i) Zoology: Zoology is that branch of biology which deals with the study of animals.
ii) Botany: Botany is that branch of biology which deals with the study of plants.
iii) Microbiology: It is the branch of biology which deals with the study of microorganisms such as viruses, bacteria etc.
iv) Morphology: It deals with the shape and structure of living organisms.
v) Histology: It is the microscopic study of tissues of plants and animals.
vi) Cytology: It deals with the structure of cell and organelles present inside the cell.
vii) Physiology: It deals with the study of functions of different parts of plants and animals.
viii) Ecology: It is the science of ecosystem and explains the relationship between organisms and their environment.
ix) Taxonomy: It deals with the naming and classification of organisms.
x) Genetics: It deals with the study of heredity and variations.
xi) Biotechnology: It deals with the application of biological processes.
xii) Haematology: Study of blood and its constituent cells.
xiii) Geology: Study of features and properties of earth and its constituents rocks.
Table of Contents
Characteristics Of Living Organisms:
Following are the main characteristics of living beings which are not present in non-living organisms.
Viruses are the micro-organisms which are strict or obligate parasites of animals or plant cells.
Many of the viruses are also parasites on bacteria.
A large number of viruses cause diseases in plants and animals.
Characteristics Of Virus:
A virus consists of two components, a protein coat and a core of nucleic acid which is either DNA or RNA.
DNA viruses are called adenoviruses and RNA viruses are called retroviruses.
The shape of a virus is due to its protein coat.
Viruses are of many shapes i.e. rods, spherical, hexagonal or icosahedral.
Sometimes their shape is complicated.
Virus replicate inside a living cell and many viruses are synthesized along with their protein coats and nucleic acid.
The nucleic acid contains instructions for the shape of the virus.
Diseases Caused By viruses:
Characteristics Of Bacteria:
Bacteria are unicellular prokaryotic organisms which generally divide by transverse binary fission.
They possess rigid cell walls and act as pathogens
Nucleus is not well organised
No definite chloroplast, chlorophyll is dissolved in chromoplasm.
There are three forms of bacteria which are:
i) Round called Cocci
ii) Rod like called Bacilli
iii) Spiral called Spirrila
Classification Of Bactria According To Mode Of Nutrition:
According to mode of nutrition, there are three types of Bactria:
Devoid of chlorophyll
Are heterotrophic and get food from living animals and plants
Lack chlorophyll hence cannot prepare their own food.
Get food from dead organic remains
Can synthesis food by photosynthesis
Few get their food by chemosynthesis
Reproduction In Bacteria
i) Vegetative: By Binary Fission
ii) Asexual: By Formation of Endospores
iii) Sexual: By Conjugation
The smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane.
The cell is the functional basic unit of life. It was discovered by Robert Hooke and is the functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life.
Cell Structure And Functions (Plant & Animal Cell)
1. Cell wall
– Most commonly found in plant cells
– Controls turgidity
– Extracellular structure surrounding plasma membrane
– Primary cell wall: extremely elastic
– Secondary cell wall: forms around primary cell wall after growth is complete
2. Plasma membrane
– Outer membrane of cell that controls cellular traffic
– Contains proteins (left, gray) that span through the membrane and allow passage of materials
– Proteins are surrounded by a phospholipid bi-layer.
-colourless, semitransparent, viscous granular fluid present inside the cell is called as protoplasm.
-colloidal in nature and considered as physical basis of life.
-exhibits the active streaming movement called cyclosis
-it consists of water, protein, lipid or fats, carbohydrates, enzymes, salts, nucleic acid in a fixed proportion.
-it is divided into Nucleus and Cytoplasm
-Protoplasm outside the nucleus is called cytoplasm
-all the organelles are present in the cytoplasm like;
i) Endoplasmic reticulum
– Tubular network fused to nuclear membrane
– Goes through cytoplasm onto cell membrane
– Stores, separates, and serves as cell’s transport system
– Smooth type: lacks ribosomes
– Rough type (pictured): ribosomes embedded in surface
ii) Golgi apparatus
– – Composed of numerous layers forming a sac
– Works as the distribution and shipping department of the cell’s chemical product.
– – Digestive ‘plant’ for proteins, lipids, and carbohydrates
– Transports undigested material to cell membrane for removal
– Vary in shape depending on process being carried out
– Cell breaks down if lysosome explodes
– Second largest organelle with unique genetic structure
– Double-layered outer membrane with inner folds called cristae
– Energy-producing chemical reactions take place on cristae
– Controls level of water and other materials in cell
– Recycles and decomposes proteins, fats, and carbohydrates, and forms urea
– Each cell contains thousands
– Miniature ‘protein factories’
– Composes 25% of cell’s mass
– Stationary type: embedded in rough endoplasmic reticulum
– Mobile type: injects proteins directly into cytoplasm
– Membrane-bound sacs for storage, digestion, and waste removal
– Contains water solution
– Contractile vacuoles for water removal (in unicellular organisms)
– A plastid usually found in plant cells
– Contain green chlorophyll where photosynthesis takes place
– Composed of microtubules
– Supports cell and provides shape
– Aids movement of materials in and out of cells
– Paired cylindrical organelles near nucleus
– Composed of nine tubes, each with three tubules
– Involved in cellular division
– Lie at right angles to each other
-Control centre of the cell
-Serves as information processing and administrative centre of the cell
-Performs the following major functions:
a) stores the cell’s hereditary material, or DNA
b) coordinates the activities of the cell, which includes growth, metabolism, protein synthesis, and reproduction or cell division.
i) Nuclear membrane
– Surrounds nucleus
– Composed of two layers
– Numerous openings for nuclear traffic
– Spherical shape
– Visible when cell is not dividing
– Contains RNA for protein manufacture
– Usually in the form of chromatin
– Contains genetic information
– Composed of DNA
– Thicken for cellular division
– Set number per species (i.e. 23 pairs for human)
Difference Between Animal And Plant Cell:
1) Cell Wall OR Cell Membrane
– The outer boundary of plant cells is known as the cell wall, which is mainly composed of cellulose.
– It helps the plant cell to maintain its shape.
– The cell wall is absent in animal cell.
– In animal cell the outer covering is known as cell membrane which is composed of lipid bilayer, proteins and carbohydrates.
– Plants cells also contain organelles which are known as plastids.
– The most common type of plastid is the chloroplast which contains chlorophyll.
– These organelles or plastids are totally absent in animal cell.
– The main difference between the vacuole of animal and plants is their size.
– The vacuole of plant cell is much bigger than that of animal cells.
– In animal cells centrosomes are present, which are responsible for making some protein fibres which help in movement of chromosomes during division of cells.
– Centrioles are absent in the plant cells.
– Lysosomes are not evident in plants while they are prominent in animal cells.
The process in which the cells divide and replicate. This process is the basis for growth and replication. There are two main types of cell division, which are as under:
A type of cell division in which a cell divides into two identical daughter cells each having same number of chromosomes as that of parent cell.
Stages Of Mitosis:
There are four stages of mitosis, which are as under:
– Prophase is the first phase of mitosis.
– Chromatin material condenses and becomes visible
– The nucleolus of the cell disappears
– The nuclear membrane also disappears
– Centrioles begin to move opposite ends of the cell
– Metaphase is the second stage of mitosis.
– Chromosomes line up in the centre of the cell, separate and become a pair of identical chromosomes.
– The chromatids become uncoiled and apart from each other.
– It is the third phase of mitosis.
– During this phase each set of chromosomes move towards the opposite end of the cell.
– The fourth phase of mitosis is known as Telophase.
– During this phase spindle fibres disappear.
– Nuclear membrane appears
– Cell divides into two daughter cells
– Nucleolus re-appear
– The chromosomes disperse and are no longer visible.
Significance Of Mitosis:
1. Growth: The number of cells within an organism increases by mitosis and this is the basis of growth in multicellular organisms.
2. Cell Replacement: Cells are constantly sloughed off, dying and being replaced by new ones in the skin and digestive tract. When damaged tissues are repaired, the new cells must be exact copies of the cells being replaced so as to retain normal function of cells.
3. Regeneration: Some animals can regenerate parts of the body, and productions of new cells are achieved by mitosis.
4. Vegetative Reproduction: Some plants produce offspring which are genetically similar to themselves. These offspring are called clones.
A type of cell division in a cell divides into four daughter cells with having half number of chromosomes as compared to parent cell.
Characteristics Of Meiosis:
Takes place in sexual reproduction at the time of formation of male and female gametes
In animals it takes place during the formation of sperms and ova while in plants during spore formation
Diploid cells reduce to haploid cells
Consists of two consecutive divisions
First division is reductional or meiotic and the second is simple mitotic division.
Stages Of Meiotic Division:
i) Prophase I
ii) Metaphase I
iii) Anaphase I
iv) Telophase I
v) Prophase II
vi) Metaphase II
vii) Anaphase II
viii) Telophase II
Prophase I consists of 5 sub stages, these are:
– Nucleus increases in size
– Chromosomes become long and uncoiled threads
– They become more visible
– Homologue (similar) chromosomes attract each other and form pairs.
– This process is called synapses
– Chromosomes become condensed due to widening of coils
– They form chiasmata i.e. cross each other in double nature or bivalents.
– Homologous chromosomes go apart from each other except at chiasmata
– Chromosomes become more short and thicker
– The bivalents become more apart.
– Chromosomes become deeply stained
– Nucleolus and nuclear membrane disappear and spindles become distinct
– Chromosomes now rearrange themselves in an equatorial line
– Spindles attach to the centrosome of the chromosomes
– Spindles start to contract
– Split the tetrahedral chromosomes into two chromatids and drag them to opposite poles
– Here the reduction takes place.
– Spitted chromosomes reach to opposite poles
– Nucleolus and nuclear membrane reappear
– At the end of Telophase I, prophase II starts.
– Chromatin network breaks into bivalent chromosomes
– Nuclear membrane and nucleolus disappear and spindles start to reappear
– Bivalent chromosomes rearrange themselves at equator
– Spindles attach to the centrosomes of each chromosome
– Spindles contract and split the chromosomes longitudinally into two chromatids
– Each chromatid travel to opposite pole
– Each chromatid reach to the opposite pole
– Spindles disappear and nuclear membrane and nucleoli reappear
– As a result 4 nuclei are formed
Significance Of Meiosis:
– To allow trait inheritance in offspring
– To maintain diploid number in each generation
– To ensure the production of haploid gametes in sexual reproduction
– To produce genetic variations among offspring
Classification Of Plants:
Plants are those organisms which contain chlorophyll and synthesize their own food through photosynthesis. Plants are divided into:
1) Flowering Plants OR Phanerogams
2) Non-Flowering Plants OR Cryptogams
Flowering plants are those plants which contain seed. These are known as Phanerogams. They are further subdivided into:
Gymnosperms are those flowering plants which contain naked and unprotected seeds.
Examples: Pine, Fir, Cedar, Spruce and Cypress etc.
Angiosperms are those flowering plants whose seeds are protected by a fruit or seed pod.
Examples: Grass, Crops, Vegetables, Fruits and weeds.
Non-Flowering plants are also known as cryptogams. These are the plants which do not have seed or in other words they are seedless. Following are the main characteristics of these plants:
– They reproduce by spores
– They have long life
– They have no long fibres
– They cannot grow to greater size
– They generally have simple structure, except ferns.
Examples: Moses, Ferns, Algae.
Flower & Its Parts:
The flower is the reproductive part of the plant. It is mainly concerned with formation of seeds. It is regarded as the modified shoot for the purpose of reproduction.
Parts Of Flower:
A typical flower consists of a short axis known as the thalamus, on which floral leaves are inserted in four distinct whorls, which are as under:
Calyx is the outermost whorl of floral leaves called sepals. The sepals can be defined as the green and leaf like structures which are mainly concerned with the protective function.
Corolla is the second whorl of floral leaves called petals. The petals are beautifully coloured which are responsible for the attraction to the insects towards them.
The third whorl of the leaves consists of stamens. It is considered as the male part of the flower.
Gynaecium is the inner most whorl of the floral leaves called carpels. It is considered as the female part of the flower.
Parts Of Plants:
Photosynthesis is a process in which plants manufacture their food (simple carbohydrates) in the presence of chlorophyll and sunlight by the combination of carbon dioxide and water.
Raw Material For Photosynthesis:
i) Carbon dioxide: Taken from air
ii) Water: Absorbed by roots from soil
iii) Sunlight: From Sun
iv) Chlorophyll: green pigment present in leaves
By-Products Of Photosynthesis:
i) Carbohydrates (simple sugar): used by plants as a food material and excess of it is converted into starch
ii) Oxygen: Released into air
Importance Of Photosynthesis:
i) Major process of food production in plants
ii) Utilization of CO2 of the atmosphere and liberation of oxygen
iii) Important in reducing CO2 of the atmosphere which is dangerous for the human beings as well as animal health.
Pollination is the phenomenon of transfer of pollen from male reproductive organ (anther) to female reproductive organ (stigma) in flowering plants through biological or physical agency.
Types Of pollination:
There are two types of Pollination
In this type of pollination pollens are transferred to the stigma in the same flower. Some plants are by nature self-pollinated as wheat and grasses.
ii) Cross Pollination:
In this type the pollen grains are transferred from the anther of one flower to the stigma of another flower. The cross pollination is considered and advantageous to the plant as the seeds produced by cross-pollination are usually greater in number and the plant germinated from them are superior in vigour, height and weight.
Vehicles For Pollination:
Vehicles for pollination are animals, water, wind and insects. Therefore cross pollination may be:
a) Entomophily-by insects
b) Anemophily-by wind
c) Hydrophily-by water
d) Zoophily-by animals
Importance Of Pollination:
• Vital process for reproduction in plants
• Reproduction is carried out by reproductory organs of plants due to pollination
• It is the process by which seeds are produced.
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