Louis Pasture determined that microbes only appeared in sterile broth if the broth was exposed to the air. He concluded that microbes were found in the air and contaminated the broth. Pasteur's findings contributed to which part of the cell theory? a. All animals are made of cells
b. All cells come from preexisting cells
c. The cell if the basic functional unit of living tings
d. Unicellular organisms inherit an exact copy of DNA from the parent cell

Louis Pasture's experiment shows that all cells come from preexisting cells.

The cell is the smallest unit of living organisms. All animals are made up of cells. It is the basic functional unit of living things. Louis Pasture was one of the earliest scientists who contributed to the cell theory.

By his experiments, we saw that the sterile broth which originally contained no microbes will contain microbes after exposure to air implying that the microorganisms came from air. Therefore, all cells come from preexisting cells.

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Louis Pasteur, by observing that the microbes were in the air and contaminated the broth helped determine that all the cells came from pre-existing cells (option b), one of the postulates of the cell theory.

Explanation:

Louis Pasteur's experiments, conducted around 1860, showed that unicellular organisms appeared in a culture broth only if it was exposed to the air, where other microorganisms were present, thus disproving the hypothesis of spontaneous generation.

On the other hand, in the broth that was not exposed to the air Pasteur did not observe microorganisms.

By rejecting the hypothesis of spontaneous generation through his experiment, Louis Pasteur reaffirmed the postulate of the cell theory that proposes that all cells come from preexisting cells.

The other options are not correct due to:

   a and c. All animals are made of cells and cell is the basic functional unit of living things are postulates of the cellular theory that were not demonstrated by Pasteur's experiment.

    d. Unicellular organisms inherit an exact copy of DNA from the parent cell is not a postulate of cell theory.

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