Lesson 1 The Cell

Spontaneous generation was first proposed by Aristotle in about 350 A.D. The theory of spontaneous generation suggested life could emerge from non-living matter. This new life could be created with no cause; it just appeared. For example, mice were thought to emerge from wheat husks and sweaty underwear. Mice were never seen to be breeding, and baby mice were never seen, since they were hidden in the nest. So the people only saw the adult mice and only saw them near food. This led them to believe mice were created from husks of wheat and sweaty underwear.

By 1668, scientists were starting to doubt the theory of spontaneous generation and were starting to perform experiments proving this theory wrong. Unfortunately, it is difficult for people to believe new theories, so the theory of spontaneous generation continued to thrive until the 1830s.

  Read This

Please read pages 247 and 248 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on the scientists, what they did, and the variables that are part of an experiment. Remember, if you have any questions or you do not understand something, ask your teacher!

  Practice Questions

Complete the following practice questions to check your understanding of the concept you just learned about. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

1. Explain the theory of spontaneous generation.
   
   
   Check your work.
   

   Spontaneous generation is the idea that life could be and was created from non-living things. See the mouse example from above. Needham suggested there was a “life force” that produced spontaneous generation, and it was suggested air was required for spontaneous generation to occur.
   
   

2. What are the manipulated variable, responding variable, and control variables present in Redi’s experiment from 1668? If you need a refresher on the different parts of an experiment, please watch this video. https://adlc.wistia.com/medias/rajbs9ceky
   
   
   Check your work.
   

   The manipulated variable is the variable that Redi changed, which was the access of the flies to the meat. He had jars that were open to the flies and jars that were not open to the flies. Remember, a variable is a factor, trait, or condition that can be changed in an experiment. The responding variable is the variable that changed because of what Redi changed, which was if flies were present in the jars or not. The control variables are the variables that Redi did not change. These were variables such as the amount of meat, the size of the jars, the temperature the jars were stored at, and the length of time that Redi left the jars. These variables are not listed in your textbook reading; you had to think of these on your own.