1. “Features of an Organism”

In biology, features of an organism refer to the structural, physiological, and functional characteristics that determine:

• The organism’s identity

• Its mode of life

• Its evolutionary relationships

• Its position in biological classification

1. What is Classification?

Definition (simple):

Classification is the way scientists group living things based on what they are similar in.

Imagine this:

You have thousands of clothes.

You sort them into shirts, pants, jackets.

Characteristics of Living Organisms

1. Nutrition

   • Process of obtaining food for energy, growth, repair, and maintenance.

   • Provides raw materials for building new cells and energy for activities.

   • Types:

     • Autotrophs: Make their own food (e.g., plants) via photosynthesis using sunlight, water, and carbon dioxide.

omologous Organs – Forelimbs of Vertebrates(Whale, Bat, Lizard, Bird, Human)

Definition

Homologous organs are organs that have the same basic structure and origin but are modified to perform different functions in different organisms.

The forelimbs of vertebrates are the best example of homologous organs.

Common Basic Skeletal Plan (Same in All)

All five vertebrates have the same arrangement of bones in their forelimbs:

• Humans belong to Kingdom Animalia and are living, multicellular, eukaryotic, heterotrophic organisms with specialized cells, tissues, organs, and organ systems that work together to maintain life.

• Humans are vertebrates (Phylum Chordata) with a backbone, spinal cord, and internal skeleton that provide support, protection, and efficient movement.

• Humans belong to Class Mammalia, so they are warm-blooded, have hair on their bodies, breathe through lungs, possess mammary glands, and mothers feed their young with milk.

• Humans are placed in the Order Primates, showing features such as forward-facing eyes for depth vision, flexible limbs, nails instead of claws, and opposable thumbs for grasping.

• Humans walk upright on two legs (bipedal locomotion), which frees the hands for tool use, writing, building, and creative activities.

• Humans have a highly developed brain, especially the cerebrum, enabling intelligence, memory, reasoning, imagination, emotions, decision-making, and learning.

Uses of DNA Sequencing in Classification (Super Easy)

1. Tells how similar two organisms are

If their DNA matches a lot → they are closely related.

If DNA is very different → they are not related.

2. Helps in correct grouping

Sometimes animals/plants look similar but are not actually related.

1. Organisms

Organisms are all living things — plants, animals, humans, insects, even tiny bacteria.Every organism has traits like color, height, speed, beak size, fur color, etc.

2. Genes

Genes are the instructions inside an organism that decide its traits.You get your genes from your parents.Different genes create different versions of traits.

Examples:

• Gene for dark fur

Selective Breeding

What is selective breeding?Selective breeding is when humans choose two parent plants or animals with good qualities and make them reproduce so their babies also have those qualities .It is also called artificial selection.

Why selective breeding is done

• more food

• better quality animals

• stronger plants

INHERITANCE – FULL DETAILED EXPLANATION

1. What exactly is inheritance?

Inheritance is the biological process where information stored in genes is passed from parents to their children.It explains why you look like your family, why you may have your father’s eyes or your mother’s smile.

2. Where is this information stored?

All inherited information is stored in DNA.

DNA → Genes → Chromosomes

1. Independent Variable (IV)

What it is:

The factor you purposely change in an experiment.

Why it’s important:

• Helps you test your question: “What happens if…?”

• Shows the cause in a cause-and-effect relationship.

1. Habitat

Why it’s used:

• Species are adapted to survive in a specific environment.

• Habitat determines: temperature tolerance, diet availability, predators, and mating areas.

• Helps scientists exclude animals that cannot survive there.Example: If a scientist is studying animals in the Sahara, polar bears and penguins are automatically excluded.

How they use it:

Keys help in classification

Keys are part of classification because they help place an organism into the correct group (like mammals, birds, insects, etc.).

Each step must have ONLY two choices

This is very important for Grade 9:

• Every step has two statements

• They must be opposites.

1. What Are Alkali Metals?

Alkali metals are very reactive metals found in Group 1 of the periodic table.They all have 1 electron in their outermost shell, which makes them react easily.

List of Alkali Metals

• Lithium (Li)

• Sodium (Na)

• Potassium (K)

1. Meaning

A population is a group of living organisms of the same species living in a specific place at a specific time.

All humans in the world → Human population

All elephants in Africa → Elephant population

All neem trees in a garden → Neem tree population

2. What decides a population size?

preserving wetland

Wetlands are areas where water covers the soil, either permanently or seasonally. Examples include marshes, swamps, and bogs. They are rich in plants, animals, and microorganisms.

Importance of Wetlands

• Biodiversity: Provide habitat for fish, birds, amphibians, and other wildlife.

• Water Purification: Filter pollutants and improve water quality.

• Flood Control: Absorb excess rainwater and reduce flooding.

Habitat Destruction

Habitat destruction means the natural home of plants and animals is damaged or removed, so they can no longer live there.

Causes of Habitat Destruction

• Deforestation – cutting down trees for wood, farms, or houses.

• Urbanization – building cities, roads, and factories.

• Pollution – chemicals, plastics, oil spills harming the environment

Decomposers

• Decomposers are living things that break down dead plants, dead animals, and animal waste.

• They turn complex materials into simple nutrients like minerals that mix with the soil.

• Without decomposers, dead bodies and waste would pile up and plants would not get nutrients.

• They play a very important role in nutrient recycling in all ecosystems.

Examples of decomposers:

• A food web is a network of many connected food chains in an ecosystem.

• It shows who eats whom and how energy moves from one organism to another.

• They show how plants, animals, and decomposers are linked.

• They help us understand what happens if one organism disappears.

• They make ecosystems stable.

• Phytoplankton and zooplankton form the base of aquatic food webs.

Ecology is the study of how living things (plants, animals, humans, microorganisms) interact with each other and with their environment (air, water, soil, sunlight)

investigating

Independent Variable

• The factor you change or control in your experiment.

• It is the variable chosen by the researcher.

Examples in Ecology:

🧬 What Are Structural Adaptations?

Structural adaptations are physical features or body parts of an animal that help it survive, hunt, protect itself, or reproduce in its environment. These features are inborn (not learned) and are passed down from generation to generation.

Animals evolve these structures over time to fit their surroundings — for example, animals in the desert need ways to save water, while those in cold places need ways to stay warm.

🌵 1. Desert Animals

Desert animals live where water is scarce and temperatures are extreme.Examples:

• Camel: Has a hump that stores fat (used for energy when food is limited), long eyelashes and closing nostrils to keep out sand, and broad feet to walk easily on sand.

Adaptations of Arabian Oryx (Desert Habitat)

White body colour reflects sunlight → keeps the body cool in the desert.

Can survive many days without drinking water → gets water from plants + reduces water loss.

Body temperature can rise safely → less sweating → saves water.

Long sharp horns → protection from predators.

Wide hooves → easy to walk and run on loose desert sand.

General Adaptations

• Adaptation means special features that help a plant survive in its environment.

• Plants adapt to get sunlight, water, air, and nutrients efficiently.

• Adaptations help plants survive in extreme conditions like deserts, water, cold regions, and rainforests.

Desert Plants (Xerophytes)

• Thick fleshy stems to store water (example: cactus).

Fruits are the developed mature ovaries of a flower that contain seeds.

They form after fertilization and help in protecting and spreading the seeds to grow new plants

dispersal

Seed dispersal is the process of spreading or moving seeds away from the parent plant.

This helps plants grow in new places and reduces competition for sunlight, water, and nutrients.

differences between fruits and vegetables

Fertilization in plants is the process where the male gamete present inside the pollen grain fuses with the female gamete (egg) present inside the ovule of the flower.

Fertilization

Fertilization is the process where the male gamete and the female gamete join together to form a new life. In humans this is when the sperm from the father meets the egg from the mother and they fuse to form a zygote. This zygote is the very first cell of a new organism and after fertilization it starts dividing to form an embryo. Fertilization is extremely important because without it, a new living organism cannot start developing.

What are the things in Fertilization

During fertilization the sperm, which is produced in the male’s testes, travels into the female reproductive system and reaches the fallopian tube. The egg, which comes from the ovary, is released during ovulation and waits in the fallopian tube. Out of millions of sperm, only one sperm successfully enters the egg. When the sperm enters, both their nuclei combine and their genetic information mixes together. This…

atomic structure

Atomic structure describes how an atom's subatomic particles are arranged: protons and neutrons form a dense, central nucleus, while electrons orbit it in shells or energy levels. The number of protons, known as the atomic number, defines the element and is equal to the number of electrons in a neutral atom. The mass number is the combined total of protons and neutrons, and the overall arrangement determines the atom's chemical properties

Pollination is one of the most important natural processes that helps flowering plants reproduce and continue their life cycle. It is the process by which pollen grains are transferred from the anther (the male part of a flower) to the stigma (the female part of a flower). This transfer allows plants to make seeds and fruits, ensuring that new plants can grow in the future. Without pollination, most plants would not be able to produce fruits or seeds, and life on Earth would be very different because plants are the base of every food chain.

A flower has both male and female parts that play special roles in pollination.

The anther is part of the male structure called the stamen. It produces pollen grains that contain the male reproductive cells.

The stigma is the top part of the female structure called the carpel or pistil, and it receives the pollen…

Definition

The digestive system (gastrointestinal system) is the part of the body that digests food, absorbs nutrients, and removes waste.

Functions

Breaks down food into simple chemicals.

Absorbs nutrients into the bloodstream.

Sends nutrients to the liver for processing.

The skeletal system is the body’s framework made of bones, cartilage, and ligaments.

Blood cell production: Bone marrow makes red and white blood cells.

Transportation in Plants is the movement of water, minerals, and food from one part of the plant to another using xylem (for water) and phloem (for food) to help the plant grow, stay healthy, and survive.

Xylem – Moves water and minerals up from roots (like pipes in a building).

Phloem – Moves food from leaves to all parts (like delivery trucks).

Roots – Absorb water and minerals (like water wells).

Leaves – Make food and release water (like factories).

Stem – Carries xylem and phloem (like a highway for transport)

🔹 1. Types of Cells (in humans)

Muscle cells 💪 – help in movement

Nerve cells (neurons) 🧠 – carry messages

Blood cells 🩸 – red blood cells carry oxygen, white fight germs

Skin cells 🧴 – protect the body

Bone cells 🦴 – give support