Karthikeyan

Plants are made up of two main systems that work together to keep the plant alive.

1. Root System

Grows below the ground

Functions:

• Absorbs water and minerals

• Anchors the plant firmly in soil

🌿 Ferns

General Features

• Ferns are land plants with:

  • Well-developed roots, stems, and leaves

  • Structures similar to flowering plants

Stem and Roots

Birds

General Characteristics

• Birds are warm-blooded vertebrates

• Body temperature remains constant

Skeleton

• Neck vertebrae are flexible

Amphibia

General Characteristics

• Cold-blooded vertebrates

• Four limbs

• No scales; skin is moist

• Name amphibian means “double life” (water + land)

Vertebrates

Definition

• Vertebrates are animals that possess a vertebral column (backbone).

Vertebral Column

• Also called the spinal column or spine

• Made of many cylindrical bones called vertebrae

Insects

Key Features

• Wings: Usually present (one or two pairs)

• Antennae: One pair

• Legs: Three pairs (6 legs) attached to the thorax

• Body regions: Head, thorax, abdomen

General Features of Animals

• Multicellular organisms

• Cells do not have cell walls or chloroplasts

• Feed by ingesting solid food and digesting it internally

Classification of Animals

• Animals are divided into groups called phyla

What is DNA?

• DNA is the genetic material found in almost all living organisms

• It carries the instructions that tell cells how to grow, function, and reproduce

Where is DNA found?

• Mainly in the nucleus of a cell

• A small amount is also found in mitochondria

• Multicellular organisms

• Cells do not have cell walls or chloroplasts

• Feed by ingesting solid food and digesting it internally

Classification of Animals

• Animals are divided into groups called phyla

• Two important phyla discussed here:

Why scientists classify organisms

• Classification helps scientists understand how organisms are related through evolution.

• Organisms that share a common ancestor are grouped together.

Vertebrates and limb structure

• All vertebrates have:

  • A vertebral column (backbone)

Why scientists classify organisms

• Classification helps scientists understand how living things are related.

• By grouping organisms with similar features, we can trace their evolutionary history.

Vertebrates

Vertebrates are animals that have:

• A vertebral column (backbone)

What is a dichotomous key?

• A dichotomous key is a tool used to identify organisms.

• It works by giving two opposite choices at each step.

• The word dichotomous means “two branches.”

• By choosing the correct option each time, you can find the correct group or class of an organism.

How does a dichotomous key work?

Species

• A species is the smallest natural group of organisms.

• Members of a species can reproduce together to produce fertile offspring.

• They usually look very similar in:

  • Appearance

  • Anatomy

Characteristics of Living Organisms (MRS GREN)

All living organisms—whether plants or animals, single-celled or multicellular—show seven basic characteristics. These can be remembered using the mnemonic MRS GREN.

M – Movement

• Movement is an action by an organism or part of an organism.

• It causes a change in position or place.

• Example: humans walking, plants bending towards light.

MRS GREN is a memory tool used in Biology to describe the seven essential life processes that all living organisms must carry out. These processes help living things survive, grow, and reproduce.

1. Movement

All living organisms show movement. Animals move their whole bodies, while plants move parts like leaves, stems, or flowers. Movement helps organisms find food, escape danger, and grow towards light.

2. Respiration

Respiration is the process of releasing energy from food. This energy is needed for every activity, including growth, repair, and movement. Plants and animals both respire.

3. Sensitivity

Cell Structure

• When a very thin slice of a plant stem is looked at under a microscope, it looks like it’s made up of many small box-like parts — these are cells.

• The slice in the picture is magnified 60 times. So if a cell looks 2 mm long in the image, in real life it’s only 0.03 mm long.

• Such thin slices are called sections.

Types of Sections

1. Longitudinal Section – Cut along the length of the stem (you see the inside part stretched out).

• Viruses come in many shapes and structures.

• Each virus has a core of genetic material — either RNA or DNA — surrounded by a protein coat.

• They do not have:

  • Nucleus

  • Cytoplasm

  • Cell organelles

Prokaryote Kingdom

• Includes bacteria and blue-green algae.

• They are unicellular (single-celled) organisms.

• No true nucleus — their DNA is not inside a nuclear membrane.

• Cells are simple in structure compared to other organisms.

• Some are useful (e.g. in food production), while others can cause diseases.

Epidermis

• The epidermis is the outermost layer of cells covering the leaves, stems, and roots of a plant.

• It protects the plant from water loss, injury, and infection.

• Cells are closely packed and often covered with a waxy cuticle to reduce evaporation.

• In leaves, it contains stomata, which control gas exchange and transpiration.

Key Points:

Plant Kingdom

• The Plant Kingdom (Plantae) includes all multicellular, eukaryotic, and autotrophic organisms that make their own food by photosynthesis.

• They have cell walls made of cellulose.

• Most plants contain chlorophyll, which gives them a green color.

• They are mainly non-motile (don’t move).

• Plants provide oxygen, food, and shelter for other living things.

• Movement.

• Respiration

• Sensitivity

• growth

• Reproduction

• Excretion

Absorption in the Small Intestine

The small intestine is the main site where digested food is absorbed. Its inner wall has finger-like projections called villi, and each villus is covered with microvilli. These structures increase the surface area, making absorption faster and more efficient.

Each villus contains blood capillaries and a lymph vessel (lacteal). Different nutrients are absorbed in different ways:

• Glucose and amino acids → absorbed into blood capillaries.

• Fatty acids and glycerol → absorbed into lacteals.

• Vitamins and minerals → absorbed depending on their solubility.

There are two main types:

1. Asexual Reproduction – only one parent is needed.

   • Offspring are identical (clones).

   • Examples: binary fission in bacteria, budding in yeast, vegetative propagation in plants.

2. Sexual Reproduction – needs two parents (male and female).

   • Involves gametes (sperm + egg).

• Definition: The system that removes waste products from your body to keep you healthy.

• Main parts & their jobs:

  1. Kidneys – filter blood and make urine.

  2. Lungs – remove carbon dioxide when you breathe out.

  3. Skin – removes waste as sweat.

  4. Liver – breaks down harmful substances (like toxins, alcohol, drugs).

The circulatory system carries blood all around the body.

• The heart pumps blood.

• Arteries take oxygen-rich blood from the heart to the body.

• Veins bring oxygen-poor blood back to the heart.

• Capillaries are tiny tubes where oxygen and nutrients go into cells, and waste like carbon dioxide comes out.

There are two pathways:

Households means the people living together in a home (like your family). In economics, we don’t just mean the building, we mean the group of people in it.

A household:

• Uses goods and services (like food, clothes, electricity).

• Provides resources to firms (like labour – when your parents go to work).

• Earns income (wages, salary, rent, profit).

• Decides how to spend money and save it.