06. Ecology

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Habitat

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Description and Tags

80 Terms

1

Habitat

Place where an organism lives

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Features of a habitat

Provides and organism with all the resources it needs to survive and reproduce

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Describe a habitat (3)

  1. Geographical location

  2. Physical location

  3. Type of ecosystem

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4

Geographical location

  • Where habitat is found

  • May refer to the localised region of the habitat

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Geographical location examples (3)

  1. Latitude

  2. Longitude

  3. Climate

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Physical location

Characteristics of geographical area where the habitat is found

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Physical location examples (4)

  1. Landforms

  2. Water bodies

  3. Vegetation

  4. Microhabitats

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Ecosystem

Location where a community of organisms interact with each other and with the abiotic environment

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Biotic factors affect communities (4)

  1. Availability of food

    • Amount of food increase more food to feed animals → More likely to survive & reproduce → Population increase

    • Reverse happens for increase amount of food

  2. Number of predators

    • No. of predators increase → More prey is consumed → Population decrease

    • Reverse for decrease in no. of predators

  3. New pathogens

    • New pathogen → Population has no resistance → Wipe out quickly

  4. Competition

    • One species is more adapted to environment than others → Outcompete till number of lesser adapted species are insufficient to breed

    • Organisms compete with other species / same species for resources

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Abiotic factors affect communities (2) [1.→4] [2.→2]

  1. Environmental conditions

    • Temperature

      • Affect rate of photosynthesis

    • Light intensity

      • Light is needed for photosynthesis

      • Rate of photosynthesis affects rate of plant growth

      • Plants are food sources / shelters for many organisms

    • Moisture

      • Plants & animals need water to survive

    • Soil pH & Mineral content

      • Soil pH affect affect rate of decay & how fast mineral ions return to soil

      • Diff species of plants thrive on diff nutrient conc. levels

  2. Toxic chemicals

    • Fertiliser - Eutrophication

    • Pesticide build up in food chains - Bioaccumulation

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Adaptations of organisms to abiotic challenges within its habitat [marram grass in sand dunes]

  1. Leaves roll into tube w/ stomata inside

    • Trap moist air inside

    • Maintain high humidity outside stomata & reduce rate of transpiration

  2. Stomata has hair & is found in sunken pits

    • Traps moist air outside stomata

    • Reduce rate of transpiration

  3. Leaves have thick waxy cuticle

    • Reduce evaporation of water from leaves

  4. Long roots that reach deep into sand for water

  5. Extensive roots near surfaceHelps sand retain water

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Xerophyte

Thrives in dry conditions where most plants would curl up and die

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Adaptations of organisms to abiotic challenges within its habitat

  • Red mangrove tree in mangrove swamp [unstable soil]

  1. Prop roots from trunks for stability

  2. Widespread & shallow root system for additional support

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Adaptations of organisms to abiotic challenges within its habitat

  • Red mangrove tree in mangrove swamp [anoxic soil]

  • Aerial roots [pneumatophores] grow above soil

    • Low tide - Gas exchange happen through open passages

    • Air transported to parts of underground roots

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Adaptations of organisms to abiotic challenges within its habitat

  • Red mangrove tree in mangrove swamp [salt water] (1)

  • Salt filtration 

    • Plasma membrane stops salt from entering cytoplasm while letting water in

  • Seeds start germinating before falling from tree

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Adaptations of plants in hot deserts (5)

  1. Succulence

    • Many desert plants have fleshy stems & leaves for water storage

  2. Reduced leaf SA

    • Reduced SA reduces water loss via transpiration

  3. Deep root system

    • Allow desert plants to access groundwater

    • Widespread root systems near surface to collect rainfall

  4. CAM physiology [Type of photosynthesis]

    • Stomata closes during the day [reduce water loss via transpiration]
      Stomata opens at night when its cooler

  5. Thick waxy cuticles

    • Reduce water loss via evaporation from plant

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Adaptations of plants in deserts [saguaro cactus] (5)

  1. Succulence

    • Fleshy stems & leaves for water storage

    • Water storage tissues - survive w/o rain

  2. Spines

    • Reduce leaf SA for transpiration

    • Protection from predators

  3. Widespread root system → Allow absorption of any available water

  4. Water storage tissues allow cacti to survive w/o rainfall for a long time

  5. Thick waxy cuticle Prevent water loss

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Adaptations of animals in hot deserts (4)

  1. Nocturnal behaviour

    • Active at night [cooler → reduce water loss]

    • Burrow underground during hottest part of the day

  2. Efficient water conservation

    • Produce concentrated urine

    • Many insects & birds produce uric acid instead of urine [reduce water loss]

  3. Efficient metabolism

    • Metabolic adaptations allow them to cope w/ limited food sources [e.g. low metabolic rates / ability to store fat]

  4. Camouflage

    • Avoid being seen by predators or prey

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Adaptations of animals in deserts [camels] (7)

  1. Efficient water conservation

    • Produce concentrated urine

    • Intestines extract lots of water from faeces

  2. High temp tolerance → Reduce water loss from sweating 

  3. Long legs → Keep body above hot sand

  4. Long nasal passages → Trap & reabsorb moisture from exhaled air

  5. Broad feet → Efficiently walk over sandy terrain

  6. Large SA : V → Efficient heat loss

  7. Fat storage

    • Store fats in humps

    • Fats are metabolised to make energy and water when scarce

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Species

  • Group of organisms capable of reproducing with each other to produce fertile offspring

  • Unable to produce fertile offspring with diff species

  • When 2 species produce offspring by cross-breeding, hybrids are reproductively sterile

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Population

All the organisms of a specific species in a habitat

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Natality

Birth rate

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Mortality

Death rate

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Immigration

New individuals entering a population

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Emmigration

Individuals leaving a population

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Change in population size equation

(Natality + Immigration) - (Mortality + Emigration)

(N + I) - (M + E)

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Intraspecific competition

Competition for resources between members of the same species

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Community

  • All the different species in a habitat

  • Formed by populations of different species living & interacting with each other in a habitat

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Interactions between species examples (5)

  1. Predator & prey

  2. Herbivory

  3. Competition for resources

  4. Mutualism

  5. Parasitism

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Factors that affect coral reef formation (5)

  1. Water clarity

  2. Water depth

  3. Temperature

  4. pH

  5. Salinity

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How does water clarity affect coral reef formation

  • Less light

  • Less photosynthesis

  • Less growth

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How does water depth affect coral reef formation

  • Deeper → Less light reaches coral reef

  • Less photosynthesis

  • Less growth

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How does temperature affect coral reef formation

  • Higher temp causes coral bleaching

  • Narrow range of tolerance

  • High temp → Enzymes denature → Less successful collisions → Less growth

  • Low temp kills corals

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How does pH affect coral reef formation

  • Narrow range

  • Ocean acidification

    • CO2 dissolve into water to form carbonic acid

    • Threat to coral reef

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How does salinity affect coral reef formation

  • Narrow range 23-42 g/kg

  • Average : 35 g/kg

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Optimum range of tolerance [Shelford’s Law of Tolerance]

16-34

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Reproductive isolation

When there’s a barrier which prevents individuals from reproducing

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Competitive exclusion

If 2 species occupy the same niche, there will be an inferior competitor that goes extinct

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Niche

The role of a species in an ecosystem

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Niche partitioning

  • For 2 species with similar niches

  • The coexistence of 2 species due to small differences in their niches

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Fundamental niche

Potential niche of a species based on adaptations & tolerance limits

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Realised niche

Actual niche of a species when in competition with other species

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Obligate anaerobe

Organism that must live in an environment without oxygen

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Obligate aerobe

Organism that must live in an environment with oxygen

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Facultative anaerobe

Organism that can live in environments with or without oxygen

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Autotrophs

  • Organism that produce carbon compounds from inorganic compounds using light / inorganic chemical energy

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Heterotrophs

  • Organism that obtains carbon compounds from other organic sources

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Saprotrophs

  • Heterotrophs but not consumers

  • Secretes enzymes to external environment & digests food externally

  • Absorbs only digested nutrients

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Holozoic

  • Obtain nutrition by ingesting food, digesting internally, absorbing it, & assimilating it

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Mixotrophs

  • Organism that is capable of both photosynthesis & heterotrophy

  • Autotroph + Heterotroph

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Obligate mixotroph

Must use both photosynthesis & heterotrophy

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Facultative mixotroph

Can use either photosynthesis or heterotrophy

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Archaea

  • Single celled organisms

  • Unique from Eukaryota & Bacteria

  • Can thrive in extreme environmental conditions
    [e.g. hot springs, salt lakes, etc]

  • Diverse groups [some are phototrophs, some are chemotrophs]

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Biodiversity

Variety of living organisms in an ecosystem

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Why is high biodiversity important

  • Makes sure that ecosystems are stable

    • Different species depend on each other [shelter, food]

    • Different species maintain the right physical environment

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Trophic levels (5)

  1. Producer

  2. Primary consumer [herbivore / omnivore]

  3. Secondary consumer [omnivore / carnivore]

  4. Tertiary consumer [top carnivore]

  5. Decomposer

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Food chains

Show whats eaten by what in an ecosystem

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Food webs

Show how food chains are linked

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Pyramid of numbers

  • Each bar shows number of organisms at each stage of the food chain

  • Goes up by the food chain

  • Doesn’t have to look like a pyramid

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Biomass

Dry mass

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Pyramid of biomass

  • Each bar shows mass of living material at each stage of food chain

  • Goes up by food chain

  • Look like a pyramid most of the time

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Pyramid of energy transfer

  • Shows the energy transferred to each trophic level in a food chain

  • Always look like a pyramid

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How is energy transferred along the food chain

  1. Sun provides energy to organisms

  2. Plants use energy from sun to make food during photosynthesis

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Not all energy is transferred (4)

  1. Some parts of food is not eaten [bones, roots]

    • Energy isn’t taken in

  2. Some parts of food is indigestible [e.g. fibre]

    • Passed out as waste [faeces]

  3. Glucose / energy used in respiration

  4. Energy transferred to surroundings as heat

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Equation for efficiency of biomass transfer

(Biomass transferred to next level / Biomass available at the previous level) x 100

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Carbon cycle (combustion) (5)

  1. Green plants & algae take in CO2 from atmosphere during photosynthesis

  2. CO2 locked up in biological molecules

  3. Plants / animals are used to make products
    Un-decayed organic material becomes fossil fuel

  4. Products are burnt
    Fossil fuel burnt for energy

  5. CO2 is produced & released into air

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Carbon cycle (animal respiration) (5)

  1. Green plants & algae take in CO2 from atmosphere during photosynthesis

  2. CO2 in plants locked up in biological molecules

  3. Passed to animals who eat the plants

  4. CO2 in animals locked up in biological molecules

  5. Animals respire to release CO2

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Carbon cycle (plant respiration) (3)

  1. Green plants & algae take in CO2 from atmosphere during photosynthesis

  2. CO2 in plants locked up in biological molecules

  3. Plants respire to release CO2

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Carbon cycle (decomposition) (6)

  1. Green plants & algae take in CO2 from atmosphere during photosynthesis

  2. CO2 in plants locked up in biological molecules

  3. Passed to animals who eat the plants

  4. CO2 in animals locked up in biological molecules

  5. Animals excrete waste / die

  6. Waste decayCO2 released from decay into air

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Carbon sink

Absorbs more carbon than it releases

Ecosystems where photosynthesis exceeds respiration

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Carbon source

Releases more carbon than it absorbs

Ecosystems where respiration exceeds photosynthesis

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Nitrogen fixation

Turning N2 from the air into nitrogen compounds in the soil which plants can use

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Decomposers

  • Break down proteins [in rotting plants & animals] & urea [animal waste] and turn them into ammonia [nitrogen compound]

  • Forms ammonium ions in soil

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Nitrifying bacteria

  • Nitrification

    Turn ammonium ions in decaying matter into nitrates

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Nitrogen-fixing bacteria

Turn N2 in air into nitrogen compounds for plants to use

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Denitrifying bacteria

Turn nitrates back into N2 gas

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Nitrogen cycle (decompose) (6)

  1. Nitrogen fixing bacteria in roots turn N2 in air into plant protein

  2. Plants are eaten by animals → Nitrogen passed to animals

  3. Animals die / produce waste

  4. Animals / waste decompose into ammonia

  5. Nitrifying bacteria turn ammonia into nitrates in soil

  6. Denitrifying bacteria turns nitrates into N2 in air

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Nitrogen cycle (lightning) (2)

  1. Energy from lightning allows nitrogen to react with oxygen in air to give nitrates

  2. Denitrifying bacteria turn nitrates in soil back into N2 in air

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Nitrogen cycle (air) (2)

  1. Nitrogen fixing bacteria turns N2 in air into nitrates

  2. Denitrifying bacteria turn nitrates in soil back into N2 in air

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Water cycle (6)

  1. Sun provide energy

  2. Water from lakes, rivers, oceans, puddles, soil, leaves evaporate

  3. Water condenses into clouds [can be blown from one region to another]

  4. Water fall back down to earth as liquid water in the form of rain [precipitation]

  5. Water seeps into soil
    Water flows into rivers
    Water taken up by plants

  6. Repeat

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