Cell theory and how it was discovered
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Ari combines events A and B. Which part of cell theory do they support together, and why?
- Part 1, because Schwann alone showed it in 1839 with animal tissue
- Part 3, because both scientists watched cells divide under the microscope
- Part 1, because Hooke had already finished it in 1665
- Part 1, because plants and animals were both found to be made of cells
Bo combines events A and B. What do they show together, and why?
- Part 2, because both events show the cell is the unit of life
- Part 3, because spontaneous generation was shown in 1862
- Part 3, because cells divide and do not form from nonliving matter
- Part 3, because Pasteur's flask work in 1862 came before Remak's evidence
Esme combines events A and B. What had scientists seen by 1674?
- Cork is built of box-like cells, and single cells can live alone
- Living cells fill cork tissue, and Hooke watched them move in 1665
- The full cell theory, finished by the two of them together by 1674
- Cells come from cells, shown by the 1674 organisms
Jun writes: Hooke discovered that all living things are made of cells. What is wrong with this claim?
- Hooke named cork cells in 1665; plants and animals came in 1838 and 1839
- Nothing is wrong with it, because Hooke saw living cells in his cork slices
- Hooke worked in 1855, after Virchow's essay, so he could not have said it
- 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?
- 1855 is later than 1838, so Virchow's essay came after Schleiden's work
- Virchow's essay was about plants, not about cells
- 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
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
- A theory is a tested and confirmed explanation
- A theory is a guess that waits for its first test
- Theories get tested after they become laws
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?
- The cork cells were empty walls left behind, with no living contents
- Plant cells are empty boxes in leaves and stems too
- Hooke cut the cork so thin that the cells fell apart
- Living contents were there, but Hooke's lens was too weak to show them
Noah reads that Schleiden thought cells formed like crystals and that Remak later showed cell division. Which statement fits?
- Cells arise by division, so Schleiden's idea about crystals was corrected
- Cells form like crystals, so Remak's evidence confirmed Schleiden
- Cells divide, which Schleiden had already shown alone in 1838
- Cells divide, but Remak's 1852 evidence came before Schleiden's 1838 idea
Pia reads that some historians say Remak deserves credit. Which timeline fact supports them?
- Remak published his evidence in 1862, seven years after Virchow's 1855 essay
- Virchow credited Remak by name in his 1855 essay
- Remak published his evidence in 1852, three years before Virchow's essay
- Virchow alone gathered the evidence, so Remak had no part
Tala asks why cell theory grew after Hooke's time. Which claim and reason are best supported?
- 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
- Cell theory came before microscopes, so lenses did not matter
- Better lenses and stains showed parts inside cells, which added evidence