Characteristics of Life
What characteristic of life helps an organism keep stable internal conditions?
Homeostasis
What is the basic unit of structure and function in living organisms?
Cell
What is the first principle of Cell Theory?
All living organisms are made of one or more cells.
Which scientist observed cork and introduced the term “cell”?
Robert Hooke
What technology made the discovery of cells possible?
Microscope
A sunflower bends toward light. What characteristic of life is this?
Response to stimuli
What word describes an organism made of only one cell?
Unicellular
What is the second principle of Cell Theory?
The cell is the basic unit of structure and function in living organisms.
Which scientist observed living microorganisms using a microscope?
Antonie van Leeuwenhoek
Scientists examine a tree, dog, mushroom, and bacterium and find cells in all of them. Which principle of Cell Theory does this support?
Principle #1 — all living organisms are made of one or more cells.
A puppy becomes an adult dog. What characteristic of life is shown?
Growth and development
What word describes an organism made of many cells?
Multicellular
What is the third principle of Cell Theory?
All cells come from preexisting cells.
Which scientist concluded that plants are made of cells?
Matthias Schleiden
Why is fire not considered living even though it grows and uses energy?
It does not meet all characteristics of life, such as being made of cells and containing genetic material.
A cheetah eats food to obtain energy. What characteristic of life is demonstrated?
Metabolism / use of energy
What is a specialized structure inside a cell that performs a specific function?
Organelle
A bacterium is one cell but can perform all the functions necessary for life. Which principle of Cell Theory does this best support?
Principle #2 — the cell is the basic unit of structure and function.
Which scientist concluded that animals are made of cells?
Theodor Schwann
Why did Cell Theory require the work of many scientists instead of just one scientist?
Scientists gathered different evidence over time and built on earlier discoveries.
A population changes over many generations and becomes better adapted to its environment. What characteristic of life is shown?
Evolution
What is a well-supported scientific explanation based on extensive evidence and repeated investigation?
Scientific theory
A scientist observes one cell divide into two new cells. Which principle of Cell Theory is supported?
Principle #3 — cells come from preexisting cells.
Which scientist is associated with the idea that cells come from existing cells?
Rudolf Virchow
If scientists discovered a living organism that was not made of cells, which principle of Cell Theory would be challenged?
Principle #1 — all living organisms are made of one or more cells.