Things arround Us
Welcome to Your Environment
There is a vast variety of things around us, from the smallest insect to the largest tree, from the soil under our feet to the sunlight from above. Together, these things make up our environment. This guide will help you explore the two major parts of our environment: the living and the non-living components.
Biotic vs. Abiotic Components
Our environment is made of two types of components that are interconnected. Biotic components are all the living or once-living parts. Abiotic components are all the non-living physical and chemical parts. Click and explore the examples below.
🌿 Biotic Components
These are all the living organisms in an environment. They have life and are characterized by all the processes of living things.
- Plants: Producers that make their own food (e.g., trees, grass, algae).
- Animals: Consumers that get energy by eating other organisms (e.g., insects, fish, birds, mammals).
- Microorganisms: Decomposers that break down dead material (e.g., bacteria, fungi).
☀️ Abiotic Components
These are the non-living parts of the environment that biotic components depend on for survival.
- Air: Provides essential gases like oxygen for respiration and carbon dioxide for photosynthesis.
- Water: Vital for all life processes, from drinking to acting as a habitat.
- Soil: Provides nutrients and water for plants and a home for many organisms.
- Sunlight: The primary source of energy for almost all ecosystems.
Focus on an Abiotic Component: Air
Air is a critical abiotic component. It's a mixture of gases that living things use for survival. The chart below shows the approximate composition of the air we breathe.
What Makes Something "Alive"?
Living things share common characteristics that distinguish them from non-living things. Click on each tab below to learn about the 9 key characteristics of life.
Food & Nutrition
All living organisms need food to get energy, grow, and repair their bodies. Plants (autotrophs) make their own food through photosynthesis. Animals (heterotrophs) get food by eating plants or other animals. This process of taking in and using food is called nutrition.
Respiration
Respiration is the chemical process of releasing energy from food, usually by using oxygen. This is different from breathing, which is the physical act of taking in oxygen. The energy released powers all life activities.
Food (Glucose) + Oxygen → Carbon Dioxide + Water + Energy
Excretion
During life processes, waste products are formed. Excretion is the process of removing these harmful waste materials from the body. In animals, this is done through organs like the kidneys (producing urine), lungs (exhaling CO2), and skin (sweating). Plants excrete waste as gases (like oxygen), or store it in leaves that fall off.
Movement
Most animals move from place to place (locomotion) to find food, shelter, or mates. Plants also show movement, but it's usually slower and fixed in one place, such as a sunflower turning to face the sun or roots growing down into the soil.
Growth
All living things grow. This involves an irreversible increase in size and complexity. In multicellular organisms, this happens by cell division. Non-living things, like a glacier, might "grow" by external addition, but this is not biological growth.
Reproduction
Living things produce more of their own kind, ensuring the continuation of their species. There are two main types:
- Asexual Reproduction: Involves only one parent (e.g., budding in yeast, binary fission in amoeba).
- Sexual Reproduction: Involves two parents (male and female) combining genetic material (e.g., in humans, most animals, and flowering plants).
Response to Stimuli
All living organisms can detect and respond to changes in their environment. These changes are called stimuli (singular: stimulus). The reaction to a stimulus is called a response. For example, a touch-me-not plant closing its leaves (stimulus: touch) or you pulling your hand away from a hot object (stimulus: heat).
Cellular Structure
All living things are made of one or more cells. The cell is the basic structural and functional unit of life.
- Unicellular Organisms: Made of a single cell that performs all life functions (e.g., Amoeba, bacteria).
- Multicellular Organisms: Made of many cells that are organized into specialized groups.
Levels of Organization in Multicellular Organisms
(Basic Unit)
(Group of Cells)
(Group of Tissues)
(Group of Organs)
(A Living Being)
Definite Lifespan
Every living organism has a life cycle. It is born, it grows, it reproduces, and eventually, it dies. This period from birth to death is called a lifespan, which varies greatly between different species.
Test Your Knowledge!
You've explored the main concepts. Now, let's see what you remember! Answer the questions below and click "Check Answers" to see your score.
Think Deeper (HOTS)
These questions go beyond simple definitions. Click on each one to reveal the explanation and challenge your understanding!
A. A glacier grows due to gradual external addition of frozen, packed snow. Is it a living thing? +
Non-living. The "growth" of a glacier is by accretion, which is the external addition of material. Living things grow from within, through processes like cell division. A glacier does not respire, reproduce, respond to stimuli, or have cells.
B. Which is bigger—a cell or a molecule? +
A cell is bigger. A cell is the basic unit of life and is made up of many, many different molecules (like water molecules, protein molecules, and DNA molecules). Molecules are the building blocks of cells.
C. Do we have the same type of cells all over our body? +
No. We are multicellular organisms with specialized cells. A muscle cell is long and thin to contract, a nerve cell has long fibers to send signals, and a red blood cell is shaped to carry oxygen. Each cell type is specialized for its specific job (forming tissues, then organs).
D. Unicellular organisms cannot move because they have no limbs. Is this true? +
False. Many unicellular organisms are very mobile. An Amoeba moves using pseudopods (false feet), and a Paramecium moves using tiny hairs called cilia. They have specialized structures for movement, just not "limbs."