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3.7.7Additional lessons

Community: Interspecific Relationships — IB Biology SL Revision Notes & Topical Questions

5 min read 5 parts Lesson 88 of 142

📚 IB Biology SL Hub / Topical Revision
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Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
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Part 1 of 5The Community

Community
  • Community All the populations of different species that live and interact in the same area.
Interaction
  • Interaction Species rarely live in isolation, so each affects the survival of others in its community.
Interspecific
  • Interspecific Interspecific means occurring between individuals of two or more different species.
Symbiosis
  • Symbiosis A close, long-term relationship between two species.

Part 2 of 5Types of Interaction

Herbivory
  • Herbivory A herbivore feeds on plant tissues, usually without killing the whole plant.
Predation
  • Predation A predator kills and eats prey, which benefits the predator but kills the prey.
Parasitism
  • Parasitism A parasite lives on or in a host and feeds from it, harming the host but usually not killing it quickly.
Mutualism
  • Mutualism Both species benefit, as when mycorrhizal fungi supply minerals to a plant in return for sugars.
Competition
  • Competition Species use the same limited resource, so both are harmed.
InteractionSpecies 1Species 2
MutualismBenefitsBenefits
PredationBenefitsHarmed
ParasitismBenefitsHarmed
HerbivoryBenefitsHarmed
CompetitionHarmedHarmed

Part 3 of 5Examples

Examples
Mutualism
  • Mutualism Rhizobium bacteria in legume root nodules fix nitrogen, and the plant gives them sugars.
Mutualism
  • Mutualism Coral polyps host photosynthetic algae and receive organic compounds from them.
Parasitism
  • Parasitism A tapeworm in the human gut absorbs digested food and harms its host.
Herbivory
  • Herbivory A cow grazing on grass takes plant tissue without killing the whole plant.

Part 4 of 5Predation versus Parasitism

1
A predator usually kills its prey quickly and is often larger than the prey.
2
A parasite is usually smaller than its host and feeds on it for a longer time.
3
Both relationships benefit one species at the expense of the other.
4
Over time, both can drive adaptations such as defences in prey and host resistance.

Part 5 of 5Exam Checklist & Tips

3.7.7 – Key Points for the Exam

  • Community All the populations in a given area.
  • Mutualism An interaction in which both species benefit.
  • Parasitism An interaction in which a parasite benefits and the host is harmed.
  • Herbivory Feeding on plants.
  • Symbiosis A close and long-term relationship between two species.

Common Mistakes

  • Labelling every symbiosis as mutualism.
  • Writing that parasites always kill their hosts quickly.
  • Describing herbivory as predation without noting the plant usually survives.
  • Saying competition benefits both species.

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