Energy Transfer & Nutrient Cycles

Question 1

What is an ecosystem?

Answer 1

⦾ All living organisms + abiotic cond. in particular area

Question 2

What is biomass?

Answer 2

⦾ mass of living material

⦾ chemical energy stored in plant

Question 3

What is the order of energy transfer in living organisms? (food chain)

Answer 3

⦾ Producers
⦾ Primary consumers
⦾ Secondary consumers
⦾ Tertiary consumer

Question 4

How can biomass be measured?

Answer 4

⦾ mass of C in organism

⦾ dry mass of its tissue per unit area

Question 5

Why is the dry mass used and not wet mass?

Answer 5

⦾ water content of living tissue varies

Question 6

How can biomass (dry mass) be measured?

Answer 6

⦾ 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

Question 7

What are the typical units for dry mass?

Answer 7

⦾ kg m^-2

Question 8

What apparatus can be used to estimate chemical energy amount stored in biomass?

Answer 8

⦾ calorimeter

Question 9

What part of the calorimeter that tells you how much energy is in it?

Answer 9

⦾ heat given off

Question 10

What is the energy from the calorimeter measured in?

Answer 10

⦾ J

⦾ kJ

Question 11

How does a calorimeter work?

Answer 11

⦾ dry biomass sample heated
⦾ energy released heats know water vol
⦾ temp change calc… chemical energy of biomass

Question 12

What does GPP stand for?

Answer 12

⦾ Gross Primary Production

Question 13

What is GPP?

Answer 13

⦾ Total amount of light energy converted to chemical energy by plants in given area

Question 14

What causes GPP to be lost to the environment?

Answer 14

⦾ R - Respiratory loss

Question 15

What is the remaining chemical energy called?

Answer 15

⦾ NPP - Net Primary Production

Question 16

What is the formula for NPP?

Answer 16

⦾ NPP = GPP - R

Question 17

What are the typical units for primary production?

Answer 17

⦾ kJ ha^-1 yr^-1

⦾ kilojoules per hectare per year

Question 18

What is it called when primary production is expressed as a rate?

Answer 18

⦾ primary productivity

Question 19

What is NPP?

Answer 19

Energy available for plant’s:
⦾ growth
⦾ reproduction

⦾ next organism in trophic level

Question 20

How do consumers get energy?

Answer 20

Ingesting:
⦾ plant material
⦾ animals that have eaten plant material

Question 21

What happens to 90% of the chemical energy that’s stored in consumer’s food as its transferred between trophic levels?

Answer 21

⦾ lost

Question 22

What are the different ways energy’s lost between trophic levels?

Answer 22

⦾ not all food eaten (roots, bones)
⦾ some parts indigestible (egested as faeces) - lost to enviro…
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Question 35

What do saprobionts do?

Answer 35

⦾ 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

Question 36

What is saprobiotic nutrition?

Answer 36

⦾ using extracellular digestion to obtain nutrient from dead organic matter + animal waste

Question 37

What is a symbiotic relationship?

Answer 37

⦾ 2 species living closely together

⦾ 1 or both depend on other for survival

Question 38

What do some fungi form symbiotic relatioships with?

Answer 38

⦾ plant roots

Question 39

What are mycorrhizae relationships?

Answer 39

⦾ fungi’s symbiotic relatioships with plant roots

Question 40

What are these fungi made up of?

Answer 40

⦾ hyphae

Question 41

What are hyphae?

How do they benefit the plant?

What do fungi gain?

Answer 41

⦾ Thin ⦾ long ⦾ strands
⦾ connected to plant roots

⦾ increase plant’s root system SA - ion absorption
⦾ increase water uptake

⦾ organic compounds e.g. glucose

Question 42

Why do plants and animals need nitrogen?

Answer 42

Make:
⦾ proteins
⦾ nucleic acids

Question 43

What are the 4 different stages of the nitrogen cycle?

Answer 43

⦾ Nitrogen fixation
⦾ Ammonification
⦾ Nitrification
⦾ Dentrification

Question 44

What are Rhizobium?

Answer 44

⦾ Bacteria found inside root nodules of leguminous plants

⦾ Form mutualistic relationship with plants - provide plant with N-compounds + plants provide carbohydrates

Question 45

Explain nitrogen fixation?

Answer 45

⦾ N2(g) → NH3 → NH4+

⦾ (Rhizobium) turns N2 in atm into ammonia
⦾ Ammonia forms ammonium ions in solution (to be used by plants)

Question 46

Explain ammonification?

Answer 46

⦾ 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

Question 47

Explain nitrification?

Answer 47

⦾ NH4+ → Nitrites → Nitrates

⦾ Nitrifying bacteria - (Nitrosomonas) - change ammonium ions into nitrites
⦾ (Nitrobacter) change nitrites to nitrates

Question 48

Explain dentrification?

Answer 48

⦾ 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

Question 49

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Answer 49

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