Biology EOC Review Guide - Semester 2 Notes

Evolution

• Natural Selection: Organisms better adapted to environmental pressures are more likely to survive, reproduce, and pass down traits.

• Genetic Variation: Differences in traits within a population.

• Environmental Pressure: A change in the environment affecting an organism's survival.

• Adaptation: A trait that helps an organism survive and reproduce; organisms more adapted have higher fitness.

  • Example: Rock pocket mice with different fur colors due to predation; dark fur is an adaptation for camouflage.

• Biological Resistance: Ability to survive effects of harmful substances due to random mutations.

  • Examples: Antibiotic, pesticide, and herbicide resistance.

• Adaptations to Biomes:

  • Cactus in the desert: Water storage in leaves.

  • Polar bear in the tundra: Dense fur, thick fat layers, white fur for camouflage.

• Genetic Drift: Chance events randomly changing trait distribution (allele frequency).

• Bottleneck Effect: Population size reduction due to random mortality events.

  • Examples: Natural disasters, disease spread, overhunting.

• Founder Effect: Few population members start a new population in a new area.

  • Example: Organisms separated by a flood.

• Asexual Reproduction:

  • Advantages: Fast, simple, one parent needed, many offspring quickly.

  • Disadvantages: No genetic diversity, offspring vulnerable to disease/environment.

• Sexual Reproduction:

  • Advantages: Genetic diversity, increased survival chance, eliminates harmful mutations.

  • Disadvantages: Slower, two parents needed, fewer offspring.

• Speciation: Development of two or more separate species.

• Isolation: Contributes to evolution by causing isolated species to become more different.

• Patterns of Evolution:

  • Divergent Evolution: Closely related species become more different.

  • Convergent Evolution: Unrelated species become more similar.

  • Coevolution: Species evolve in response to one another.

• Examples of Evolution Patterns:

  • Convergent Evolution: Sharks and dolphins with streamlined bodies.

  • Coevolution: Hummingbirds and flowers evolving together.

  • Divergent Evolution: Wolves and domestic dogs with different traits.

  • Coevolution: Cheetahs and gazelles evolving greater speed.

• Adaptive Radiation: Single species diversifying into multiple species adapted to different food sources; Darwin’s finches are an example.

• Homologous Structures: Similar anatomical structures with different functions, indicating a common ancestor.

• Analogous Structures: Different anatomical structures with similar functions, showing similar adaptations to environments.

• Vestigial Structures: Structures that once had a function but no longer do, evidence that species evolved from preexisting species.

• Rates of Evolution:

  • Gradualism: Slow, constant change over time.

  • Punctuated Equilibrium: Rapid change followed by stability.

• DNA as Evidence: DNA is the best indicator of relatedness between species due to its genetic code.

Classification

• Six Kingdoms Characteristics:

  • Archaea: Prokaryotic, unicellular, both autotrophic and heterotrophic, cell wall (not peptidoglycan).

  • Eubacteria: Prokaryotic, unicellular, both autotrophic and heterotrophic, cell wall (peptidoglycan).

  • Protista: Eukaryotic, both unicellular & multicellular, both autotrophic and heterotrophic, cell wall (in some).

  • Fungi: Eukaryotic, mostly multicellular (some unicellular), heterotrophic, cell wall (chitin).

  • Plantae: Eukaryotic, multicellular, autotrophic, cell wall (cellulose).

  • Animalia: Eukaryotic, multicellular, heterotrophic, no cell wall.

• Kingdom Identification Examples:

  • Organism A (Eubacteria): Prokaryotic, unicellular, peptidoglycan cell wall.

  • Organism B (Fungi): Multicellular, non-motile, heterotrophic decomposer.

  • Organism C (Archaea): Unicellular, prokaryotic, cell wall lacking peptidoglycan, found in extreme environments.

  • Organism D (Plantae): Multicellular, photosynthetic autotroph, cellulose cell wall.

  • Organism E (Animalia): Heterotroph, no cell wall, non-motile, eukaryotic.

• Similarities Between Plants and Fungi: Both have cell walls, can be multicellular, non-motile.

• Differences Between Bacteria and Archaebacteria:

  • Bacteria in common environments, archaebacteria in extreme environments.

  • Different cell wall structures and genetic sequences.

  • Archaebacteria more closely related to eukaryotes.

• Differences Between Eukaryotic and Prokaryotic Organisms:

  • Eukaryotic cells have a nucleus and membrane-bound organelles; prokaryotic cells do not.

  • Eukaryotes can be multicellular or unicellular; prokaryotes are almost always unicellular.

  • Eukaryotes include plants, animals, fungi, and protists; prokaryotes include bacteria and archaea.

• Endosymbiotic Theory: Prokaryotes engulf other prokaryotes, which become organelles; this explains the evolution of eukaryotic cells.

• Cladogram Interpretation:

  • Shared traits and common ancestors can be determined from a cladogram.

  • Example: Birds share the most recent common ancestor with crocodiles.

• Virus Classification: Viruses are considered non-living because they need a host to reproduce and are not cellular.

• DNA and Living Organisms: Organisms must contain the DNA to be considered living.

Ecology

• Niche: The role or job an organism has in its environment.

• Abiotic vs. Biotic Factors:

  • Abiotic: Non-living factors (e.g., water, weather).

  • Biotic: Living or once-living factors (e.g., competition, predators).

• Food Web Analysis:

  • Primary Consumers: Grasshopper, butterfly, fruit fly.

  • Secondary Consumers: Rat, dragonfly, thrush.

  • Primary Producers: Corn, flowering plant, lavender, mangoes.

  • Food Chain Example: Mangoes → Fruit fly → thrush → eagle.

  • Predator-Prey Relationship: Wolf (predator), rat (prey).

  • Competition: Frog and dragonfly compete for butterfly.

• Impact of Population Changes:

  • If rat population decreases: Python population decreases, grasshopper population increases, corn population may increase.

• Ecological Pyramids:

  • Trophic Level Labels: Leaves → insects → mice → red fox.

  • Energy Amount: Least at the tertiary level, most at the producer level.

  • Energy Loss: Energy lost as heat due to metabolic processes; only ~10% passed on to the next level.

• Energy Calculation Examples:

  • 75,000 kcal at producer level → 750 kcal at secondary consumer level (75,000 ems 10\% = 7,500; 7,500 ems 10\% = 750).

  • 670 kcal at secondary consumer level → 6,700 kcal at primary consumer level (670 iv 10\% = 6,700).

• Keystone Species: Disproportionately large effect on ecosystem, maintains biodiversity.

  • Example: Sea otters control sea urchin populations; removal leads to kelp forest destruction.

• Population Growth:

  • Logistic growth levels off at carrying capacity.

  • Carrying capacity is the maximum number of individuals an environment can sustain (80 individuals in the example graph).

  • Factors affecting carrying capacity: limited food, space, predation, disease, competition.

  • Exponential growth is rapid and unsustainable due to resource depletion.

• Limiting Factors:

  • Density-dependent: Affect populations based on size (disease, competition, predation).

  • Density-independent: Affect populations regardless of size (natural disasters, climate events).

• Ecological Succession:

  • Primary Succession: Ecosystem development from bare rock (no soil).

  • Secondary Succession: Ecosystem recovery where soil remains.

  • Pioneer Species: First organisms to colonize an area (lichens, mosses).

  • Climax Community: Stable, mature ecosystem.

• Stages of Primary Succession:

  1. Lava or rocks.

  2. Lichens/mosses.

  3. Grasses and flowers.

  4. Small shrubs and trees.

  5. Climax forest.

• Succession Examples:

  • Secondary Succession: Weeds and grasses grow in a vacant lot.

  • Primary Succession: Mosses and lichens grow on bare volcanic rock.

  • Secondary Succession: Spruce seedlings sprout after logging.

• Comparison of Primary and Secondary Succession:

  • Primary succession takes longer because soil must be formed from rock.

  • Primary succession pioneer species: lichens, mosses (break down rock).

  • Secondary succession pioneer species: grasses, weeds (require existing soil).

• Carbon Cycle:

  • Carbon transfer from animals to plants: respiration (CO₂), decomposition.

  • Deforestation impact: Reduces CO₂ absorption, increases atmospheric carbon.

• Nitrogen Cycle:

  • Bacteria needed to fix atmospheric nitrogen into usable forms.

  • Atmospheric nitrogen must be converted into absorbable forms for plants.

  • Plants receive nitrogen from nitrates in soil; animals get it by eating plants/animals.

  • Human impact: Fertilizers, fossil fuels, and waste disrupt nitrogen balance.

• Phosphorus Cycle:

  • Unique because it lacks an atmospheric component; phosphorus is found in rocks, soil, and water.

  • Fertilizer advantages: Boosts plant growth.

  • Fertilizer disadvantages: Causes runoff, algal blooms, and water pollution.

• Natural Selection: Organisms better adapted to their environment survive and reproduce.

• Genetic Variation: Differences in traits within a population.

• Adaptation: Traits that enhance survival and reproduction (e.g., dark fur in rock pocket mice for camouflage).

• Genetic Drift: Random changes in trait distribution.

• Bottleneck Effect: Population reduction due to random events (e.g., natural disasters).

• Asexual Reproduction: Fast but lacks genetic diversity.

• Sexual Reproduction: Slower but enhances genetic diversity.

• Speciation: Development of new species often due to isolation.

• Evolution Patterns:

  • Divergent: Related species become different.

  • Convergent: Unrelated species become similar.

  • Coevolution: Species evolve in response to each other.

• Adaptive Radiation: Single species diversifying into multiple forms (e.g., Darwin’s finches).

• Homologous Structures: Similar structures indicate a common ancestor.

• Analogous Structures: Different structures serving similar functions indicate similar adaptations.

• Vestigial Structures: Non-functional remnants from ancestors.

• Evolution Rates:

  • Gradualism: Slow changes.

  • Punctuated Equilibrium: Rapid changes followed by stability.

• DNA Evidence: DNA shows genetic relationships among species.

• Six Kingdoms Characteristics:

  • Archaea: Prokaryotic, unicellular, varying nutrition.

  • Eubacteria: Prokaryotic, unicellular, peptidoglycan cell wall.

  • Protista: Eukaryotic, diverse forms.

  • Fungi: Eukaryotic, multicellular, chitin cell wall.

  • Plantae: Eukaryotic, multicellular, cellulose cell wall.

  • Animalia: Eukaryotic, multicellular, heterotrophic, no cell wall.

• Virus Classification: Non-living, needs a host to reproduce.