Key Takeaways for Adaptations, Interdependence, and Competition

1. Communities

  • Population: All organisms of the same species in a geographical area (e.g., all grey squirrels in the UK).
  • Community: Multiple populations of different species living together (e.g., lions, zebras, and grass in the African savannah).
  • Competition:
    • Intraspecific: Same species competing (e.g., two hair grass plants in Antarctica).
    • Interspecific: Different species competing (e.g., lions vs. hyenas for prey).

Tip: Use Darwin’s “struggle for existence” to explain why competition drives evolution.

2. Plant Competition

Plants compete for:

  • Light (e.g., bluebells flower early before trees block sunlight).
  • Water, nutrients, and space (e.g., rainforest seedlings racing to fill a gap).

Key Rule: Plants disperse seeds to reduce competition (e.g., dandelion seeds carried by wind).

Math Example:
If a tree canopy allows 20% light penetration, calculate light available at ground level:
Light=100%−80%=20%Light=100%−80%=20%

3. Animal Competition

Animals compete for:

  • Food (e.g., lions scavenging hyena kills).
  • Mates (e.g., alpha male gorillas dominating breeding).
  • Territory (e.g., domestic cats fighting over gardens).

Adaptation Tip: Structural features (sharp teeth) and behaviours (courtship displays) improve survival chances.

4. Interdependence

  • Predator-prey cycles: Lynx and snowshoe hare populations rise and fall in cycles (Figure 18.6).
  • Stable communities: Balanced predator-prey ratios ensure survival.

Graph Tip: In exams, describe peaks/troughs and time lags (e.g., prey numbers drop after predator numbers rise).

5. Abiotic Factors

Non-living environmental factors:

  • Light: Affects photosynthesis (e.g., hostas in shade have large leaves).
  • Soil pH: Hydrangeas change flower colour (pink in acidic soil, blue in alkaline).
  • Temperature: Determines tree lines in the Arctic.

Key Reaction: Adding lime (calcium carbonate) to reduce acidity:
CaCO3+2H+→Ca2++CO2+H2OCaCO3​+2H+→Ca2++CO2​+H2​O

Exam Tip: Link abiotic factors to plant adaptations (e.g., cactus spines reduce water loss).

6. Biotic Factors

Living factors affecting communities:

  • Invasive species: Grey squirrels outcompete red squirrels due to higher fat storage and immunity to disease.
  • Disease: Myxomatosis reduced UK rabbit populations by 95%.

Math Example: Calculate red squirrel percentage in the UK:
15, ⁣00015, ⁣000+2, ⁣500, ⁣000×100≈0.6%15,000+2,500,00015,000​×100≈0.6%

7. Adaptations

  • Structural: Polar bear fur for insulation.
  • Behavioural: Emperor penguins huddling to conserve heat.
  • Physiological: Venom production in snakes.

Mimicry Example: Hoverflies mimic wasps to deter predators.

Tip: Always link adaptations to survival advantages (e.g., giraffe’s long neck for reaching leaves).

8. Extreme Environments

  • Polar regions: Emperor penguins survive -89°C by huddling.
  • Hydrothermal vents: Extremophile bacteria use chemosynthesis.

Key Term: Extremophiles thrive where most life cannot (e.g., bacteria in boiling vents).

Exam Technique

  • Define terms first (e.g., “A population is…”).
  • Use SPECIFIC examples (e.g., “Cane toads in Australia”).
  • Label graphs fully (axes, units, trends).

Practice Question Tip: For experiments (e.g., penguin huddling), evaluate control variables and anomalous results.

Summary: Adaptations enhance survival, competition shapes communities, and interdependence maintains ecosystems. Use real-world examples and equations to secure top marks! 🌱🔬

50 GCSE Biology Questions: Adaptations, Interdependence, and Competition

Section A: Definitions and Key Concepts

  1. Define the term population.
  2. What is a community in ecological terms?
  3. Explain the difference between intraspecific and interspecific competition.
  4. Define interdependence in a community.
  5. What is an alpha male?
  6. What does abiotic factor mean? Give three examples.
  7. Define biotic factor and provide two examples.
  8. What is an invasive species?
  9. Explain the term extremophile.
  10. What is predator-prey cycling?

Section B: Plant Competition

  1. Name three resources plants compete for in a rainforest.
  2. Why do bluebells flower in early summer?
  3. How does seed dispersal reduce competition between plants?
  4. Explain why adding lime (calcium carbonate) reduces soil acidity.
  5. Calculate the percentage of light reaching the forest floor if a tree canopy blocks 85% of sunlight.

Section C: Animal Competition

  1. What do lions and hyenas compete for?
  2. Describe two resources domestic cats might compete for.
  3. How does being an alpha male benefit a gorilla?
  4. Why might grey squirrels outcompete red squirrels?
  5. Explain Darwin’s concept of the “struggle for existence”.

Section D: Abiotic Factors

  1. How does soil pH affect hydrangea flower colour?
  2. Why can’t trees grow beyond the Arctic tree line?
  3. Explain why cacti die if moved to the UK.
  4. What happens when farmers add manure to fields?
  5. Describe how wind affects tree growth on coastlines.

Section E: Biotic Factors

  1. How did myxomatosis impact UK rabbit populations?
  2. Why are cane toads invasive in Australia?
  3. Explain how Dutch elm disease spread in Europe.
  4. Calculate the percentage of red squirrels in the UK if there are 15,000 red squirrels and 2.5 million grey squirrels.
  5. Why do grey squirrels store more fat than red squirrels?

Section F: Adaptations

  1. Give two structural adaptations of polar bears.
  2. How does mimicry help hoverflies survive?
  3. What behavioural adaptation do emperor penguins use to stay warm?
  4. Name a physiological adaptation in venomous snakes.
  5. Why do hosta plants have large, dark green leaves?

Section G: Extreme Environments

  1. How do extremophiles survive near hydrothermal vents?
  2. Describe the conditions in Antarctica.
  3. Why is there no photosynthesis at deep-sea vents?
  4. What is chemosynthesis?
  5. Name two animals adapted to polar regions.

Section H: Data and Experiments

  1. Interpret Figure 18.6: Why do lynx numbers lag behind hare numbers?
  2. Design an experiment to compare lichen growth on north- vs. south-facing tree sides.
  3. Evaluate the method for the penguin huddling experiment (Figure 18.21).
  4. What conclusion can be drawn from the penguin huddling experiment?
  5. Why might global warming threaten bluebell reproduction?

Section I: Extended Response

  1. Explain how biotic and abiotic factors could affect a zebra herd.
  2. Discuss the impact of introducing invasive species on native ecosystems.
  3. Why are predator-prey cycles essential for stable communities?
  4. Compare structural, behavioural, and physiological adaptations with examples.
  5. How do hydrothermal vents challenge traditional food web models?

Detailed Answers

Section A

  1. Population: All organisms of the same species in a geographical area (e.g., UK grey squirrels).
  2. Community: Multiple populations interacting in the same area (e.g., lions, zebras, grass).
  3. Intraspecific: Same species compete (hair grass in Antarctica). Interspecific: Different species compete (lions vs. hyenas).
  4. Interdependence: Species rely on each other; disrupting one affects others (e.g., phytoplankton → zooplankton → fish).
  5. Alpha male: Dominant male in a group (silverback gorilla).
  6. Abiotic factors: Non-living environmental factors (light, soil pH, temperature).
  7. Biotic factors: Living factors (predators, disease, invasive species).
  8. Invasive species: Non-native organism harming ecosystems (cane toads in Australia).
  9. Extremophile: Organism thriving in extreme conditions (hydrothermal vent bacteria).
  10. Predator-prey cycling: Linked population fluctuations (lynx-hare cycles).

Section B

  1. Light, water, nutrients.
  2. To avoid competition with trees for light after canopy closure.
  3. Seeds spread far reduce parent-offspring competition (dandelion wind dispersal).
  4. Reaction:
    CaCO3+2H+→Ca2++CO2+H2OCaCO3​+2H+→Ca2++CO2​+H2​O
  5. Calculation:
    Light=100%−85%=15%Light=100%−85%=15%

Section C

  1. Food (scavenging kills).
  2. Territory, mates.
  3. Mates with all females, dominates breeding.
  4. Grey squirrels store more fat, breed faster, and are immune to pox virus.
  5. Competition drives evolution; only the fittest survive.

Section D

  1. Acidic soil → pink flowers; alkaline soil → blue flowers.
  2. Insufficient light/temperature for tree growth.
  3. UK’s excess water drowns cacti adapted to deserts.
  4. Adds nutrients but increases acidity; farmers add lime to neutralise.
  5. Wind stunts growth; trees grow bent (hormones overpowered).

Section E

  1. Reduced rabbit populations by 95% in 2 years.
  2. No natural predators; poison native Australian species.
  3. Fungus spread by beetles killed 25 million UK elms.
  4. Calculation:
    15, ⁣00015, ⁣000+2, ⁣500, ⁣000×100≈0.6%15,000+2,500,00015,000​×100≈0.6%
  5. Larger size allows greater fat storage for winter survival.

Section F

  1. Thick fur, small ears (reduce heat loss).
  2. Mimic wasps’ coloration to deter predators.
  3. Huddle in circles to conserve heat.
  4. Venom production for hunting/defence.
  5. Maximise light absorption in shade.

Section G

  1. Bacteria use chemosynthesis with sulfur compounds.
  2. Temperatures below -89°C; 24-hour daylight in summer.
  3. No sunlight; energy comes from chemicals (chemosynthesis).
  4. Process using chemicals (not sunlight) to produce energy.
  5. Polar bears (Arctic), emperor penguins (Antarctic).

Section H

  1. Predator numbers rise after prey peaks due to reproduction lag.
  2. Measure lichen coverage on both sides; control for tree species/age.
  3. Evaluation: Test tube groups may not mimic penguin huddles; improve with insulation controls.
  4. Huddling reduces heat loss (slower cooling in grouped tubes).
  5. Early flowering may mismatch pollinators’ active periods.

Section I

  1. Biotic: Predators, disease. Abiotic: Drought, temperature.
  2. Invasives outcompete natives (grey vs. red squirrels), disrupt food webs.
  3. Prevents overpopulation, maintains ecosystem balance.
  4. Structural: Polar bear fur. Behavioural: Penguin huddling. Physiological: Snake venom.
  5. Food webs rely on chemosynthesis, not photosynthesis.

Tip: Revise using past papers and flashcards for key terms! 🌿🔍