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Gd 10 - Life Sciences 2017 > Ecosystems > Flashcards

Flashcards in Ecosystems Deck (73):



Small enclosed (glass) case holding:

  • a mini terrestrial ecosystem
  • a mini aquatic ecosystem



  • Living and non-living parts of a particular area
  • that interact together
  • parts termed biotic and abiotic
  • can be any size


Biotic factors

Living organisms


Abiotic factors

Non-living parts of an ecosystem

E.g. Soil, water, temperature and sunlight



  • Make their own food from abiotic factors
  • Also called autotrophs
  • photosynthesis uses sunlight, water and carbon dioxide to make glucose and oxygen


Examples of producers

  • Plants
  • Algae
  • Cyanobacteria


Plants which grow in water



Plants growing on land that need a moderate supply of water



Plants that grow in very dry regions




  • Organisms that must eat to get food
  • also called heterotrophs
  • E.g. animals


Different trophic levels of consumers

  • Primary consumers - eat producers
  • Secondary consumers - eat primary consumers
  • Tertiary consumers - eat secondary consumers


Different modes of feeding

Herbivores - only eat plants

Omnivores - eat both plants and animals e.g. Humans

Predators - eat different animals by hunting

Scavengers - eat leftovers



  • Break down organic material (organisms and wastes) to get their food
  • also called saprotrophs
  • return inorganic nutrients to the environment


Physiographic factors

Abiotic factors to do with position and shape of area

  • slope
  • aspect
  • altitude


Slope and slope effects of an ecosystem

How steep or flat an area is (inclination)

  • runoff
  • soil erosion rates
  • soil depth
  • soil fertility
  • types of plants and animals


Aspect of an ecosystem

Direction it faces (e.g. north, south, east or west)

  • amount of sunlight hitting the ecosystem
  • amount of rain, evaporation and moisture
  • depending on prevailing winds in the area
  • how sheltered
  • plant and animals living there


How aspect affects Table Mountain ecosystems

  • South slopes cool and moist
  • e.g. Newlands = forest
  • North slopes warm and dry
  • e.g. Front of table mountain = fynbos


Altitude (elevation) effects on ecosystems

Height above sea level (elevation) 

As you go up:

  • temperatures get cooler
  • amount of precipitation increases
  • solar radiation increases
  • wind increases
  • fewer plant and animal species


Edaphic factors

Soil factors

  • pH
  • humus content
  • soil texture
  • soil air
  • Water-holding capacity
  • Water drainage


pH of soil

  • How alkaline or acidic
  • pH less than 7 is acidic
  • pH greater than 7 is alkaline
  • pH of 7 is neutral
  • different plants live in different levels


Humus content of soil

  • How much dead and decaying plant and animal material
  • humus makes soil fertile
  • provides nutrients
  • keeps oxygen in soil
  • holds water but allows excess to drain away


Soil texture

Different sized soil particles

  • sand - large particles
  • silt - small particles
  • clay - tiny particles


Properties of sandy soil

  • Large air spaces
  • allows water to pass through easily
  • low water retention
  • higher leaching of nutrients


Properties of clay rich soil

  • Tiny air spaces
  • does not drain easily
  • becomes waterlogged easily
  • high water retention


Loam soil

  • Mixture of all particle sizes and humus
  • excess water drains quickly
  • holds a good amount of water
  • lots of air in the soil
  • Generally rich in nutrients


Soil air

  • Found in spaces between soil particles
  • sand has large spaces
  • clay has small spaces
  • more air the more oxygen available for plant roots


Investigation of soil water retention

  • Different types of soil
  • each put into filter
  • Same volume of water added to each
  • Measure amount of water retained by each


Investigation of soils rate of drainage

  • Different types of soil each put into filter
  • Same volume of water added to each
  • Measure amount of time for water to stop draining


Physical factors in an ecosystem

  • Sunlight
  • Temperature
  • Water
  • Atmospheric gases


Sunlights effects on an ecosystem

Main source of energy

  • plants use sunlight during photosynthesis
  • more plants grow where there is higher light intensity
  • some plants suited to lower intensity (e.g. ferns)



How organisms respond to the length of day and night

  • effect on plant growth or
  • flowering when the day is longer or shorter
  • also affects behaviour in animals



  • Animals more active at night
  • e.g. moths and bats



Animals more active in the day


Ectothermic animals

  • Cold-blooded animals
  • Animals that cannot regulate their own body temperature.
  • Become inactive when the temperature is too hot or cold
  • E.g. fish, amphibians, reptiles


Endothermic animals

  • Warm-blooded animals
  • Regulate their body temperatures at a constant temperature
  • environment does not affect body temperature
  • e.g. mammals and birds


How some animals survive seasonal changes in temperature

  • Migration (e.g. Birds)
  • Hibernation in cold months (e.g. Snakes and rodents)
  • Aestivation in hot months (e.g. Snails and insects)


How some plants survive seasonal changes in temperature

  • Deciduous (dormant in winter) shed leaves and become inactive (e.g. Oak)
  • Above surface parts die back with underground storage (e.g. Potato)
  • Annuals die and leave seeds (e.g. Daisies)


Limiting factors

A factor that limits the presence or growth of a particular type of organism

  • Too little of something
  • Too much of something
  • E.g. Too little or too much water for a terrestrial plant


Xerophyte adaptations to conserve water

Limit water loss:

  • Waxy cuticle
  • bark on stems
  • leaves modified to be smaller to reduce surface area
  • thick organs to store water (e.g. succulents)

Increase water uptake:

  • shallow, branched roots to rapidly absorb surface water
  • long taproots to reach underground water


Hydrophyte adaptations to survive excess water

  • floating leaves
  • Stoma on top surface of leaf to absorb gases
  • waxy cuticle on upper surface to encourage water to run off
  • little or no xylem (a plant tissue for transporting water)
  • large air spaces between cells to encourage floatation.


Animal adaptations to conserve water

  • Scaly skins to reduce water loss
  • Excess water removed before urine formed in kidneys
  • Nocturnal behaviour


Gases in the atmosphere

  • Oxygen (21%)
  • Carbon dioxide (0,035%)
  • Nitrogen (78%)
  • Water vapour (variable)


Importance of oxygen in air

  • Produced by plants during photosynthesis
  • Used for cellular respiration in animals and plants


Importance of carbon dioxide in the air

  • Produced by animals and plants during cellular respiration
  • Plants need it for photosynthesis
  • Increased levels due to human activity causes climate change


Importance of nitrogen in the air for organisms

  • Converted into usable forms by bacteria
  • Plants need nitrogen to make proteins


Wind in ecosystems

  • affects rainfall
  • affects transpiration and evaporation in plants 
  • wind disperses seed and spores in plants and fungi


Energy in an ecosystem is mainly lost as...

Heat loss from each trophic level


Food chains

  • Shows energy flow from one organism to the next as a flow diagram
  • Arrows indicate direction of energy flow


Levels in a food chain

Trophic or feeding level


Food webs

  • Many interlocking food chains
  • Shows most of the feeding relationships in a community
  • Shows organisms with specialised and limited diets
  • Shows organisms with varied diets


Food pyramids

Diagrams showing 'how much' at each trophic level

Include measurements of:

  • numbers
  • biomass
  • energy


Energy amount generally passed on to the next trophic level

  • 10%
  • I.e. 90% is lost in the form of heat


Effect of energy lost as heat at each trophic level

  • Organisms at the top of the food pyramid ultimately are using vastly more food to survive
  • There are able to be fewer carnivores than herbivores in any ecosystem


Problems with using pyramids of numbers

Does not account for:

  • Organisms size
  • How quickly they reproduce


Problems with using pyramids of biomass

Does not account for how quickly organisms reproduce


Biomass measurement

  • Using the organic molecules to estimate amount of energy
  • Dry mass (e.g. kg) is measured for fair comparisons


Steps in drawing an energy pyramid

  1. Lightly draw in pencil a set of rough axes (extending the 'x-axis' on both sides of the 'y-axis' forming an upside down T on your page)
  2. Start with the producers at the bottom and choose a suitable x-axis scale (e.g. 1cm = 1000Kj)
  3. Draw the producers bar to the length representing the energy of producers (extending equally on both sides of the y-axis).
  4. Using the same scale repeat for all trophic levels (ensure height of bars is equal)
  5. Label each trophic level and provide a title for the pyramid.
  6. Erase the rough axes.


Nutrient cycles

  • Fixed amount of nutrients in biosphere
  • these need to be cycled over and over in ecosystems
  • e.g. water, carbon, nitrogen and oxygen cycles


Water cycle

Driven by suns energy

  • Evaporation of water from land and sea
  • Water vapour condenses into clouds
  • Water falls as precipitation
  • Leaves land as run-off in streams and rivers

Biotic element:

  • Take water in through roots or by consuming it
  • Lost by evaporation: transpiration (plants) and excretion (animals)


Carbon cycle

  • Plants take in carbon dioxide from atmosphere and make glucose through photosynthesis
  • Glucose metabolised by plants into other organic compounds
  • Animals get carbon by eating plants
  • Animals and plants respire releasing carbon dioxide as waste back into the atmosphere
  • Decomposers break down organic matter and carbon dioxide returns to the atmosphere
  • Some carbon is fossilised (e.g. coal)
  • When carbon rich material burnt, carbon dioxide returns to the atmosphere


Three ways nitrogen is converted to nitrates for plants

  • Nitrogen fixing bacteria
  • lightning
  • Nitrifying bacteria


Nitrogen fixing bacteria

  • Often found in soil and in root nodules
  • e.g. Legume plants
  • Can absorb nitrogen gas and convert it to nitrates
  • Nitrates used by plants to make proteins


Role of lightning in nitrogen cycle

High temperatures causes nitrogen and oxygen to form oxides which dissolve in water and form nitrates in soil


Role of nitrifying bacteria in nitrogen cycle

  • Dead organism proteins and wastes are rich in nitrogen compounds
  • which are broken down and converted into nitrates


Role of denitrifying bacteria in the nitrogen cycle

Convert some nitrates back into nitrogen gas


Oxygen cycle

  • Oxygen produced from photosynthesis
  • Used by organisms during cellular respiration
  • Linked closely with the carbon cycle
  • Oxygen also found as ozone (molecule with three atoms of oxygen) which protects biosphere from UV radiation



  • Visitors travelling in a caring and responsible way to natural areas
  • Enjoying the area in a way that conserves the environment
  • and improves the well-being of local people



People with an interest in and involved in something


Examples of stakeholders in an ecotourism area

  • Developers building infrastructure
  • Tourism companies bringing in tourists
  • The tourists themselves
  • Local communities providing services


Some economic benefits of ecotourism

  • Local people can earn money without harming the environment
  • Traditional lifestyle must be preserved
  • Brings in money for national parks and country as a whole


Ethics and doing things ethically

Things done in a moral, thoughtful, acceptable and correct way


Why it is important to involve local inhabitants in ecotourism

  • for long term success, locals need to become stakeholders
  • prevents problems and conflicts between stakeholders
  • avoid negative environmental, social and cultural effects by empowering locals
  • encourages locals to conserve environment and culture
  • traditions and lifestyles respected
  • more likely to support conservation laws


Opportunities of ecoturism

  • Education and training of local communities
  • Job opportunities for local communities
  • Appropriate infrastructure developed