Cell theory and how it was discovered
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Esme combines events A and B. What had scientists seen by 1674?
- Cells come from cells, shown by the 1674 organisms
- Cork is built of box-like cells, and single cells can live alone
- The full cell theory, finished by the two of them together by 1674
- Living cells fill cork tissue, and Hooke watched them move in 1665
Jun writes: Hooke discovered that all living things are made of cells. What is wrong with this claim?
- Hooke worked in 1855, after Virchow's essay, so he could not have said it
- Nothing is wrong with it, because Hooke saw living cells in his cork slices
- Hooke named cork cells in 1665; plants and animals came in 1838 and 1839
- Hooke named cells, but Virchow alone completed the theory
Kira writes: Virchow's essay came before Schleiden's work, so Virchow started cell theory. What is wrong with this claim?
- Schleiden worked alone, so Virchow had no part in the theory
- 1855 is earlier than 1839, so Virchow's essay came before Schwann's work
- 1855 is later than 1838, so Virchow's essay came after Schleiden's work
- Virchow's essay was about plants, not about cells
Luz writes: Cell theory is just a theory, so scientists have not tested it. What is wrong with this claim?
- Cell theory is a hypothesis until scientists vote
- Theories get tested after they become laws
- A theory is a guess that waits for its first test
- A theory is a tested and confirmed explanation
Two cutaway drawings, not to scale. Milo sees Hooke's cork drawing, box-like cells with nothing inside, next to a living plant cell. Why does the cork look empty?
- Plant cells are empty boxes in leaves and stems too
- The cork cells were empty walls left behind, with no living contents
- Living contents were there, but Hooke's lens was too weak to show them
- Hooke cut the cork so thin that the cells fell apart
Noah reads that Schleiden thought cells formed like crystals and that Remak later showed cell division. Which statement fits?
- Cells divide, but Remak's 1852 evidence came before Schleiden's 1838 idea
- Cells arise by division, so Schleiden's idea about crystals was corrected
- Cells divide, which Schleiden had already shown alone in 1838
- Cells form like crystals, so Remak's evidence confirmed Schleiden
Pia reads that some historians say Remak deserves credit. Which timeline fact supports them?
- Remak published his evidence in 1852, three years before Virchow's essay
- Remak published his evidence in 1862, seven years after Virchow's 1855 essay
- Virchow credited Remak by name in his 1855 essay
- Virchow alone gathered the evidence, so Remak had no part
Ren's class imagines a newly found organism made of one swimming cell. Does it fit cell theory, and why?
- Yes, because one or more cells make up living things
- Yes, because it formed from nonliving water
- No, because cell theory covers just plants and animals
- No, because a basic unit of life must have many cells
Tala asks why cell theory grew after Hooke's time. Which claim and reason are best supported?
- Better lenses and stains showed parts inside cells, which added evidence
- Cell theory came before microscopes, so lenses did not matter
- One scientist's new lens alone supplied the whole cell theory in one step
- Hooke's lens already showed living cells, so the theory was complete
A museum sign says cell theory was finished in 1665. Zee checks the timeline. Which claim fits best, and why?
- It built up over time, with parts added in 1838, 1852 and 1855
- It is a guess, because it has an old date and no one has tested it
- It was finished in 1665, because Hooke alone named cells
- It was finished by Virchow in 1855, before Remak's work