Sunday, April 29, 2018

Test on Chapter 1 "Crop Production and Management"


This is Online Practice Test on 

Chapter 1 "Crop Production and 

management" of CLASS 8th.












Test-1 

Chapter-1  (Crop Production and Management)

TIME: 1 hour                                                                                         MARKS: 20


Q.1  Why storage of food is done?                                                                1

Q.2  What do you mean by seed drill?                                                         1

Q.3  What is sowing?                                                                                      1

Q.4  What do you understand by harvesting and  hreshing?                     2

Q.5  Differentiate between plough and hoe?                                                2

Q.6  What is winnowing?                                                                               2

Q.7  What are Rabi season crops? Give examples.                                     2

Q.8  What do you understand by weeds. And what are the different

           methods use by the farmers to remove weeds?                                    3

Q.9 Why is it necessary to sow seeds at an appropriate depth and

           distance?                                                                                                  3

Q.10  Differentiate between fertilizers and manures.                                3

Questions on Chapter = 5 ( THE FUNDAMENTAL UNIT OF LIFE)

Practice Questions on Chapter =  5 ( THE FUNDAMENTAL UNIT OF LIFE) These are Online Practice Questions on Chapter =  5 ( THE FUNDAMENTAL UNIT OF LIFE) 




VERY SHORT ANSWER TYPE QUESTIONS (1 Mark):


1. Name the largest cell of living world ?

2. Amoeba is a.............organism.

3. Who gave the fluid mosaic model of plasma membrane ?

4. Movement of solvent into the cell is called as................. .

5. Which cell organelle is called as the ‘Head quarter of cell’ ?

6. Which cell organelle is called as ‘Power house of cell’ ?

7. Which cell organelle contains enzymes for ATP production ?

8. In mitochondria, which portion contains specific proteins ?

9. Which cell organelle is called as ‘Digestive bag’ ?

10. Which organelle controls osomostic pressure in a cell ?

11. Plastids having coloured pigments are called as............... .


SHORT ANSWER TYPE QUESTIONS (2 Marks):


1. What is the composition of protoplasm ?

2. Define cell ?

3. What is the difference between diffusion and osmosis ?

4. Why plasma membrane is called as selectively permeable                 membrane ?

5. Define Cristae ?

6. State any two function of Golgi body ?

7. Name various type of plastids present in a plant cell ?

8. State the main function of lisosome ?


LONG ANSWER TYPE QUESTIONS (5 Marks):


1. Who gave the cell theory ? What does it state ? Which organism      is an exception of cell theory ?

2. Draw a neat and labelled diagram of nucleus. State its main              function.

3. Describe the types of endoplasmic reticulum and draw necessary      figure ? Give its main functions also?

4. Draw a neat and labelled diagram of mitochondria.

5. Differentiate between plant and animal cell with suitable figures.

Online Notes on Chapter = 5 ( THE FUNDAMENTAL UNIT OF LIFE) Part 4

 THE FUNDAMENTAL UNIT OF LIFE) Part 4This is Online Notes on Chapter =  5 ( THE FUNDAMENTAL UNIT OF LIFE)  Part 4 for preparation of CBSE BOARD Examination, NTSE etc.

Mitochondria:

Mitochondria:


It is a rod shaped structure found in cytoplasm of all eukaryotic cells except mammalian RBC’s.

• These are also absent in prokaryotes.

• It was first seen by Kolliker in insect cells.

• Maximum mitochondria are found in metabolically active cells.

• It is also called as ‘Power House of the Cell’ or the ‘Storage Battery’.
• It is double membranous structure where outer membrane has specific proteins while inner membrane is folded inside to form chambers called "Cristae".

Functions of Mitochondria :


(a) Its main function is to produce and store the energy in the form of ATP.

(b) It is the site of Kreb cycle of respiration

Ribosomes:

Ribosomes:

Ribosomes are the sites of protein synthesis.

All structural and functional proteins (enzymes) coded by the nuclear DNA are synthesized upon cytoplasmic ribosomes. The DNA codes are transcripted into messenger RNA (mRNA) molecules in the chromosomes of the nucleus.

Functions of Ribosomes :


(a) Ribosomes are the main site of protein synthesis. Synthesized
proteins is transported by endoplasmic reticulum.


Plastid:

Plastid:

• It is double membranous discoidal structure, found only in plant cells.

• Besides being discoidal of rhombic in plant cells, they occur in variable shapes like in algae. They can be ‘U’-shaped, spiral, coiled, ribbonshaped etc.

Depending upon the type of pigment present in them, they are of following three types :

(i) Leucoplast – White, found in underground parts

(ii) Chloroplast – Red, brown

(iii) Chloroplast – Green in colour, found in aerial parts of plants
These are found only in plant cell. It helps in the process of photosynthesis so it is called the ‘Kitchen of Plants’.

Chloroplast have following two parts :


(i) Grana : It constitutes the lamellar system. These are found layered on top of each other. These stacks are called Grana. Each granum of the chloroplast is formed by superimposed closed compartments called Thylakoids.

Function : They are the sites of light reaction of photosynthesis as they contain photosynthetic pigment chlorophyll. In each thylakoid,
Quantasomes are present which are called as Photosynthetic units.

(ii) Stroma : It is a granular transparent substance also called as
matrix. Grana are embedded in it. Besides Grana they also contain lipid droplets, starch grains, ribosomes etc.

Function : This is the site of dark reaction of photosynthesis. Also helps in protein synthesis due to presence of ribosomes.

Vacuoles:

Vacuoles

• These are membrane bounded regions in the cytoplasm containing water and other substances.

• They are bounded by a single membrane called Tonoplast.

• In animal cells vacuoles are smaller in size and numerous while in plant cells a single large vacuole is found which occupies about 90% of the volume of cell.

Functions :

It helps in maintaining osmotic pressure in a cell & stores toxic metabolic products of plant cell.

Lysosome:
 Lysosome:

• They are tiny sac-like granules containing enzymes of intracellular digestion.

• They are bounded by a single membrane.

• They occur in animal cells and a few plant cells.

• They do not have a definite shape or size.

Functions :

(a) Their main function is phagy = digestion.
(b) They are kind of waste disposal system.
(c) They help in digesting foreign materials & cells.

Suicidal Bag : During disturbances in cellular metabolism i.e., in case of cell damage, lysosomes burst and their enzymes are released into the cytoplasm and they digest their own cell. So they are also called ‘Suicidal Bag’.
Suicidal Bag :

Online Notes on Chapter = 5 ( THE FUNDAMENTAL UNIT OF LIFE) Part 3

 ( THE FUNDAMENTAL UNIT OF LIFE) Part 3This is Online Notes on Chapter =  5 ( THE FUNDAMENTAL UNIT OF LIFE)  Part 3 for preparation of CBSE BOARD Examination, NTSE etc.

Cell Wall:

• It is the outermost covering of the plant cells.
• It is absent in animal cells.
• Cell wall is rigid, strong, thick, porous and non-living structure. It is made up of cellulose and hemicelluloses. Cell walls of two adjacent cells are joined by a layer called middle lamellae.

Cell Wall


Functions of Cell Wall :

(a) It provides definite shape to the cell.
(b) It provides strength to the cell.
(c) It is permeable and allows entry of molecules of different sizes.
(d) It has the characteristics of repair and regeneration.

Nucleus:

Nucleus


•Nucleus is the most important cell organelle which directs and controls all its cellular activities.

• It is called as ‘Headquarter of the cell’.

• It was discovered by Robert Brown in 1831.

• In Eukaryotes, a well-defined nucleus is present while in Prokaryotes, a well-defined nucleus is absent.

• Prokaryotes contain a primitive nucleus.

• It has double layered covering called as nuclear membrane.

• Nuclear membrane has pores which regulate the movement of materials in & out of the cell.

• Besides nuclear membrane, nucleus also contains nucleolus and
chromatin material and the substance filled inside the nucleus is nucleolus.

• Chromosomes or chromatin material consists of DNA which stores and transmits hereditary information for the cell to function, grow and reproduce.

Functions of Nucleus :

(a) It controls all the metabolic activities of the cell and regulates the cell cycle.
(b) It helps in transmission of hereditary characters from parents to
off springs.


Cytoplasm:


Cytoplasm

• Cytoplasm was discovered by Kolliker in 1862.
• It is the site of both biosynthetic and catabolic pathways.


• It can be divided into two parts :


(i) Cytosol : Aqueous soluble part contains various fibrous proteins
forming cytoskeleton.

(ii) Cell organelles : Living part of the cells having definite shape,
structure and function bounded by plasma membrane.

Endoplasmic Reticulum:


• It is the network of membranes present in the cytoplasm.
• It was discovered by Porter, Claude and Fullam.
• These are present in all cells except prokaryotes and mammalian
erythrocytes.
Endoplasmic Reticulum


Functions of ER :


(a) It is the only organelle which can move within a cell so it serves
as a channel for the transport of materials between various regions of cytoplasm and between cytoplasm and nucleus.

(b) It also functions as a cytoplasmic framework to provide space for some of the biochemical activities. It forms endoskeleton of cell.

(c) It helps in synthesis of fats, steroids, cholesterol etc.

(d) SER plays a crucial role in detoxification of drugs and poisonous by-products.


Golgi Apparatus:


Golgi apparatus consists of a system of membrane bounded vesicles arranged parallel to each other in stacks called Cisternae along with some large and spherical vacuoles. It was discovered by Camilo Golgi. In plants Golgi membrane is bounded. It is single membrane bounded. It is absent in prokaryotes, mammalian
RBC’s & sieve cells.
Golgi Apparatus:


Functions of Golgi apparatus :


(a) It helps in formation of lipids.
(b) It helps in formation of middle lamellae.
(c) It is secretary in nature.
(d) It helps in melanin synthesis.
(e) Lipids and proteins synthesized in endoplasmic reticulum are
packed at Golgi complex. They provide the site for assembly of
new membrane material.

Saturday, April 28, 2018

Online Notes on Chapter = 5 ( THE FUNDAMENTAL UNIT OF LIFE) Part 2

Online Notes on Chapter =  5 ( THE FUNDAMENTAL UNIT OF LIFE) Part 2This is Online Notes on Chapter =  5 ( THE FUNDAMENTAL UNIT OF LIFE)  Part 2 for
preparation of CBSE BOARD Examination, NTSE etc.





Cell Shape : 


Cells are of variable shapes and sizes. Their shape is according to the function. Generally cells are spherical but they may be elongated (nerve  cell), branched (pigmented), discoidal (RBC), spindle-shaped (muscle cell) etc. 

Cell Shape :


Different kinds of cell found in the human body.

Cell Size : 


Size of cell is variable depending upon the type of organism.

Some are microscopic while some are visible with naked eyes. 

Their size may vary from 0.2 mm to 18 cm.

• Size of a typical cell in a multicellular organism ranges from 20-30 mm.

• The largest cell is ostrich egg (15 cm in diameter with shell & 8 cm in diameter without cell).

• The longest cell is nerve cell (upto 1 m or more).

• Smallest cells so far known are PPLOs e.g., mycoplasma (0.1 mm in diameter).

• Human egg is 0.1 mm in diameter.
Components of Cell

There is an occurrence of division of labour within a cell as they all got certain specific components called ‘Cell organelles’.

Each of them perform a specific function.

The three basic components of all the cells are :

(i) Plasma membrane
(ii) Nucleus

(iii) Cytoplasm

Plasma membrane, Nucleus, Cytoplasm

Cell Membrane :


(a) Cell membrane is also called as plasma membrane or plasma
lemma.

(b) It is the limiting boundary of each cell which separates the
cytoplasm from its surroundings.

(c) It is found in both plant as well as animal cells.

(d) It is the outermost covering of a cell in case of animals and lies
below the cell wall in case of plants.


(e) It is made up of proteins and lipids where proteins are sandwiched between bilayer of lipids.

(f) Plasma membrane is selectively permeable in nature. It allows or permits the entry and exit of some materials in and out of the cell.

(g) Singer and Nicholson gave the fluid mosaic model of plasma
membrane. According to them, it consists of a protein layer
sandwiched between two layers of lipids. It is in quasifluid state.
It is 75A thick.


(h) It is flexible and can be folded, broken and reunited.


Functions of Plasma Membrane :

(a) It regulates the movement of molecules inside and outside the
cell.
(b) It helps in maintaining the distinct composition of the cell.

(ii) Transportation of molecules across the Plasma Membrane :

This can be done by following ways :

Functions of Plasma Membran


Diffusion : Movement of solutes or ions from higher concentration to lower concentration is called as diffusion. It does not require energy therefore, it is called as passive transport.

Osmosis : The movement of solvent or water from higher concentration (solvent) to lower concentration (solvent) through a semipermeable membrane is called as "osmosis" Or the movement of solvent or water from lower concentration to higher concentration of solution through a semipermeable membrane is called as osmosis.

• Osmosis can also be called as ‘Diffusion of solvents’.

Endomosis : Movement of solvent into the cell is called as Endomosis.

Exosmosis : Movement of solvent outside the cell is called as Exomosis.

Types of Solutions on the Basis of Concentration:

Types of Solutions on the Basis of Concentration:



(a) Isotonic Solution : When the concentration of the solution
outside the cell is equal to the concentration of cytoplasm of the
cell, it is called as isotonic solution.

(b) Hypertonic Solution : When the concentration of the solution
outside the cell is more than the inside the cell. Due to this, cell
looses water and becomes plasmolysed.

(c) Hypotonic Solution : When the concentration of the solution
outside the cell is lesser than that of cytoplasm of cell. Due to

this, cell swells up and bursts

Online Notes on Chapter = 5 ( THE FUNDAMENTAL UNIT OF LIFE) Part 1

THE FUNDAMENTAL UNIT OF LIFEThis is Online Notes on Chapter =  5 ( THE FUNDAMENTAL UNIT OF LIFE)  Part 1 for
preparation of CBSE BOARD Examination, NTSE etc.








CHAPTER AT A GLANCE


Study Key Points :


Discovery of Cell, Types of Cell & Organism, Unicellular & Multicellular,Prokaryotic & Eukaryotic, Plant Cell & Animal Cell, Cell Shape, Cell Size, Cell Membrane, Cell wall, Diffusion & Osmosis, Nucleus, Cytoplasm, Endoplasmic Reticulum, Golgi Apparatus, Mitochondria, Ribosomes, Plastid, Vacuoles, Lysosomes.


Plant Cell and RBCs


All living forms are composed of microscopic units called as ‘Cells’.


• A cell is the basic structural and functional unit of all life forms.

• Study of structure and composition of cell is called as ‘Cytology’.

• Cell was first observed by Robert Hooke in a dead cork slice in the year 1665.

• First living cell was discovered by A. V. Leeuwenhoek.

• Its consistency differs under different condition. It exists in sol gel states.

• Protoplasm is an aggregate of various chemicals such as water, ions, salts and other organic molecules like proteins, carbohydrates, fats, nucleic acids, vitamins etc.


Cell Theory :


Two biologists, Schleiden and Schwann gave the Cell theory which states that :

(i) All plants and animals are composed of cells.
(ii) Cell is the basic unit of life.
(iii) All cells arise from pre-existing cells.

• Viruses are the exceptions of cell theory.


Types of Cell & Organism :


Types of Cell


On the Basis of Type of Organization:


On the Basis of Type of Organization




Plant Cell and Animal Cell


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