Notes of class 7

Animal tissue :- There are four major types of animal tissue :-

(i) Epithelial tissue :- [ Epi = Upper ; Thelium = Layer ]

Epithelium is covering on internal tissue. It is protective in function. All types of epithelial tissue are situated on the basement membrane. On the basis of its structure and location there are three types of epithelial tissue.

(A) Squamous epithelium :- 

• Squamous epithelial cells are flat, irregular.
• It is also called pavement epithelium.
• This tissue is present on outer layer of skin, lining of alveoli, blood vessels, body cavity.
• Squamous epithelium is involve in protection of underlying tissue.

(B) Cuboidal epithelium :- 

• Cells of this tissue is cube like.
• It is found as single layer.
• Each cell of cuboidal epithelium has single nucleus in it.
• Cuboidal epithelium is found on the lining of kidney tubule, thyroid gland, germinal epithelium in testes and ovaries.
• Main function of cuboidal epithelium is secretion and absorption.
• In testes ( found in male ) and ovaries ( found in female ), cuboidal epithelium is involve in production of male gamete ( sperm ) and female gamete ( ovum ).

Notes of class 9

(ii) Plastid :- 

• Plastids are the cell organelles present in plant cell only.
• There are three kinds of plastids - Chloroplast ; Chromoplast and leucoplast.

(A) Chloroplast :- The chloroplast is surrounded by double membrane. Ground material of chloroplast is called stroma. In chloroplast coin like/disc like structure is present called thylakoid. Pile of thylakoid is called Granum ( plu. Grana ). One granum is attached with other granum by fret ( stromatal thylakoid ). In the sroma of chloroplast ribosome and DNA is present which make it semi autonomous cell organelle. Granum contain chlorophyll pigment in it . Main function of chloroplast is photosynthesis.

(B) Chromoplast :- Chromoplast is coloured plastid . It gives colour ( except green, voilet, blue, purple ) to flower fruit and other parts of plant. Example - Xanthophyll, carotene etc.

(C) Leucoplast :- The leucoplast is colourless plastid. Its main function is to store the food. There are three kinds of leucoplast on the basis of stored food in it :-

(a) Amyloplast :- Store starch in it.

(b) Proteinoplast :- Store protein in it.

(c) Elaioplast :- Store fat in it.

     

Notes of class 8

Artificial vegetative propagation :- Vegetative propagation in plants performed by human for economic benefit or for getting new variety is called artificial vegetative propagation.
Following methods are used for artificial vegetative propagation :-
(i) Cutting :- 

• In cutting method a small piece of stem (which bears buds ) from parent plant is cut and  put in the soil .
• The bud present on the node of that cut stem grow as a new plant.
• Since new plant is growing with the help of vegetative part ( stem ), it is called vegetative propagation.
• Example - Rose, Sugar cane etc.

(ii) Layering :- 

• Layering process is performed in shrub which has flexible stem.
• In layering process a flexible stem of shrub is bent and a part of it is put in the soil.
• After some time under ground part of stem start growing root and its shoot system grows upward.
• Now new plant should be separate from parent plant and new plant start its individual growth. 

(iii) Grafting :-

• Stock is the rooted part of graft.
• Scion is the aerial part of graft.
• In grafting method new variety is produced by mixing the desired features of two or more plants.
• Stock of one plant and scion of another plant are tied together and their vascular bundles (xylem and phloem) join after some times.
• New plant produced after grafting represent features of both plants.

(iv) Tissue culture :- 

• Explant :- A small piece of tissue cut from vegetative part of plant ( Stem, Root, Leaf ), used for the tissue culture is called explant.
• Antiseptic :- A chemical which prevent growth of micro organisms on living tissue is called antiseptic.
• Medium :- Medium is the solution of nutrient ( Minerals ) in which explant is kept for cell division.
• Callus :- The callus is mass of undifferentiated cells in the medium.
• Plantlet :- Callus is given command to develop root and shoot by using the phyto hormones in laboratory. Small growing root and shoot from callus make it the plantlet.

In tissue culture many plantlets can be produced at a time.

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About sexual reproduction in plant we will discuss in our next class............

Bye!

Notes of class 9

Cytoplasm :- Cytoplasm is the ground material of the cell. Living cytoplasm exist in two inter convertible forms sol and gel. Cell organelles are present in the cytoplasm. Cytoplasm of a cell is the site of vivo reactions ( chemical reaction ) in the living body.
The part of cell present between cell membrane and nuclear membrane is called the cytoplasm.

Cell organelles present in the cytoplasm :- 
(i) Mitochondria :- 

• The mitochondria is surrounded by double membrane. Outer membrane is continuous and inner wall is folded inward.
• Inner wall of mitochondria after folding inward forms finger like structures called cristae. The cristae contain large number of oxysomes on it which secrete enzymes.
• Ground material of mitochondria is called the matrix.
• Matrix of mitochondria has Ribosomes and DNA. Due to presence of DNA the mitochondria becomes semi autonomous cell organelle.

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In today's class we have discussed till here. We will continue notes in next blog.
Bye...

Notes of class 8

Clones :- Next generation of  plants obtained by asexual method or by vegetative propagation are exact copies of parent plant, there is no genetic variations. These are called the clones.

Offsprings :- Next generations of plant obtained by sexual reproduction has some genetic variations. These are called offsprings.

Vegetative Propagation :- Reproduction in the plants by using their vegetative parts like root, stem, leaf is called vegetative propagation or vegetative reproduction.

Natural methods of vegetative propagation :- 

1. Vegetative propagation by root :- 

• Roots are underground part of plant.
• The root which store food in it, is called root tuber.
• Stored food in the root enable the root for production of next generation ( clone ) in next growing season.
• Dahalia, sweet potato are the examples.

2. Vegetative propagation by stem :-

• The stem is part of plant which has nodes and inter nodes on it.
• Node of stem has bud on it which may grow as leaf, side branch, flower etc.
• The stem in the plant may be under ground ( e.g. potato ), sub aerial ( e.g. grass ) or aerial.

(i) Vegetative reproduction by under ground stem :-

• Under ground stem store food in it and become stem tuber.
• Stored food in the stem tuber is utilized by plant for vegetative reproduction.

(a) Tuber :- 

• Potato is under ground stem tuber.
• Potato has small depressions on it called eyes. These eyes of potato are the nodes of under ground stem.
• Eyes of potato has axillary bud in it.
• Under favourable conditions of growth the axillary buds give rise new plant of potato.

(b) Bulb :- 

• Bulb is a short , flat disc like under ground stem.
• Onion is the example of bulb.
• Terminal buds and axillary buds are present on disc like stem ( bulb ).
• Axillary bud of bulb grow as aerial shoot ( green ) which develop as new plant. 

(c) Rhizome :-

• The rhizome is under ground stem which has branches.
• On the rhizome buds are present at terminal position which grow as new plant under favourable conditions.
• Ginger, Bamboo, Sugar cane, turmeric etc. are examples of rhizomes.

(d) Corm :- 

• Corm is the flat, rounded bulb. It stor food in it.
• Each corm grow as new plant.
• Each corm can give rise many small corms.
• Example is Gladiolus.

(ii) Vegetative reproduction by sub aerial stem :-

• Sub aerial stem grows horizontal to soil surface.
• From the nodes of sub aerial stem there is growth of root ( under grond ) and stem (as a new plant ).
• These horizontal running sub aerial stem are called stolon.

3. Vegetative reproduction by leaf :-

• Leaves of Bryophyllum is best example of vegetative reproduction by laf.
• Bryophyllum leaf is fleshy. It bear adventitious buds on the margin.
• Each bud can grow in to new individual plant.

Notes of class 8 : Reproduction in plants

Reproduction :- Reproduction is the process in which every living organism produce their own kind.

Significance ( importance ) of Reproduction :- 

• Reproduction multiplies number of individual of a population.
• Reproduction maintain continuity of life on earth. 

Modes of reproduction in the plants :- Plants reproduce by following three methods :

1. Asexual Reproduction
2. Sexual reproduction
3. Vegetative propagation ( reproduction )

Characteristics of Asexual reproduction :-

• In asexual reproduction only one parent member is required.
• During asexual reproduction there is no formation of gametes ( single sex cell ).
• For asexual reproduction in plant body there is formation of some special asexual structures like spores, bud, conidia etc.

The plants perform asexual reproduction by following methods :-

(i) Binary Fission :- 

• In binary fission an individual divides in to two identical daughter cells.
• In binary fission at first nucleus divide in to two parts ( Karyokinesis ) it is followed by division of cytoplasm ( Cytokinesis ).
• The binary fission is visible in unicellular organisms like bacteria, unicellular algae and fungi.

(ii)Budding :-

• In budding a small out growth develop on the body of parent. It is called bud.
• The bud contains small part of nucleus of parent .
• Bud separate from parent body after some times and grow as new individual.
• Unicellular fungus Yeast is best example of budding process.

(iii)Fragmentation :-

• Fragmentation method of asexual reproduction is commonly reported in filamentous algae spirogyra in which the cells are arranged in linear manner.
• From body of mature spirogyra few linearly arranged cells split and after some time find its attachment on submerged rock. This cell is called hold fast.
• The hold fast ( basal cell ) starts the cell division and grow as new spirogyra.

(iv)Spore formation :-

• Spores are the special structure develop on the body of parents for asexual reproduction under unfavourable conditions.
• Spores are microscopic, thick walled, resistant structure.
• Spores develop in the special structure called sporangia ( sing. sporangium ).
• Fungi like Rhizopus ( bread mould ) show asexual reproduction by this method.
• Mature Rhizopus spread spores in air and these spores grow under favourable conditions of food, temperature.

Notes of class 9 : Structure of Cell

Generalised cell :- Different kinds of cells show some basic structural plan which may be expressed in the term of generalised cell.

In a generalised cell there are three basic parts :-

1. Cell membrane/ Plasma membrane/ Plasma lemma
2. Nucleus
3. Cytoplasm

Organelles :- As organs are functioning in the body of organism for its survival and normal life, the cells also need help of many small structures present inside it for its proper functioning. These small structures inside cell are called the cell organelles.

In the diagram above animal cell and plant cell are compared by considering their generalised form and cell organelles present in it.

Some cell organelles are present only in animal cell some are present only in plant cell and some cell organelles are present in animal as well as in plant both.

Cell wall :-

• Cell wall is present in plant cells only. It is outer most covering of plant cell.
• Cell wall is made up of cellulose ( A kind of complex carbohydrate ; Polysaccharide ). The cellulose is nonliving material so cell wall is also nonliving part of cell.
• Cell wall surrounds the cell membrane in the plant cell.
• Cell wall provide shape and rigidity to the plant cell.
• The cell wall is freely permeable i.e. it allows solvent and solute to pass trough it according to concentration gradient.
• Cell walls of two adjacent plant cells are attached with the help of "middle lamillae".

Plasmodesmata :- 

• The plasmodesmata are minute openings between cell walls of adjacent cells.
• Cytoplasm of one plant cell is continue with adjacent plant cell through plasmodesmata.
• Through plasmodesmata one plant cell can communicate with adjacent plant cell.

Cell membrane :- 

• The cell membrane is outer most covering of animal cell and it is present in the plant cell just below cell wall.
• Cell membrane is made up of lipid ( Fat ) and protein. The cell membrane is living component of a cell.
• Cell membrane is selective permeable i.e. it allows material to pass through them in case of requirement.

 

Notes of class ix 

Topic : Cell

• Meaning of term cell is the small compartment. Robert Hooke observed bee hives like small compartments in the thin slice of cork with the help of self invented microscope. These small chambers were considered as "cell".
• Antony van Leeuwenhoek was credited to observe the first living cell in pond water, sputum, blood  etc.
• The branch of science which deals with study of cell is called "Cytology".

The cell is a microscopic structure so for better understanding of a cell, at first we should have some idea about evolution of microscope which is very first requirement of cytology.

• Antony Van Leeuwenhoek designed first simple microscope having power of magnification 200 times. There was single biconvex lens in this microscope.
• Robert Hooke developed the microscope by using two lenses. It was compound microscope having power of magnification 2000 times.
• Knoll and Ruska designed electron microscope which is having power of magnification 200,000 times.

Cell Theory :- Cell theory was proposed by J.M. Schleiden and Theodor Schwann in 1838/39. Later on in 1858 Rudolf Virchow added one more point in the cell theory.

1. J.M.Schleiden a botanist in 1838 proposed that "Every plant is made up of large number of cells and each cell performs various life processes".
2. Theodor Schwann a zoologist in 1839 proposed that "All animals and plants are composed of cells which serves as a unit of structure and function".
3. Rudolf Virchow said - "Omnis cellula e cellula" that is all cells originate from preexisting cells.

Some important points about cell :-

• Bacterial cell and RBC of human body is considered as smallest cell.
• Nerve cells ( Neuron ) is the longest cell of the body.
• Ostrich egg is the largest cell.
• Small size of cell is facilitating better diffusion of materials through it, so efficiency increases.

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That's all for this session. We will meet in our next session with the notes on topic "Structure of Cell".

Notes of class 7

Sclerenchyma tissue :- 

• Sclerenchyma is made up of dead cellls.
• Cells of sclerenchyma become dead due to excess deposition of material around the cells.
• Sclerenchyma cells provide mechanical strength to the plant parts.

Complex permanent tissue :- The complex permanent tissue is represented by conducting tissue xylem and phloem. Xylem is responsible for transportation of water and minerals in the plant and phloem is responsible for translocation of prepared food from the leaf to all parts of plants.

Xylem :- 

• Xylem is made up of four types of cells - (i) Xylem tracheids (ii) Xylem vessels (iii) Xylem fibres (iv) Xylem Parenchyma.
• Cells of xylem are thick walled, tubular.
• All cells of xylem are dead except xylem parenchyma.
• Xylem vessels are long tubular cells joint end to end and form a long tubular pipe for transportation of water and mineral in the plant.
• Xylem tracheids are responsible for transverse transportation of water and mineral.
• Xylem fibres are helpful in joining all other cells of xylem tissue together.

   Phloem :- 

• Phloem is made up of four types of cells - (i) Sieve tubes (ii) Companion cells (iii) Phloem Parenchyma (iv) Phloem fibres.
• All cells of phloem are living except phloem fibres.
• Sieve tubes joint end to end and form a long tube through which soluble food move from leaves to other parts of plants.
• At the junction of sieve tube perforated ( with small holes ) cell wall is present which make the sieve plates. It slow down gravitational movement of soluble food.
• Phloem parenchyma cells store the food.
• Phloem fibres join other components (cell ) of phloem tissue.

Notes for class 7

Location of permanent tissue in the plants :- The permanent tissue is present in all parts of plant except meristematic zone.

Permanent tissues are of two types :-

1. Simple permanent tissue :- Simple permanent tissue is called simple because it is made up of only one kind of cells. All the cells of this type of tissue are identical in structure and function. For example :- Epidermis, Cork, Parenchyma, Collenchyma, Sclerenchyma etc.
2. Complex permanent tissue :- In complex permanent tissue more than one kind of cells are present which perform a specific function. For example :- Xylem and Phloem.

Protective simple permanent tissue :-

Epidermis :- 

• Epidermis is present as external protective cover over all parts of plant.
• The epidermis is made up of living cells.
• Epidermis is present as single layer.
• Ex. - Epidermis of leaves secrete a waxy substance called cuticle.

Cork :- 

• Cork is simple permanent tissue which is protective in function.
• Cells of cork are dead.
• Cork is found in woody dicot stem.

 Supportive simple permanent tissue :-

Parenchyma tissue :-

• Cells of parenchyma tissue are living.
• Cell wall is thin and large vacuole is present in the center of cell for storage of materials.
• Cells are oval or polygonal in shape and nucleus ,cytoplasm shifts towards periphery.
• Parenchyma tissue stores food material and help in cell to cell conduction of water in the plant.

Note :- The parenchyma tissue having chloroplast in it, is called Clorenchyma  . The chlorenchyma tissue is involve in photosynthesis. It is found in the leaves.

Collenchyma tissue :-

• Cells of collenchyma is living but its shape is elongated.
• Collenchymatous cells are thick at the corners due to deposition of materials.
• Main function of collenchyma tissue is to provide the mechanical strength and flexibility to aerial parts of plants.

Internal stucture of root :- In T. S. of root given in previous class, root hairs are visible surrounded by soil particles. Just behind epidermis, there is a cortex ( a group of parenchymatous cells ) . Last layer of cortex is called the endodermis. Xylem tissue is present behind endodermis. Water from soil enter to root hair cell by endosmosis process. From here the water move from cell to cell from cortex and reach to  endodermis. The endodermis does not allow water to return back from xylem vessels.

Root pressure :- Pressure created by the water in  xylem vessels by continuous entry of water from root hairs to xylem vessels via cortex of root, is called root pressure.
 Root pressure is important for plants for ascent of sap. It is initial pushing force.

Note :-  Water column is continue, without any air bubbles in the xylem of root, xylem of stem and xylem of leaves.

Transpiration :- Loss of water in the form of water vapour through the aerial parts of plants ( leaf, stem etc. ) is called the transpiration.

Transpiration pull :- Transpiration pull is the force which pull water through xylem vessels of leaf, stem and root. This pull force plays a vital role in the ascent of sap.

Minerals :- Minerals are important for proper growth and development of plants and for proper functioning of its different physiology.
More than 60 elements are found in different plants out of which approx. 17 elements come under category of essential elements and rest all are considered as non-essential elements.

NOTES OF CLASS 8

Structure of root :- 

• Root is underground part of plant.
• Root hairs are unicellular structure of root which absorb the water and dissolved minerals from soil.
• Root hairs originate from epidermal cell.
• Cell membrane and cell wall of root hairs are very thin and concentrated cell sap is filled in root hair cells.
• Root hairs have large surface area so it is an adaptation for absorption of water and minerals.

Active transport :- Transport of molecules and ions against concentration gradient ( from less to more ) by using energy molecule ATP is called active transport.

In plants, minerals are absorbed and transported through active transportation .

Path of water and mineral ( sap ) in the plant :- This diagram will illustrate the path of sap in plants from root to leaves -

Internal structure of root :- 

Draw above diagram and its description will appear in tomorrow's notes.

take care ..... Bye.

FOR CLASS 7 :-
Many students are asking that where to write these notes. So, my dear students you have to write it in your fair biology copy.

Kinds of meristematic tissue :-

1. Apical meristematic tissue ( Apical meristem ) :- This tissue is present in the tip portion of plants like root tip, stem tip and tip of side branches. Main function of apical meristem is to help plant in its primary growth (growth in height of plant).

2. Lateral meristematic tissue ( Lateral meristem or Cambium ):- This meristematic tissue is responsible for increase of thickness of plant (Secondary growth).

3. Intercalary meristematic tissue ( Intercalary meristem ) :- Intercalary meristem is responsible for growth of side branches in the plants.

Permanent tissue :- 

• Cells of permanent tissue do not have power of cell division.
• Nuclear content of these cells are less in comparison to cytoplasmic contents.
• These cells have large vacuoles for storage of different kinds of materials.

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Draw following diagrams in your fair copy :-

Description of above diagrams will appear in our next session , next week monday & tuesday.

Till then take care bye.....

After discussion of different levels of organisations, now I am going to start discussion about tissue.

Plant Tissue

Plants are the organisms who grow through out their life. The plant tissues are mainly divided in to two main types :- 1.  Meristematic tissues    2.  Permanent tissues.

1. Meristematic tissue ( Meristem ) :- Meristematic tissue is the group of actively dividing young cells. These cells contain more nuclear contents and less cytoplasmic content in it because they will have to divide itself through out life for growth of plant.

Main characteristics of meristematic tissue cells are as follows :-

• Cell wall of meristematic cell is thin.
• Inter cellular space is not visible.
• Large nucleus and less cytoplasm.
• Vacuoles are absent or very small in size.

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That's all for today, we will meet tomorrow with types of meristematic tissue.

Bye....

 

NOTES OF CLASS 7

Hi my dear students ! How are you? I hope you are healthy and safe. So, let's start our journey of learning. Today I will give you some facts related to higher level of organisation.

Population :- Group of similar kind of organisms forms the population. For example - Group of human ( human population ), Group of cow ( Cow Population ) and so on.

Community :- Combination of populations form the community. For ex. In our surrounding community, following populations are present - Human population, Goat population, Mosquito population, Cow population etc.

Ecosystem :- Some abiotic substances like soil, water, air are necessary for life activities of community members. Community along with abiotic substances is known as Ecosystem.

Biosphere :- All ecosystems of earth collectively called the biosphere. Broadly the biosphere contain hydrosphere (all water bodies), lithosphere ( solid surface of earth ), atmosphere ( gaseous cover around earth ).

Notes of Class 8

Above diagram is the T.S. (tranasverse section) of leaf in which conducting tissues are visible. Let's label the parts in the diagram.

(a)Cuticle (b)Palisade tissue (c)Xylem (d)Sub stomatal space (e)Phloem (f)Lower epidermis 

Above diagram represents the parts of phloem. (a)Sieve tube (b) Phloem parenchyma (c)Companion cell (d) Sieve plate.

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For better understanding of transportation of mineral and water by root let us understand following terms :-

Semipermeable membrane :- The membrane which allows only solvent to pass through it not the solute is called semipermeable membrane.

Cell sap :- Cell sap is the watery liquid contained in the vacuole of root hair cells. Concentration of cell sap is more than concentration of soil water.

Diffusion :- Movement of material from its higher concentration to the lower concentration.

Osmosis :- Movement of solvent from its higher concentration ( Low conc. of solution ) to its lower concentration ( High conc. of solution ) through a semipermeable membrane is called osmosis.

In our next session we will discuss the structure of root. Your assignment is to draw the labeled diagram given above and learn the notes. Bye...... take care.

Wed. & Thu. is the time for class 8 students. Here i am going to start the chapter Transport of food and minerals in the plants. My dear students ! right down my notes in the copy ( Interleaf ) study it and prepare it with confidence.

NOTES OF BIOLOGY FOR CLASS 8 STUDENTS

Transport :-

Every living organism ( From simple unicellular to complex multicellular ) shows signal of life by performing a lot of vivo reactions in the body. Many useful and excretory materials need to be transport in the body for this purpose. This is called transportation in the body of organisms. 

Transport system in the plant body :-

• Plant vegetation varies from unicellular to multicellular. In unicellular algae like chlamydomonas transportation takes place by simple diffusion process. In complex multi cellular plant body the transportation takes place through well developed Vascular system or Conducting system.
• Vascular system in the plant body is made up of complex permanent tissue called xylem and phloem. 
• Xylem conduct water and mineral in the plant body from root to other parts of plant.
• Phloem perform translocation of soluble prepared food from leaves to all other parts of plant..
• The xylem is made up of four kinds of cells - Xylem vessels (Non living), Xylem tracheids (non living), Xylem fibres ( Non living ) and Xylem parenchyma (living).
• Phloem is made up of following components - Phloem vessels ( Sieve tube ), Sieve plates, Phloem parenchyma and Phloem fibres. Among all these cells the phloem fibres is nonliving rest all are living cells.