Topic 4 Flashcards
Define species
- Groups of organisms that can potentially interbreed to produce fertile offspring
Define population
Group of organisms of the same species who live in the same area at the same time
Define autotroph
- Organisms that make their own carbon compounds from CO2 and other substances
Ex) plants
Define heterotroph
- Organisms that obtain their carbon compounds from other organisms
Ex) animals
Give an example of an organism that uses both autotrophic and heterotrophic method of nutrition
- Euglena gracilis have chlorplasts and carry out photosynthesis with the presence of light
- Feed on detritus or smaller organisms by endocytosis
- Mixotrophic
List 3 types of heterotrophs
- Consumers
- Detrivores
- Saprotrophs
Define consumers
- Heterotrophs that feed on living organisms (plants, animals, or both) by ingestion
- Take in undigested materials and digest them to absorb the products
Define detrivores
- Heterotrophs that obtain organic nutrients from detritus by internal digestion
- Dead organic materials inclue dead leaves, feathers, ahirs, feces
- Detrivores ingest dead organic matter then digest it internally and absorb the products
Define saprotrophs
- Heterotrophs that obtain organic nutrients from dead organic matter by external digestion
- Secrete digestive enzyme into the dead organic matter and digest it externally
- Then absorb the products of digestion
Define community
- Formed by populations of different species living together and interacting with each other
- Composed of all organisms living in an area
Define ecosystem
- Community of organisms in an area and their non-living environment in a single highly complex interacting system
- Biotic and abiotic factors influence each other
Explain how the supply of inorganic nutrients is maintained
- Limited supplies of chemical elements
- Nutrients can be endlessly recycled – organisms absorb the elements, use them, then return them to the environment
State the three requirements for sustainability in ecosystems
- Nutrient availability
- Detoxification of waste products
- Energy availability
How does energy flow in the ecosystem
- Intial form of energy is sunlight
- Converted into chemical energy through photosynthesis
- Chemical energy in carbon compounds flows through food chains by means of feeding
- Energy is released by repiration and converted to heat
What do organisms need energy for
- Synthesizing large molecules like DNA, RNA, and proteins
- Pumping molecules or ions across membranes by active transport
- Moving things around inside the cell or muscle clles in contraction
What happens to the heat produced in respiration
- Lost from ecosystem
Why do food chains only have a few trophic levels?
- The energy added to biomass by each successive trophic level is less (10%)
- Most of the energy in food that is digested and absorbed is released in respiration and lost as heat
- Organisms are not usually entiredly consumed by the next trophic level
- Not all parts are digested
Define biomass
- Total mass of a group of organisms
- Consists of the cells and tissues of those organisms
Outline the carbon cycle
- Carbon exists in aquatic habitates as dissolved gas CO2 and hydrogen carbonate ion
- Carbon exists in the atomphere in the form of CO2 gases
- Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds
- Carbon compounds are consumed by the next trophic level and move along the food chain
- CO2 is produced by respiration and diffuses out of organisms into water or the atmosphere
Define peat
Forms when organic matter is not fully decomposed because of anaerobic conditions in waterlogged soil
Outline the formation of methane
- Bacteria convert organic matter into a mixture of organic acids
- Bacteria produce acetate, CO2, H2
- Archaeans produce metahne from CO2, H2 and acetate
- Methane diffuses into the atmosphere
What happens to the methane molecule in the atmosphere
- Oxidized to CO2 and water
Outline the formation of coal
- Deposits of peat are buried under other sediments
- Peat is compressed and heated, gradually turning into coal
Outline the formation of oil and nautral gas
- Formed in the mud at the bottom of seas and lakes
- Conditions are usually anaerobic, and so decomposition is often incomplete
- The partially decomposed matter is compressed and heated and produce oil and natural gas
How does carbon stored in fossilized organic matter enter the carbon cycle again?
- Combusion of biomass and fossilized organic matter produce CO2 and can enter the carbon cycle again
Give an example of animal that have hard body parts composed of calcium cabonate
- Mollusc shells contain calcium carbonate
- Hard corals that build reefs produce their exoskeletons by secreting calcium carbonate
Outline the formation of limestone
- In neutral or alkaline conditions, calcium carbonate is stable
- When animals with CaCO3 die, it accumulates and forms limestone
Construct a labelled diagram of the carbon cycle
State three greenhouse gases
- Carbon dioxide
- Water vapour
- Methane
- Nitrous oxides
- Sulphur dioxide
Explain the factors that determine the warming impact of a greenhouse gas
- How readily the gas absorbs long-wave radiation (from the earth)
- The concentration of the gas in the atmosphere
- CO2 and Water vapour are the most significant gases while methane and nitrous oxides have less impact
Explain the greenhouse effect
- The sun emits short-wave radiation and warms up the earth
- The warmed earth emits longer-wave radiation to the atmosphere
- The longer-wave radiation is reabsorbed by greenhouse gases which retains the heat in the atmosphere
- The heat is trapped in atmosphere and warms up the earth
Some people argue that temperature has been fluctuating since the beginning of time; therefore, CO2 concentration does not affect global temperature. Explain why this claim is incorrect
- It ignores the fact that temperature on Earth are influenced by many factors, not just greenhouse gas concnetrations (volcanic activity, ocean currents, etc.)
- Humans are emitting carbon dioide by burning fossil fuels after industrial revolution
- Although the global temperature fluctuates, the general trend is getting warmer
Explain the threats to coral reefs from increasing concentrations of dissolved carbon dioxide
- Dissolved carbon dioxide makes the carobnate concnetration lower as a result of chemical reactions
- Difficult for reef-building corals to absorb them to make their skeletons
- Exisitng calcium carbonate tends to dissolve if seawater ceases to be a saturated solution fo carbonate ions
