Question

By the late 1600s, scientists began using a new tool, the microscope. Their observations proved the existence of a whole new world of microorganisms and helped to establish the tenets of the Cell Theory, including that life is made of cells. However, most still held that these microorganisms arose spontaneously from a “vital force.” In the late 1700s, Lazzaro Spallanzani designed an experiment to show that life did not arise spontaneously from food. He inferred that some foods spoil because of growing populations of microorganisms. Spallanzani boiled meat broth in open flasks. He sealed the flasks of the experimental group which showed no signs of microbe growth. Critics of Spallanzani said that he only showed that organisms cannot live without air.

In 1859, Louis Pasteur designed an experiment to address the spontaneous generation. He used a curved-neck flask that allowed the air inside the flask to mix with air outside the flask, but prevented solid particles, like microorganisms, from entering the body of the flask. Compare and contrast the work of Pasteur and Spallanzani and explain how both men influenced the cell theory


A.)They proved that plants, animals, fungi, protists, and bacteria are all made of cells
B.)They proved that cells cause disease.
C.) They proved that boiling kills microorganisms.
D.) They proved that cells do not appear spontaneously, but only come from pre-existing cells.

Answer 1

D.) They proved that cells do not appear spontaneously, but only come from pre-existing cells

Answer 2

Answer: D.) They proved that cells do not appear spontaneously, but only come from pre-existing cells.

Step-by-step explanation:

Both Spallanzani and Pasteur contributed to the understanding of the Cell Theory, which states that all living things are composed of cells and that cells only come from pre-existing cells.

Spallanzani's experiment showed that microorganisms do not arise spontaneously from food or other materials, but instead come from pre-existing microorganisms. He did this by boiling meat broth in open flasks, and then sealing some of the flasks to prevent microorganisms from entering. The sealed flasks showed no signs of microbe growth, indicating that microorganisms only appear when they are introduced from an outside source.

Pasteur's experiment built on Spallanzani's work by using a curved-neck flask that allowed air to enter and mix with the broth, but prevented solid particles, like microorganisms, from entering. He observed that even though the broth was exposed to air, no microorganisms grew in the broth, as they were trapped in the neck of the flask. This experiment definitively showed that microorganisms only come from pre-existing microorganisms, and that they do not arise spontaneously from non-living matter.

In summary, both Spallanzani and Pasteur contributed to the understanding of the Cell Theory by proving that cells do not appear spontaneously, but only come from pre-existing cells. They showed that microorganisms cannot arise from non-living matter, and that living organisms can only be generated by other living organisms.