Nature of Science
Natural World
- “Science is more than a body of knowledge. It is a way of thinking: a way of
skeptically interrogating the universe,” - Carl Sagan
- Natural world is understandable
- behaves according to laws of physics and chemistry
Science
Best tool to discern fundamental nature of reality.
- Science demands evidence. Requires us to be skeptical of truth unless
supported by evidence
- Ex. anti-vaxers
- Science is a blend of logic and imagination
- Ex. time slows down when matter approaches speed of light
- 3 laws of motion: inertia, force=mass*acceleration, and action has equal but
opposite reaction
- Scientific knowledge is durable and subject to change
- Scientists attempt to avoid bias like pseudo-science (appears to be scientific but
its biased)
- Ex. tobacco industry leading people to think they don’t cause lung cancer
and linking human-generated greenhouse gasses to climate change
- Science is a complex social activity. Science builds upon itself like computer
generations.
Properties of Life
Organisms
- Made of one or more cells
- Respond to stimuli
- Ex. plants bend toward light
- Reproduction:
- single-celled organisms reproduce by duplicating DNA and dividing
- Multicellular use gametes/oocytes ad sperm cells to fertilize and create
new individuals. DNA has genes which is passed to offspring
- Adaptation: organisms are “fit” to their environment. Enhances reproductive
potential of individuals
- Growth and development: direct cellular growth
, - Regulation/homeostasis:
- Homeostasis: relatively stable internal environment to maintain life, ex.
thermoregulation
- Energy processing: convert source of energy for metabolic activities
- Evolution: mutations or changes in hereditary material over time
Biological Organization
Life hierarchy
Organized by pyramid. Small simple atoms on top and entire biosphere at base.
- Atoms join together in chemical bonds to create molecules
- Level 1: atom (of differing elements)
- Most abundant: oxygen, carbon, hydrogen, nitrogen
- Life is mostly carbon
- Level 2: molecules
- 4 classes of macromolecules: carbs, lipids, proteins, nucleic acids
- Most abundant organic molecule: cellulose (type of carb)
, - Level 3: organelles
- Ex. mitochondria, chloroplasts
- Level 4: cells
- Organisms consist of a single cells, others are multicellular aggregates of
specialized cells
- Level 5: tissues
- ensemble of similar cells that together carry out specific function
- Level 6: organs
- collection of tissues joined in a structural unit to serve a common function
- Level 7: organ systems
- group of organs that work together to perform one or more functions
- Level 8: organism
- Level 9: population
- localized group of organisms belonging to the same species capable of
interbreeding
- Level 10: community
- populations of several species in the same area
- Level 11: ecosystem
- interactions between these communities and their physical environment
- Level 12: biosphere
Historical Context of Darwin’s Idea
- Darwin’s “Descent with Modification by Natural Selection,” (i.e. evolution)
explains diversity and unity of all life
- Implies species change, get modified, and lineages descend through
time by natural selection
- 1700s: dominant philosophy was species didn’t change over time. Adaptations
were evidence of purposeful creation
Scientists
- Carolus Linnaeus: developed nomenclature (2-name) system of classification
- Ex. Canis lupus
- Georges Cuvier: developed paleontology, study of fossils
- Charles Lyell: promoted geology founded on gradualism
- Jean-Baptist de Lamarck: developed early incorrect hypothesis for evolution
based on use and disuse
, - Scooped by Alfred Russel Wallace, Darwin published On the Origin of Species
(1859)
Descent with Modification by Natural Selection
Natural Selection Rests On
- Observation 1: members of a population vary in their inherited traits
- Observation 2: species produce more offspring than the environment can
support. Thus, many fail to survive and reproduce
- Inference 1: individuals whose inherited traits give them a better chance at
surviving and reproducing leave more offspring
- Inference 2: favorable traits accumulate in populations over generations
Evidence for Evolution
Big ideas
- Evolution is universally accepted by scientists as the best available explanation
for biological diversity on Earth
- Evidence for evolution is overwhelming and is corroborated across the many
different biological sciences
Artificial selection
- Human modification of other species over generations by selecting for desirable
traits in plants and animals
- Ex.
Natural World
- “Science is more than a body of knowledge. It is a way of thinking: a way of
skeptically interrogating the universe,” - Carl Sagan
- Natural world is understandable
- behaves according to laws of physics and chemistry
Science
Best tool to discern fundamental nature of reality.
- Science demands evidence. Requires us to be skeptical of truth unless
supported by evidence
- Ex. anti-vaxers
- Science is a blend of logic and imagination
- Ex. time slows down when matter approaches speed of light
- 3 laws of motion: inertia, force=mass*acceleration, and action has equal but
opposite reaction
- Scientific knowledge is durable and subject to change
- Scientists attempt to avoid bias like pseudo-science (appears to be scientific but
its biased)
- Ex. tobacco industry leading people to think they don’t cause lung cancer
and linking human-generated greenhouse gasses to climate change
- Science is a complex social activity. Science builds upon itself like computer
generations.
Properties of Life
Organisms
- Made of one or more cells
- Respond to stimuli
- Ex. plants bend toward light
- Reproduction:
- single-celled organisms reproduce by duplicating DNA and dividing
- Multicellular use gametes/oocytes ad sperm cells to fertilize and create
new individuals. DNA has genes which is passed to offspring
- Adaptation: organisms are “fit” to their environment. Enhances reproductive
potential of individuals
- Growth and development: direct cellular growth
, - Regulation/homeostasis:
- Homeostasis: relatively stable internal environment to maintain life, ex.
thermoregulation
- Energy processing: convert source of energy for metabolic activities
- Evolution: mutations or changes in hereditary material over time
Biological Organization
Life hierarchy
Organized by pyramid. Small simple atoms on top and entire biosphere at base.
- Atoms join together in chemical bonds to create molecules
- Level 1: atom (of differing elements)
- Most abundant: oxygen, carbon, hydrogen, nitrogen
- Life is mostly carbon
- Level 2: molecules
- 4 classes of macromolecules: carbs, lipids, proteins, nucleic acids
- Most abundant organic molecule: cellulose (type of carb)
, - Level 3: organelles
- Ex. mitochondria, chloroplasts
- Level 4: cells
- Organisms consist of a single cells, others are multicellular aggregates of
specialized cells
- Level 5: tissues
- ensemble of similar cells that together carry out specific function
- Level 6: organs
- collection of tissues joined in a structural unit to serve a common function
- Level 7: organ systems
- group of organs that work together to perform one or more functions
- Level 8: organism
- Level 9: population
- localized group of organisms belonging to the same species capable of
interbreeding
- Level 10: community
- populations of several species in the same area
- Level 11: ecosystem
- interactions between these communities and their physical environment
- Level 12: biosphere
Historical Context of Darwin’s Idea
- Darwin’s “Descent with Modification by Natural Selection,” (i.e. evolution)
explains diversity and unity of all life
- Implies species change, get modified, and lineages descend through
time by natural selection
- 1700s: dominant philosophy was species didn’t change over time. Adaptations
were evidence of purposeful creation
Scientists
- Carolus Linnaeus: developed nomenclature (2-name) system of classification
- Ex. Canis lupus
- Georges Cuvier: developed paleontology, study of fossils
- Charles Lyell: promoted geology founded on gradualism
- Jean-Baptist de Lamarck: developed early incorrect hypothesis for evolution
based on use and disuse
, - Scooped by Alfred Russel Wallace, Darwin published On the Origin of Species
(1859)
Descent with Modification by Natural Selection
Natural Selection Rests On
- Observation 1: members of a population vary in their inherited traits
- Observation 2: species produce more offspring than the environment can
support. Thus, many fail to survive and reproduce
- Inference 1: individuals whose inherited traits give them a better chance at
surviving and reproducing leave more offspring
- Inference 2: favorable traits accumulate in populations over generations
Evidence for Evolution
Big ideas
- Evolution is universally accepted by scientists as the best available explanation
for biological diversity on Earth
- Evidence for evolution is overwhelming and is corroborated across the many
different biological sciences
Artificial selection
- Human modification of other species over generations by selecting for desirable
traits in plants and animals
- Ex.
