Download A brief theory. (you can say it in one sentence)

Scientific Theories and Laws
in Biology
Mr. Carter’s Science Class
There are 3 Theories and a Law that support
most of what we know about Biology.
 1. What is a Scientific Theory?
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
An explanation of something in nature that is
widely accepted and heavily supported by
experimental data. It has not yet been disproven.
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2. What is a a Scientific Law?

A brief theory. (you can say it in one sentence)
The 1st Law of thermodynamics
Matter and energy
cannot be created or
destroyed.
 They can change
forms, though.
 4. Give an example
of a reaction where
matter changes forms
but DOES not lose
mass.

The 1st Law of thermodynamics

5. Describe the energy
transformations shown in
the picture at right.
The Atomic Theory
All matter is made of
atoms
 Atoms of one element
have unique
properties and are
identical
 Atoms of different
elements are
distinctly different
 Atoms can bond with
other atoms to form

compounds
The Atomic Theory
Atoms are made of smaller
particles (protons,
electrons, and neutrons)
 The protons and neutrons
have the most mass and
occupy the solid nucleus at
the center of the atom
 The electrons orbit around
the nucleus at distinct
energy levels

The Atomic Theory

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4.
5.
Protons have a positive
charge
Neutrons have a neutral
charge
Electrons have a negative
charge
Draw the model of the
carbon atom in your
notebook?
How many electrons are
there in the 1st Energy
Level?
The Atomic Theory
6. Draw a model of an
Oxygen atom in your
notebook.
7. Draw a model of a
Hydrogen atom in your
notebook.
The first energy
level can contain 2
electrons, all other
ones can contain 8
 Draw a diagram of
the following
atoms.
 6. Chlorine
 7. Magnesium
 8. Argon

The Kinetic Molecular Theory
All matter is made of atoms
 Those atoms are constantly
moving.
 Atoms do not slow down, but
they do change direction
when they hit other atoms.

The Kinetic Molecular Theory
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Solid - Molecules are held close
to each other by their attractions
of charge. They will bend and/or
vibrate, but will stay in close
proximity.
Liquid - Molecules will flow or
glide over one another, but stay
toward the bottom of the
container. Motion is a bit more
random than that of a solid.
Gas - Molecules are in continual
straightline motion. When the
molecules collide with each
other, or with the walls of a
container, there is no loss of
energy.
The Kinetic Molecular Theory
Knowing what you know now, heat (or
thermal energy) is just a measure of how
fast atoms are moving.
8. Imagine dropping an ice cube into a cup
of hot tea. Can you explain then how
heat gets transferred from the tea to the
cube? (explain in terms of molecular
collisions)
Cell Theory
All living things are
made out of at least
one cell (some are
made of trillions).
 All cells come from
other cells.

Cell Theory
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Cells are able to copy
themselves
Cells contain special
machines in them
called “organelles” that
carry out operations
within the cell.
All cells contain DNA,
the instructions for
making more cells.
The Germ Theory of Disease
Validated by Luis
Pasteur in the 19th
century.
 All living things come
from other living things.
 All living things will die.
 Living organisms must
enter an closed system
in order to grow in it.

The Theory of Evolution
DNA changes over
time through random
mutations
 Some mutations are
helpful and are kept
 Living things change
over time
 Eventually living things
can become separate
species.
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