productivity exam questions Flashcards
Arbuscular mycorrhiza fungi (AMF) are fungi that grow on, and into the roots of plants
AMF can increase the uptake of inorganic ions such as phosphate ions
Suggest one way in which AMF may benefit from their association which plants
can use the amino acids/ carbon-containing molecules in the plant
how do we work out the mass from density and mass
density x volume
the ecologist dried the samples in an oven at 103C for 24 hours
Describe how the ecologist could have determined whether or not this drying removed all the water from a sample of wood
record mass and rehat
until constant mass recorded
what does the graph show about the relationship between the diameter of the trunk
as the diameter increases the biomass increases (1 mark)
for the extra point, further, stat the relationship e.g. is it linear, does it level out
however, this relationship is not linear (1 mark)
Plantations of trees are often created to remove carbon dioxide from the atmosphere, to help to balance the carbon dioxide released by burning fossil fuels.
For different species of tree, information is available for:
•the relationship between diameter of trunk and freshly cut biomass•the percentage of water in fresh-cut wood
•the mean dried density of wood.
Using only the information provided in part (c), suggest how the mass of carbon in the wood of a plantation of trees of a particular species could be estimated.
Start with measuring the diameter of a large number of trees.
Assume that the dry biomass of a tree consists of biological molecules that contain carbon.
- Calculate a mean diameter;
- (Use this to) estimate / determine the mean fresh biomass of trees;
- Use the percentage water content to find the dried biomass
;4. Use the dried density to calculate the mass of the tree; - Count / estimate the number of trees in plantation and multiply by (mean) carbon content (to find total carbon);
what is a chi-squared test used for
assess the significant difference between observed and expected data
give two ways in which energy is lost between PRODUCERS and HERBIVORES
Repository loss
heat/ undigested
what is the importance of decomposes to the producers
supply of inorganic molecules e.g. CO2/ nitrates
releases CO2
there are more secondary consumers than primary consumers in this pyramid
Suggest one reason why
the secondary consumer is small/ has a rapid reproductive cycle
what is important to note about trophic levels
the bottom level is not a consumer but is actually the producer
explain why a food chain rarely contains more than 4 trophic level
energy is used at each trophic level
energy is lost via excretion and respiratory loss
therefore little is left to sustain higher trophic levels
red blood cells do not contain mitochondria but they use ATP
By what processes do red blood cells produce ATP
Suggest a reason for your answer
Glycolysis
does not occur in mitochondria/ takes place in the cytoplam
not all light energy entering the leaves of the oak tree is used in photosynthesis
light is the wrong frequency
why are micro-organisms important in ecosystems
nutrients are recycled within nutrient ecosystems
microorganisms play a vital role in recycling chemical elements such as phosphorus and nitrogen
what are saprobiants
saprobiants are organisms that digest their “food” externally and then absorbs the products
what are mycorrhizae
these are fungi “associates between plant roots and fungi
they provide a large surface area for uptake of water and inorganic ions
-they act like a “sponge” so can absorb and hold water and minerals easily
what is the relationship between mycorrhizae and the plants
the relationship between plants and fungi is symbiotic as the plant provides the fungi with carbohydrates
they both benefit each other
what are the stages of the nitrogen cycle
- nitrogen fixation
- ammonification
- nitrification
- Denitrification
what is nitrogen fixation
nitrogen-fixing bacteria convert atmosphere N2 to ammonium ions
either free-living in the soil or have a mutualistic relationship with leguminous plants e.g. clovers and beans as they can live in their root nodes
what is ammonification
ORGANIC NITROGEN from decomposition of proteins, DNA, urea e.t.c are converted to ammonium ions which are released into the soil
This is carried out by sapriobionts
what is nitrification
Ammonium ions in the soil are oxidised to nitrates then nitrites by nitryfying bacteria
this is two stage oxidation reaction
what is denitrification
it converts nitrogen in compounds back to nitrogen gas
This is a cycle as the nitrogen gas cannot be absorbed by plants
This occurs in anaerobic conditions hence why farmers aerate their soils
what is the phosphorus cycle
- environmental conditions e.g. erosion and weathering causes the release of phosphate ions by rocks into soil and bodies of water
- plants take in these phosphate ions
- animal eat the plants ad use these ions to synthesis organic materials
- animals die and decompose, returning phosphate ions to the soil
- Bacteria in the soil break down phosphate into inorganic forms
- inorganic forms of phosphorus can end up in waterways again and be assimilated by plants
what are the different types of fertilisers used
natural and artificial
why do we use fertilisers
they replace nitrogen and phosphates by harvesting plants and removing livestock
what are natural fertilisers
manure, seaweed,peat guano e.tc.
cheap
free if from own livestock
negatives
exact amount and proportions of minerals can’t be controlled
what are artificial fertilisers
contains the exact amount of minerals
strengths
more water-soluble so higher absorption of inorganic ions
negatives
leads to eutrophication and leaching if there is rainfall/ flooding
what is leaching
water soluble components are washed away into bodies of water e.g. rivers and ponds
this is caused by flooding and heavy rainfall
what iseutrophication
- leached nitrates in bodies of water causes algae growth
- excessive algae growth blocks light, so plants below the surface can’t photosythesise and therefore die
- aerobic bacteria feed on dead plant matter and respire using up the oxygen in the eater
- fish and other aquatic organisms die due to the lack of oxygen
