Energy Transfer and Nutrient Cycles Flashcards
why is the leaching of phosphates less likely than leaching of nitrates?
phosphate less soluble in water
process of eutrophication?
- mineral ions leached from fertilised fields
- stimulates rapid growth of algae in ponds and rivers
- large amounts of algae block light from reaching plants below
- plants die because unable to photosynthesise
- bacteria feed on remains
- inc number of bacteria reduce oxygen conc in water due to areobic resp
- fish and other organisms die because not enough dissolved oxygen
describe the role of microorganisms in producing nitrates from remains of dead organisms?
- saprobionts feed on remains of dead plants and animals
- convert ammonia into nitrites
- then nitrates
- by nitrifying bacteria
upwelling often results in high primary productivity in coastal waters.
explain why some of the most productive fishing areas are found in coastal waters?
- nitrate/phosphate used by plants
- more producers
- fish grow more
what is the advantage of using dry mass and not fresh mass to compare yield of plants?
- water content varies
- water would have effect on mass
leguminous crop plants have nitrogen-fixing bacteria in nodules on their roots.
on soils with a low concentration of nitrate ions, leguminous crops often grow better than other types of crop.
explain why?
- nitrogen converted to ammonia
- produce proteins
applying high conc of fertiliser to soil can reduce plant growth.
use your knowledge of WP to explain why?
- soil has lower WP
- OSMOSIS from plant
from a bar chart, a student concluded that changes in phosphate concentration caused changes in plant biomass.
explain why this conclusion may not be valid?
- have continuous data for phosphate but not for biomass
- other factor e.g. light cause change
explain how change in phosphate concentration may have resulted in a decrease in the fish population?
- inc phosphate causes inc in plant growth/ algal bloom
- plants block light so plants under under surface die
- inc decomposers
- decomposers use up oxygen
- in respiration
- plants unable photosynthesise - less oxygen produced
explain how farming practices increase productivity of agricultural crops?
- fertilisers added to soil
- phosphate for ATP
- selective breeding of crops
- ploughing allows nitrification
- benefit of crop rotation in terms of soil nutrients
needed for production of ATP
suggest one way in which AMF may benefit from their association with plants?
make carbohydrates
explain why an increase in shoot biomass can be taken as a measurement of net primary productivity?
- represents dry mass
- represents GPP - RL
using the data from the figure, evaluate the effect on plant productivity of adding AMF species and adding phosphate to the soil?
- no stats test used to see if difference in results significant
- only 20 weeks of growth
- underground root growth uknown
- for control, inc in phosphate inc plant growth
- for entrophosphora ins in phosphate reduced plant growth
describe and explain the effect of rhizobium bacteria on growth of soybeans?
- forms mutualistic relationship with soybean
- rhizobium makes ammonium ions
- helps form proteins
- increase in depth linked to decrease in temp
- correlation between temp and fish distribution doesnt indicate causal effect
- overlap in ranges
- other abiotic and biotic factors involved
- contains no chlorophyll
- so dont photosynthesise and dont produce oxygen
- oxygen inhibits nitrogen fixation
