Cell theory and how it was discovered
Grade 9 Science Worksheet
Circle the best answer.
Read this first
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Cell theory card. Part 1: one or more cells make up all living things. Part 2: the cell is the basic living unit. Part 3: new cells arise from existing cells.
Ari reads that Schleiden looked at many plant tissues in 1838 and found cells in each. Which part of cell theory does this support, and why?
- Part 3, because the cells formed from the plant's sap
- Part 2, because each tissue was one living cell
- Part 3, because Schleiden watched cells divide
- Part 1, because the plant tissues were made of cells
Bo reads that in 1674 Leeuwenhoek saw single-celled organisms swim in lake water. Which part does this best support, and why?
- Part 3, because the organisms were seen dividing
- Part 1, because the organisms were made of many different cells
- Part 3, because the organisms formed from lake water
- Part 2, because one cell on its own can be a living thing
Esme reads that in 1852 Remak published convincing evidence that cells come from other cells by cell division. Which part does this support, and why?
- Part 1, because the cells that divided made up a whole tissue
- Part 3, because new cells formed from nonliving matter
- Part 3, because new cells arose from cells that divided
- Part 2, because a dividing cell is the unit of life
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Microscope facts (real data, OpenStax Biology 2e). Columns: microscope, magnification, resolution, living cells. A light microscope magnifies up to about 400 times and has a resolution of about 200 nanometers; it can view living cells. An electron microscope magnifies up to 100,000 times and has a resolution of 50 picometers; it cannot view living cells.
Jun wants to watch a single-celled organism swim in a drop of water. Which microscope fits, and why?
- Electron microscope, because it can view living cells
- Light microscope, because it can view living cells
- Light microscope, because its resolution is 50 picometers
- Electron microscope, because 100,000 times shows the most
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Light microscope facts (model data and real data, OpenStax Biology 2e). Columns: measure, value. Gap between the two structures: 100 nanometers (model data). Resolution of a light microscope: about 200 nanometers. Magnification of a light microscope: up to about 400 times.
Two structures in a cell sit 100 nanometers apart. What does Kira see through a light microscope?
- One blurred spot, because the lens magnifies 100 times
- One blurred spot, because 100 is less than 200 nanometers
- Two clear spots, because 100 is less than 200 nanometers
- Two clear spots, because the microscope magnifies 400 times
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Microscope magnification (real data, OpenStax Biology 2e). Columns: microscope, magnification. Light microscope: up to about 400 times. Electron microscope: up to 100,000 times.
Luz compares two microscopes. About how many times greater is the electron microscope's top magnification than the light microscope's?
- 25 times
- 250 times
- 99,600 times
- 400 times
Noah finds the gap between events A and B. How many years apart are they, and which came first?
- 16 years; Schwann's work came first
- 6 years; Schwann's work came first
- 26 years; Schwann's work came first
- 16 years; Virchow's essay came first
Which two events on Pia's timeline are closest in time?
- B and C, 3 years apart
- C and D, 7 years apart
- A and B, 13 years apart
- A and C, 16 years apart
Tala says cell theory is just a guess because it is called a theory. Which fact best answers Tala?
- A theory is another word for a hypothesis
- Theories are guesses until a scientific law replaces them one day
- Many scientists tested and confirmed its parts over the years
- It is called a theory because Virchow named it
Zee reads that Schleiden's 1838 idea began as a suggested explanation. After Schwann, Remak and Virchow added evidence, what did cell theory become?
- A hypothesis that still needs its first test
- A finished idea that Schleiden proved alone
- A tested and confirmed explanation
- A guess that gained more names