4 — ecology Flashcards
1
Q
describe processes in the carbon cycle that produce or use carbon dioxide (7)
A
- photosynthesis uses carbon dioxide/ reduces carbon dioxide concentration of the atmosphere
- autotrophs fix carbon dioxide into carbon compounds
- cell respiration releases carbon dioxide
- glucose combines oxidised to produce carbon dioxide
- carbon dioxide released from saprotrophs from dead organic matter
- undecomposed organic matter can lead to the formation of peat
- carbon dioxide released during combustion of fossil fuels
- carbon dioxide dissolves in aquatic ecosystems/ can form carbonic acid
- reef building corals use calcium carbonate to make exoskeletons
2
Q
discuss the relationship between atmospheric carbon dioxide concentration and global temperatures (4)
A
- greenhouse effect keeps earth warm
- over-time earth’s temperature has fluctuated naturally
- changes in human activities have led to increases in CO2 concentration
- CO2 absorbs infrared radiation
- increase in atmospheric CO2 concentration correlates with increased global average temperature
- use of fossil fuels increases atmospheric CO2
- deforestation removes a carbon sink
- loss of polar ice causes less reflection of surface light
- CO2 is not the only greenhouse gas
3
Q
explain the transformations of carbon compounds in the carbon cycle (7)
A
- autotrophs convert carbon dioxide into carbon compounds in photosynthesis
- carbon dioxide diffuses from the atmosphere into autotrophs
- carbon compounds are transferred through food chains
- carbon dioxide produced by respiration diffuses out of organisms into water
- decomposers release carbon dioxide during decay
methane is produced from organic matter in anaerobic conditions - some methane diffuses into accumulates in the ground
- methane is oxidised to carbon dioxide in the atmosphere
- peat forms when organic matter is not fully decomposed because of anaerobic conditions in waterlogged soils
- partially decomposed organic matter from fossils was converted into coal/ oil/ gas
- carbon dioxide is produced by the combustion of fossilised organic matter
- hard parts of some animals are composed of calcium carbonate
- can become fossilised in limestone
4
Q
explain the movement of energy and inorganic nutrients in an ecosystem (7)
A
- autotrophs obtain inorganic nutrients from the abiotic environment ‘energy provided by sunlight
- light energy converted to chemical energy through photosynthesis
- photosynthesis converts inorganic carbon and water into organic compounds
- these carbon compounds contain a source of usable energy for life
- carbon compounds are transferred along food chains when eaten by consumers
- respiration returns carbon dioxide to the environment
- respiration releases chemical energy as ATP
- ATP i s used to carry out life functions
- energy is lost
- nutrients are recycled
- decomposers recycle minerals/ organic nutrients
5
Q
outline the roles bacteria play in the carbon cycle (3)
A
- decomposition of dead organic material by saprotrophic bacteria
- decomposition leads to CO2 formation
- saprotrophic bacteria only partially decompose dead organic matter in anaerobic conditions
- results in peat formation
- photosynthetic bacteria fix CO2 in photosynthesis
6
Q
describe the process of peat formation (4)
A
- formed from dead plant material/ leaves/ mosses
- formed in waterlogged sites/ bogs/ mires/ swamps
- where saprotrophs are not active
- organic matter not fully decomposed
- occurs in acidic conditions
- occurs in anaerobic conditions
- very slow process
7
Q
outline the energy flow through a food web (3)
A
- light energy of the sun is converted by plants/ autotrophs to chemical energy
- detritivores/ saprotrophs decay plant material to obtain energy
- consumers release energy from the carbon compounds by cell respiration, energy is lost as heat
- energy is used by organisms for metabolism
- energy is transferred between organisms through the food web
- energy is lost at each tropic level so lengths of food webs are restricted
8
Q
discuss the process in the carbon cycle that affect concentrations of carbon dioxide and methane in the atmosphere and the consequences for climate change (8)
A
- CO2 is produced from respiration in organisms/ combustion of biomass/ fossil fuels
- Ch4 is produced by anaerobic respiration of biomass/ bacteria
- CH4 is oxidised to Co2 and water
- Co2 is converted into carbohydrates by autotrophs
- CO2 can be converted to calcium carbonate/ fossilised into limestone
- partially decomposed organic matter can be converted to peat
- CO2 and CH4 are both greenhouse gases that increases the greenhouse effect
- both absorb long wave radiation from the earth and retain the heat in the atmosphere
- increased CO2 concentrations in the atmosphere correlate with increased combustion of fossil fuels
- rising average global temperatures correlate with more greenhouse gases in the atmosphere
- cattle production increase CH4 in the atmosphere
- CO2 leads to acidification of marine environments
- the global temperature increase influences climate patterns
9
Q
outline 2 general characteristics of all ecosystems (2)
A
- interactions between organisms
- shows sustainability
- nutrients are recycled in ecosystems
- energy flows through ecosystems
- producers are part of all ecosystems
- decomposers/ saprotrophs present
10
Q
explain the role of decomposers in an ecosystem (2)
A
- saprotrophs/ decomposers break down dead organic matter
- saprotrophs/ decomposers release energy
- accelerating decomposition
- saprotrophs/ decomposers recycle nutrients/ make
- nutrients available to producers
- saprotrophs/ decomposers detoxify waste
11
Q
producers extract phosphates and nitrates from soil. outline how these ions are used in the synthesis of organic molecules (3)
A
- by photosynthesis
- attached to carbon compounds
- phosphates used to make phospholipids/ nucleotides/ nucleic acids
- nitrates are used to mak amino acids/ proteins/ nucleotides/ nucleic acids
- transported from roots to leaves in xylem
12
Q
describe how energy flows through and is used by organisms in ecosystems (4)
A
- producers/ plants/ autotrophs obtain energy from light
- food contains energy
- consumers obtain energy from other organisms of the previous trophic level
- energy released in organisms by cell respiration
- ATP produced
- energy used for biosynthesis/ movement/ active transport
- less energy available/ energy lost at each trophic level
13
Q
explain the process by which energy enters and flows through ecosystems (8)
A
- light energy is the initial energy source for all organisms
- producers/ autotrophs change light into chemical energy
- producing carbohydrates
- carbon/ organic compounds used for energy/ growth/ repair/ storage
- compounds/ energy pass as food along food chains
- cellular respiration releases energy as ATP from food
- energy is lose as heat
- only approximately 10% of energy is passed to the next trophic level
- energy lost in bones/ hair, when they die not fully eaten by the next trophic level
- energy lost in feces/ urine
- decomposers/ saprotrophs remove energy from non living organic compounds
14
Q
define saprotrophs (1)
A
- an organism that secrets enzymes in dead organic matter and absorbs its nutrients/ products of digestion
15
Q
aquatic and other environments are being affected by a global rise in temperature. outline the consequences of this on artic ecosystems (6)
A
- warming results in melting polar ice caps/ loss of ice habitats
- warming raises sea level/ floods coastal areas/ destroys coastal habitats
- warming of habitat would change species that can be supported
- decrease in size of population/ possible extinction of species
- temperate species move into area/ artic species move
- change in distribution of species/ changes in migration patterns
- ecological changes will affect higher trophic levels
- increased rates of decomposition of detritus from melting permafrost
- increased success of pest species including pathogens
