Cell Theory, Theories vs. Laws, & Cell Transport

When cells are damaged, new cells are created by cell division. How does the cell theory support this fact?

• It states that all cells have a nucleus which divides.

• It states that cells come from previously existing cells.

• It states that all living things are made up of one or more cells.

•  It states that the basic units of structure and function are cells.

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The cell theory states that the cell is the most basic unit of life, all organisms are made of cells, and all cells come from cells. What makes the cell theory a scientific theory?

• It is based on a scientific publication that is read by scientists worldwide.

• It is based on ideas that have been proven true and that are not subject to revision.

• It is based on the work of many scientists and leads to accurate predictions.

• It is based on preliminary evidence but still needs to be confirmed with experiments.

Which of the following was removed and is no longer part of the Cell Theory?

• All living things are made of cells.

• Cells form through spontaneous generation.

• All cells come from other preexisting cells.

• Cells are the basic structural and functional units of life.

Which of the following could cause a long-held theory to be challenged or even overturned by the scientific community?

• New evidence that better matches the new theory than previous evidence

• A popular celebrity who disagrees with the ideas outlined in the old theory

• A scientist who has strong beliefs that the old theory is wrong but little evidence

• A group of scientists who believe that new theories are usually better than old theories

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Which of the following explains why cell theory will not ever become the law of cells?

• Scientific theories are well-tested explanations, while laws are well-tested descriptions of natural phenomena; one cannot become the other.

• Cells of different organisms are so diverse that it is impossible to come up with a law that would apply to all of them.

• Because cells undergo change as mutations occur within them, developing anything beyond a cell theory would be impractical.

• Scientific theories can only become laws if all possible cases can be tested; it would be impossible to test all living things to see if they have cells.

Cell theory is a result of the contributions of several different scientists, and applies to all living things. Which of the following explains why cell theory will not ever become the law of cells?

• Cells of different organisms are so diverse that it is impossible to come up with a law that would apply to all of them.

• Because cells undergo change as mutations occur within them, developing anything beyond a cell theory would be impractical.

• Scientific theories are well-tested explanations, while laws are well-tested descriptions of natural phenomena; one cannot become the other.

• Scientific theories aren't well-tested explanations, but, laws are well-tested descriptions of natural phenomena; one cannot become the other.

A cell membrane is composed of a double layer of lipids in which many kinds of proteins are embedded. Many of these proteins act like gates, allowing only certain particles to enter or leave the cell. When a particle has to go against its concentration gradient through one of these gates, energy is supplied by the cell to the correct protein to move the particle through the membrane. Which type of cell transport does this describe?

• Diffusion

• Passive Transport

• Osmosis

• Active Transport

The cell membrane of the red blood cell will allow water, oxygen, and carbon dioxide to pass through. Because other substances are blocked from entering, this membrane is called

• perforated

• permeable

• non-conductive

• semi-permeable

In 1897, Joseph Thomson discovered that atoms contained electrons. He proposed a change in the atomic theory of that time, and the theory was modified because of his discovery. Since Thomson’s discovery, atomic theory has been further modified. What is the best explanation for why scientific theories are modified?

• Theories more than ten years old are usually out of date.

• Scientists want to prove that the work of other scientists is wrong.

• New evidence that supports a change prompts scientists to modify earlier theories.

• So much information is available today that it is harder to focus research and disprove theories.

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Lilly was trying to explain to her friend the difference between a theory and a law in science. She used the theory of plate tectonics and the law of superposition as examples. Lilli explained the difference by using non-scientific language. Which statement could Lilly use to correctly describe the difference between a theory and a law in science?

• A theory describes a natural event, while a law explains it.

• A theory explains a natural event, while a law predicts it.

• A theory explains a natural event, while a law describes it.

• A theory predicts a natural event, while a law explains it.