BIOLOGY BASICS SERIES
A Beginner’s Guide to Biology: Chapter 2
EDITION: 2026
KOMAL BHARDWAJ
Biology Basics Series: Chapter 2
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Chapter 2: Characteristics of Living Organisms
In Chapter 1, we learned that Biology is the study of life and living organisms. To study Biology
further, we must clearly understand what makes something “living.”
Living organisms are different from non-living things because they perform specific life processes
that keep them alive. These characteristics help us identify and study living organisms more
clearly.
Topics Covered
• Characteristics of living organisms
• Difference between living and non-living things
• Basic life processes
• Introduction to MRS GREN
• Importance of life processes in living organisms
What Are Living Organisms?
Living organisms are things that show life. They can grow, move, reproduce, and respond to their
environment. Examples include humans, animals, plants, and microorganisms.
Non-living things such as stones, water, and air do not show these life activities.
The main difference is that living organisms carry out life processes continuously, while non-living
things do not.
Characteristics of Living Organisms (MRS GREN)
All living organisms share certain basic characteristics. These are often remembered using the
term MRS GREN.
Movement
Living organisms can move. Animals move from one place to another, while plants show
movement through growth towards light or water.
Example: A sunflower plant slowly bends and turns toward sunlight during the day so that it can
receive maximum light for making food.
Respiration
Respiration is the process of releasing energy from food. All living organisms need energy to
survive and perform activities.
Example: Humans breathe oxygen and use it to break down food in the body, releasing energy
needed for walking, working, and other activities.
Sensitivity
Living organisms respond to changes in their environment. These changes are called stimuli.
Example: When a person touches a hot object, they quickly pull their hand away to avoid injury.
This response shows sensitivity.
Growth
All living organisms grow over time. Growth is an increase in size and development of the body.
Example: A small seed grows into a large plant after receiving water, sunlight, and nutrients from
Biology Basics Series: Chapter 2