Energy Transfer & Nutrient Cycles Flashcards
What is an ecosystem?
⦾ All living organisms + abiotic cond. in particular area
What is biomass?
⦾ mass of living material
⦾ chemical energy stored in plant
What is the order of energy transfer in living organisms? (food chain)
⦾ Producers
⦾ Primary consumers
⦾ Secondary consumers
⦾ Tertiary consumer
How can biomass be measured?
⦾ mass of C in organism
⦾ dry mass of its tissue per unit area
Why is the dry mass used and not wet mass?
⦾ water content of living tissue varies
How can biomass (dry mass) be measured?
⦾ dry organism (low temp in oven)
⦾ weigh sample regular intervals
⦾ when mass becomes constant, all water’s removed
⦾ C mass is 50% of dry mass
⦾ scale results to give biomass of total pop…/area
What are the typical units for dry mass?
⦾ kg m^-2
What apparatus can be used to estimate chemical energy amount stored in biomass?
⦾ calorimeter
What part of the calorimeter that tells you how much energy is in it?
⦾ heat given off
What is the energy from the calorimeter measured in?
⦾ J
⦾ kJ
How does a calorimeter work?
⦾ dry biomass sample heated
⦾ energy released heats know water vol
⦾ temp change calc… chemical energy of biomass
What does GPP stand for?
⦾ Gross Primary Production
What is GPP?
⦾ Total amount of light energy converted to chemical energy by plants in given area
What causes GPP to be lost to the environment?
⦾ R - Respiratory loss
What is the remaining chemical energy called?
⦾ NPP - Net Primary Production
What is the formula for NPP?
⦾ NPP = GPP - R
What are the typical units for primary production?
⦾ kJ ha^-1 yr^-1
⦾ kilojoules per hectare per year
What is it called when primary production is expressed as a rate?
⦾ primary productivity
What is NPP?
Energy available for plant’s:
⦾ growth
⦾ reproduction
⦾ next organism in trophic level
How do consumers get energy?
Ingesting:
⦾ plant material
⦾ animals that have eaten plant material
What happens to 90% of the chemical energy that’s stored in consumer’s food as its transferred between trophic levels?
⦾ lost
What are the different ways energy’s lost between trophic levels?
⦾ not all food eaten (roots, bones)
⦾ some parts indigestible (egested as faeces) - lost to enviro…
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What do saprobionts do?
⦾ Decomposer - feed on dead plant + animal remains + their waste - break down - help recycle chemical elements
⦾ Extracellular digestion - secrete enzymes + digest food externally + absorb nutrients needed
What is saprobiotic nutrition?
⦾ using extracellular digestion to obtain nutrient from dead organic matter + animal waste
What is a symbiotic relationship?
⦾ 2 species living closely together
⦾ 1 or both depend on other for survival
What do some fungi form symbiotic relatioships with?
⦾ plant roots
What are mycorrhizae relationships?
⦾ fungi’s symbiotic relatioships with plant roots
What are these fungi made up of?
⦾ hyphae
What are hyphae?
How do they benefit the plant?
What do fungi gain?
⦾ Thin ⦾ long ⦾ strands
⦾ connected to plant roots
⦾ increase plant’s root system SA - ion absorption
⦾ increase water uptake
⦾ organic compounds e.g. glucose
Why do plants and animals need nitrogen?
Make:
⦾ proteins
⦾ nucleic acids
What are the 4 different stages of the nitrogen cycle?
⦾ Nitrogen fixation
⦾ Ammonification
⦾ Nitrification
⦾ Dentrification
What are Rhizobium?
⦾ Bacteria found inside root nodules of leguminous plants
⦾ Form mutualistic relationship with plants - provide plant with N-compounds + plants provide carbohydrates
Explain nitrogen fixation?
⦾ N2(g) → NH3 → NH4+
⦾ (Rhizobium) turns N2 in atm into ammonia
⦾ Ammonia forms ammonium ions in solution (to be used by plants)
Explain ammonification?
⦾ N2(g) → NH3 → NH4+
⦾ N-compounds from dead organisms turned into ammonia by saprobionts + form ammonium ions
⦾ animal waste contains N-compounds + are turned into ammonia by (saprobionts) + form ammonium ions
Explain nitrification?
⦾ NH4+ → Nitrites → Nitrates
⦾ Nitrifying bacteria - (Nitrosomonas) - change ammonium ions into nitrites
⦾ (Nitrobacter) change nitrites to nitrates
Explain dentrification?
⦾ Nitrates → N2(g)
⦾ Dentrifying bacteria in soil use nitrates in soil to respire + produce N2 gas
⦾ anaerobic cond.
⦾ lightning fixes atm N into nitrogen oxides or artificial fetilisers
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