5- Flashcards
What is another name for producers?
autotroph
Why are quaternary consumers less common in mammals, but common in aquatic environments?
- mammals lose energy in maintaining body temp
- ↓ energy to pass on
- aquatic = stable environment
- fish = cold-blooded–> x lose heat for body temp
What are sugars used for in plants?
- most = resp
- some = make bio molecules eg. cellulose
- –> biomass- chemical energy stored –> next trophic level
Why do we measure the dry mass of tissue per given area?
amount of water varies –> affects overall mass
How do we obtain a dry sample to measure mass?
- dry in oven 40-80°C (too high- burn sample)
- weigh at regular intervals until constant mass (all water evaporated)
What are the units for dry mass?
gm-2 / kg h-2 (hectare)
- if grown within specific time- kg m-2 y-1 (per year)
How can we estimate the mass of carbon in a sample?
calorimeter
- burn biomass
- measure energy given off as heat
- by cal. temp it heats a known vol of water to
Evaluate pyramid of biomass
➕ ↑ reliable than pyramid of individual no. of organisms
➖ only estimated w/ small sample –> x representative
➖ drying + weighing –> time consuming/ ethical issues
Evaluate pyramid of energy
➕ most accurate- organisms w/ same biomass could have diff. amounts of energy
➖ data is difficult to collect
➖ only representative of given area at one time point
Def for productivity
rate of generation of biomass in an ecosystem
- unit: g m-2 y-1
def for GPP
gross primary production
- total amount of chemical energy converted from light energy by plants in a given area
4 reasons why not all light energy from sun is converted into chemical energy by plants
- reflected
- wrong wavelength
- transmitted thru leaf
- hits parts of plant x photosynthesise
What is respiratory loss?
50% of GPP lost to environment as heat when plants respire
def for NPP
net primary productivity
- energy available for plant growth & reproduction
- stored in plant biomass
- energy available for next trophic level
NPP = GPP - R
def for secondary productivity
energy stored in biomass by primary consumers –> passed on to secondary consumer/ decomposer
Why is only 10% of chem energy passed on to the next trophic level?
- x all food eaten
- some parts indigestible –> returned to environment as faeces
- energy lost as heat in resp. & excretion of urine
formula for net secondary production (N)
N = I - (F + R)
- I = energy in ingested food
- F = energy lost in faeces & urine
- R = resp.
Why can food chains only support 4/ 5 trophic levels?
- net prod. v. low at top
- apex predators must eat large amounts of prey to consume enough energy
- energy transfer ↑ efficient up the chain ∵ plants have ↑ indigestible matter
How do farming practices increase efficiency?
- ↓ energy lost to pests- chemical pesticides, herbicides (weeds), biological controls 🐞 kill aphids
-
↓ resp of livestock- controlling conditions –> ↑ energy for growth
- ↓ costs
- ↑ food in less time
Ethical issues surrounding controlling living conditions of llivestock
- restricts natural behaviour
- pain thru uncomfortable conditions
- diseases ↑ likely to spread (animals kept close tgt) –> overuse of antibiotics
negative impact of using chemical pesticides & herbicaides on the environment
- ↓ biodiversity
-
eutrophication
- fertilisers get into rivers
- algae growth over water
- plants at bottom die
- decomposers used up all O2
- organisms die
Give 2 uses of nitrogen in animals.
- make a.a. –> proteins –> newcells + enzymes
- nitrogenous bases –> nucleotides –> replication of DNA + RNA
4 uses of phosphorus in animals
- phosphate backbone of DNA
- ATP
- phospholipids in cell mem
- calcium phosphate –> bones
Why is phosphorus usually a limiting nutrient?
found in low conc, esp in aquatic systems
limits:
- ATP –> ↓ energy for growth
- ↓ DNA + mRNA –> ↓ proteins for growth
- ↓ phospholipids for cell mem
- ↓ photosynthesis ∵ needed in regen of RuBP
What form does most phosphorus exist as?
PO4 3- in sedimentary rocks
- released in weathering
- taken up by a.t. in roots
How do plants absorb the maximum amount of phosphates from soil?
symbiotic relationship w/ mycorrhizae (in return for sugars)
- hypae ↑ s.a. of root system
- ↑ phosphate, nitrates, water absorbed
my core is sane
What is a major source of phosphate in waste?
guano of sea birds –> natual fertiliser
2 advantages of using fertilisers in farming
- ↑ productivity
- improves efficiency of energy transfer
Artificial fertilisers
- inorganic (pure chemicals)
- eg. ammonium nitrate from Haber process- N2 fixation
Natural fertilisers
- organic matter
- eg. manure, compost
How does crop rotation work?
- alternating growing crops for harvest + leguminous plants
- leguminous plants w/ N2 fixing bacteria- replace nitrates lost
- left to decay- recycle other nutrients
Why is the excess use of fertilisers bad?
- ↑ nutrients
- ↓ Ψ
- ↓ water uptake
- water loss (dehydration) by osmosis
Process of eutrophication
- excess mineral ions leach into ponds/ rivers
- rapid growth of algae (algal bloom)
- algae on surface blocks light –> x reach plants below –> die
- bacteria decompose dead plant matter
- O2 used up as bacteria respire
- fish + larger aquatic organisms die
↑ likely w/ nitrates ∵ phosphorus is ↓ soluble (natural fertilisers also x soluble, need to be broken down by saprobionts)
