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.