Characteristics of Living Things
What Makes Something Alive?
Living things are referred to as organisms.
Organisms can vary greatly in size, from microscopic bacteria to massive blue whales.
All living organisms share specific features that differentiate them from nonliving entities such as rocks or water.
Defining Life
Living Things: Definitions and Examples
Living things are composed of cellular structures and partake in vital biological functions.
Examples of living organisms include:
Dogs
Trees
Mushrooms
Nonliving Things: Definitions and Examples
Nonliving entities do not possess the properties of life.
Examples include:
Rocks
Water
Pencils
Living vs. Nonliving
Characteristics of Living Things
Living beings exhibit the following properties:
Grow and Change: They undergo development and increase in size or number of cells over time.
Need Energy: They require energy to survive, which can come from food or sunlight.
Respond to Environment: They detect and respond to changes in their surroundings, enhancing their chances of survival.
Characteristics of Nonliving Things
Nonliving entities display the opposite characteristics:
Do Not Grow or Change: They remain static and do not evolve naturally.
Do Not Need Energy: They do not require sustenance of any kind to exist.
Do Not React: They do not show responses to environmental changes.
The 7 Characteristics of Life
Organization: Living things are composed of cells, which are considered the fundamental building blocks of life.
Growth: Organisms can increase in size or cell number as they develop.
Reproduction: Living beings have the ability to reproduce, creating offspring of their own kind.
Response: Organisms are capable of reacting to environmental changes.
Energy Use: All living things require energy to perform life processes.
Homeostasis: Living organisms maintain stable internal conditions regardless of external environmental changes.
Adaptation: Over generations, organisms evolve and adapt to better survive in their environments.
Cells: The Building Blocks of Life
All living organisms are composed of cells:
Types of Cells: These range from single-celled entities, like bacteria, to complex multicellular organisms, such as humans, which may contain trillions of individual cells.
Cells are responsible for performing essential life functions, including nutrient intake and waste elimination.
How Living Things Respond
Living beings detect and react to changes in their environment:
Example 1: A sunflower aligns itself toward the sun to maximize photosynthesis.
Example 2: A cat may flee from sudden loud noises as a survival mechanism.
These reactions are crucial for the survival and flourishing of the organisms within their habitats.
Real-World Connections
Understanding life characteristics has significant implications:
It aids in the search for extraterrestrial life.
Informs conservation strategies for endangered species.
Drives the development of novel medical treatments.
Fosters appreciation for Earth's biodiversity.
Discussion: Is It Alive?
Engage in group discussions concerning borderline cases of life such as:
Fire: Although it consumes energy and appears to grow, it lacks cellular structure and does not reproduce like living organisms.
Viruses: They exhibit reproduction and adaptation, yet they do not possess cells or independently utilize energy, relying on a host to propagate.
Robots: While they may display organization and responsiveness through programming, robots do not naturally grow, reproduce, or maintain homeostasis.
Summary: What Makes Life? Key Takeaways
All living entities can be grouped based on seven main characteristics:
Organization, Growth, Reproduction, Response, Energy Use, Homeostasis, Adaptation.
Every living thing is comprised of cells and requires energy, emphasizing their role in biological processes.
The understanding of these traits is essential for exploring and safeguarding the living world.
Characteristics of Living Things Multiple Choice Quiz
Questions and Answers
Which characteristic is shared by all living things and sets them apart from nonliving things?
a) Ability to dissolve in water
b) Presence of cells
c) Ability to fly
d) Made of metal
Why is fire NOT considered a living thing, even though it grows and uses energy?
a) Because fire does not need oxygen
b) Because fire is not hot
c) Because fire does not have cells or reproduce like living organisms
d) Because fire is always blue
Which characteristic allows organisms to keep internal conditions stable even when their external environment changes?
a) Adaptation
b) Energy Use
c) Homeostasis
d) Organization
A scientist discovers a new microscopic entity that reproduces and evolves but cannot use energy on its own and lacks cellular structure. What is most likely true about this entity?
a) It can be classified as a living thing
b) It is likely a type of mineral
c) It is most likely not a living thing, similar to a virus
d) It is a large multicellular organism
Which of the following BEST explains why adaptation is an important characteristic of life?
a) It allows all organisms to become larger in size
b) It lets organisms move faster
c) It enables populations to survive changes in their environment over many generations
d) It makes organisms immortal
Some robots can respond to their environment using sensors and artificial intelligence. Why are they still NOT classified as living things?
a) Because they need recharging
b) Because they can only move on wheels
c) Because they do not grow, reproduce naturally, or maintain homeostasis
d) Because they have complex programming