Key Concepts in Scientific Method and Evolution

scientific method

A flexible, non-linear process involving observations, forming hypotheses, conducting experiments, analyzing results, and drawing conclusions.

empirical

Based on observation or experience.

self-correcting

A characteristic of scientific thinking that allows for the correction of errors through new evidence.

null hypothesis

States there is no relationship between variables and is often what researchers aim to disprove.

experimental design

Key elements include controlled treatments, experimental and control groups, randomization, and large sample sizes to minimize bias.

bias

Can be prevented or minimized through blind or double-blind testing, where participants and/or experimenters are unaware of treatment assignments.

scientific theory

A well-supported explanation backed by extensive research and consistent observations, not just a guess.

observable world

The realm that scientific thinking helps to understand, but has limitations regarding value judgments or non-quantifiable information.

data visuals

Graphs and charts that can effectively communicate information but must be interpreted carefully.

biological literacy

The ability to creatively process scientific inquiry, communicate thoughts, and integrate ideas.

characteristics of life

Include cellular structure, metabolism, response to the environment, homeostasis, growth/development/reproduction, and the capacity for evolution.

evolution

Change in allele frequencies in a population over time.

mutation

Random changes in DNA sequences, the ultimate source of new genetic material passed to offspring.

genetic drift

Refers to random changes in allele frequencies, especially in small populations.

Founder Effect

A new population started by a few individuals has different allele frequencies than the source.

Bottleneck Effect

A sharp reduction in population size drastically alters allele frequencies and reduces genetic diversity.

natural selection

Requires variation for a trait within a population, heritability of that trait, and differential reproductive success due to that trait.

variation

Differences for a trait within a population.

heritability

The ability of a trait to be passed down from parents to offspring.

differential reproductive success

The concept that individuals with advantageous traits are more likely to reproduce.

systems organization

One of the five key themes that unify biology.

Fixation

An allele becomes the only allele for that gene in the population.

Allele Frequencies

Helps predict genotypes and phenotypes in a population.

Fitness

Refers to an organism's reproductive success.

Adaptations

Traits that enhance fitness.

Inheritance

The passing of genetic information from parents to offspring.

Cell Division

The process by which a parent cell divides into two or more daughter cells.

Mitosis

Produces genetically identical cells for growth and repair.

Meiosis

Produces genetically unique reproductive cells (gametes).

Crossing Over

Occurs during meiosis and increases genetic variation.

Species

A group of organisms that can interbreed and produce fertile offspring under natural conditions.

Speciation

The evolutionary process where new species arise.

Reproductive Isolation

Barriers preventing gene flow.

Genetic Divergence

Isolated populations evolve independently.

Hybridization

The interbreeding of closely related species, often resulting in sterile offspring.

DNA

Carries the genetic instructions for building proteins.

Proteins

Perform most cellular functions.

Evolutionary Trees (Phylogenies)

Hypotheses about ancestor-descendant relationships among species.

Convergent Evolution

Where unrelated species independently evolve similar traits.

Analogous Traits

Traits that are similar due to convergent evolution.

Macroevolution

Refers to large-scale evolutionary changes at or above the species level.

Domains

All life is categorized into three: Bacteria, Archaea, and Eukarya.

Eukarya

Includes protists, plants, fungi, and animals.

Linnaean System

A hierarchical classification still used today, employing a two-part scientific name and various taxonomic ranks.

Origin of Life

A hypothesis suggesting it began with simple molecules that became stable enough to react.

Questioning Long-held Assumptions

Often leads to new scientific breakthroughs.