Topic 10.2 Flashcards
Why is the nitrogen cycle so important?
Vital part of amino acids, hence proteins, and nucleic acids
What does nitrosonomas spp. convert?
Ammonium -> nitrites
What does nitrobacter convert?
Nitrites to nitrates
What is the role of nitrogen fixing bacteria?
Convert nitrogen gas -> ammonium
In soil or root nodules of legumes
What does denitrifying bacteria do?
Converts nitrates to atmospheric nitrogen
(Bad) (they really like waterlogged soil) (can be prevented by churning soil)
What conditions are best for nutrient cycling? + why?
- Warm (chemical reactions occur faster)
- Moist (able to dissolve food for absorption)
- High oxygen levels (microbes respire more efficiently)
What is NPP and GPP?
Net primary productivity
Gross primary productivity
What is the definition of GPP?
Rate of energy incorporated into biomass in plants
(although energy is lost through respiration, less energy is available to the primary consumer)
What is NPP? (2 marks)
Rate of production of biomass
NPP = GPP - R(espiration)
In plants
What is the unit for GPP and NPP?
kJ m-2 y-1
(Energy/area/time)
Or
Biomass - (g m-2 y-1)
Carbon ( gC m-2 y-1)
Why is there energy not passed on/ lost in a food chain?
- losing energy from respiration like heat and movement
- stored in parts that can’t be eaten/digested
- dead organisms are not eaten
Why does temperature and hours of sunlight affect NPP? (6 marks)
Correlation between NPP and light
NPP increases as light increases
Temp affects rate of enzyme activity
Light affects respiration rate
Light/temp could be limiting factor
What is the risk of carrying out the experiment of measuring sand dunes? How to reduce this risk?
- animal bites
- allergies from plants
- Adverse weather
- wear suitable clothing
- sunscreen
What are you looking at with Spearman’s rank?
Correlation
Describe how waterlogged soil can cause nitrate to be removed from the soil.
denitrification takes place
Nitrate -> nitrogen gas into atmosphere
Denitrification requires anaerobic conditions, useful nitrogen fixing bacteria aren’t able to survive in these conditions
Explain why nitrogen fixing bacteria in the root nodules of leguminous plants are an example of mutualism
Nitrogen fixing bacteria convert nitrogen gas into nitrates.
taken up directly by the roots of the plant
bacteria themselves get glucose that the plant makes.
can be used in respiration by the bacteria.
Nitrogen fixing bacteria need lots of glucose.
Explain why nitrogen fixing bacteria in the root nodules of leguminous plants are an example of mutualism
Nitrogen fixing bacteria convert nitrogen gas, which is inaccessible to plants directly, into nitrates. This can be taken up directly by the roots of the plant. The bacteria themselves get glucose that the plant makes. This is useful because it can be used in respiration by the bacteria. Nitrogen fixing bacteria need lots of glucose.
What is the name of the group of organisms that settle after succession?
Climax community
Why would NPP increase as more herbaceous plants and shrubs with higher leaf areas grow?
- more photosynthesis
- as larger leaf SA allows more CO2 and light intake
- so higher rate of biomass production
What could reduce NPP?
- increase in proportion of non-photosynthetic tissue (wood, roots)
- lack of decay of leaves = reduced mineral ions
- anything reducing photosynthesis rate
