Variation means differences.So, variation in species means differences among living things of the same species.
A species is a group of living things that are similar and can have babies together.Example: All humans are one species.
Even in the same species, no two are exactly the same!
In humans
A species is a basic group in living things used by scientists.
Living things of the same species:
Look almost the same
Have the same body parts
Live in similar ways
Can reproduce and have babies together
Energy Resources
Definition:
Energy resources are things from nature that give us energy to do work like lighting, heating, cooking, moving vehicles, and making electricity.
Main Types of Energy Resources
1. Renewable Energy Resources
These do not finish and can be used again and again.
Simple meaning:
Conservation is taking care of nature and resources so they are available for the future.
Examples:
Conserving forests – not cutting too many trees, planting new ones
Conserving water – turning off taps, not wasting water
Conserving electricity – switching off lights and fans when not needed
Ozone Depletion
Ozone depletion means the thinning of the ozone layer in the Earth’s atmosphere.
What is the ozone layer?
It is a protective layer of gas high up in the sky.
It protects us from harmful UV (ultraviolet) rays from the Sun.
What causes ozone depletion?
Pollution:
Definition:
Pollution is when harmful things make air, water, or land dirty and unsafe for living beings.
Types of Pollution
Air pollution – Smoke from vehicles and factories makes the air dirty.
Water pollution – Waste and chemicals pollute rivers, lakes, and seas.
Humans and the Food Chain
A food chain shows how food and energy move from one living thing to another.
Humans are omnivores.
We eat plants (rice, fruits, vegetables) and animals (milk, eggs, fish, meat).
So, humans usually come at the top of the food chain.
Definition
A food chain is a sequence that shows how energy moves from one living thing to another.
It starts with plants and ends with decomposers.
Food Chain Example
Grass → Goat → Lion Fungi
Examples (Plants)
Adaptations:
Thick stem stores water
Spines protect from animals
Leaves reduced to spines (less water loss)
Cell
Definition:
A cell is the smallest living unit of a living organism. All plants and animals are made of cells.
Main points:
Cells are very tiny (you need a microscope to see most of them).
Different cells do different jobs (muscle cells, nerve cells, etc.).
Definition
Plant cells are the basic living units of plants. They have special parts that help plants make food, grow, and stay upright.
Main Points
Plant cells have a cell wall for strength
They contain chloroplasts for photosynthesis
A large vacuole stores cell sap
Microorganisms and Disease:
Microorganisms are very tiny living things that we cannot see with our eyes. Some microorganisms are helpful, but some can cause diseases.
What is a Disease?
A disease is a condition that makes us feel sick or unhealthy.
When harmful microorganisms enter our body, they can cause diseases. These are called pathogens.
Types of Microorganisms that Cause Diseases
Micro-organisms:
Micro-organisms are very tiny living things that we cannot see with our eyes.We can see them only using a microscope.
Examples of micro-organisms:
Bacteria
Fungi
Protozoa
Definition:
Microorganisms are very small living organisms that can be seen only under a microscope.
Where are they found?
Microorganisms are found everywhere:
In air
In water
The cell membrane is a thin, flexible, living layer that surrounds the cell and controls what enters and leaves the cell.
It is also called the plasma membrane
It surrounds the cytoplasm of the cell
It is selectively permeable
Definition:
Reproduction is the ability of living organisms to make more organisms like themselves.
Why is reproduction important?
It prevents living things from becoming extinct
It helps increase the number of organisms
It passes features from parents to children
Living organisms are things that have life. Humans, animals, plants, birds, insects, and microorganisms are all living organisms.
1. They Need Food
All living things need food to get energy.
Plants make their own food.
Animals depend on plants or other animals.
Definition:
Living organisms are beings that grow, reproduce, respond to their environment, and carry out life processes such as nutrition, respiration, and excretion.
Main points
Growth – They increase in size and develop over time.
Reproduction – They can produce offspring (young ones).
Nutrition – They take in food to get energy and build their body.
Definition:
The human body is the structure of a person, made up of many parts and systems that work together to keep us alive.
Main points:
Head – holds the brain, eyes, ears, nose, and mouth.
Neck – connects the head to the body.
Trunk – chest and stomach, protects important organs.
Definition:
Muscles are soft tissues in the body that can contract (shorten) and relax (lengthen) to produce movement, maintain posture, and perform essential functions like pumping blood and moving food in the body.
Interesting points:
Muscles are everywhere: About 40–50% of your body weight comes from muscles!
Muscles can only pull, not push: They work in pairs to move your body.
Fastest muscles: Your eyelid muscles are the fastest—they can blink up to 100 times per minute!
Definition:
Joints are the places where two or more bones meet
they help our body move and bend.
Interesting points:
Joints help us walk, run, jump, and write.
Some joints can move in many directions, like the shoulder.
Definition:
The human skeleton is the hard framework of bones inside our body. It gives shape to our body and supports us.
Main points:
The human skeleton has 206 bones.
It supports the body and gives it shape.
It protects important organs like the brain, heart, and lungs.
A human organ system is a group of organs that work together to perform a particular job and keep our body healthy.
The human body has many organ systems.
Each organ system has a special function.
Definition:
A human organ system is a group of organs that work together to perform a particular job and keep the body healthy.
Main points:
The human body has many organ systems.
Each organ system has a special function.
Definition:
Reproduction is the biological process by which living beings produce new young ones or offspring to continue their species.
Interesting points:
Life continues: Reproduction is the reason all living things exist today.
Two ways to reproduce: Some organisms need only one parent (asexual), while others need two parents (sexual).
Asexual is fast: Single-celled organisms like amoeba can reproduce quickly and make many offspring.
Definition:
A human organ system is a group of organs that work together to perform a particular job and keep the body alive.
Interesting points:
The heart beats about 100,000 times every day.
The brain sends messages faster than a blink of an eye.
The lungs have millions of tiny air sacs called alveoli.
Definition:
Sexual reproduction is making a new living thing using two parents.
Interesting points:
Two Parents Are Needed – Male and female both contribute cells.
Sperm and Egg Join – Fertilization forms a zygote, the first cell of a new life.
Offspring Are Unique – Children are similar but not exactly the same as parents.
Definition:
The human organ system is a group of organs that work together to keep our body healthy and alive.
Interesting points:
The heart works day and night without resting.
The brain controls the whole body, even when we sleep.
We breathe automatically without thinking about it.
Definition:
The human organ system is a group of organs that work together to keep our body alive and health.
Interesting points:
The brain uses energy all the time, even when we are resting.
The heart starts beating before we are born.
The lungs help us laugh, cry, and talk.
Definition:
Reproduction is the process by which living things make new living things of their own kind.
Importance:
It keeps living things from dying out
Helps increase the number of living things
Life continues from generation to generation.
Definition:
A human organ system is a group of organs that work together to perform a special function in our body.
Main points:
Digestive system – Digests food and gives energy.
Respiratory system – Helps us breathe.
Circulatory system – Carries blood and oxygen.
The skeletal system is the framework of bones in our body. It gives our body shape, support, and protection.
Skull – Protects the brain
Spine (Backbone) – Helps us stand straight and bend
Rib Cage – Protects the heart and lungs
A human organ system is a group of organs that work together to do a special job in our body.
Our body has many organ systems.
Each organ system has a different function.
The digestive system digests food.
Digestive system – Digests food and gives energy.
Respiratory system – Helps us breathe.
Circulatory system – Carries blood, oxygen, and nutrients.
Nervous system – Controls thinking and body actions.
Skeletal system – Gives shape and support to the body.
Definition:
An organ system is a group of organs that work together to perform a special function in our body.
The human body has many organ systems.
Each organ system has a specific job.
Digestive system helps in digesting food.
It’s a nice post.
What happens when an organ fails like the kidney? Is there a back up organ which could help?
What all organs are present in the digestive system and respiratory system?
Definition:
Digestive system Helps in digesting food and giving energy to the body.
2. Respiratory system Helps us breathe in oxygen and breathe out carbon dioxide.
3. Circulatory system Helps in carrying blood, oxygen, and nutrients to all parts of the body.
4. Nervous system Helps us think, feel, and control our body actions.
5. Skeletal system Gives shape and support to the body and protects organs.
Definition:
A human organ system is a group of organs that work together to do an important job in our body.
Digestive System
Helps us digest food.
Gives energy to our body.
The root grows under the soil.
It holds the plant firmly in the ground.
It absorbs water and minerals from the soil.
The stem is the main support of the plant.
Particle theory says that everything is made up of tiny particles and these particles behave in certain ways.
Here are the 5 main ideas:
Everything—air, water, solids, liquids, gases—is made of very small particles.
Has a fixed shape
Has a fixed volume
Particles are packed very tightly
Example: Ice, rock, wood, pencil
Vertebrates are animals with a backbone. They are divided into 5 main groups:
Live in water
Have gills to breathe
Body covered with scales
Lay many eggs
Simplest plants — no true roots, stems, or leaves.
They grow mostly in water (fresh or salty).
They make their own food using sunlight water and Carbondioxid(photosynthesis).
Some are green, others can be red or brown.
Examples: Spirogyra, Seaweed, Ulva, Volvox
Investigating Variation
Variation means differences among living things of the same species.For example, all humans are the same species, but we don’t all look the same — we have different heights, hair colors, and eye colors.
To investigate variation, scientists or students can collect data and compare characteristics.
Example investigation: Investigating height in your class
Measure the height of all students in the class.
The nervous system is one of the most important systems in our body. It helps us feel, move, think, and respond to what is happening around us. It acts like the contrl centerol for our whole body.
Brain:
The main control center.
It helps us think, learn, remember, and make decisions.
Meaning:Variation means small difference in a species.
Example: All humans are the same species, but we are differ in skin type, hair colour, height etc.
Cause: Variation happens because of the genes.
Types:
Inherited variantion
Environmental Variation
What are species ?
ANS: Scientist group living organisms in to diffrent kinds , called species .
. A species is a group of organisms that all share the same characterastics .
key word
. classification
. It shows how every type of organism we know of is connected to all the others .
🌿 What Are Species?
Scientists group living organisms into different kinds called species.
A species is a group of organisms that share similar characteristics.
All organisms are connected to one another through classification — it helps scientists understand how living things are related.
🧩 Classification
Classification means sorting living things into groups based on how they are alike.
It helps scientists study and understand the great variety of life on Earth.
Deciding how to classify a new organism can sometimes be difficult.
For example, it’s easy to tell that a jellyfish and a tiger are different species — but some cases are not so simple!
👩🔬 Taxonomists
Taxonomists are scientists who study how living things are classified.
They carefully observe animals and plants to decide which species they belong to.
🔬 Biological Species Concept (BSC)
According to the Biological Species Concept,
Organisms belong to the same species if they can mate and produce offspring that can also reproduce.
If they cannot produce offspring together, they belong to different species.
🧬 Reproductive Isolation
Reproductive isolation means two species cannot reproduce with each other.
This keeps species separate and helps new species evolve over time.
🌱 Introgression (Gene Flow)
Sometimes, offspring from two different species can still mate with one of the parent species.
This process is called introgression.
It allows gene flow (sharing of genetic traits) between two species.
🏞️ Habitat
A habitat is the natural home or environment of a species.
Different species live in different habitats — like forests, oceans, deserts, or grasslands.
People use a lot of energy each day .
. our body use energy for moving , for thinking , for growing and keeping warm .
Energy - is the ability to do work .
Question
From were do we get energy ?
ANS: Well, according to the law of conservation of energy.
Because I had only that much in that topic and it is a small topic in my note I have done more drawings and a digram
We share our earth with million of other organisms .
What is conservation ?
ans: Saving something or someone
Key word
. Ecosystem - al around us is ecosystem.
. Urbanisation - The. process of an ingresing preperation .
Ozone is a gas . There is a layer of ozone high up in the atmosphere. The Ozone layer is about 25 kilometres above the ground.
Keywords:
Radiation - Known as UV - Full form of UV is Ultra Violet rays entering from the Sun.
. Too much UV rays can cause skin cancer.
. Can even harm the single cell organisms like plants and aquatic animals.
. Between the Earth and Sun, there is an invisible pale blue protective shield called Ozone layer.
Pollution happens when people throw waste or pollute the air.
Water Pollution
We throw water in water, so the fishes come and eat, so they die.
What is water pollution?
Ans : Water pollution is dirty water.
Did you know?
Humans and food chain
Key words
. Woolly mammoth
. Mammoth
. Hunter
. Gater
Food chain - Describes how different organisms eat other for survival . The food chain usually starts with a plant and ends with an animal . The food chain comprises of the producers , consumers and decomposers :
Plants - Producers
Animals - consumers
Primary consumers = herbivores or secondary consumers eat other animals .
Secondary consumers - carnivores
If carnivores eats another carnivore , it is called a tertiary consumer , Some animals play both roles like crows . They are called omnivores.
Adaptation - Helps animals to servive aand thrive in wild .
The process of adjusting according to the environment and situation is called adaptation .
Question
How do animals adapt ?
ANS: There types of adaptation process in the animal world , That is : 1. Behairoral 2. Structural and physical
Behaviural adaptation :
Animal cell are suruonded by a semi - permeatain membarain . cell membarain alows only spsific matirial to move in and out of the cell . The diffrent parts of the cell are called organells . The cytoplasm is a jelly like substence . Cytoplasm provides a surface for all the center of the cell . Mitochondria are the sites for cellular respiration in cell. It is the power house for the cells. ATP is needed for the functioning or growth and maintence of the body . The endoplasmic reticulam is a large network of membaraine bounds sheet . They help in transporting and exanchaging materials between the virouse regions of thecytoplasm . The cytoplasm reticulum is two types The smooth endoplasmic riticulume helps in the formantation of lips . The rough endoplasmic reticulum has ribosomes . When the damaged , the lysosome bursts .
List the organelles.
How many organelles are there in the animal, plant, and human cell?
A cell is the smallest unit of life . It’s like a tiny room where all the work happens to keep a living thing alive.Every plant, animal, and human is made up of cells! Types of Cells
There are two main types:
Plant cells
Animal cells
Both are similar, but plant cells have some extra parts!
Organism
Organ system - 11 organe system
Organ - 78 organs
Tissues
cells - 37 trillion - 12 zeros in trillion
11 organ system
Key words
1 . Trillion - A number with 12 0's .
Amoebae - A tiny living organism .
Obtained - Naturally obtained , Chemically obtained , Biologycally obtained , Mechically obtained .
Obtain - To get or to receive something .
Butcher - A person who cuts and sells meat .
Points and questions
Why does a plant need a cell?
Ans: A plant needs cells because they are the fundamental building blocks for all functions providing structure, and enabling process like photosynthesis.
What is photosynthesis?
Ans: The process plants use to convert light energy to chemical energy to produce their own food, sugar, and oxygen.
What is chemical energy?
2 . 5
Points
What is the meaning organisms ?
ANS : Organisms are living things that means they can breath , grow , move , eat , and reproduce .
What is micro ?
ANS : The word 'micro' means very very small .
Mucles are organes that help us to move .
The mucles are atached to our bones.
Tendones are very strong.
And they don't stretch.
Mucles can get shorter .
This is called Contraction
Points
A joint is place where to bones meet.
There are two types of joints one is fixed joints second one is moveble joints.
The skull has fixed joints.
The crianium is made up of sevral bones .
This helps cranium to protect the brain.
The human skeletal system wasn't found by one person.
Yes , bones need blood.
There are 7 cervical vetibrae in almost all humans because They need to support the head
yes , animal organs work together
The name digestive system Came from the word digest
The meaning of respiration is to breath
Rain is water that falls from the clouds in the sky as drops.
Here’s a simple way to understand it:
Clouds form when water from rivers, lakes, or oceans evaporates into the air as water vapor.
The water vapor cools high up in the sky and turns back into tiny water droplets, making clouds.
When the droplets get too heavy, they fall to the ground as rain.
Rain is important because it gives water to plants, fills rivers and lakes, and helps animals and people.
Chlorophyll is a green pigment found in the leaf.
plants make oxygen from their leaves.
Plants give oxygen in the day because they need sunlight.
Asexual reproduction is a type of reproduction where only one parent is needed to make a new organism.
In this process, the new organism (offspring) is an exact copy of the parent — it has the same genes. Examples:
Bacteria reproduce by splitting into two (called binary fission).
Plants like money plants or potatoes can grow from cuttings or tubers.
Hydra and yeast reproduce by budding.
. Epidermis:
It is the outermost layer of the skin.
Protects the body from germs, sunlight, and water loss.
Makes new skin cells to replace old ones.
2. Dermis:
The middle layer of the skin.
Cells are the smallest building blocks of all living things.
Just like bricks make a house, cells make up our body — and the bodies of plants, animals, and all living things.
There are two main types:
Plant cells (found in plants)
Animal cells (found in animals and humans)
There was never just one first person to live on Earth. Humans didn’t suddenly appear — they slowly evolved over millions of years from earlier animals.
An ecosystem is a community where living things (plants, animals, humans, tiny organisms) interact with non-living things (air, water, soil, sunlight). 🌍✨
For example:
A pond ecosystem has fish, frogs, plants, insects (living) and water, mud, sunlight (non-living).
All of them depend on each other to live.
Gives shape – It gives our body its shape.
Supports – It supports the body and holds us up.
Protects organs – Like the skull protects the brain, and the rib cage protects the heart and lungs.
Helps movement – Bones join with muscles to help us move.
Makes blood cells – Some bones make red and white blood cells.
Carbohydrates → Give energyExamples: Rice, bread, potatoes, chapati
Proteins → Help in growth and repairExamples: Milk, eggs, pulses (dal), fish
Fats → Give extra energy and keep us warmExamples: Butter, ghee, nuts, oil
Vitamins → Protect us from diseasesExamples: Fruits (orange, mango), vegetables (carrot, spinach)
Minerals → Make bones and teeth strong, help body functionsExamples: Calcium (milk), Iron (spinach), Iodine (salt)
They grow (baby → adult, seed → tree).
They breathe (plants & animals).
They eat food & drink water for energy.
They move (run, swim, bend to light).
They make more of their kind (reproduce).
They do not grow.
They do not breathe, eat, or drink.
They can’t move on their own.
They do not reproduce.
They don’t react to things.
What is an embryo?