BIO120 Final Review

What is science?

A testable, falsifiable, and iterative way to explain natural phenomena using evidence.

Hypothesis

A testable explanation for an observation or question.

Prediction

A specific expected outcome if a hypothesis is correct.

Null Hypothesis

Statement that there is no effect or no difference.

Alternative hypothesis

Statement that there is an effect or difference.

p-value

Probability of obtaining results as extreme as observed if the null hypothesis is true.

What does p ≤ 0.05 mean?

Reject the null hypothesis; results are unlikely due to chance.

Mean

Average; sensitive to outliers.

Median

Middle value; resistant to outliers.

Mode

Most frequent value.

Range

Maximum minus minimum.

Standard Deviation

Measures variation around the mean.

Standard Error

Measures precision of the sample mean.

Independent variable

Variable manipulated; x-axis.

Dependent variable

Variable measured; y-axis.

Defining features of eukaryotic cells

Nucleus, membrane-bound organelles, linear chromosomes.

Prokaryotic cells

No nucleus, circular DNA, no membrane-bound organelles.

Three domains of life

Bacteria, Archaea, Eukarya.

Correct species name formatting

Genus species (Genus capitalized, species lowercase, italicized).

Taxonomic order

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

LUCA

Last Universal Common Ancestor of all life.

What do nodes represent on a phylogenetic tree?

Common ancestors.

How is relatedness determined on a tree?

By most recent common ancestor, not physical closeness.

Monophyletic group

Ancestor and all of its descendants.

Paraphyletic group

Ancestor and some, but not all, descendants.

Polyphyletic group

Group with multiple ancestors; does not include common ancestor.

Origin of mitochondria

Alpha-proteobacteria.

Origin of chloroplasts

Cyanobacteria.

Primary endosymbiosis

Eukaryote engulfs a prokaryote.

Secondary endosymbiosis

Eukaryote engulfs another eukaryote.

Opisthokonts

Group that includes animals and fungi.

Bryophytes (mosses)

Nonvascular plants; no seeds.

Ferns

Vascular plants without seeds

Gymnosperms

Seed plants without flowers ("naked seeds").

Angiosperms

Flowering plants; seeds enclosed in fruit.

Natural selection

Differential survival and reproduction of individuals due to heritable traits.

Key requirement for speciation

Reproductive isolation.

Allopatric speciation

Speciation due to geographic isolation.

Sympatric speciation

Speciation without geographic isolation.

Biological species concept

Species are groups that can interbreed and produce fertile offspring.

Morphological species concept

Species defined by physical traits.

Phylogenetic species concept

Species defined by evolutionary history.

Complete dominance

One allele masks the other in heterozygotes.

Incomplete dominance

Heterozygote shows intermediate phenotype.

Codominance

Both alleles expressed in heterozygote.

Hardy–Weinberg conditions

Large population, random mating, no mutation, no migration, no selection.

Hardy–Weinberg equation

p² + 2pq + q² = 1.

What does deviation from H–W indicate?

Evolution is occurring.

What shapes animal behavior?

Natural selection and fitness trade-offs.

Exponential growth

Population growth with unlimited resources.

Logistic growth

Growth limited by carrying capacity (K).

Keystone species

Species with disproportionately large effects on community structure.

Trophic cascade

Effects that propagate through food webs after changes at one trophic level.

Bottom-up control

Community structure controlled by resources/nutrients.

Top-down control

Community structure controlled by predators.

Energy flow in ecosystems

One-directional (sun → producers → consumers → decomposers).