Transcript Scientific Method

Chapter 1 An Introduction to
Life on Earth
• What are the characteristics of living
things?
• How do scientists categorize the diversity
of life?
• What is the science of biology?
• Evolution: The unifying theory of biology
Characteristics of Living Things
• Living things have a complex, organized
structure made up of organic (carbon
based) molecules
Characteristics of Living Things
Element
Carbon
Hydrogen
% of
Earth’s
Crust
0.19
0.22
% of
Human
Body
9.5
63.0
Oxygen
47.0
25.5
Silicon
28.0
<0.01
Characteristics of Living Things
• The cell is the basic unit of life
Characteristics of Living Things
Characteristics of Living Things
• Living things respond to stimuli from their
internal and external environment
• A stimulus is a change that brings about a
response
Characteristics of Living Things
• Living things maintain their complex
structure and internal environment in a
process called homeostasis
Characteristics of Living Things
•
This occurrence is known as physiological homeostasis and it is essentially
a corrective mechanism. Consider the following scenario in a person:
•
The level of glucose in the bloodstream drops
•
The person requires glucose in cells to meet the demand for ATP
•
The body detects this with a particular receptor designed for this function
•
These receptors release hormones, chemical messages that initiate the
start of the feedback mechanism
•
The hormones travel to their target tissue and initiate a corrective response
•
In this case, the corrective response is the secretion of more glucose into
the bloodstream
Characteristics of Living Things
• Living things acquire and use materials
and energy from their environment in a
process called metabolism
• Catabolism <-> Anabolism
• Cellular Respiration <-> Photosynthesis
• C6H12O6 + 6O2 + 6H2O <-> 12H2O + 6
CO2
Characteristics of Living Things
• Living things grow
• Materials acquired from the environment
are converted into the specific molecules
of the organism’s body
Characteristics of Living Things
• Continuity of life occurs because
organisms reproduce offspring of the
same type (species)
• Diversity of life occurs because offspring
are slightly different from their parents due
to sexual reproduction and mutation
Characteristics of Living Things
• Living things
reproduce themselves
using a molecular
blueprint called
deoxyribonucleic acid
(DNA)
Characteristics of Living Things
• Living things, as a whole, have the
capacity to evolve
• The theory of evolution states that modern
organisms arose, with modification, from
preexisting life forms
Diversity of Life
Domains of Life
Bacteria
Archaea
Eukarya
Diversity of Life
Eukarya
Protista
Fungi
Plantae
Animalia
Diversity of Life
Level of Cellular Organization
Prokaryotic
Eukaryotic
Do not have a nucleus
Have a nucleus
Do not have organelles
Have membrane bound organelles
Diversity of Life (Student Completion)
Domain
Kingdom Cell
Type
Bacteria
Archaea
Eukarya Protista
Fungi
Plantae
Animalia
Cell
Number
Mode of
Nutrition
Scientific Method
• The scientific method is the experimental
testing of a hypothesis formulated after the
systematic, objective collection of data.
Scientific Method
The scientific method is often
divided into steps. This is
helpful for putting the method
into context, but keep in mind
that the key element of the
scientific method is testing the
hypothesis. In other words, can
you prove that you are wrong?
Steps of the Scientific Method
• Observe the situation
• Ask a question
• Turn that question into a testable
hypothesis
• Predict the outcome of your experiment
• Perform your experiment
• Analyze the results
• Evaluate your hypothesis
Evolution
• Evolution is the unifying theory that
explains the origin of diverse forms of life
as a result of changes in their genetic
makeup.
• Modern organisms descended, with
modification, from preexisting life-forms.
Evolution
• Darwin and Wallace formulated a theory of
evolution in the 1800’s based on three
natural processes:
• Genetic variation within a population
• Inheritance of variation by offspring of
parents who carry the variation
• Natural selection: the survival and
enhanced reproduction of organisms with
favourable variations
Evolution
• Darwin's finches. The finches
numbered 1-7 are ground
finches. They seek their food
on the ground or in low shrubs.
Those numbered 8-13 are tree
finches. They live primarily on
insects.
• Since Darwin's time, these
birds have provided a case
study of how a single species
reaching the Galapagos from
Central or South America
could - over a few million years
- give rise to the 13 species
that live there today.
Evolution
• Structures or behaviours that aid survival
and reproduction in a particular
environment are called adaptations