Energy And Ecosystem Flashcards
🔴️ How does intensive rearing increase net productivity
1 Movement is restricted so less energy is used
2 Kept warm inside so less heat loss and no predators
3 Some livestock are genetically selected for higher productivity
4 Fed on controlled diet so higher proportion of digested food absorbed
5 Some are killed when young so more energy transferred to biomass
🔴️Describe and explain why the efficiency of energy transfer is different at different stages
1 Some light from the sun is reflected as it’s isn’t of an appropriate wavelength
2 The efficiency of photosynthesis Is approx 2%
3 Energy is lost as part of the plants is not eaten. And some is lost in faeces/ urine
4 It may be lost as heat to the environemt
5 The efficiency of transfer to consumer is greater than transfer to producers as 10% of energy is absorbed
6 The efficiency is lower in warm blooded animals as energy is used to maintain temp
7 Carnivores use more of their food than herbivores
🔴️Why do food chains rarely have more than 5 trophic levels?
- some energy is lost at each trophic level in the food chain due to respiration
- less energy is available to be passed on in the next food chain
🔴️ Advantages of biological control
- Specific to one pest
- Only 1 application needed as it reproduces
- Pests don’t get resistance
- No chemical residues left
- Keeps pests population consistently low
- Can be used in organic farming
🔴️Disadvantages of biological control
- Doesn’t eradicate pest completely
- Slow acting
- May become the pest itself
Why do native organisms become the dominant species in a new environment
- They have few consumers
- They out compete the other organisms for resources e.g light
How farming practices increase the productivity of agricultural crops
- Fertilisers are added to soil e.g nitrates
- Nitrogen for protein and phosphorus for DNA
- Pesticides and biological agent prevents consumption of crop;
- Herbicides remove competition;
- Selective breeding of crops
- Glass houses enhance conditions temp/CO2/ light;
- Ploughing aerates soil which allows nitrification
How do we use Integrated control
- Uses biological control more and minimal pesticide
- It controls pest population instead of eradicating it
- Monitor area and look for pests
- Mechanically remove pests if present
- Supply initial dose of pesticide as it is fast acting
- Then apply biological control .
- These will increase in number over time and provide long term control
- Reapply pesticides whenever there is an uncontrollable outbreak
Describe the carbon cycle?
- Carbon Dioxide removed from atmosphere by plants by photosynthesis
- Carbon Dioxide removed from atmosphere by ocean (CO2 dissolves in ocean)
- Plants and animals respire returning CO2 to the atmosphere
- When plants die they’re broken down by decomposers which respire,returning CO2 to the atmosphere
- Combustion of fossil fuels returns CO2 to the atmosphere
- Evaporation of the ocean returns CO2 to the atmosphere
Effects of global warming?
- Melting of polar ice caps: extinction of polar bears
- Rise in sea level could lead to coastal flooding, reducing crop productivity
- Intense whether conditions, changing the distibution of organisms
- The life cycle of insect pests would change as they adapt
- Changes proportion of organisms as only xerophytes survive due to the changed rainfall patterns
Ways in which energy is lost between primary and secondary consumers.
- Heat loss to environment by respiration
- movement e.g running (muscle contraction)
- faeces due to indigestible material
- inedible parts as not all eaten;
- excretion e.g urine
Reasons why very little of the sunlight energy falling on the leaves of a plant can be used
- Some light may have wrong wavelength
- Reflected;
- Misses chloroplasts
- May be other limiting factor
Why does deforestation reduce the diversity index of an area cleared in by deforestation
- deforestation removes many habitats
- less variety and quantity of food
- so fewer species can live there
Explain the potential benefit of applying a fertiliser containing ammonium nitrate [((NH4)(NO3)] rather than one containing KCN.
- ammonium nitrate contains more nitrogen per molecule than potassium nitrate;
- nitrate ions in fertiliser is absorbed immediately;
- nitrifying bacteria convert ammonium to nitrate so more nitrate made
- the KCN fertiliser would provide only the initial release of potassium nitrate
Disadvantages of chemical control
- Non-biodegradable so may store in tissues;
- Non-specific as it may kill predators of pests;
- Builds up in food chain (bioaccumulation)
- May develop resistance;
- Not cost-effective as needs to be reapplied
if pigeons consume a poison, how can eagles die from eating pigeons
- accumulation of posion within tissue
- poison is non-biodegradable
- eagles eat large numbers of birds;
- biomagnification leads to a high concentration of poison which kills eagles;
Describe and explain the effects of monoculture on the environment.
- Other plant species removed so reduction in biodiversity
- Less variety of food
- Less habitats so less organisms can live there
- Reduces soil fertility so more fertilisers required;
- Could lead to large scale crop failure if new disease emerges ,
How can an ecosystem become more stable?
- Have more species (biodiversity)
- More variety of food sources
- More niches/habitats
Factors that need to be considered before using an organsim as a biological control
- Specificity: Only affects target species;
- Can survive in conditions of use;
- Ability to work on a large scale;
- Can the produced on a large scale;
Explain how regular use of a pesticide could result in a resistant pest population
- Variation in population due to chance mutation
- Some individuals in population acquire allele for resistant so they’re not killed by pesticide;
- These survive when pesticide applied whereas non-resistant ones are killed;
- They reproduce and pass on resistant allele
- This Increases the frequency of resistant allele ;
Why isn’t biomass an accurate representation of food availability
- Not all of animal eaten e.g large bones/skin;
- Inedible parts make up different proportions in different organisms
3 ways deforestation has increased CO2 conc?
- decrease in photosynthesis causes less removal of CO2
- burning trees releases CO2
- decay of wood by microorganisms releases CO2
How does deforestation reduce biodiversity?
- loss of habitat for certian species
- loss of food source
- fewer plant species due to clearing
Why don’t biological control completely eradicate pest
- because biological control never eats all pests;
- as pests diminish so do control agents and vice versa
How can we measure the dry mass of an organism?
- Heat at 100 C to evaporate water;
- Weigh and heat until no further change in mass;
Why is dry mass better than fresh mass when comparing yield of plants
- Amount of water present will vary;
- This will affect fresh mass but will not affect dry mass
Advantages of using integrated control
Biological Agents
- Only needs one application as they reproduce
- Specific;
- Keeps population consistently low;
- Pests do not develop resistance;
- No bioaccumulation;
Chemical pesticides
- Acts quickly;
- Can apply to specific area;
- Can eliminate pests;
- Kills wide range of pests
Why does efficiency of food converted to biomass of an organism decrease at a lower temperature
- Lose more heat
- More energy used to maintain body temperature;
- More respiration needed
- More food used in respiration;
- Less energy to grow
As the predator increases why does the mass of prey increases
- Fewer prey as most are consumed by predators
- More food available for surviving prey so they grow more
Factors farmers need to consider before investing in a new treatment plan
- How treatment may affect other organisms and environment (yield)
- Cost of substance
- Amount of substance needed for an effect
Define biological control
- Use of parasite/predator/pathogen;
- To control numbers of a pest organism;
Explain why the increase in the dry mass of a plant over twelve months is less than the mass of hexose produced over the same period.
- some hexose/biomass used in respiration;
- some parts of the plant are eaten;
- some parts lost to decomposers as leaf fall;
Why is the dry biomass of plants is always higher than that of animals?
- Plants are producers
- Animals are consumers of plants;
- Loss of energy between trophic levels;
- Due to respiration as heat;
- Less energy available to grow
