AP Bio

### In-Depth Review of AP Biology Chapters 53–55

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#### 1. Survivorship Curves

- Type I (Convex): Low juvenile mortality, high survival until old age (e.g., humans, elephants). Energy is invested in parental care.

- Type II (Linear): Constant mortality risk across all ages (e.g., squirrels, some birds). Deaths are unrelated to age.

- Type III (Concave): High early mortality, but survivors live long (e.g., fish, insects). Many offspring with minimal care.

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#### 2. Population Estimation Methods

- Quadrat Method:

- Use: Stationary organisms (plants, corals). Grid squares sample density.

- Limitations: Misses patchy distributions; assumes uniformity.

- Mark-Recapture:

- Use: Mobile animals. Formula: \( \text{Population} = \frac{\text{Marked in 1st catch} \times \text{Total in 2nd catch}}{\text{Recaptured marked}} \)

- Limitations: Assumes closed population, no mark loss, and equal catchability.

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#### 3. Exponential vs. Logistic Growth

- Exponential Growth:

- Equation: \( \frac{dN}{dt} = rN \)

- Phases: Lag (slow initial growth) → Exponential (J-curve).

- Causes: Unlimited resources (e.g., invasive species colonizing new habitat).

- Logistic Growth:

- Equation: \( \frac{dN}{dt} = rN \left(\frac{K - N}{K}\right) \)

- Phases: Lag → Exponential → Deceleration → Stabilization at \( K \).

- Causes: Resource limitation (e.g., carrying capacity \( K \) for food, space).

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#### 4. Energetic Trade-Off

- Organisms allocate energy among growth, reproduction, and maintenance.

- Example: A bird investing energy in fewer, well-cared-for offspring (K-selected) vs. many neglected offspring (r-selected).

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#### 5. K-selected vs. r-selected Species

- r-selected: High \( r \) (reproductive rate), small body size, short lifespan (e.g., bacteria, weeds). Thrive in unstable environments.

- K-selected: Competitive specialists, large body size, parental care (e.g., elephants, whales). Stable environments near \( K \).

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#### 6. Boom and Bust Cycles

- Causes: Predator-prey dynamics (e.g., lynx-hare cycles), resource overexploitation, or climatic shifts (e.g., locust swarms after droughts).

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#### 7. Developed vs. Developing Countries

- Developed: Low birth/death rates, aging populations (e.g., Japan). Stage IV demographic transition.

- Developing: High birth rates, declining death rates, youth-heavy age pyramids (e.g., Nigeria). Stages II–III.

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#### 8. Age Structure Diagrams

- Pyramid: Rapid growth (broad base; developing nations).

- Column/Inverted Pyramid: Stable/declining populations (narrow base; developed nations).

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#### 9. Reducing Competition

- Resource Partitioning: Species use different resources (e.g., warblers feeding in tree layers).

- Character Displacement: Traits diverge to reduce overlap (e.g., finch beak sizes).

- Temporal/Spatial Avoidance: Active at different times or areas.

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#### 10. Symbiosis

- Mutualism (+/+): Clownfish-anemone.

- Commensalism (+/0): Barnacles on whales.

- Parasitism (+/-): Tapeworms in hosts.

- Predation (+/-): Wolf-deer.

- Competition (-/-): Lions and hyenas.

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#### 11. Fundamental vs. Realized Niche

- Fundamental Niche: Full potential range without competition (e.g., a barnacle’s ideal zone).

- Realized Niche: Actual range due to biotic constraints (e.g., restricted by competitors).

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#### 12. Competitive Exclusion Principle

- Two species cannot coexist in the same niche. Example: Paramecium species in lab cultures.

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#### 13. Mimicry and Aposematic Coloration

- Batesian: Harmless species mimics harmful (e.g., hoverfly vs. wasp).

- Müllerian: Multiple harmful species share warning signals (e.g., toxic butterflies).

- Aposematic Coloration: Bright colors warn predators (e.g., poison dart frogs).

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#### 14. Community Interactions

- +/+: Mutualism (bees-pollinators).

- +/0: Commensalism (epiphytes on trees).

- +/-: Predation, parasitism.

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#### 15. Keystone Species

- Disproportionate impact (e.g., sea otters control sea urchins, preserving kelp forests). Loss leads to trophic cascades.

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#### 16. Factors Affecting Community Diversity

- Intermediate Disturbance Hypothesis: Moderate disturbances (e.g., storms) maximize diversity.

- Resource Availability: High nutrients can reduce diversity via competitive exclusion.

- Latitudinal Gradient: Higher diversity near tropics due to stable climate and productivity.

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#### 17. Energy/Biomass Transfer

- 10% Rule: ~10% energy transferred between trophic levels; rest lost as heat.

- Biomass Pyramids: Inverted in aquatic systems (e.g., phytoplankton support larger zooplankton biomass).

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#### 18. Invasive Species

- Causes: Lack natural predators, rapid reproduction (e.g., kudzu, zebra mussels). Outcompete natives via superior traits.

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#### 19. Food Chains/Webs

- Function: Depict energy flow (producers → consumers → decomposers). Webs show complexity and interdependence.

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#### 20. Disturbance Effects

- Positive: Fire clears underbrush, promoting prairie diversity.

- Negative: Deforestation leads to soil erosion and biodiversity loss.

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#### 21. Biodiversity Hotspots

- Regions: Tropical rainforests, coral reefs. High due to stable climates and evolutionary history.

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#### 22. Zoonotic Diseases

- Examples: COVID-19, Ebola. High initial virulence due to lack of host adaptation; later, pathogens may evolve lower virulence to sustain transmission.

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#### 23. Energy Flow vs. Chemical Cycling

- Energy: Unidirectional flow (sun → autotrophs → heterotrophs → heat loss).

- Chemicals: Recycled via decomposition (e.g., carbon, nitrogen cycles).

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#### 24. Solar Energy Conversion

- Autotrophs: Convert solar energy to glucose (photosynthesis: \( 6CO_2 + 6H_2O → C_6H_{12}O_6 + 6O_2 \)).

- Losses: ~90% reflected/absorbed by atmosphere; only 1–2% used for photosynthesis.

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#### 25. Decomposers’ Role

- Function: Break down detritus, release nutrients (e.g., fungi, bacteria). Essential for nitrogen/phosphorus cycles.

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#### 26. Gross vs. Net Primary Production

- GPP: Total CO2 fixed by photosynthesis.

- NPP: GPP minus respiration (\( NPP = GPP - R \)). Represents biomass available to consumers.

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#### 27. Global NPP Factors

- Terrestrial: Light, temperature, rainfall (highest in tropical rainforests).

- Aquatic: Light penetration, nutrient availability (upwelling zones).

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#### 28. Eutrophication

- Cause: Excess nitrogen/phosphorus from fertilizers → algal blooms → hypoxia (dead zones).

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#### 29. Nitrogen Cycle Bacteria

- Nitrogen Fixation: Rhizobium converts N2 to NH3.

- Nitrification: Nitrosomonas (NH3 → NO2−), Nitrobacter (NO2− → NO3−).

- Denitrification: Pseudomonas converts NO3− → N2.

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#### 30. Energy Transfer Efficiency

- ~10% Efficiency: Due to metabolic heat loss, indigestible biomass, and waste.

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#### 31. Logged Rainforests’ Low Productivity

- Cause: Nutrient-poor soils (most nutrients stored in biomass). Logging removes organic matter, leading to rapid soil degradation.

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#### 32. Restoration Ecology Goals

- Objectives: Reestablish ecosystems (e.g., wetland restoration), enhance biodiversity, improve ecosystem services (water filtration).

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### Free Response Focus Areas

1. Carbon Cycle: Deforestation reduces decomposers, lowering CO2 absorption → increased atmospheric CO2.

2. Energy Flow: Deforestation disrupts food webs, reducing NPP and exacerbating climate change via reduced carbon sinks.

3. Logistic Growth: Density-dependent factors (disease, competition) stabilize populations near \( K \).

4. GPP/NPP: NPP decreases with trophic level due to energy loss (e.g., 10% rule).

5. Producers/Decomposers: Producers fix energy; decomposers recycle nutrients (e.g., nitrogen for plant uptake).

6. Nitrogen Cycle: Fertilizers → runoff → eutrophication; excess NOx → acid rain.

7. Chemical Cycling: Deforestation disrupts carbon storage → increased CO2 → climate change.

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This structured approach ensures mastery of key concepts, equations, and real-world examples essential for AP Bio success.