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Which are the main points of the cell theory? Select all that apply.
Cells are the basic units of structure and function in living things.
b. New cells are produced from existing cells.
c. All cells enclose their DNA within a nucleus.
d. All living things are made up of cells.
The invention of which instrument allowed scientists to discover cells?
Which describes a light microscope but not an electron microscope?
uses a beam of light to produce magnified images
has very high magnification power
can be used to study cells and cell structure
requires a computer to operate
Which model shows a prokaryotic cell?
Which describes a eukaryotic cell, but not a prokaryotic cell?
Uses DNA to control cell activities
Is surrounded by a cell membrane
Makes and uses proteins
Contains DNA in a nucleus
Josey wants to look at the cells of an onion under a light microscope. She peels off a thin, transparent layer of onion and places it on a microscope slide. Josey places the sample on the microscope stage, looks through the eyepiece, and adjusts the stage to focus the image. However, she is unable to see any details of the cells.
Which of the following solutions will best enable Josey to see the onion cells in detail?
a. Josey should use a thicker piece of onion for her sample.
b. Josey should place her onion sample in a vacuum.
c. Josey should place a drop of water on her sample.
d. Josey should apply a stain, such as iodine, to her sample.