DAV school class 7science ch 1,2,3fair please class 7 DAV class 7 students. Answers this please. l will make you brainlist give me right answer.and 10thanks.
Answers
Explanation:
Living and Non-Living Organisms
Living organisms like human beings, plants and animals need food to survive and exist.
Living organisms reproduce, respond to the environment and also adapt.
Living organisms respire and excrete as well.
Cells
Cells are tiny units that help make up a living organism. Hence, they are also called building blocks of an organism.
A cell is constituted of three major parts :
A thin outer layer called the cell membrane.
A spherical structure located at the centre of the cell called a nucleus.
A jelly-like substance that surrounds a nucleus called the cytoplasm.
To know more about Cell, visit here.
Single and Multi-Cellular Organisms
Organisms that are made up of just one cell are called single-celled or Unicellular organisms. E.g. Amoeba
Organisms with more than one cell in their body are called multicellular organisms.
All human beings, plants and animals are multicellular organisms.
To know the difference between Unicellular and Muti-Cellular Organisms, visit here.
Nutrition
Nutrition is the mode of taking food by an organism and its utilisation by the body.
Nutrition is very important as the nutrients from the food consumed enables living organisms to build their bodies and grow.
Nutrition helps to repair damaged parts and organs.
Nutrition also provides energy for carrying out various functions.
For More Information On How do Plants Get Their Nutritions, Watch The Below Video:
To know more about Nutrition, visit here.
Autotrophs and Heterotrophs
Organisms that make food themselves are called autotrophs.
Plants are an example of autotrophs as they make their own food using carbon dioxide, water and light energy.
Organisms that rely on others and usually take in ready-made food made by the autotrophs are called heterotrophs.
Animals and human beings are an example of heterotrophs as they depend on plants in many ways for their food.
To know the difference between autotrophs and heterotrophs, visit here.
Photosynthesis
Photosynthesis is the process of synthesis of food by green plants.
This process usually takes place in the leaves of plants.
The process requires chlorophyll (green coloured pigment), sunlight, carbon dioxide and water.
For More Information On Photosynthesis, Watch The Below Videos:
To know more about Photosynthesis, visit here.
Organelles
Organelles are tiny cellular structures inside a cell and perform specific functions that are important for the cell.
They are found in the cytoplasm of a cell.
E.g. Chloroplast is the cell organelle that carries out photosynthesis.
Chloroplasts
The chloroplast is a type of organelle that exists in plants.
These organelles contain chlorophyll, the green coloured pigment that is responsible for carrying out the process of photosynthesis in plants.
Chlorophyll
Chlorophyll is the pigment that is responsible for the synthesis of food in green plants.
This pigment green colour to its bearers and i abundantly found in leaves.
Chlorophyll is locked inside the chloroplast.
Process of Photosynthesis
The process of photosynthesis takes place in the leaves, the “food f
Answer:
Ch - 1
essential notes :-
Food is essential for living organisms
Nutrients are 'taken in' through their food by living organisms and are utilised in their bodies.
- This process of obtaining, and utilising food by an organism, is known as nutrition.
The process of obtaining food is not the same in all organisms.
there are 3 types of nutrition-
- Heterotrophs
- Autotrophs
- Saprotrophs
Autotrophic nutrition- it includes plants as producers , which produce there own food.
Heterotrophic nutrition- Organisms dependent on another organisms for their food and survival .
Saprotrophic nutrition- organisms feed on dead and decaying matter.
- Plant makes there own food by the process of photosynthesis.
It includes green colour pigment consisting chlorophyll, CO2 and sunlight .
Glucose in form of carbohydrates and O2 is produced during this process.
Symbiotic Relationship
2 organisms live in close association and develop a Relationship that benefits both organisms.
like, algae and fungi lives in Symbiotic Relationship.
Ch - 2
Essential notes
On basis of food habits organisms are classify into 3 types :
- Herbivores
- Carnivores
- Omnivores
Herbivores - Dependent on plants .
Carnivores- Dependent on other animals
Omnivores- Eat plants as well as animals
Modes of nutrition in animals-
- Saprotrophic nutrition
- parasitic nutrition
- Holozoic nutrition
Intake of food by digestive system-
- Ingestion
- Digestion
- Absorption
- Assilimation
- Egestion
Besides these parts, there are a number of glands, associated with the alimentary canal, which play their roles in the process of digestion of food.
The salivary glands, pancreas and the liver, are the three main such glands.
Teeth or bucal cavity
Humans have 4 types of teeths
- Incisors
- Canines
- Premolars
- Molars
Tongue
Tongue is a muscular organ attached to the floor of the buccal cavity.
It is free to move at its front end where it can
move in all directions.
The tongue helps in mixing up of
saliva with food;
- it also helps in swallowing food.
It has four types of taste buds which help
us to know about the-
- sweet,
- sour,
- bitter
- and salty tastes,
associated with different types of items, in our food.
Digestion includes -
- Mouth
- Food pipe
- Stomach
- Intestines
Intestines -
Small Intestine have Finger like projection called villi.
These villi increase surface area for Absorption pf digested food.
Nutrition in cud chewing animals
Cud chewing herbivore animals are called ruminants. Cow, deer,camel, buffalo, sheep and giraffe are some of the well-known ruminants.
- They have a special four-chambered stomach.
also reffer to the above attachment in which system of cow is showed.
(it is old book that's why in bad condition)
Ch - 3
Essential notes
Matter exists in 3 states
- Solid
- Liquid
- Gas
Matter is made up of small particles called atom
Atom combine to form molecules.
Like , H2 ( 2hydrogen atom) + O ( oxygen atoms)
= H20 ( which is a water molecule)
Pure substance is classified into 2 types
- Element
- Compound
A mixture is unpure substance
Chemical Formula-
For this you need to know Names of Elements amd symbols.
- Hydrogen = H
- Sodium = Na
- Magnesium = Mg
- Aluminium = Al
- Calcium = Ca
- Potassium = K
- Iron = Fe
- Copper = Cu
- Gold = Au
- Silver = Ag
- Carbon = C
- Oxygen = O
- Sulphur = S
- Nitrogen = N
- Phosphorus = P
- Chlorine = Cl
- Bromine = Br
- lodine = I
