Evolution and Scientific Method Quiz

Reasoning and Science

• Deductive reasoning: applying general laws to understand specific phenomena
• Inductive reasoning: using many observations to form a conclusion
• Strong inference: testing and rejecting multiple hypotheses
• Use of experiments

Scientific Method

• Recognition and formulation of a problem
• Collection of data through observation and experiment
• Formulation of hypothesis (best guess at solution for the problem)
• Testing hypothesis in laboratory/controlled conditions

Hypothesis versus Theory

• Hypothesis: a tentative explanation based on collected data
• Theory: a hypothesis that has survived repeated challenges and gained substantial experimental support
• Law: a statement of an observed phenomenon that never changes
• How a hypothesis becomes a theory: experimental testing
• Questions not addressable by science: supernatural/religious explanations
• Hypotheses must be testable and falsifiable

Experimental Design

• Manipulative experiments: conditions purposefully altered for one variable while all others are constant
• Controlled experiments: comparing a manipulated group to a control group that is not manipulated
• Natural experiments: observing events that have already happened
• Blind experiments: researcher doesn't know which group received the treatment
• Double-blind experiments: neither subject nor researcher knows treatment assignment

Null versus alternative hypotheses

• Null hypothesis: there will be no effect.
• Alternative hypothesis: there will be an effect.

Variables

• Dependent variable: affected by independent variable
• Independent variable: affects the dependent variable.

Graphs

• Bar graphs: useful for comparing counts/averages/summary statistics
• Line graphs: used for continuous data with a fixed order
• Scatter graphs: used for sets of data where dependent and independent variables can be plotted as (X,Y) coordinates and are independent from each other.

Peer-reviewed scientific literature

• Importance of peer review for original research, systematic reviews, and meta-analyses.
• Different types of scientific literature can yield different results.

The Process of Scientific Research and Publication

• Conducting research activities: experiments/comparisons/reports of events/reviews/meta-analysis
• Data analysis and paper writing: include background, conclusions
• Submission to journals and editor evaluation: whether paper is a proper fit
• Anonymous reviewers: judging the accuracy, interpretation and soundness of methods; deciding if conclusions meet data
• Publication outcome: revised, resubmitted if necessary, or rejected

Biology: The Study of Life

• Homeostasis: regulation of the internal environment to maintain equilibrium
• Organization: structure composed of cells
• Metabolism: transformation of energy (anabolism, catabolism)
• Living things: require energy for internal organization and other life phenomena
• Growth: maintenance of higher anabolism than catabolism

Characteristics of Living Things

• Growth: organism increases in size
• Adaptation: changing over time in response to the environment
• Response to stimuli: reacting to external factors
• Reproduction: creating new organisms
• Cellular structure: made of cells as basic units

The Origin of Life

• Evidence of common origin: all living things share characteristics (e.g. L-isomers of proteins, nucleic acids, codons, lipid membranes)
• Common ancestor: all life evolved from a single entity.
• Life arose approximately four billion years ago.

Levels of Biological Organization

• Biosphere, ecosystem, community, population, organism, organ, tissue, cell, molecule, atom

Emergent Properties and Systems Biology

• Emergent properties: properties arise from the interactions of parts within a system
• Reductionism: breaking complex systems into simpler components for study.
• Systems biology: analyzing interactions among parts of a biological system

Molecules: Interactions Within Organisms

• Cells coordinate chemical pathways through feedback regulation (positive, negative).
• Positive feedback: self-perpetuating
• Negative feedback: suppressing change and maintaining status quo

Evolution

• Evolution: change in frequency of genes in a population over time
• Natural selection: heritable traits increase or decrease in population
• Adaptations: features evolved through selection (vary by environment)

Other mechanisms of evolution:

• Genetic drift: random demographics
• Gene flow: genetic change from migration
• Sexual selection: effect of mate choice on gene frequency
• Populations separated long enough: can become very different due to accumulated evolutionary changes

Chemistry: The Chemical Context of Life

• Matter: anything that takes up space and has mass
• Elements: substances that cannot be broken down into simpler substances through chemical reactions
• Compounds: substances composed of two or more elements in a fixed ratio.
• Importance of elements in the human body: oxygen, carbon, hydrogen, nitrogen form 96% of body mass (including water)
• Atoms: smallest unit of matter retaining element properties
• Subatomic particles: protons (+), neutrons (neutral), electrons (-)

Atoms: Structure and Bonds

• Atomic mass: number of protons and neutrons

• Atomic number: number of protons in an atom

• Isotopes: atoms of an element with the same number of protons but differing numbers of neutrons (important for radioisotope use in fossil dating)

• Electron shells: regions of three dimensional space occupied by electrons around an atom's nucleus.

• Each shell holds a limited number of electrons

• Bonding electrons, also known as valence electrons, are important for chemical reactions.

• Ionic bonds (involve electron transfer)

• Covalent bonds (involve electron sharing)

• Polar covalent bonds: unequal sharing of electrons creates partial charges

• Nonpolar covalent bonds: electrons are shared equally, no resulting charges.

Polar Covalent Bonds & Electronegativity

• Electronegativity: ability of an atom to attract electrons to itself in a covalent bond
• Polar covalent bonds demonstrate an unequal sharing of electrons leading to partial positive and negative charges in the bonding molecule.
• Unequal sharing of electrons leads to partial charges
• Polar covalent bonds play an important role in creating hydrogen bonds.

Hydrogen Bonds

• Attraction between a partially positive hydrogen atom in one molecule and a partially negative atom in another molecule.
• Important force in the structure and properties of water.

Chemistry of Water

• Polar covalent bonding and hydrogen bonding (how water molecules are held together)
• Unique properties arising from hydrogen bonds (e.g. cohesion, high heat of vaporization, excellent solvent.)

Acids, Bases, and Salts

• Acids: substances that donate H+ ions in a solution (increase H+ concentration)
• Bases: substances that accept H+ ions in a solution (decrease H+ concentration)
• Salts: compounds formed when an acid and base combine.
• pH: measure of H+ concentration in a solution
• Logarithmic scale
• Neutral pH: pH 7
• Acidic pH: 0–7
• Basic pH: 7-14

Organic Molecules

• Carbon: important element in organic molecules due to its capacity to form four covalent bonds
• Organic chemistry: Study of carbon-based compounds
• Types of organic molecules: Hydrocarbons, Carbohydrates (1:2:1 ratio C:H:O), Lipids, Proteins, Nucleic acids: DNA, RNA
• Monomers: simple building blocks of polymers
• Polymers: large molecules made of monomers
• Dehydration reaction: creating polymers
• Hydrolysis: breaking polymers
• Carbohydrates: Structural and energy
• Lipids: Nonpolar, hydrophobic, energy storage and membranes
• Proteins. Catalyze chemical reactions, structural, transport, communication, defense.
• Nucleic acids: store, transfer genetic information
• Primary, Secondary, Tertiary, Quaternary structures of proteins

Polysaccharides

• Storage: starch (plants), glycogen (animals)
• Structural: cellulose (plants), chitin (exoskeletons)

Lipids

• Energy storage: fats
• Membranes: phospholipids
• Other roles: steroids (e.g., hormones)

Four types of molecules characteristic to life:

• Carbohydrates: provide energy and structural support (1:2:1 ratio of carbon to hydrogen to oxygen)
• Lipids: insulation and building cell membranes (e.g., phospholipids, steroids)
• Proteins: catalyze chemical reactions, structural, transportation, communication, defense (ex enzymes, hormones)
• Nucleic acids: store and transfer genetic information (ex, DNA, RNA).

Nucleic Acids: DNA and RNA

• DNA: stores genetic information, double stranded, deoxyribose sugar, and has the nitrogenous bases: adenine, guanine, cytosine and thymine
• RNA: involved in protein synthesis, single stranded, ribose sugar, and has the nitrogenous bases: adenine, guanine, cytosine and uracil.
• Polymers of nucleotides
• Directionality: 5' to 3' (synthesis of new strands)

Proteins

• Structure: primary (linear sequence of amino acids), secondary (folding patterns), tertiary (3D structure), quaternary (multiple polypeptide chains)
• Functions: wide range of functions including structural support, catalysis, transportation, defense and signaling (ex. hormones).
• Composed of monomers: amino acids
• Two reactions: dehydration reaction, hydrolysis