The Scientific Study of Life

1
Chapter 1

• Introduction
• The Scientific Study of Life

2
The Scope of Biology

• 1.1 Lifes levels of organization define the
  scope of biology
• Biology is the scientific study of life
• Interactions between different kinds of organisms
  affect the lives of all
• A structural hierarchy of life, from molecules to
  ecosystems, defines the scope of biology

3
The Hierarchy of Life

• An ecosystem consists of
• all organisms living in a particular area
• all nonliving physical components of the
  environment that affect the organisms (soil,
  water)

4
The Hierarchy of Life

• Community- all the organisms in an ecosystem
• Plants, insects, and animals
• Population- Interacting group of individuals of
  one species
• A group of flying foxes
• Organism- An individual living thing
• One individual flying fox

5
Organisms

• Organisms are made up of
• Organ systems
• Circulatory system, nervous system
• Organs
• Heart, lungs
• Tissues
• Muscle tissue, nerve tissue
• Cells
• Red blood cells, skin cells
• Molecules
• DNA, Proteins

6
The Process of Science

• 1.2 Scientists use two main approaches to learn
  about nature
• Discovery Science- Scientists see something in
  nature and observe and measure variables to
  decide why it happens
• Hypothesis-Driven Science- Scientists make a
  hypothesis and then test the hypothesis using the
  scientific method

7
Discovery Science

• Scientists describe some
• aspect of the world and use
• inductive reasoning to draw general conclusions
• Example
• Scientists observe that all the calico cats they
  have seen were female, through years of
  observations the general conclusion has been
  drawn that All calico cats are female

8
Hypothesis-Driven Science

• In hypothesis-driven science, scientists use the
  scientific method
• They propose a hypothesis
• They make deductions leading to predictions
• They then test the hypothesis by seeing if the
  predictions come true

9
Hypothesis-Driven Science

• Example
• Hypothesis All human males have a Y sex
  chromosome.
• Prediction If this hypothesis is correct,
• Experiment and I test all human males,
• Predicted result these males should have the Y
  sex chromosome.

10
The Process of Science

• 1.3 With the scientific method, we pose and test
  hypotheses
• The main steps of the scientific method

11
Deductive Reasoning

• If a hypothesis is correct, and we test it, then
  we can expect a particular outcome
• Experiments designed to test hypotheses must be
  controlled experiments
• Control groups must be tested along with
  experimental groups for the meaning of the
  results to be clear

12
The Spider Mimic
Figure 1.3C
13
The Spider Mimic
14
Evolution, Unity and Diversity

• 1.4 The diversity of life can be arranged into
  three domains
• We group organisms by features to make them
  easier to study
• Organisms are classified by features into broader
  and broader groups
• The broadest of these groups is domain
• There are 3 domains Bacteria, Archaea, and
  Eukarya

15
The Three Domains

• Archaea
• No nucleus (Prokaryote)
• Ancient bacteria
• Bacteria
• Prokaryote

Figure 1.4A, B
16
Eukarya

• Eukaryotes
• Nucleus
• Organelles
• Contains
• Algae
• Fungi
• Plants
• Animals

17
1.5 Unity in Diversity All forms of life have
common features

• All organisms share a set of common features
• All are made of cells
• All have DNA as their
• genetic blueprint
• Vast variety possible within one species

Figure 1.5A
18
DNA(Deoxyribonucleic Acid)

• Made of chemical units called nucleotides
• Each species has its own nucleotide sequence

19
DNA

• The genetic information in DNA underlies all
  features that distinguish life from non-life
• Order and regulation
• Growth and development
• Use of energy from the
• environment
• Response to environmental
• stimuli
• Ability to reproduce
• Evolutionary change

20
1.6 Evolution explains the unity and diversity
of life

• Charles Darwin developed the theory of evolution
  by natural selection
• Evolution is the major theory of biology
• The theory of natural selection explains the main
  mechanism whereby all species of organisms
  change, or evolve

21
Natural Selection

• Population with varied traits
• Individuals with certain traits are eliminated by
  some natural process
• Only surviving individuals can reproduce

Figure 1.6B
22
Evolution

• Evolution happens when environmental factors
  favor the success of some traits over others
• Natural selection is the editing mechanism
• Individual populations evolve due to adaptation
  to these environments

Figure 1.6C
23
1.7 Living organisms and their environment form
interconnecting webs

• Natural selection applies to all organisms and
  levels of the hierarchy of life
• In an ecosystem, interactions between organisms
  make up an interconnecting web of relationships

24
Web of Interaction
Figure 1.7A
25
Role of Organisms In This Web

• Plants-
• Provide much of the food that supports the
  ecosystem, directly or indirectly
• Animals-
• Eat plants or plant products, eat each other
• Bacteria, fungi-
• Decomposers that provide nutrients for plants

26
Biology and Everyday Life

• 1.8 How biology is connected to our lives
• Biology is connected to a number of important
  issues
• Environmental problems and solutions
• Genetic engineering
• Medicine

27
How biology is connected to our lives

• Many technological advances stem from the
  scientific study of life
• Evaluating everyday reports in the press about a
  large range of subjects requires critical
  thinking and some familiarity with many areas of
  biology