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Date Shared: 2 December 2016
Read through the passage and place the correct words in the spaces. You can use your Year 8, Unit 7 Assessment Stimulus: Development of cell theory
Schwann studied plant and animal cells under a microscope. He could see that both types of cell had a nucleus and other cell structures that were the same.
Schleiden studied plant and animal cells too. He also saw that the plant and animal cells had the same cell structures. Animal cells from different tissue around the body were found to have differences, but they still had a nucleus in their structure.
Schwann and Schleiden both came to the conclusion that cells were the basic building blocks of all life, but they did not agree on how cells originated. Schleiden believed that cells originated through ' spontaneous generation '. Schwann believed that cells originated from pre-existing cells. He also believed that cells, once generated, could develop in different ways to form different parts of a living organism, like cheek cells, skin or cartilage in a human body. The process of cells originating from other cells is called 'cell division'.
About 20 years later, Pasteur put soup in two different flasks. One was open and the other had an s-shaped neck. The broth in the container that was left open changed over time and became discoloured and cloudy. Pasteur said that if 'spontaneous generation' was a real process, both containers of broth would have changed.
As technology has progressed, scientists have had better microscopes so that they could research more about cells and cell theory. Over time scientists have been able to prove the theories of scientists like Schwann and Pasteur correct, and they have been able to build on the knowledge of cell theory. Microscopes now can see the tiniest structures in the tiniest cells, and scientists now know a lot more about how cells originate, and how they work and form into different types of cells.
Schwann plant animal cell tissue differences nucleus conclusion building blocks originated spontaneous pre-existing develop parts organism cartilage human division' Pasteur open discoloured cloudy process changed technology scientists microscopes theory prove build tiniest
2 December 2016
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