Cell Theory 1
Where do all cells come from?
Another preexisting cell of the same type.
In 1838, German scientists Theodor Schwann and Matthias Jakob Schleiden first proposed the cell theory based on evidence they obtained by drawing together data from their own scientific investigations on plant and animal cells. Over time, additional investigations carried out by other biologists resulted in changes being made to the 1838 version of the cell theory. This led to the cell theory widely accepted today. Which statement describes a component of an early version of the cell theory, which was later removed due to new scientific findings determining that while the idea had resembled science, it wasn’t science after all? (Cells are the basic unit of life; All cells come from other cells; All living things are made up of cells; Cells form through spontaneous generation.)
Cells form through spontaneous generation.
What major improvement came with the development of the scanning electron microscope (SEM)?
The SEM images were three-dimensional.
Which scientist first used the term cell?
Robert Hooke
What is the basic unit of life?
A cell
Biology students are walking around the classroom observing different types of cells under a microscope. A student makes the following observations. Which observation supports cell theory? Multiple answers
1. Red blood cells do not contain a nucleus.
2. Meristematic cells on a garlic root tip actively dividing to form new cells through the process of mitosis.
3. Most muscle cells are connected together as the building blocks of muscle tissue.
4. Bacterial cells found in river water do not contain any membrane-bound organelles.
2 and 3
Which is a disadvantage of a transmission electron microscope? (Thin slices of tissue are required for viewing cells with a TEM; The specimen viewed must be nonliving; Electrons are transmitted through a specimen onto a fluorescent screen; Images of cells can only be magnified 1000x)
The specimen viewed must be nonliving.
What does the prefix micro- mean?
Small
What are all living things made of?
Cells
Which statements are true regarding cell theory?
1. All new cells come from existing cells.
2. All living cells require water and nutrients.
3. All living cells must have genetic material.
1 only
Which is an advantage of a compound light microscope over a transmission electron microscope? (A compound light microscope relies on readily available visible light; A compound light microscope does not blur magnified images; A compound light microscope can view living microorganisms; A compound light microscope has a greater degree of magnification)
A compound light microscope can view living microorganisms.
Which statement is true of all prokaryotic cells? (They are eukaryotes; They have membrane-bound organelles; The cells have no nucleus; The cells have no cytoplasm.)
The cells have no nucleus
What are the three components of cell theory?
1. All living things are made of cells.
2. Cells are the basic unit of life.
3. Cells are generated as copies of preexisting cells.
Findings from scientific investigations carried out by scientists such as Hooke, Leeuwenhoek, Schleiden, and Schwann all provided ample evidence to back up a scientific explanation for their many observations about cells. What is a well-supported scientific explanation for many observations, that has ample evidence to back it up known as?
A theory
What is an optical instrument that uses multiple lenses to magnify an object?
Compound Microscope
Which structure is only found in plant cells? (Cell Wall, Ribosome, Nucleus, Plasma Membrane)
Cell Wall
Which best describes the connection of cell theory to microscopes? (The invention of microscopes made the development of cell theory possible; The invention of electron microscopes caused scientists to determine the cell as the basic unit of life; The microscope was invented so that scientists could develop cell theory; The development of the cell theory inspired people to improve existing electron microscopes.)
The invention of microscopes made the development of cell theory possible.
Which statement does NOT describe a main component of cell theory? (All cells contain genetic material; All living things are made up of cells; All cells come from other preexisting cells; Cells are the basic structural and functional units of life.)
All cells contain genetic material.
An electron microscope can magnify an object about 500,000 times. How does this magnification compare with the magnification of a compound light microscope?
500 Times Higher
Which correctly contrasts a prokaryotic cell and a eukaryotic cell? (Only prokaryotic cells can have a plasma membrane; Only eukaryotic cells can have ribosomes; Only eukaryotic cells can have chloroplasts; Only prokaryotic cells can have a cell wall.)
Only eukaryotic cells can have chloroplasts.