Living vs. non-living
This characteristic of life states that all living things must maintain a stable internal environment.
What is homeostasis?
This scientist first used the term “cell” after observing cork.
Who is Robert Hooke?
He improved the microscope and observed living cells he called “animalcules.”
Who is Anton van Leeuwenhoek?
A group of similar cells working together to perform a function.
What is a tissue?
Viruses cannot reproduce on their own; they must infect a host. This is why many scientists consider them ____.
What is nonliving?
A rock does not meet this basic requirement of life because it cannot produce new individuals.
What is reproduction?
This scientist concluded that all animals are made of cells.
Who is Theodor Schwann?
These two scientists disagreed at first about whether plants and animals were made of the same basic unit.
Who are Schleiden and Schwann?
This level of organization is made of different tissues working together.
What is an organ?
This structure, found in all living things, is sometimes present in viruses but not always.
What is DNA or RNA?
Fire grows and uses energy, but it is still nonliving because it lacks these two things.
What are cells and DNA?
This scientist concluded that all plants are made of cells.
Who is Matthias Schleiden?
This scientist’s work helped disprove spontaneous generation by showing cells arise from other cells.
Who is Virchow?
The heart, blood, and blood vessels together form this system.
What is the circulatory system?
Viruses lack these structures that living cells use to make proteins.
What are ribosomes?
This term describes the ability of living things to respond to changes in their environment.
What is the response to stimuli?
This scientist stated that all cells come from pre‑existing cells.
Who is Rudolf Virchow?
This scientist’s drawings of cork cells helped establish the foundation of cell biology.
Who is Hooke?
Place these in order from simplest to most complex: organ, cell, tissue, organ system.
What is cell → tissue → organ → organ system?
Some scientists argue viruses show this characteristic of life because they evolve over time.
What is adaptation/evolution?
Name three criteria scientists use to determine if something is living.
What are: cellular organization, use energy, grow & develop, reproduce, responds to the environment, maintain homeostasis, have DNA and adaption or evolve?
State the three main tenets of the cell theory.
What is:
1. All living things are made of cells. 2. Cells are the basic unit of structure and function. 3. All cells come from pre‑existing cells.
These three scientists together contributed the most to the modern cell theory.
Who are Schleiden, Schwann, and Virchow?
Explain how muscle cells become part of a functioning organ system.
Muscle cells form muscle tissue → muscle tissue forms the heart → the heart works with blood vessels to form the circulatory system.
Using scientific evidence, explain why viruses do not meet all criteria for life.
Viruses cannot reproduce independently, do not maintain homeostasis, lack cellular structure, and cannot perform metabolism. They only show life‑like behavior inside a host cell.