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HL Biology - topical sets > Topic 4 > Flashcards

Topic 4 Flashcards

1
Q

Species

A

group of organisms that can interbreed to produce fertile, viable offspring

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2
Q

population

A

a group of organisms of the same species, living in the same area at the same time

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3
Q

Community

A

a group of populations living together and interacting with each other in a given area

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4
Q

Habitat

A

the environment in which a species normally lives

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5
Q

Ecosystem

A

A community and their abiotic environment all interacting with each other at a given time

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6
Q

Ecology

A

study of relationship between living org, or living org and their env

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7
Q

Ways of obtaining chemical energy

A
  • Autotrophs: synthesise organic molecules from simple inorganic substances. Energy from sunlight or from the oxidation of inorganic molecules
  • Heterotrophs: obtain organic molecules by consuming other organisms
  • Mixotrophs: use both methods based on resource availability
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8
Q

Types of heterotrophs

A
  • Saprotrophs: Release digestive enzymes and absorb the products of digestion of dead organic matter/fecal matter/humus. external digestion (fungi, bacteria)
  • Detritivores: consume non-living remnants of organisms (detritus, dead organic matter) (earthworms, woodlice)
  • Consumers: consume living/recently killed organisms
    • Herbivore, Carnivore, Omnivore
    • Scavenger: feeds on dead/decaying carcasses ->
      doesn’t hunt live prey
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9
Q

Inorganic molecules from env

A
  • Autotrophs obtain their inorganic molecules from the env (CHOPN)
  • Heterotrophs may obtain some from the environment but mostly obtain the C and N from the organisms they consume
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10
Q

Explain why ecosystems are sustainable [5]

A
  • Nutrient cycling
  • Example: Carbon, Nitrogen
  • Autotrophs take in nutrients from the surroundings -> travel along food chain -> broken down by decomposers and returned to env
  • Energy for photosynthesis from the sun
  • Energy is passed down the food chain through feeding
  • Autotrophs make food to support the primary consumers
  • photosynthesis produces O2 used in resp
  • Resp produces CO2 used in photo.
  • populations regulated by negative feedback
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11
Q

Explain the movement of energy and inorganic nutrients in an ecosystem [8]

A
  • Autotrophs obtain inorganic nutrients CHOPN from env.
  • They obtain energy from sun/oxidation of inorganic molecules
  • Light energy to chemical energy via photosynthesis
  • Inorganic carbon into organic molecules
  • nutrients are passed down the food chain via feeding by consumers
  • C compounds a source of usable energy for life
  • Respiration returns CO2 to env
  • Resp releases stored chemical energy as ATP
  • ATP needed to carry out life functions/growth/synthesis/movement
  • Energy is lost/not recycled
  • Nutrients cycle in a closed system -> finite amount
  • nutrients are returned to env when dead organic matter of consumers/autotrophs and their feces are broken down by saprotrophs
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12
Q

3 main components of ecosystem sustainability

A
  • Nutrient availability -> recycled
  • Energy availability -> Sun
  • Recycling of wastes -> certain bacteria detoxify wastes
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13
Q

Define trophic level

A

the position an organism occupies in a feeding sequence

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14
Q

What does a food chain show

A

Linear feeding relationships between species in a community

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15
Q

energy loss

A

when talking about energy flow in the system remember
-> organic molecules broken down in respiration to form ATP
-> ATP is used to fuel growth/homeos/other life processes
-> heat released as a by-product (energy loss)

Other forms of loss:
- Uneaten parts of food
- Faeces

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16
Q

Biomass

A

Total mass of a group of organisms (consisting of carbon compounds in the cells and tissues) (g m-2)

  • C compounds contain energy -> biomass used as a measure of the amount of energy added to organisms
  • biomass diminishes down a food chain -> loss of heat, urea, waste
  • therefore limited trophic levels
  • Higher TLs need to eat more food -> lesser biomass from food -> more energy expended hunting/searching food -> if the energy spent hunting > energy from food, TL is unviable
17
Q

What is a pyramid of energy

A
  • graphical representation of the amount of energy in each trophic level
  • measures in kJ m-2 yr-1
18
Q

Carbon cycle

A

biogeochemical cycle through which carbon is exchanged between different earth spheres: atmosphere, lithosphere, biosphere, hydrosphere

19
Q

Ways C is stored

A

CaCO3, CO2 in atm, organic molecules in organisms, fossils/fossil fuels, rocks, CH4, detritus

20
Q

How autotrophs obtain CO2

A

Water: diffuses into the aquatic autotroph directly
Terrestrial: diffuses into auto through stomata -. [] of CO2 outside the plant must be higher than inside

21
Q

What is the compensation point

A

CO2 absorbed by photosynthesis = CO2 produced by respiration

22
Q

Forms in which C exists in water

A
  • as a dissolved gas
  • as HCO3- ions as:

CO2 + H2O –> H2CO3
H2CO3 ⇌ H+ + HCO3-
HCO3- ⇌ CO3(2-)

Carbonates react with metal ions on the sea bed, such as Ca2+, to form compounds like CaCO3. CaCO3 used to make coral exoskeletons, shells of molluscs, etc.

23
Q

Formation of methane

A

Methanogens -> archaen microorganisms that produce methane as a metabolic by-product in anaerobic conditions. form methane from the waste products of anaerobic respiration

2 reactions

CO2 + 4H2 –> CH4 + 2H2O
CH3COO- + H+ –> CH4 + CO2

Locations this occurs:
- wetlands
- digestive tracts of ruminants
- marine sediments

When it is buried in anoxic conditions underwater/sea beds –> forms natural gas reserves

24
Q

Oxidation of methane reaction, time

A
  • CH4 + 2O2 –> CO2 + 2H2O
  • CH4 persists in atmosphere for 12 yr
25
Q

How coal is formed

A
  • Anaerobic conditions needed: bacteria need oxygen to completely break down organic matter into nutrients.
  • If no/little oxygen -> anaerobic respiration –> produce organic acids (like ethanoic acid).
  • increases the acidity of the soil and kills the saprotrophic bacteria/fungi -> therefore org matter only partially decomposed
  • C-rich molecules stay in soil, form peat
  • when it is partially decomposed and if exposed to heat/pressure -> impurities + moisture forced out of the material + it os condensed -> forms coal after chem transformation
26
Q

How oil and gas are formed

A
  • marine organisms on the sea floor
  • sediment is dumped/accumulates on top of it –> anoxic conditions created, prevent decomposition aerobic
  • heat forms hydrocarbonds from the organic matter
  • HCs form oil and gas -> escape the source rock and accumulate in porous rock
27
Q

what is a carbon flux

A

the rate of exchange of carbon between the various carbon sinks

28
Q

Lithification

A

compaction of carbon containing sediments into fossils and rocks in the earths crust

29
Q

Largest carbon flux

A

photosynthesis

30
Q

Greenhouse gases

A
  • Absorb and emit longwave radiation -> trap heat in atm
  • CO2 and water vapour have the largest warming effect on the atm
    • But H2O not released in large quantities as a result of
      human activity
  • NOx and CH4 also are GHG -> car engines and ruminants, landfills, marshes
31
Q

Factors affecting the impact of a GHG

A
  • How rapidly it enters the atmosphere
    • CO2 and H2O are released in much larger quantities
      than CH4
  • Its persistence
    • CO2 lasts much longer than CH4 or H2O
  • Its potency
    • CH4 absorbs much more heat
32
Q

The Vostok ice core conclusions

A
  • Positive correlation found between temperature and [CO2]
  • there were global ice ages and warm ages which correlated with fluctuating cycles of [CO2]
  • rn [CO2] is the highest
33
Q

Ocean acidification

A
  • CO2 in water forms H2CO3, which dissociates into H+ and HCO3-. H+ acidifies water and reacts with available CO3(2-) in water, which wouldve been used to form CaCO3
  • Acidic waters -> thin the shells of marine organisms
  • Lack of CaCO3 -> cannot form shells/exoskeletons properly

HL Biology - topical sets (11 decks)

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