- describe and compare the characteristics of prokaryotes, protists, and viruses
- examine important relationships between organisms, the environment, and human health
- explain how viruses cause disease
- recognize the impact that human actions can have on the survival of even the smallest organisms
- explain key steps in the evolution of eukaryotes
- classify and draw biological drawings of micro-organisms
How Important Are Microscopic Organisms?
Most living things are not visible to the unaided human eye. You are surrounded by billions of microscopic organisms. Even your own body is inhabited by countless organisms that go unnoticed. What are these organisms, and what do they do in the air, water, and soil that surround us? And what do they do inside us?
The cause of infectious diseases was a mystery for much of human history. Then, in the seventeenth century, the microscope was invented and the amazing world of micro-organisms was revealed.
Scientists now know that microscopic bacteria, viruses, and protists are the cause of most infectious diseases. Scientists also know that these simple organisms are present in abundant quantities and play key roles in ecosystems. Some of these organisms recycle nutrients, and others are important producers. Some can cause disease, while others provide substances that we can use to treat disease. Our own bodies contain bacteria that help us digest food, as well as bacteria that can make us sick. Scientists have even discovered that some of the largest organisms on Earth are actually multicellular versions of these simple microscopic life forms.
Understanding the microscopic and remarkable world of prokaryotes, viruses, and protists is extremely important. Our knowledge of the smallest organisms is helping us address some of our greatest concerns about our health and the health of our environment. This knowledge has led to dramatic improvements in medicine, including ways to prevent and treat many serious diseases. We also use our knowledge of micro-organisms to help us fight pollution and climate change.
In this chapter you will explore the great variety and value of Earth's simplest life—and life-like—forms.
STARTING POINTS
Answer the following questions using your current knowledge. You will have a chance to revisit these questions later, applying concepts and skills from the chapter.
1. How do you think microscopic organisms benefit you in your everyday life?
2. Overall, would you describe microscopic organisms as helpful or harmful?
3. In what ways do you think microscopic organisms are different from one another? In what ways do you think they are the same?
4. How do you think microscopic organisms can significantly influence an ecosystem that includes many very large organisms?
The Prokaryotes, Viruses, and Protists
KEY CONCEPTS
After completing this chapter you will be able to
- describe and compare the characteristics of prokaryotes, protists, and viruses
- examine important relationships between organisms, the environment, and human health
- explain how viruses cause disease
- recognize the impact that human actions can have on the survival of even the smallest organisms
- explain key steps in the evolution of eukaryotes
- classify and draw biological drawings of micro-organisms
How Important Are Microscopic Organisms?
Most living things are not visible to the unaided human eye. You are surrounded by billions of microscopic organisms. Even your own body is inhabited by countless organisms that go unnoticed. What are these organisms, and what do they do in the air, water, and soil that surround us? And what do they do inside us?
The cause of infectious diseases was a mystery for much of human history. Then, in the seventeenth century, the microscope was invented and the amazing world of micro-organisms was revealed.
Scientists now know that microscopic bacteria, viruses, and protists are the cause of most infectious diseases. Scientists also know that these simple organisms are present in abundant quantities and play key roles in ecosystems. Some of these organisms recycle nutrients, and others are important producers. Some can cause disease, while others provide substances that we can use to treat disease. Our own bodies contain bacteria that help us digest food, as well as bacteria that can make us sick. Scientists have even discovered that some of the largest organisms on Earth are actually multicellular versions of these simple microscopic life forms.
Understanding the microscopic and remarkable world of prokaryotes, viruses, and protists is extremely important. Our knowledge of the smallest organisms is helping us address some of our greatest concerns about our health and the health of our environment. This knowledge has led to dramatic improvements in medicine, including ways to prevent and treat many serious diseases. We also use our knowledge of micro-organisms to help us fight pollution and climate change.
In this chapter you will explore the great variety and value of Earth's simplest life—and life-like—forms.
STARTING POINTS
Answer the following questions using your current knowledge. You will have a chance to revisit these questions later, applying concepts and skills from the chapter.
1. How do you think microscopic organisms benefit you in your everyday life?
2. Overall, would you describe microscopic organisms as helpful or harmful?
3. In what ways do you think microscopic organisms are different from one another? In what ways do you think they are the same?
4. How do you think microscopic organisms can significantly influence an ecosystem that includes many very large organisms?