(UPDATED) Biology Exam 2: Evolution, Cell Structure, and Life Cycles

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Natural selection

Process where individuals with advantageous traits survive/reproduce more successfully (V + I + S = A).

Adaptation

Inherited trait improving survival or reproduction in a specific environment.

Inheritance

Passing traits genetically from parents to offspring.

Struggle for existence

Competition for limited resources that drives selection.

Fitness

Reproductive success relative to others in the population.

Artificial (domestic) selection

Human-driven breeding for specific traits.

Sexual selection

Selection for traits increasing mating success (e.g., bright colors, songs).

Sexual dimorphism

Physical differences between sexes due to sexual selection.

Unequal mating success

Some individuals leave more offspring because of mating advantages.

Mate choice

Selection of mates based on displays or characteristics.

Mutation

Random change in DNA sequence; source of new variation.

Neutral mutation

No effect on fitness.

Deleterious mutation

Harmful to fitness.

Beneficial mutation

Improves fitness.

Genetic drift

Random changes in allele frequencies (strongest in small populations).

Bottleneck event

Drastic reduction in population → loss of diversity.

Founder effect

New population formed by few individuals → limited variation.

Allopatric speciation

New species form via geographic isolation + reproductive isolation.

Geographic isolation

Physical separation prevents gene flow.

Reproductive isolation

Populations cannot interbreed successfully.

Cell membrane

Controls movement of substances in/out of the cell.

Nucleus

Eukaryotic organelle housing DNA.

Organelle

Specialized cell compartment (mitochondrion, chloroplast, etc.).

Mitochondrion

Performs aerobic respiration (sugar + O₂ → CO₂ + H₂O + ATP).

Chloroplast

Performs photosynthesis (CO₂ + H₂O → sugar + O₂).

Prokaryotic

No nucleus or membrane-bound organelles (Bacteria, Archaea).

Eukaryotic

Has nucleus and organelles (Protists, Plants, Animals, Fungi).

Lateral transfer

Horizontal gene transfer between species (common in microbes).

Nitrogen fixation

N₂ → NH₄⁺/NO₂⁻/NO₃⁻; converts atmospheric nitrogen to usable form.

Photosynthesis

Autotroph process converting CO₂ + H₂O → sugars + O₂.

Heterotroph

Obtains energy by consuming organic matter.

Respiration

Breaks down sugars to produce ATP.

Gram stain

Differentiates bacterial cell walls (Gram + = thick; Gram - = thin).

Extremophile

Organism thriving in extreme environments (e.g., Archaea).

Nuclear membrane

Double membrane around nucleus.

Pseudopodia

"False feet" used for movement/feeding (Amoebozoa).

Bioluminescence

Production of light by living organisms (many marine protists).

Multicellularity

Organism composed of multiple cooperating cells.

Alternation of generations

Life cycle alternating haploid (gametophyte) and diploid (sporophyte) stages.

Sporophyte

Diploid stage producing spores (2N → 1N).

Gametophyte

Haploid stage producing gametes (1N).

Meiosis

2N → 1N + 1N (produces gametes).

Fertilization

1N + 1N → 2N (forms zygote).

Mitosis

Cell division producing identical cells (2N → 2N or 1N → 1N).

Prokaryotes

No nucleus

Bacteria

Peptidoglycan walls

Archaea

Unique membranes

Eukarya

Nucleus + organelles

Firmicutes

Gram+

Actinobacteria

Gram+, filamentous

Proteobacteria

Gram-, diverse

Cyanobacteria

Photosynthetic

Dinoflagellates

2 flagella, bioluminescent

Diatoms

Silica shells, photosynthetic

Brown algae

Multicellular kelp

Amoebozoa

Pseudopodia movement

Endosymbiosis theory

Mitochondria/chloroplasts originated as free bacteria engulfed by larger cells.

Primary endosymbiosis

Eukaryote engulfed cyanobacterium → first chloroplasts.

Secondary endosymbiosis

Eukaryote engulfed another eukaryotic alga → extra membranes (multiple-walled plastids).

Chlorophyll

Pigment capturing light for photosynthesis.

Logic of natural selection

Variation + Inheritance + Struggle = Adaptation.

Evolutionary mechanisms

Selection, drift, mutation, gene flow.

Prokaryote vs eukaryote

Nucleus absent vs present.

Lateral transfer + recombination

Add genetic diversity.

Sexual recombination

Meiosis (1N), fertilization (2N).

Metabolism diversity

Photosynthesis, respiration, nitrogen fixation.

Key innovations

Organelles, photosynthesis, respiration, sex, multicellularity.