Biology

An adaptation is a feature of a living organism that helps it survive and reproduce in its environment. Adaptations can be structural (body features), behavioural (actions), or physiological (internal processes).

Camouflage allows animals to blend into their surroundings to hide from predators or prey. Mimicry is when one species resembles another to gain a survival advantage. Both are powerful evolutionary adaptations.

Migration is the seasonal movement of animals from one region to another, typically to find food, better conditions, or breeding sites. Many birds, fish, insects, and mammals migrate thousands of kilometres each year.

Birds and reptiles are both vertebrates descended from a common ancestor. Reptiles are scaly and cold-blooded; birds have feathers, are warm-blooded, and evolved from theropod dinosaurs.

Fish are aquatic vertebrates that breathe through gills, while amphibians live both in water and on land, breathing through lungs and moist skin. Together they form two of the five main vertebrate groups.

Invertebrates are animals without a backbone. They make up over 95% of all animal species and include insects, spiders, worms, and molluscs.

Mammals are warm-blooded vertebrates that breathe air, have hair or fur, and feed their young on milk produced by the mother.

Vertebrates are animals with a backbone (vertebral column) that protects the spinal cord. They include fish, amphibians, reptiles, birds, and mammals.

Study of animal diversity, classification, adaptations, and life cycles across the animal kingdom.

Insects go through a life cycle that includes distinct stages of development. Most insects undergo either complete metamorphosis (four stages) or incomplete metamorphosis (three stages) as they grow from egg to adult.

Metamorphosis is the process by which some animals transform their body shape dramatically during development. Insects and amphibians are the best-known examples, undergoing either complete or incomplete metamorphosis.

Animal cells are eukaryotic cells without a cell wall or chloroplasts, containing a nucleus, mitochondria, and other organelles suspended in cytoplasm.

Cell division is the process by which one cell splits into two daughter cells. It is essential for growth, repair, and reproduction. The two main types are mitosis (producing identical cells) and meiosis (producing sex cells).

The cell membrane is a thin, flexible barrier surrounding every cell, controlling the movement of substances in and out.

Chloroplasts are organelles found in plant cells that capture light energy and use it to produce food through photosynthesis.

Animal and plant cells share many features — nucleus, cell membrane, cytoplasm, and mitochondria — but plant cells have three additional structures: a cell wall, chloroplasts, and a large central vacuole.

Mitochondria are the organelles responsible for cellular respiration, converting glucose and oxygen into usable energy (ATP) for the cell.

The nucleus is the control centre of eukaryotic cells, containing DNA that carries the instructions for all cell activities.

Plant cells have a rigid cell wall, chloroplasts, and a large central vacuole — features that distinguish them from animal cells.

Study of cell structure and function as the foundation for understanding all living organisms.

Biodiversity is the variety of life on Earth — the number and variety of species, genes, and ecosystems in a given area. High biodiversity makes ecosystems more stable and resilient, and provides many resources that humans depend on.

A species is endangered when its population has declined so much that it faces a real risk of extinction. The main causes are habitat loss, hunting, pollution, climate change, and invasive species. Conservation efforts work to protect and recover threatened populations.

Decomposers are organisms that break down dead plants and animals, returning nutrients to the soil. Without decomposers, dead matter would pile up and nutrients would be locked away, making life impossible.

An energy pyramid shows how energy moves through the levels of a food chain. At each level, about 90% of energy is lost as heat, so only 10% passes to the next level. This limits the length of food chains.

A food chain shows the flow of energy from one organism to the next, starting with a producer and moving through consumers.

A food web is an interconnected network of food chains showing the complex feeding relationships within an ecosystem.

Producers make their own food through photosynthesis; consumers obtain energy by eating other organisms. Together they form the foundation of all food chains.

Deserts are dry ecosystems that receive very little rainfall, yet support a surprising variety of specially adapted plants and animals.

Forests are complex ecosystems with multiple layers of life, from the forest floor to the canopy, supporting extraordinary biodiversity.

Freshwater habitats — rivers, lakes, ponds, and wetlands — cover less than 1% of Earth's surface but support about 10% of all known species. They include still (lentic) and flowing (lotic) water environments.

Grasslands are biomes dominated by grasses, with few or no trees. They cover about 40% of Earth's land surface and include tropical savannas, temperate prairies, and steppe regions. They support huge numbers of grazing animals.

Oceans cover over 70% of Earth's surface and contain a huge variety of habitats, from sunlit surface waters to the pitch-dark deep sea.

Study of energy flow, biodiversity, species relationships, and how organisms interact within their environments.

A vertebrate is an animal that has a backbone, including fish, amphibians, reptiles, birds, and mammals.

A cell is the basic structural and functional unit of all living organisms.

An ecosystem is a community of living organisms interacting with each other and their non-living environment.

An organ is a group of tissues working together to perform a specific function in the body.

Key definitions and terms across biology topics for quick lookup and concept reinforcement.

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to produce glucose and oxygen.

Study of human anatomy, body systems, and physiological processes supporting human life.

Food groups categorise foods by their main nutrients. A healthy diet includes appropriate amounts from each group.

A balanced diet provides the right amounts of all nutrients needed for health, energy, and growth without excess of any harmful component.

Macronutrients — carbohydrates, proteins, and fats — are the three main groups of nutrients needed in large amounts to provide energy and support body growth and repair.

Vitamins and minerals are micronutrients needed in small amounts to support vital body processes, from bone formation to immune function.

Your five sense organs — eyes, ears, nose, tongue, and skin — detect signals from your environment and send nerve messages to the brain so you can respond to the world around you.

The circulatory system transports oxygen, nutrients, hormones, and waste products around the body using the heart, blood vessels, and blood.

The digestive system breaks down food into small molecules that can be absorbed into the blood and used by the body's cells.

Your immune system is your body's defence network against disease. It recognises harmful invaders like bacteria and viruses, attacks them, and remembers how to fight them quickly if they return.

The muscular system consists of over 600 muscles that produce movement, maintain posture, and generate body heat.

The nervous system detects stimuli, processes information, and coordinates responses, allowing the body to react to internal and external changes.

The respiratory system brings oxygen into the body and removes carbon dioxide, enabling cells to release energy through aerobic respiration.

The skeletal system is the framework of bones that supports the body, protects organs, enables movement, and produces blood cells.

Skin is the largest organ in your body. It protects you from the environment, regulates body temperature, allows you to sense touch and pain, and helps prevent infection.

Study of plant structure, photosynthesis, and reproduction mechanisms in the plant kingdom.

Chlorophyll is the main photosynthetic pigment in plants that absorbs light energy, giving leaves their green colour.

Plants exchange gases with the atmosphere mainly through tiny pores called stomata on their leaves, which open and close to control gas flow.

Photosynthesis is powered by light — the more light a plant receives, the faster it can photosynthesise, up to a maximum rate. Light intensity is one of several factors that can limit how quickly photosynthesis occurs.

Photosynthesis is the process by which plants use sunlight, carbon dioxide, and water to make glucose and oxygen.

Flowers are the reproductive organs of flowering plants. Pollination transfers pollen from one flower to another, leading to fertilisation and seed production.

Leaves are the main organs of photosynthesis, with a flat blade, network of veins, and thousands of stomata for gas exchange.

Roots anchor plants in the soil and absorb water and dissolved minerals that the plant needs to survive and grow.

A seed is a fertilised plant embryo enclosed in a protective coat. Germination is the process by which a seed sprouts and begins to grow into a new plant. It requires water, warmth, and oxygen — but not light at first.

Stems support the plant and contain xylem and phloem vessels that transport water, minerals, and sugars throughout the plant.

Plants can reproduce sexually (using flowers, pollen, and seeds) or asexually (producing genetically identical offspring from roots, stems, or leaves). Sexual reproduction increases genetic variety; asexual reproduction is faster and reliable.