Biology Notes for Classes Nine and Ten

শিক্ষাক্রম (Curriculum)

শিক্ষাক্রম is related to:

Textbooks.
Biology.
Classes Nine and Ten.
National Curriculum and Textbook Board, Bangladesh.

Biology Classes Nine and Ten

Revised for the year 2025
National Curriculum and Textbook Board, Bangladesh

Preface

Importance of formal education.
Goal: To build a prosperous nation by developing skilled human resources as well as a society free from superstitions. Education helps adhere to science and facts.
Quality education is needed to stand as a developed nation in the 21st century.
Government is determined to ensure education as per the demand of the age.
Education is the backbone of the nation, and curriculum provides the essence of formal education.
The most important tool for implementing curriculum is the textbook.
The National Curriculum 2012 has been adopted to achieve the goals of the National Education Policy 2010.
NCTB works to develop, print, and distribute textbooks and revises curriculum, textbooks and methods.
Secondary education is a vital stage; textbook caters to the aptitude and inquisitiveness of students.
The book is edited by experienced and skilled teachers and experts which will be conducive to a joyful experience for the students.
The book will play a significant role in promoting creative and aesthetic spirits among students.
Emphasis given on scientific concepts, theories, and practical applications of Biology to contribute to human welfare.
Each chapter includes a variety of tasks to understand the text through hands-on work to build confidence, thinking skills and creativity.
The textbook has been reviewed and revised for the academic year 2025 based on the curriculum of 2012.
Meticulous attention has been paid to make it more learner-friendly and error-free; suggestions for improvement are welcome.
Thanks to all contributors: writers, editors, reviewers, illustrators and graphic designers.

Chapter One: Lessons on Life (Pages 1-15)
Chapter Two: Cells and Tissues of Organisms (Pages 16-47)
Chapter Three: Cell Division (Pages 48-60)
Chapter Four: Bioenergetics (Pages 61-81)
Chapter Five: Food, Nutrition and Digestion (Pages 82-121)
Chapter Six: Transport in Organisms (Pages 122-156)
Chapter Seven: Exchange of Gases (Pages 157-174)
Chapter Eight: Excretory System (Pages 175-185)
Chapter Nine: Firmness and Locomotion (Pages 186-198)
Chapter Ten: Coordination (Pages 199-225)
Chapter Eleven: Reproduction in Organism (Pages 226-248)
Chapter Twelve: Heredity in Organisms and Biological Evolution (Pages 249-277)
Chapter Thirteen: Environment of life (Pages 278-300)
Chapter Fourteen Biotechnology (Pages 301-312)

Lessons on Life

Challenges of the present century: food production, medical science development and protection of living beings in adverse conditions.
Biology's role is indispensable.
This chapter discusses the definition of biology, its branches, and the naming system of organisms.

Concept of Biology

Nature includes non-living things and living organisms. Biology studies life and characteristics of organisms.
Distinction between living and non-living is faint. Physics and chemistry explain life's fundamentals, even in non-living things. Knowledge of physical sciences is necessary to understand living organisms.
Life is a complex combination of non-living things, with new characteristics. Water's properties differ from hydrogen and oxygen.
Biology is a fundamental branch of science. The term 'biology' comes from the Greek words, 'bios' (life) and 'logos' (knowledge).
Biology's practice dates back to the beginning of civilization in regions like Greece, Egypt, Middle East, India and China because Biology plays an important role in agriculture and medicine.

Branches of Biology

Living things are classified as plants and animals but this has changed.
Biology includes the two main branches of Botany and Zoology.
Other living beings include bacteria, fungi. The classification is not appropriate when analyzing common characteristics of animals, plants, bacteria, fungi, viruses etc.
Biology is classified into Physical Biology and Applied Biology.
Physical Biology emphasizes theoretical concepts, while Applied Biology focuses on practical applications.

Physical Biology

Morphology: Study of the form and structure of organisms; divided into external and internal morphology.
Taxonomy: Classification of organisms and related principles.
Physiology: Study of the biochemical activities of organs, such as respiration, excretion, photosynthesis.
Histology: Microscopic structure, arrangement, and function of plant and animal tissues.
Embryology: Study of gamete origin, embryo development, structure, growth, and development.
Cytology: Study of cell structure, function, and division.
Genetics: Study of genes and heredity.
Evolution: Study of the gradual development of life and organisms.
Ecology: Study of the relationship between organisms and their environment.
Endocrinology: Study of endocrine glands and hormones.
Biogeography: Study of geographical distribution of organisms and their evolution.

Applied Biology

Palaeontology: Study of prehistoric life forms and fossils.
Biostatistics: Statistics of organisms.
Parasitology: Study of parasitism, parasitic organisms, and related diseases.
Fisheries: Study of fish, fish harvesting, management, and conservation.
Entomology: Study of insects, their life, merits, demerits, and control.
Microbiology: Study of viruses, bacteria, fungi, and other microorganisms.
Agriculture: Science concerning agriculture.
Medical Science: Study of the human body, diseases, treatment, etc.
Genetic Engineering: Study and uses of gene technology.
Biochemistry: Study of biochemical processes and diseases.
Environmental Science: Study related to the environment.
Marine Biology: Study of marine living beings.
Forestry: Study of forests, management, and conservation.
Biotechnology: Technology of using organisms for mankind's benefit.
Pharmacy: Study on the technology and industry of medicine.
Wildlife: Study of wild animals.
Bioinformatics: Biological information based on computer technology.

Classification of living beings

Millions of plant and animal species have been named and described.
Systematic grouping is needed for easy study and understanding.
Taxonomy emerged to classify living world under a natural system.
The main aim of classification is to understand the vast and diverse living world accurately and classify them quickly and easily.

Carolus Linnaeus

Carolus Linnaeus (1707-1778): a contribution in the field of taxonomy.
He classified living world into two kingdoms by observing the characteristics of numerous sample organism- Plant and Animal.

Aim of Classification

To acquire knowledge of groups and subgroups of organisms, maintain systematic documentation, present concise knowledge, identify organisms, and conserve useful organisms.

Living World

All living organisms were classified in two kingdoms, Animals and Plants (up to the middle of the twentieth century).
Five-kingdom classification was proposed by R.H. Whittaker in 1969, based on cell type, features, and number, and mode of nutrition.
Margulis modified and expanded Whittaker's classification in 1974.
She divided the whole living world into two super-kingdoms and grouped the five kingdoms under these two super-kingdoms.
Super kingdom-1: Prokaryota
Kingdom- I: Monera
Kingdom-2: Protista
Super kingdom-2: Eukaryota
Kingdom-3: Fungi
Kingdom-4: Plantae
Kingdom-5: Animalia

Super kingdom-1

Prokaryota are primitive, prokaryotic (no distinct nucleus), microscopic unicellular organisms.

Kingdom- I: Monera

Mostly unicellular, filamentous, or colonial.
No nuclear membrane or nucleolus but chromatin material present.
No plastids, mitochondria, endoplasmic reticuli, but ribosome present.
Cell divides through binary fission.
Mode of nutrition is absorption, though some produce food through photosynthesis.
Examples: Bacteria, blue green algae (Nostoc).

Super kingdom-2: Eukaryota

Eukaryotic cell are well structured nucleus, unicellular or multicellular and live individually or in a colonial form.

Kingdom-2: Protista

Unicellular or multicellular, individual, colonial or filamentous, nuclei are well structured.
Membrane bound Nuclei inside the cell, there is DNA materials such as RNA and protein.
Cell organelles are present.
Modes of nutrition: absorption, ingestion or photosynthesis.
Asexual reproduction via mitosis; sexual reproduction via conjugation.
No embryo development.
Examples: Amoeba, Paramecium, algae (diatom, Spyrogyra etc).

Kingdom-3

Fungi
Characteristics:
Most are terrestrial, saprophytic or parasitic. Body is single cell or mycelium.
Nucleus is well organised. Cell wall is composed of chitin.
Mode of nutrition is absorption. Chloroplasts are absent
Reproduce by haploid spores through mitosis.
Examples: Yeast, Penicillium, Mushroom etc.

Kingdom-4: Plantae

Photosynthetic and eukaryotic.
Have advanced tissue systems.
Develop embryos.
Most are terrestrial, some aquatic.
Sexual reproduction which is happened by union of structurally and physically different gametes.
Are archegoniates and flowering plants.
Examples: Advanced green plants.
Divisions of plantae
Bryophyta (Non-vascular plant): Moss
Trachaeophyta (Vascular plant): Fern, Gymnosperm, Angiosperm

Kingdom-5 Animalia

Eukaryotic and multicellular.
No cell walls, plastids, or vacuoles.
Heterotrophs, depend on other organisms for food.
Digest food after ingestion.
Advanced and complex tissue systems.
Sexual reproduction.
Haploid gametes produced from mature and diploid males and females.
Embryonic layers develop during embryonic development.
Examples: all invertebrates and vertebrates except protozoa.

Thomas Cavalier-Smith (Oxford University, 2004) grouped the living world into six kingdoms

Divided Protista into Protozoa and Chromista.
Renamed Monera as Bacteria.

Different steps of Classification

Codified units or ranks are used in taxonomy, which are called Taxa.
The largest classification rank is kingdom, and the smallest classification rank is species.
Each rank of taxonomy adds new characteristics to those of the lower rank.
The higher the rank, the lower the number of characteristics, and the higher number of living organisms belonging to this rank the lower the rank, the higher number of characteristics, and the number of living beings belonging to this rank.
There are seven main taxonomic ranks according to International Code.

Classification (Taxa)

Kingdom
Phylum Division
Class
Order
Family
Genus
Species
Subset of Kingdom is Phylum, the subset of Phylum is Class, the subset of Class is Order…etc.
This system of scientific classification is called 'nested hierarchy'.
Common characteristics of the previous rank are often not mentioned in the next rank.
Taxonomic rank of human being (homo sapience)
Kingdom: Animalia (cells with distinct nucleus, multicellular, heterotrophs and have complex tissue system).
Phylum: Chordata (possess notochord in any one phase of life).
Class: Mammalia (feed their young on milk and their body is covered with hair).
Order: Primate (hands with five fingers suitable to grasp and vision more developed than sense of smell).
Family: Hominidae (similarity with chimpanzee, gorilla, orangutan).
Genus: Homo (brain is bigger compared to the body and can walk erectly on two feet).
Species: Homo sapience (wide and high forehead, skull is thinner compared to other species, more intelligent).

System of Binomial Nomenclature

The scientific name of an organism has two parts: the genus and the species.
The first part (genus) is followed by the species name.
e.g scientific name of potato is Solanum tuberosum words are solanum and tuberosum.
The aim is to identify every organism unambiguously.
Scientific naming follows international rules and regulations
International Code of Botanical Nomenclature (ICBN)
International Code of Zoological Nomenclature (ICZN)
Names are expressed in Latin and are accepted worldwide.

Carolus Linnaeus (1753) laid the foundations for the naming of organisms
defines the term species and genus
used the ranks of classification class, order, genus and species in his work.

Principles of Binomial Nomenclature

Scientific naming uses Latin.
Every scientific name has two parts: genus and species. E.g., Labeo rohita (ruhit fish). Labeo is the genus and rohita is the species.
Scientific name should be unique; same name cannot be used for two organisms.
The first alphabet of the genus name is capitalized, the rest are small letters, the second part of the name would be with small letters. E.g., Onion- Allium cepa.
Scientific name should be in italics when printed. E.g., Rice- Oryza sativa, Katla fish- Catla catla.
When handwritten, the two parts should be underlined: Oryza sativa, Catla catla.
The earliest legitimate name has priority. The scientist who gives the name can be cited in abbreviated form (e.g., Homo sapiens L., 1758).

Binomial names of some organisms

Rice: Oryza sativa
Jute: Corchorus capsularis
Mango: Mangifera indica
Jackfruit: Artocarpus heterophyllus
Water lily: Nymphaea nouchali
China rose: Hibiscus rosa-sinensis
Cholera: Vibrio cholerae
Malaria: Plasmodium vivax
Cockroach: Periplaneta americana
Honey bee: Apis indica
Ilish: Tenualosa ilisha
Asian toad: Duttaphrynus melanostictus (Bufo melanostictus)
Oriental Magpie-Robin: Copsychus saularis
Tiger: Panthera tigris
Human: Homo sapiens

Cells and Tissues of Organisms

Views of a cell of an organism appear the same under both a light microscope and an electron microscope. In this chapter, you will find the answers to these kinds of questions..

Learning outcomes

Functions of main organelles of plant and animal cells.
Comparison of plant and animal cells.
Roles of different types of cell in performing the functions of nerve, muscles, blood, skin and bones
Appropriateness of cell in the body of an organism;
Plant tissues;
Animal tissues;
Functions of tissue on the basis of grouping the similar type of cells and performing the same action;
Organisation of cells in tissue, organs and organ systems;
Functions of tissue system;
Concept and importance of organs and organ systems;
Diagrams of plant cell (onion cell) and animal cell (buccal mucosa cell).
Correctly use a microscope
Roles of cells in different activities of organisms.

Living Cell

The cell is the structural unit of an organism
A living cell is unit of structure and biological function of an organism.
Loey and Siekevitz (1969) described a cell as the unit of living activity which can duplicate itself without any different living medium and is surrounded by a selectively permeable membrane.

Types of Cells

Cells differ in structure, size, shape, and function. On the basis of the organisation of the nucleus, cells can be divided into two types- prokaryotic cell and eukaryotic cell.

Prokaryotic cell

A prokaryotic cell does not contain a true nucleus hence called cell with primitive nucleus.
Nuclear materials not surrounded by a nuclear membrane are dispersed in its cytoplasm.
Organelles including mitochondria, plastids, endoplasmic reticulum not found here but ribosomes are present.
Blue green algae and bacteria are the examples of the cell.

Eukaryotic cell

Nucleus is well structured with nuclear membrane.
Other cell organelles are present, including ribosome.
Chromosomes consist of DNA, histone, protein etc.
Most living cells are of this type.
Somatic cell: Composition of the body, divide through finary fission and mitotic division, involved in organization of organs and organ systems.
Gametic cell: involve in sexual reproduction and alternation of generations and produced in the organisms in which sexual reproduction and alternation of generations occur, primordial germ cells divide through meiotic division and produce gametic cells, number of chromosomes becomes half. Zygote is the first cell produced after the union of male and female gametic cells.

Main Organelles of Plant and Animal Cells and their Functions

Each eukaryotic cell consist of organelles.
Some organelles are found only in plants and some are found only in animals.

Cell wall

a unique feature of plant cell, absence in an animal cell
Chemical composition: cellulose, hemicelluloses, lignin, pectin, suberin.
Bacterial cell wall contains protein, lipid and poly saccharide.
Fungal cell wall—chitin.
Primary cell wall is single layered. The secondary cell wall develops gradually, cavities are formed called pits, retains shape and size of cell, Plasmodesmata are formed in the cell wall, controls water and minerals

Protoplasm

Translucent, semi fluid viscous substance that constitutes the interior matter of a living cell is called protoplasm.
Surrounded by the cell wall, contain cytoplasmic organelles and nucleus.

Plasmalemma

The double layered membrane around the protoplasm or cell membrane or plama membrane.
Flexible, has folds called microvilli and is mainly composed of lipids and proteins.
Selectively permeable, controls osmosis, separates cell from neighbors

Cytoplasmic Organelles

Semi fluid, jelly like substance of a cell that is external to the nuclear membrane and internal to the cellular membrane.
It contains Membrane-bound cytoplasmic organelles and Non-membranous cytoplasmic organelles-

Membrane-bound cytoplasmic organelles

1: Mitochondria

discovered by Richard Altmann in 1886
takes part in respiration, current name 'given by Benda.
Surrounded by a double-layered membrane of phospholipid and protein.
Inner membrane has finger-like infoldings called cristae, contain enzymes, encloses matrix.
Cellular respiration: glycolysis, Acetyl-CoA formation, Kreb's cycle and electron transport system
Kreb's cycle occurs in mitochondria
Maximum energy produce in Kreb's cycle
Powerhouse of a cell
Mostly found in plant and animal cell

2: Plastid

discovered by the scientist Ernst Hackle in 1866.
functions are to produce food, store food, and gives colour to flowers, fruits and leaves.
Three categories: chloroplast, chromoplast and leucoplast.

a) Chloroplast:

Green plastids, found in leaves, young stems, and green parts.
Grana capture solar energy to make carbohydrates from water and carbon dioxide.
Green due to chlorophyll, but also has carotenoids.

b) Chromoplast

Colored, but not green; contain yellow (xanthophyll), orange (carotene), red (phycoerythrin), blue (phycocyanin)
Gives attractive colors to flower and leaves to make flower more attractive and for pollination
Synthesize and store different photosynthetic pigments.

c) Leucoplast

Non-pigmented. Found in cells where sunlight doesn't reach (e.g., root, gamets, embryo).
Stores food.
Can transform into chromoplasts or chloroplasts.

3: Golgi body:

Found within the cytoplasm of animal cells
Composed of stacks of membrane-bound structures( cisternae and vesicles)
Hydrolysis of enzymes take place in its membrane.
Involve in the secretion of some hormones and other substances in a living cell
Important roles in metabolic activities
Sometimes, the golgi body stores protein.

4: Endoplasmic reticulum

Ribosomes are studded with the cytoplasmic side of rough endoplasmic reticulum.
So Proteins are synthesized in these places, Membrane bound vesicles from the endoplasmic reticulum shuttle proteins and other materials produced in a cell.
Enzymes for other cells and other substances produced inside the cell are transported by the endoplasmic reticulum.
Found in both the plant and animal cells.

5: Cell vacuole:

Hollow space seen in the cytoplasm of a cell mainly seen in plant cell
Its main function is to contain cell sap
Vacuole is generally not found in any animal cell. Present if any in animal cell and usually be much smaller.

6. Lysosome:

protect cells from germs by killing them with enzymes
enzymes are protected by a membrane so other organelles don't get digested
Adjacent organelles are digested if lysosome's membrane is destroyed due to oxygen deficiency, this can kill the cell

Non-membranous cytoplasmic organelles

Cytoskeleton: network of fibers shaping cell and holding organelles, beneath plasmalemma, uses proteins like actin, myosin and tubulin
Ribosome: Lacks membrane, helps protein synthesis, matrix of mitochondria and stroma of plastids contain ribosomes
Centrosome: Found in animal cells but not in cells of lower plants,Centriole is a hollow, cylindrical organelle inside the centrosome. The thick liquid surrounding the centriole is called centrosphere.
Develop astral rays, participates in formation of various types of flagella

Nucleus

membrane bound organelle found in eukaryotic cells, carries chromosomes found in cell of all organisms and roughly round or spherical in structure.
Nucleus is not found in mature sieve cells and red blood cells for control heredity information of the organism, and controls the activities of a cell. It has:

A) Nuclear membrane:

The membrane that encloses the nucleus is called nuclear membrane.
A double layered membrane, is composed of lipids and proteins.
In this membrane, there are some pores called nucleopores and controls the transport system from the nucleoplasm to the cytoplasm. The membrane separates the contents of the nucleus from the cytoplasm.

B) Nucleoplasm:

surrounded by nuclear membrane, similar to cytoplasm, contains nucleic acids, proteins, enzymes and some other substances dissolved in and mixed with it.

C) Nucleolus:

In a nucleus the round structure attached to a chormosome,This is composed of RNA and proteins,store nucleic acid and synthesize protein,

D) Chromatin reticulum

Thread-like materials which are tangled in the nucleus of non-dividing cells, these threads are chromatin composed of DNA and proteins, acts as a medium for the transmission of genetic characteristics. During cell division, the tangles shorten slightly and the chromatin becomes thicker and shorter. Then chromatin is divided into a pair of chromosomes to form a pair of chromosomes and centromere, kinetochore, chromatids are formed.

Roles of different cells in proper functioning of plants and animals

Function of Tissue cell is the structural and functional unit of organisms.

Plant tissue

Tissue: Similar or different types of cells with the same origin and performing a specific function.
Plant tissue: Meristematic (Capable of cell division) and Permanent tissue (do not capable of cell division).

Simple tissue

Permanent tissue which contains cells of same shape, size and structure.
Divided into Parenchyma, Collenchyma, and Sclerenchyma.

A) Parenchyma:

Seen almost everywhere in plant, living, thin, isodiametric, protoplasm filled
Intercellular spaces are found, walls are cellulose, with chloroplast it looks like the Chlorenchyma, with air big sized space called aerenchyma and found in aquatic plants.
Organizes body parts, produces, transports, stores food.

B) Collenchyma:

Special Parenchyma, thicker with the compilation of cellulose and pectin.
Thickened unevenly, corners thicker (pectin deposit), polygonal cells, elongated with protoplasm present
May have intercellular spaces, produces food and Provides plant mechanical rigidity and support and are found in the veins and petioles of leaves. This provides rigidity to the stems of various plants.

C) Sclerenchyma:

Thickening of cells walls with lignin provides mechanical support.
Cells lose protoplasm when mature.
Functions: mechanical support, rigidity, conducts water and minerals
There are two types of sclerenchyma cells, fibers.and sclereids.

a) Fibers

Elongated, slender, and sharp ended with thick walled, pores called pits
Originate in different ways based on structure; bast, surface, xylem, wood fiber.

b) Sclereids:

Hard (stone cells), shorter compared with fibers, isodiametric or long and star shaped.
Secondary walls are thick, lignified and pitted.
Mature cells are usually dead.
Found in cortex, fruits, seed shells of gymnosperm and dicot plants and petioles of leaves

Complex tissue

Permanent tissues made of more than one type of cells i.e Conducting water, minerals and prepared food, Xylem and pholem
Xylem and pholem together create vascular bundle

Xylem

Two types Xylem: Protoxylem and Metaxylem.
Protoxylem during primary stage and after maturity called metaxylem which develops before secondary growth and primary develops during primary growth from the procambium and Secondary xylem from the vascular cambium during secondary growth
Protoxylem has small cells so vessel looks narrower
Tracheids, vessels, xylem parenchyma, and xylem fibers are its components.

a) Tracheids:

elongated with slender ends, lumen may become narrower based on lignification so water is transported through lateral paired pits, walls show elliptical thickening,spiral and are found in ferns and gymnosperms and are also present in the primary and secondary xylem of angiosperms.
Their primary main functions are the conduction of cell sap and to provide the organs with proper rigidity. Sometimes they also store food.

b) Vessels:

Short, tubular, connected end to end when their terminal walls are dissolved, filled with protoplasm during early stage, eventually die by losing it differently thickened walls like tracheids, scalariforms, spiral etc and are present in angiosperms, some advanced gymnosperms like gnetum have primary vessels.transprot minerals and proper rigidity.
c) Xylem parenchyma:
The parenchyma cells in the xylem are called xylem parenchyma or wood parenchyma their walls may be thick or thin, primary xylem has thin walls but those in secondary xylem are thick and provide store food and transportation of water.
b) Xylem fiber:
sclerenchyma cells in the xylem with Tapered cells, mature cells don't contain protoplasm, so they are dead, the dicots have present and provide mechanical support and strength, storage of food, transportation of minerals and their major functions.

Phloem

tissue composes the vascular bundle in associated with xylem, Xylem transports water as the raw materials of food and the pholem conducts food manufactured in leaves to the different parts of a plant and consists of sieve tube, companion cell, phloem parenchyma and pholem fiber.
a) Sieve cell:
Special types of cells, arranged head to tail make the sieve tube, plate separates the cells called sieve plate, The protoplasm in a sieve cell is closer to the wall, walls are lignified, mature doesn't contain nucleus these and companion cells are present in angiosperms. their main function in different parts of a plant to transport food.
b) Companion cell:
Parenchyma is found with each sieve cell, not in pholem of angiosperms and ferms, the nucleus is much larger, its assumed that the nucleus of companion cell controls activities of its neighbouring cell so it becomes thin and turgid with protoplasm.\
c) Phloem parenchyma:
The pholem contains this with thin walls, and they have a protoplasm to store and conduct food, but they are not present in monocots angiosperms and are found in ferns and gymnosperm.
d) Phloem fiber:
Sclerenchyma cells called best fiber that are long cells, that has developed time of cells containing lignified walls the secondary growth of plant parts, They can move both down and up

Animal tissues

Animal tissues is the structural and functional unit of tissue

For example, red blood corpuscles, white blood corpuscles, blood platelets are different types of tissues, called connective tissues. The liquid connective tissue takes part in different physiological processes.
Cells engaged in different activities. Nerve cells form a network and receives stimuli and send to brain. Muscle cells are writing, walking. Red blood corpuscles absorb oxygen. White blood corpuscles prevent diseases. Platelets start blood clotting. Bone cells constitute bones with deposition of minerals or cartilage, which makes structure and supports the body.
Classifications:
Four main categories based on structure presence or absence of the internal material and number of cells.

1) Epithelial tissue:

Functions as the lining of various organs, this tissue also provides cover to the organs which is a main features of this tissue, it’s function are: protection of underlying tissues, secretion of waste products, including protein; absorption of water and nutrients; transcellular transport of specific materials, the cells of the tissue lie closely or side by side on a base membrane\Based on size, nature of work and the location it is three types:

I) Squamous epithelial tissues:

Cells are found like scales, large nucleus
Example: wall of the Bowman's capsule of kidney performs the filtration

II) Cuboidal epithelial tissue:

length, width and the height are nearly equal
Example: the collecting tubules of the kidney covers and transportation in process

III) Columnar epithelial tissue:

cells are column like cells, narrow and elongatedExample: Found in the internal wall of intestine of vertebrates secretion mostly active in protection and absorbtion.
three types membrane based I) Simple: single layer on the layer of Bowman's capsule of kidney Example : kidney tubules, wall of intertine; II) Stratified: layers that can change Three or four layers can turn into seven or eight layersExample: Integument of vertebrate animals; III) Pseudo stratified tissues are arrange on cell basement but not all height is same.
Trachea.
Different transformed functions of cells are-
i. ciliated epithelial tissue
Traches or vertebrate is exampleii. Flagellated muscular
endotherm of hydra is example
iii. Epithelial tissues are example by pseudopodial in Intermembrane in vertebrate and edoderm in hydria
v. Reproductive produce sperm and overum secrete fluid
glands necessary tissue form an internal external covering and take part in secretion diffusion protection transport by transformations

2) Connective tissues:

Has matrix: Less no cells, connective tissue is mostly of three types based on function and structure(i) Fibrulous internalment connective tissue lies within the body of internalment and it's sparsely(ii) Skeletal has two formation, forming hard substance: Catilage and Bone catage is kind of flexible skeleton Elastic bone
(iii) Flued connective : fluid matrix that called lymph
Blood: alcael slightly saline liquid containing corpuscles of red, white and platelets
(a), (b) White:
destroy
c) Platelet takes part in regulation(i+ii) the intergrumenty maintains human balance. Within the lymphatic vessel (a type of fluid connective)

3) Muscular tisse

form the vertebrate animals (skeletal) muscular part is mesoderm( capable of contracting and expanding tissues in muscles vertebrate tissues. Three types are- (i) valuntry tissues that expand according to animal and unbranched is 2 muscle tissues not depend on expansion the animals.
Cardiac muscles: Heart muscles control the ciriculation in their body from embryonic to death.

4. Nerve Tisses:

Is a type of nervous system, receives stimulus from the heat light pressure or touches, transmits these stimuli throughout body and from this it an also make accurate response (neuron cell); and each one has two parts - cell is neurite or neuronal.soma body cell in nuclei. Axion dendrite which and transmit it to other by synapse and also transmit in neuron. In hiher animals these tissues form control or act of stored memory by the body also coordination thems which brain and memory make coordination amoung
2.4 Organ and System
Organ Combination of tissue and perform partcular function; may have more tissues , performs particular functions and called morphology .
External-eye, ear, nose and Internal-Stomach internal organs
To perform some tasks sevaral organs working togather is digestive system

Digestive -mouth/cavity esophagous stomach and liver
Respiratory system -lung/bronchius
Intergument - skin structure 4. Nervous system - spinal code
endocrine system- pituitary 6. Excretary kidney
system -reproducty organ/system
Various systems human body

2.5 Miscrosocope

just as is important a telscope to astramer the same way essential studyology

Simple: plane stage, stage made of class, Mirror base and foot , and clips vertical
compound: the revolving part or turred is Nosepiece, 3 objectibes low poewe, and hiugh power
Illimunator: base form light
Staining: to diffiernce is through in slides that why slide dying

Electron microscope

Use short focus of wavelength by light Ordinarly be well magnified, use to make clearly the visibilitu by object use election magnet