Understanding Life: Biology Concepts

• BIOL1307: General Biology II covers biological principles, characteristics of life, historical figures, and the scientific method.

Biology

• Biology is the study of life.
• Biologists seek to define what characteristics all life forms share.

What is Science?

• There are three main ways humans try to explain the world: religion, philosophy, and science.

Characteristics of Life

Chemical Complexity

• Living organisms assemble and use large macromolecules.
• Nucleic acids like DNA and RNA are essential macromolecules.
• Proteins are composed of amino acid chains.
• Carbohydrates include sugars and chitin.
• Lipids include fats, waxes, and oils.

Hierarchical Organization

• Living organisms exist within complex hierarchical levels.
• Emergence is the appearance of a new characteristic at a given level of organization.
• Properties can arise from interactions among the components of a system.
• The hierarchy of biological organization includes subatomic particles, atoms, molecules, cells, multicellular individuals, populations, species, communities, ecosystems, and the biosphere.

Reproduction

• Reproduction occurs at multiple hierarchical levels, including DNA, cells, individuals, and species.

Genetic Program

• All life forms have DNA, with the possible exception of viruses.
• Some viruses have closely related RNA.
• If viruses are "alive" is debatable.
• DNA contains genetic information in the form of genes.
• The rules to translate information in all life forms are the same.
• A "universal" genetic code exists.

Metabolism

• All organisms acquire and use energy.
• All organisms use the same basic chemical processes to transfer energy.

Development

• All organisms have developmental phases.
• Animal development includes zygote, juvenile, breeding adult, and post-breeding adult phases.

Environmental Interactions

• All organisms respond to their environment.
• Environmental factors that organisms respond to include light, temperature, and other organisms.
• Adaptations evolve to allow organisms to respond appropriately to environmental stimuli.

Life Obeys Physical Laws

• Vitalism is rejected by science.
• Vitalism posits that life has a mystical vital force.
• The first and second laws of thermodynamics apply to living organisms.
• The first law of thermodynamics is the conservation of energy.
• Energy is neither created nor destroyed.
• Photosynthesis changes the form of energy, converting sunlight to carbohydrates.
• Metabolism transfers energy from one organism to another.
• The second law of thermodynamics states that physical systems proceed toward increasing disorder.
• Entropy is a measure of disorder in a system.
• Energy is lost at each trophic level.
• Energy transfers from plants to herbivores to carnivores, with energy loss at each step.
• Survival, growth, and development require a constant supply of energy.
• Metabolism provides this energy.

The Evolution of Science

Nature of Science

• Science comes from the Latin "Scientia," meaning "to know."
• Science seeks natural explanations for natural phenomena.
• Scientific explanations are in the form of hypotheses and theories.
• Science is empirical and is based on observations.
• Science relies on repeatability.
• Science includes shared information.
• Scientific findings are peer-reviewed and tested.

Limitations of Science

• Science cannot explain or invoke supernatural phenomena.
• Science examines nature, the observable universe.
• Science does not address basic philosophical questions, like "Why are we here?"
• Science does not make direct ethical decisions.
• Science cannot decide if one "should" choose the sex of offspring or "should" promote genetically modified foods.
• Science does not address theology since beliefs are not testable.

Historical Figures

Aristotle

• Aristotle lived from 384-322 BC.
• Aristotle was a student of Plato.
• Aristotle emphasized the importance of empiricism.
• Empiricism relies on observation or experiment.
• Aristotle studied behavior and habitats of birds, seasonal effects on reproduction, animal geography, hibernation and migration, color change, feeding habits, and symbiosis.

Scientific Revolution

• The scientific revolution occurred roughly from 1550-1700.
• The scientific revolution saw a fundamental change in approaching the explanation of phenomena.
• The scientific revolution unofficially began with Copernicus.

Mikołaj Kopernik (Nicolaus Copernicus)

• Mikołaj Kopernik (Nicolaus Copernicus) lived from 1473-1543.
• Copernicus was a Polish astronomer.
• Copernicus was the first to argue for a heliocentric view of the solar system.

Johannes Kepler

• Johannes Kepler lived from 1571-1630.
• He was German.
• Kepler formulated laws of planetary motion.

Galileo Galilei

• Galileo Galilei lived from 1564-1642.
• He was Italian.
• Galilei provided empirical support for Copernicanism.

Isaac Newton

• Isaac Newton lived from 1643-1727.
• He was English.
• Newton was a physicist, mathematician, and astronomer.

René Descartes

• René Descartes lived from 1596-1650.
• He was a French mathematician.
• Descartes developed analytical geometry.
• Descartes wrote "Discourse on Method".
• Descartes' writings had 4 precepts that emphasized objective observations.

Karl Popper

• Karl Popper lived from 1902-1994.
• Popper emphasized falsifiability in science.
• Popper pointed out the elusiveness of "proof".
• Popper suggested strong hypotheses are not proven correct but survive attempts to disprove them.

Essentials of Scientific Inquiry

• Science is the pursuit of knowledge using observations, questions, hypotheses, deductions, and conclusions.
• Science produces natural explanations for natural phenomena in the form of hypotheses and theories that can be falsified.
• Essentials of scientific inquiry include:
  • Being guided by natural explanations.
  • Being explanatory by reference to natural mechanisms.
  • Being testable against the empirical world.
  • Conclusions are tentative, meaning are not necessarily the final word.
  • Being falsifiable.
• _____: observation repeatedly verified.
• _____: hypothesis of broad scope with overwhelming evidence.
• _____: powerful theory that guides a field of knowledge.
• _____: description of how a system behaves under specific circumstances.

Scientific Method (Hypothetico-Deductive System)

• The scientific method consists of making observations, asking questions, forming hypotheses, testing hypotheses, forming conclusions, and undergoing publication, peer review, and intense scrutiny.
• Hypotheses are tentative answers to questions.
• A null hypothesis states there is no effect or no difference.
• An alternative hypothesis posits there is an effect or difference.
• Hypotheses and predictions must be testable by additional observations or experiments.
• Conclusions involve accepting or rejecting the hypothesis.
• Acceptance does not equal proof.
• If results of continued testing support a hypothesis, it may become a theory.
• If results do not support a hypothesis, it may be modified or abandoned.
• Most tests of hypotheses are of three types.

Hypothesis Testing

• Testing includes observational methods, experimental manipulations, along with other methods.
• Sample size is crucial in all studies.
• Accurate sampling of patterns is important despite occasional atypical data points.
• Statistical methods are applied to quantify levels of support.

Observational Methods

• Observational methods test without manipulation.
• Groups are compared.
• Often deals with causation.
• An example of an observational method is peppered moth studies in England.
• Observations of peppered moths include that moths hide on trees, polluted areas have trees with dark, soot-covered bark, and moths in polluted areas are darker than in clean areas where trees are grey.
• Hypothesis 1 from peppered moth studies is that moth colors are not adaptations to tree bark.
• The moth population colors are compared before and after pollution levels changed.
• Under Hypothesis 1, which asserts that moth colors are not adaptations to tree colors, the number of dark moths should not change.
• Prediction under Hyp. 2 (moth colors adaptations to tree colors): # dark moths should decrease after pollution levels drop.

Experimental Manipulations

• Experimental manipulations is when one variable is manipulated to learn its effects.
• Withholding manipulation allows for clean comparison and checks assumptions
• Experimental manipulations often involve establishing causation.
• Study the function of wing display in Tephritid Flies as an experimental manipulation example.
• Observations for Tephritid Flies include flies have banded wings and wings are displayed when disturbed.
• An experimental question about Tephritid Flies is: Do flies mimic jumping spiders to scare off predators?
• A hypothesis test includes offering flies to spiders, comparing their behaviors to fruit flies and house flies, and preforming manipulations.
• Control group is the test where there is no manipulation to ensure that experimental manipulations are not clouding the results.

Test your understanding of fundamental biology concepts. Questions cover topics such as development, thermodynamics, energy flow, and scientific investigation in living organisms. Explore the core principles that govern life processes.