at puberty - Change in body shape

In boys, shoulders become broad and body becomes muscular.
In girls, shoulders and hip become rounded. Breasts get enlarged.

Changes at puberty - Voice change

In boys, voice becomes deep and the Adams apple (partial growth of voice box or larynx) becomes prominent.
In girls, the voice becomes thin.

Changes at puberty - Increased activity of sweat and sebaceous glands

The secretions of sweat and sebaceous glands in adolescents increases which leads to pimple and acne.

Changes at puberty - Development of sex organs

In boys, sex organs like testes and penis develop completely. The testes also produce sperms.
In girls, ovaries enlarge and eggs begin to mature. The ovaries also start releasing mature eggs.

Changes at puberty - Reaching mental, intellectual and emotional maturity

Girls and boys in adolescence becomes more self conscious and independent.
Remarkable intellectual development takes place during this phase.
Sometimes, they feel insecure about their mind and body.

Secondary sexual characters

Hairs grow under the armpit and in the pubic region in adolescent.
The changes which occur at adolescence are controlled by hormones secreted from endocrine glands into the bloodstream.
Testosterone is the male hormone and estrogen is the female hormone that bring about the development of several secondary sexual characters.

Onset of puberty in human male

The onset of puberty is signaled by high pulses of GnRH secreted by the hypothalamus; this in turn signals the release of FSH and LH from the pituitary gland.
FSH causes the Sertoli cells of the testes (which help nurse developing sperm cells) to begin the process of spermatogenesis in the testes.
LH triggers the production of testosterone from the Leydig cells of the testis; testosterone causes the development of secondary sex characteristics in the male.
As spermatogenesis and testosterone production increase, the Sertoli cells produce inhibin, which, together with rising levels of testosterone, inhibit the release of FSH and LH from the pituitary gland.

Onset of puberty in human females

Females attain puberty at about the age of 13 years.
FSH induces development of ovaries, which in turn produce oestrogen.
Oestrogen is responsible for development of secondary sexual character in females.

Changes in the body with ageing

Ageing is the process of attaining maturing and growing old. As the metabolism comes to a steady state, the body undergoes several changes.
Morphological changes involves changes like skin dryness, decreased elasticity of pulmonary tissue and weakness of muscles.
Cellular changes involves decrease in the volume of body cells, reduced DNA replication and decrease in the synthesis of proteins.
Extracellular changes involves the distortion of collagen proteins.

Adulthood

Adulthood, the period in the human lifespan in which full physical and intellectual maturity have been attained. Adulthood is commonly thought of as beginning at age 20 or 21 years.

Understanding puberty

Puberty is the time during which adolescents develop secondary sexual characters and become capable of reproduction. It starts when the brain gives hormonal signals to the sexual organs. It leads to physical and psychological changes.

Defination of menstrual cycle

It is the cycle of physiological changes from the beginning of one menstrual period to the beginning of the next.

Menstruation

The start of the period or the menstrual cycle is counted from the day of onset of blood flow to the next onset after 28 days.
It involves menstrual phase, ovulatory phase, follicular phase and luteal phase.
The menstrual phase lasts for 3 to 5 days involving discharge of blood.
In follicular phase there is secretion of hormones which make the uterus ready to receive a fertilized egg and nourish the embryo.
In ovulatory phase involves rupture of the follicle and release of eggs on about 13th or 14th day.
Luteal phase involves the thickening of the uterus wall and formation of hormone producing corpus luteum. It lasts from 15 to 28 days.

Menarche

The onset of menstruation is known as menarche, in young females at the age of 13 on average.

Menopause

When the menstruation in females stops at the age of 45 on average the stage is called as menopause.

Process of fertilization in human beings

The process of union of male gamete and the female gamete to form zygote is called as fertilization.
The sperms are ejaculated in the female vagina near the cervix during copulation. A single ejaculation contains four hundred million sperms, which actively swim by their tails into the uterus at the rate of 1.5mm per minute.
They reach the oviducts from the uterus and one sperm fertilize the egg.

When the sperms reach the oviducts several sperms surround the egg but only one gets the entry in it.
The head part of the sperm which contains nucleus enters the egg and the tail is left behind. There is fusion of sperm nucleus and egg nucleus in the process of fertilization.
After fertilization the entry of other sperms is prevented by chemical barrier.

Embryo

After fertilization the egg continues to grow till it forms all the vital part of the body this growing egg is known as embryo.

Reproduction

Reproduction is a life process in which a new individual is formed by sexual or asexual mode.

Purpose and basic feature of reproduction

Purpose of reproduction:

Continuity of species
Population organisation
Variations
Life

Basic features of reproduction:

Synthesis of RNA, proteins and other bio-chemicals
Replication of DNA
Cell division
Growth of cells
Formation of reproductive units
Formation of new individuals from reproductive units

Significance of variation

1. Variations make some individuals better fitted in the struggle for existence.2. They help the individuals to adapt themselves according to the changing environment.
3. Discontinuous variations or mutations produce new traits in the organisms.
4.

Variations allow breeders to improve races of useful plants and animals

for increased resistance, better yield, quicker growth and lesser

input.
5. They constitute the raw material for evolution.
6. Variations give each organism a distinct individuality.
7. Because of variations, species do not remain static. Instead, they are slowly getting modified forming new species with time.
8.

Pre-adaptations caused by the presence of neutral variations are

extremely useful for survival against sudden changes in environment,

e.g., resistance against a new pesticide or antibiotic.
9. Orthogenetic (directional or determinate) variations take part in formation of new species.

Modes of Reproduction

Reproduction takes place in asexual and sexual modes.
Asexual mode of reproduction:
It is a method of reproduction without the involvement of male and female gametes. The process requires only one organism.
Organisms can reproduce asexually by different methods. They are- Fission, Budding, Fragmentation, Gemmae, Regeneration, Vegetative Propagation and Spore Formation.
Plants like potato, ginger, etc. and animals like amoeba, hydra, etc. reproduce asexually.
Sexual mode of reproduction:
In case of sexual reproduction, male and female gametes are required. They are fused together. The process of fertilization generates a new organism. It requires the involvement of two organisms (male and a female).
Plants like mustard, maize and animals like frogs, lizards and cockroach reproduce sexually. Human beings reproduce sexually.

Introduction to Reproduction

Reproduction is a process which is required to produce new organisms/offsprings. Characters of the organisms are passed to future generations.
Reproduction is required so that species continue to live and do not face extinction.

Pattern of reproduction

Sexual reproduction

It is a mode of reproduction in which the male gamete and the female gamete unites to form a zygote.
The zygote divides and develops in an individual.
The gametes are produced in male and female reproductive systems respectively.

Asexual reproduction

It is a mode of reproduction which involves any part of the body of the parent.
The part of the parent body involved may be in units or whole of it.
A new individual is developed from it.

Animal breeding

On the basis of time of breeding, animals are of two types:

Seasonal breeders: They reproduce at particular period of the year.
Continuous breeders: They continue to breed throughout their sexual maturity.

Binary fission

Binary fission is a type of fission where the cells divide into two equal parts.
Each part forms daughter cells.
It is a type of asexual reproduction.

Budding

Budding is a type of asexual reproduction.
The small bulb-like projection from the parent plant which grows into a fully grown individual is known as a bud.
The bud has nucleus and cytoplasm which helps it to generate into a new organism.

Fragmentation

Fragmentation is the process by the which the broken parts of the parent body germinate into a new individual. Each fragment contains a nucleus and cytoplasm so that they can develop into a new plant.

Reproduction in Spirogyra

In presence of water and nutrients, spirogyra grows and multiplies rapidly by fragmentation. It breaks into fragments/pieces. These fragments grow into new individuals.

Fragmentation

During the process of fragmentation, a fragment of the parent forms a new being. It occurs when a shoot that is rooted becomes detached from the main group.
Multicellular organisms with simple body organization can divide or reproduce by fragmentation. But, it cannot be used by all multi-cellular organisms. Organisms with complex structures cannot undergo cell-by-cell division. This is because, in complex multicellular organisms, each set of cells have specialized functions. These specialized cells are organized as tissues and are placed in organs. Organs are placed in different positions of the body.

Pollination and its types

Pollination is the transfer of pollen grains from the anther to stigma of the flower.
If the pollen lands on the same plant are known as self-pollination.
If the pollen is transferred from the anther of one plant to the stigma of another plant it is known as cross-pollination.
Wind, air, water, insects are the common agents of pollination.

Fragmentation in Spirogyra

Fragmentation is a type of asexual reproduction in which an organism simply breaks in individual pieces at maturity.
These individual small pieces then grow to form a new organism e.g., Spirogyra. Spirogyra undergoes fragmentation which results in many filaments. Each filament grows into mature filament.

Fragmentation

Fragmentation is a type of asexual reproduction in which an organism simply breaks in individual pieces at maturity.
These individual small pieces then grow to form a new organism e.g., flatworm.
Flatworms fragments exactly in the center splitting in two equal halves. Each of the part is the clone of the parent.

Regeneration and its types

The ability of the organism to regenerate, replace and restore the cut organs or whole body from a small fragment is known as regeneration.
Reparative regeneration involves the repairing of damaged organs.
Restorative regeneration involves the reconstruction of lost organs.
Physiological regeneration involves the repairment of the tissues and organs of the body damaged during normal activities.
Compensatory hypertrophy involves the regeneration of fully developed organs from the lost organs.
Heteromorphic regeneration involves the formation of an organ which is different from an organ lost.

Regeneration

GIF

It is a type of asexual reproduction in which an organism can grow an entire new organ or a part of it in the case if injury or damage.
Some of the amphibians and vertebrates are able to grow a limb, tail, eyes etc.

Budding in Protista

In budding, a small outgrowth develops from the parent body which separates and develops into a new individual.
For example, Arcella (a sarcodine).

Angisperms

Angiosperms are plants which have flowers.
Flowers are used for reproduction. They have male and female reproductive parts.

Male reproductive part of a flower
The third whorl of the plant is called Androecium. It consists of stamens. Stamen is the male reproductive part of the plant. It contains anther and a filament. Anther produces pollen. Pollen consist of male reproductive cells. They fertilize ovules.

Female reproductive part of a flower
The female reproductive part of the plant is known as a Gynoecium. It is also called a pistil or carpel. It is the innermost whorl. A pistil consists of many carpels. Each carpel is made up of style, stigma and an ovary. Ovules (female reproductive cells) are produced in the ovary. Style acts as a tube from the ovary. Stigma is a sticky substance present on the top of style. It receives pollen for fertilization.Pollen from the male part (anther) is carried to the female part by wind, insects or other animals. This process is called as pollination. The male gametes are released and are fertilized with the female gamete in the ovule. Ovules develop into seeds. These seeds grow to new plants.
Examples: Pine cone, grasses, etc

Gymnosperms

Gymnosperms are plants which contain seeds but their seeds are held in cones. Male cones produce pollen. Wind carries these pollen to female cones. After the female gametes are fertilized by male gametes, female cones produce seeds. These seeds are then scattered away from the plant by wind or animals.
Examples of Gymnosperms: Cycads, Conifers

Reproductive parts of a Plant

Flower, seeds and spores act as reproductive parts of a plant, i.e. they are used for reproduction.

Reproduction by Spores

Some plants like ferns and mosses grow from spores. Spores are different from seeds. They do not contain plant embryos or food stores/reservoirs. Tiny unusual structures present over a fern leaf are called sporangia. Sporangia break opens and releases spores.
Wind handles spore dispersion. If a suitable environment is provided to the spore, it grows into a tiny plant which is called a gametophyte. Gametophytes do not have roots, stems or leaves. They contain male and female reproductive parts which produce gametes. These male and female gametes fertilize (combine) to produce an embryo. After the fertilization, a new plant (eg: fern) starts to grow.
Examples of plants which reproduce using spores-Ferns, Mosses, Liverworts and green algae.

Reproduction by Seeds

Few plants use seeds for reproduction. Male and female cells combine/join together through a process called fertilization. Fertilization results in embryo formation. The embryo is formed inside a seed. The seed protects the embryo and stores food for it. The parent plant disperses or releases the seed. If the seed is provided with desirable environmental conditions, the embryo germinates and grows into a new plant. Plants containing seeds are divided into two types:
Angiosperms- Plants which have flowers
Gymnosperms- Plants which do not have flowers. They store their seeds in cones.

Vegetative parts of a plant

Stems, roots and leaves are vegetative parts which can be used by the plant to reproduce asexually.

Reproduction using roots

The process of vegetative propagation can also take place with the help of roots. For example: In sweet potatoes, the roots bear adventitious buds. New plants develop from these buds when the bud is buried in the moist soil.

Root- Structure and Functions

Roots have following functions and characteristics:

Roots anchor the plants and hold the stem upward.
Its function includes gripping of the soil.
They absorb water and nutrients from the soil which is then transported to other parts of the plant.
Roots are also responsible for food storage.

Reproduction using stems

Reproduction is also possible by stem.
There are certain natural as well as artificial methods for reproduction. A new plant can be developed using the method of vegetative propagation.
Vegetative propagation can take place from the stem in ginger and potatoes. The stem bears small outgrowths called buds. A cutting of such a stem is buried in moist soil along with the bud. Thus, a new plant develops from these buds.

Stem- Structure and Functions

Stem has following characters and functions:

Stem is the vegetative organ which supports the leaves and flowers.
It provides a pathway for transportation of nutrients.
The stem consists of nodes and internodes.
Lenticels are tiny structures which serve the purpose of gas exchange. They are present on the surface of the stem.

Reproduction using leaves

Leaves can be used for reproduction.
For example: Bryophyllum is a plant which is known for its ability to reproduce using leaves. In this type of reproduction, plantlets develop from buds. These buds are present on the marginal notches of the leaves.

Leaf- Structure and Functions

Leaf has following features and functions:

Leaf is a green colored structure that takes in carbon dioxide and gives out oxygen. Water vapor is also released.
Gases pass through the small openings found on the surface of the leaf. These openings are called stomata.
The green color of the leaf is due to the presence of a pigment called Chlorophyll.
Leaves make food which provides nutrition to the plant and supports in plant growth.
The vein of the leaf carries food to different parts of the plant.
A leaf is connected to the stem by means of petiole at the nodes of the stem.
Leaf carries out the functions of photosynthesis and transpiration.

Vegetative propagation

Vegetative propagation is a mode of asexual reproduction.
The vegetative parts of the plants like leaf, roots, stem and leaf give rise to a new individual.
The detached part of the plant has cells enough to divide and produce a new individual.

Introduction of vegetative propagation

Vegetative propagation is the asexual form of reproduction wherein part of plant other than seeds are used for the production of new plants.
There are two methods of vegetative propagation: natural and artificial.

Gemmae

They are unicellular or multicellular propagules that detach from the parent and grow into new individuals.

Spore formation

Reproducing using spores is an asexual method. Many spores are stored in sacs called Sporangia. The sporangia are knob-like structures. They are present at the top of the thread-like structures called hyphae. When Sporangia burst; minute, single-celled, thin or thick walled structures called spores are obtained. They are dispersive, i.e. they are scattered by rain, wind or insects. Under suitable conditions, they develop into a new plant. The suitable condition is provided by a substance, like bread.

Spore formation in Bread Mould

The bread mould or Rhizopus plant undergoes asexual reproduction using spores. Spores are resistant to adverse environmental conditions. Though spores are present in the environment, fungus does not grow on dry surfaces. They need moisture to grow. Hence, fungus is seen on the bread. The dispersed spores fall on the bread's surface. As desirable conditions are obtained, they germinate and reproduce.

Post fertilization

After the process of fertilization the embryo divides mitotically to form multicellular embryo.The endosperm nucleus divides to form a mass of endosperm cells and provide nutrition to the developing embryo.
Many changes occur in the flower after the process of fertilization. A zygote is formed which is diploid in nature and later on forms a new plant
An ovary is transformed in a fruit and ovules in seeds.The integuments form the testa and seed coat. The antipodal cell and the synergids disintegrate.
The petals and the anthers fall off.

Fruit and seed formation

A fruit is a ripened ovary.
After fertilisation, the ovary grows into fruit.
The seed develops from the ovules of the fruit.
The seed is enclosed in a seed coat.

Seed formation

After fertilization the ovules become seeds.One ovule produces a single seed and many ovules produce a multi seeded fruit.
These ovules are attached to the wall of the ovary with help of the placenta.
As the fruit becomes ripe these seeds will come out of of the fruit and grow in new plants.

Eng Portal for English literature students.

Monday, October 28, 2019

HOW ORGANISM REPRODUCE CLASS 10 FULL CHAPTER

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