Biology: Cell Theory: The Discovery of Cells
How microscopes helped scientists understand living things
Biology: Cell Theory: The Discovery of Cells
How microscopes helped scientists understand living things
Biology - Grade 6-8
- 1
What tool made the discovery of cells possible, and why was it so important?
Think about what scientists needed in order to see objects smaller than dust.
The microscope made the discovery of cells possible because it allowed scientists to see tiny structures that cannot be seen with the unaided eye. - 2
Robert Hooke looked at thin slices of cork in 1665. What did he observe, and what word did he use to describe what he saw?
Robert Hooke observed small box-like spaces in cork. He called them cells because they reminded him of small rooms. - 3
Explain why the cork cells Robert Hooke saw were not living cells at the time he observed them.
Cork comes from the outer bark of a tree.
The cork cells Hooke observed were not living because cork comes from dead plant tissue, and he was mainly seeing the empty cell walls left behind. - 4
Anton van Leeuwenhoek observed tiny living organisms in pond water. Why was this discovery important?
This discovery was important because it showed that living things could be microscopic and that there was a hidden world of tiny organisms. - 5
Match each scientist with the correct contribution: Robert Hooke, Anton van Leeuwenhoek, Matthias Schleiden, Theodor Schwann, Rudolf Virchow. Write one contribution for each scientist.
Think about the order: cork, microorganisms, plants, animals, and cells from cells.
Robert Hooke named cells after observing cork. Anton van Leeuwenhoek observed living microorganisms. Matthias Schleiden concluded that plants are made of cells. Theodor Schwann concluded that animals are made of cells. Rudolf Virchow stated that cells come from preexisting cells. - 6
State the three main parts of modern cell theory.
Modern cell theory states that all living things are made of one or more cells, the cell is the basic unit of structure and function in living things, and all cells come from preexisting cells. - 7
A student says, "Rocks must be made of cells because they are found in nature." Explain why this statement is incorrect.
Cell theory is about living organisms, not all objects found on Earth.
The statement is incorrect because rocks are nonliving things. Cell theory applies to living things, and living things are made of cells. - 8
How did improved microscopes help scientists develop cell theory over time?
Improved microscopes helped scientists see cells more clearly, observe living microorganisms, and compare tissues from plants and animals. These observations led to stronger evidence for cell theory. - 9
Matthias Schleiden studied plants, and Theodor Schwann studied animals. How did their conclusions work together to support cell theory?
Plants and animals are two major groups of living things.
Schleiden concluded that plants are made of cells, and Schwann concluded that animals are made of cells. Together, their work supported the idea that living things are made of cells. - 10
Rudolf Virchow said that all cells come from preexisting cells. Explain how this idea changed earlier thinking about where cells come from.
Virchow's idea showed that cells do not simply appear from nonliving material. Instead, new cells form from cells that already exist. - 11
Put these events in the correct historical order: Schwann concludes animals are made of cells, Hooke observes cork, Virchow states cells come from preexisting cells, Leeuwenhoek observes microorganisms, Schleiden concludes plants are made of cells.
Start with the 1600s and end with the idea that cells come from cells.
The correct order is Hooke observes cork, Leeuwenhoek observes microorganisms, Schleiden concludes plants are made of cells, Schwann concludes animals are made of cells, and Virchow states cells come from preexisting cells. - 12
Why is the cell called the basic unit of structure and function in living things?
The cell is called the basic unit of structure and function because living things are built from cells, and cells carry out the activities needed for life. - 13
A microscope image shows many similar rectangular plant cells arranged in rows. What evidence from the image supports the idea that plants are made of cells?
Look for repeated small units that make up the larger tissue.
The image supports the idea that plants are made of cells because it shows the plant tissue is made of many small repeating cell units arranged together. - 14
Compare Robert Hooke's observations with Anton van Leeuwenhoek's observations. How were they similar, and how were they different?
Focus on what each scientist looked at and whether it was living.
Their observations were similar because both used microscopes to study tiny structures. They were different because Hooke observed dead cork cells, while Leeuwenhoek observed living microorganisms. - 15
Write a short paragraph explaining how the discovery of cells shows that scientific knowledge can change over time.
The discovery of cells shows that scientific knowledge can change over time because scientists built on one another's observations. As microscopes improved, scientists gathered new evidence and developed cell theory to better explain living things.