Class 7 Science Chapter 1 - Nutrition in Plants Notes PDF
In this post we are providing you the pdf notes of Class 7 Science Chapter 1 - Nutrition in Plants .The PDF Download link is given below.
PDF Download Button is given at the bottom.
Nutrients: Those components of food that are essential for our body
are called nutrients.
Nutrition: Nutrition is the method of taking and consuming food by
living organisms.
Types of nutrition:
There are two types of nutrition -
(i) Autotrophic Nutrition: The method of nutrition in which the
organisms synthesize their food itself, is called autotrophic nutrition.
This type of nutrition occurs in plants all green.
(ii) Hetrotrophic Nutrition: Animals and most other organisms
consume food synthesized by plants. They are called hetrotrophic
nutrition.
Like - humans, animals, insects, amoeba, fungus, frogs, and mushrooms
Etc.
Types of Hetrotrophic nutrition in plants -
There are two types of heterotrophic nutrition -
(A) Saprophytic Mode of Nutrition: The method of nutrition in which
the organisms obtain their food by dead-decay substances, this type of
nutrition is called Saprophytic Mode of nutrition.
For example,
mushrooms, fungus and some bacterias are examples.
(B) Parasitic Mode of Nutrition: The method of nutrition in which the
organism depends on food made by other organisms, this type of
nutrition is called parasitic mode of nutrition.
An example of this, is Cuscuta.
Difference between parasites and Saprophytes:
Parasites:
(i) They get their food from other organisms.
(ii) Parasites usually live on or above the body of the host.
Saprophytes:
(i) Saprophytes get their nutrition from the living and dead and
decay organic substances of living organisms.
(II) Saprophytes live on dead and rotten substances.
Require food/energy for organisms:
The need for food in organism is due to the following reasons:
(I) Need to take food:
(II) Get energy to do work.
(III) Build up body.
(IV) Repair damages in the body.
(V) Maintain the function of the body.
Photosynthesis
Photosynthesis: Green plants make their food themselves in the
presence of sunlight and chlorophyll. This process is called
photosynthesis.
Leaves are Food Factory of Plants: Only plants are the only living
organisms who can make their food with the help of water, carbon
dioxide and minerals. All these substances are available in their
surroundings. Since the plants are synthesised in their leaves in plants,
therefore, leaves are the food factories of the plant.
Stomata: On the surfaces of leaves, there are many small holes are
present, by which gasious exchanges are taken place through these
holes. These holes are called stomata.
Stomata in the leaves
Functions of the stoma in the leaves:
(i) Gasious exchanges are taken place through the stomata.
(ii) The process of transpiration in plants is also taken place through
the stomata.
(iii) Light energy is also absorbed by the stomata in the plants.
Chlorophyll: The leaves contain a green pigment called chlorophyll.
Function of chlorophyll: It provides green color to the leaves.
Process of food synthesis in plants: In plants, the synthesis of food is
taken place in their leaves. The water and minerals present in the soil are
transported to the leaves through the stems by absorbing by root in
plants. The small tiny holes e.i stomata present on the surface of the
leaves obsorb carbon dioxide present in the air. Photosynthesis is a
chemical reaction occurring in the leaves in which water and carbon
dioxide are used by plants as raw materials, this reaction occurs in the
presence of sunlight and chlorophyll. After this reaction carbohydrates
(glucose) and oxygen are formed. Carbohydrates are used as energy by
the plants to store them in leaves for energy consumption, while the
oxygen comes back out in environment by the stomata.
Function of photosynthesis in other parts of plants besides leaves:
In addition to the leaves, photosynthesis also occurs in other green
parts of plants such as green stems and green branches. In order to
reduce water decation by transpiration in desert plants, the leaves
become scales or stalks. The stems of these plants are green, which
function as photosynthesis.
Algae: You may have seen green panicles (plants like moss) on wet
walls, ponds or reservoirs. These are usually caused by the growth of
some organisms, which are called algae.
Green colour in algae: Algae also make their food through
photosynthesis. Chlorophyll is found in algae. Due to this the reason
algae is seen in green colour.
Functions of the vessels in plants:
(i) Water and minerals are transported to the leaves by vessels.
(ii) These vessels are like tubes and extend to root, stem, branches and
leaves.
(iii) These vessels make a continuous route to reach the nutrients to the
leaves.
Cell:
Cell: The structural and functional unit of living organisms is called cell.
This is the smaalest unit od body, which can only be seen with the
microscope.
Some organisms are made of a cell called unicellular organism - like
amoeba and some bacterias.
Major parts of the cell:
(i) Cell wall: the outermost wall in plant cells made up of complex
carbohydrate which is called cell wall.
(ii) Cell membrane: The cell is surrounded by a thin external structure
called the cell membrane.
(iii) Nucleus: There is a distinct structure located in the center of the
cell, which is called a centrifuge.
(iv) Cytoplasm: The nucleus is surrounded by a substance similar to
jellies, Which is called cytoplasm.
Diagram of cell
Examining the presence of starch in the leaves:
If the leaves have starch, then it indicates that the process of
photosynthesis has taken place. Starch is also a type of carbohydrate.
To test this, we will plant two types of two plants and keep one in the
dark for 72 hours, and we can test the present in the sun by dropping
the iodine billions droplets on the plants of both the plants in the
sunlight. | When iodine comes in contact with billions (starch) then a
dark blue color comes up. This shows the presence of starch in the
leaves.
Synthesis of foods in plants:
(i) Synthesis of carbohydrate: The synthesis of carbohydrate in plants
is done by photosynthesis which is formed by carbon, hydrogen and
oxygen.
(ii) Synthesis of proteins: Protein is a nitrogenous substance which
contains the amount of nitrogen in addition to carbon, oxygen and
hydrogen. There are some specialized bacteria named Rhizobium in the
soil which convert gaseous nitrogen into useful compounds and
release it in soil. These solvents are absorbed by the plants with water.
These bacteria will stabilize these atmospheres of nitrogen into
nitrates. These nitrate plants are used in protein synthesis.
0 Comments