Cells and Their Processes

Which invention from the 17th century allowed for the development of modern cell theory?

• x-rays
• computers
• the light microscope
• the scanning electron microscope

Cell theory was first proposed in 1838. Evidence obtained through additional scientific investigations resulted in the current cell theory. Which statement describes a component of the original cell theory that was removed because of the new scientific knowledge?

•  All living things are made of cells.
• All cells come from other preexisting cells.
• Cells form through spontaneous generation.
•  Cells are the basic structural and functional units of life.
  

 Cells are the basic structural and functional units of life.

• Plants have cells but animals do not.
•  They are both made of one or more cells. 
• They both come from the same kind of cell.
• They both come from a non-living organism.

A plant and an animal are both living things. According to the Cell Theory, what can you conclude about these two very different organisms?

• Plants have cells but animals do not.
• They are both made of one or more cells. 
• They both come from the same kind of cell.
• They both come from a non-living organism.

 Which of the following is NOT one of the main components of the cell theory?

• cells must contain DNA
• all living things are made of cells
• cells can only come from other cells
• cells are the basic unit of life

Unlike eukaryotes, prokaryotes do not have:

• DNA
• cytoplasm
• cell walls
• a membrane bound nucleus

The smallest unit that can perform the basic activities of life is

• a cell 
• a tissue
• an organ
• an organism

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• Theories more than ten years old are usually out of date.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 revision prompts scientists to modify earlier theories.
• So much information is available today that it is harder to focus research and disprove theories.

Tags

NGSS.HS-PS1-2

The law of universal gravitation states that both mass and distance of objects affect the gravitational force between them.  Gravitational force increases as the mass of the objects increase.  Gravitational force decreases as distance between the objects increases.  Why are these statements considered scientific law, and not scientific theory?

• The statements tells what happens, and not why the even occurs.
• This statement involves mass and distance measurements.
• This statement explains the attractive force between two objects.
• This statement predicts what will happen under certain conditions.

Tags

NGSS.HS-PS2-4

A broad and comprehensive statement of what is thought to be true; it is supported by much evidence.

• hypothesis
• theory
• guess
• fact

Tags

NGSS.HS-LS4-1

NGSS.HS-LS4-2