7. AQA GCSE Biology: Ecology questions and solutions

7. AQA GCSE Biology: Ecology questions and solutions

Ecosystem - answersThe interaction of a community of living organisms with the non-living parts of their
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environment
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What is a community made up of? - answersThe populations of different species or organisms that are all
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interdependent in a habitat
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Habitat - answersThe environment in which an organism lives
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Population - answersThe total number of organisms of the same species living in the same geographical area
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Interdependence - answersThe way in which each species within a community depends on other species for food, wu wu wu wu wu wu wu wu wu wu wu wu wu wu wu wu




shelter, pollination, seed dispersal etc
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Competition - answersThe process by which living organisms compete with each other for limited resources
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(such as food, light or reproductive partners)
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What do organisms require to survive and reproduce? - answersA supply of materials from their surroundings and
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from the other living organisms there
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What do plants often compete with each other for? (4) - answersLight, space, water, and mineral ions from the soil
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What do animals compete with each other for? (3) - answersFood, mates and territory
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Stable community - answersWhere all the species and environmental factors are in balance so that population
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sizes remain fairly constant
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What happens if one species is removed from a community? - answersIt can affect the whole community
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Abiotic factors - answersNon-living factors
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Biotic factors - answersLiving factors
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Name 7 abiotic factors and how they might affect a community - answersLitmuswoc
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1. Light intensity - photosynthesis, breeding cycles linked to day length
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2. Temperature - photosynthesis/plant growth, therefore animals which can survive
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3. Moisture levels - both plants and animals need water to survuve
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4. Soil pH and mineral content - distribution of plants, most struggle to grow where there is few mineral ions; low pH
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inhibits decay and therefore release of mineral ions
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5. Wind intensity and direction - shape of trees and landscape, increases plant transpiration
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6. Availability of oxygen - aquatic animals e.g. fish require high levels of dissolved oxygen
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7. Availability of carbon dioxide - photosynthesis
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Name 4 biotic factors and how they might affect a community - answersFPOP
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, 1. Availability of food - food allows animals to survive and breed successfully
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2. New predators arriving - organisms with no defences against these predators may die out
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3. One species outcompeting another so the numbers are no longer sufficient to breed - e.g. grey squirrels in
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Britain
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4. New pathogens - organisms have no resistance so populations can be wiped out
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Adaptations - answersFeatures which enable an organism to survive in the conditions in which they normally live
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Adaptations may be... - answers...structural, functional or behavioural wu wu wu wu wu wu wu




Examples of structural adaptations (4) - answersFeatures of body structure, shape or colour - e.g. animals living in
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cold environments have small ears (low SA:vol ratio), Arctic foxes have white fur, whales have blubber,
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herbivores have teeth for grinding up plant cells
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Examples of behavioural adaptations (3) - answersBasking, migration, tool use - e.g. reptiles bask to absorb
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energy from the sun and warm up, birds migrate, nocturnal to avoid heat of day
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Examples of functional adaptations (3) - answersProcesses inside body like metabolism and reproduction - e.g.
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delayed implantation of embryos, reduced sweating, organisms in extreme winter temperatures produce a
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chemical in cells which acts as an antifreeze
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Extremophiles - answersOrganisms that live in very extreme environments, such as high temperature, pressure wu wu wu wu wu wu wu wu wu wu wu wu wu




or salt concentration
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Example of extremophiles - answersbacteria living in deep sea vents (at very high pressure, no light, acid pH)
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Photosynthetic organisms are... - answers...the producers of biomass for life on earth wu wu wu wu wu wu wu wu wu wu wu




How can feeding relationships within a community be represented? - answersWith food chains
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Describe the structure of food chains, giving examples. (3) - answers1. All food chains begin with a producer
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which synthesises molecules e.g. green plants, algae, which make glucose by photosynthesis
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2. Primary consumers eat producers
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3. In turn these may be eaten by secondary and then tertiary consumers
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Predators - answersConsumers that eat and kill other animals wu wu wu wu wu wu wu wu




Prey - answersAnimals eaten by predators
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In a stable community, the numbers of predators and prey... - answers...rise and fall in cycles
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What are 2 methods used by ecologists to determine the distribution and abundance of species in a ecosystem? -
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answersTransects and quadrats
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Quadrat - answersA square made of wire used to estimate population size of plants or slow moving animals. It may
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have smaller squares of wire within it.
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