Chapter 13.2 - Energy + Ecosytems Flashcards
What are producers?
photosynthetic organisms that manufacture organic substances
How do producers manufacture organic substances?
Using light energy, water, carbon dioxide and mineral ions
What are consumers?
Organisms that obtain their energy by feeding on other organisms
What are primary consumers?
Those that directly eat producers (they are first in the chain of consumers)
What are secondary consumers?
Those animals eating primary consumers (normally predators)
What are tertiary consumers?
Those eating secondary consumers (normally predators)
What are saprobionts?
A group of organisms that break down the complex materials in dead organisms into simple ones.
What do saprobionts usually release?
They release valuable minerals and elements in a form that can be absorbed by plants - and so contribute to recycling
What is a food chain?
Desccribes a feeding relationship in which producers are eaten primary consumers etc
What is each stage in a food chain called?
Trophic level
What is biomass?
total mass of all living material in a specific area, habitat or region at any given time
What is biomass measured in?
grams per square metre(gm-2)
What is the best form to measure biomass in, and why?
As dry mass - although fresh mass is easy to assess, varying amounts of water makes it unreliable.
Measuring dry mass overcomes this, although organisms must be killed
How is biomass lost?
Urine/faces
Not all of organisms eaten (bones)
Not all of organism digested
Organism dies/decays before eaten
CO2 excreted
What does calorimetry do?
Can be used to estimate the chemical energy store in dry mass
Why is bomb calorimetry preferable to simple calorimetry?
Reduces heat loss to surroundings
What equation is used in calorimetry to estimate chemical energy in a dry biomass sample?
Energy released = specific heat capacity of water x volume of water x temperature increase of water
How could a student ensure all water has been removed from sample before weighing
Heat sample and reweigh until mass remains constant
How much will 1kcal raise water temperature by?
I degree
How many J of energy does 1 calorie equal to?
I calorie = 4.2J
What do pyramids of energy show?
The amount of energy available to the next level
What is energy measured in, in pyramids of energy?
kJm-2 year-1 to ensure seasonal abnormalities are not shown
Why is some energy unavailable to the next level in pyramids of energy?
-Chemical energy (biomass, usually glucose) is used by each organism in respiration to form ATP
- Respiration releases heat energy to surroundings
- Energy remains stored in dead organisms
- Animals excrete waste
- Whole organism not consumed by next trophic level
What % of light energy will be converted to chemical energy in plants?
Plants convert 1%-3% of the Sun’s energy available to them into organic matter
Why is so little of the Sun’s energy absorbed?
Wrong wavelengths
Light may not fall on a chlorophyll molecule
Over 90% is reflected off the atmosphere
Define gross primary production(GPP)?
Total chemical energy in plant biomass within a given volume or area
How much GPP is lost when plants respire?
approx 50% - known as respiratory loss (R)
Define net primary productivity?
The chemical energy store which is left after respiratory losses
What is the equation that links NPP and GPP?
Net primary production = gross primary production - respiratory losses
How do consumers store their energy?
In their biomass
How much total available energy is lost in consumers and why?
Approx 90% due to:
-respiration
-not all food eaten
-egested
How can the Net production of consumers be calculated?
N= I - (F +R)
I: chemical energy ingested
F: chemical energy lost in faeces +urine
R: respiratory loss
Why do most food chains only have 4 or 5 trophic levels?
Due to inefficient transfer of energy between levels
What is the equation for efficiency of energy transfers?
efficiency = energy available after transfer / energy available before x100
Define secondary production
The rate at which energy is uses to make new organic molecules within heterotrophs (consumers)
Outline farming practices used to increase efficiency of energy transfer
- Exclusion of predators
- Artificial heating - reduces heat loss to environment
- Restriction of movement
- Feeding is controlled at optimum (high in kcal)
- animals treated with growth hormones
Outline some disadvantages of factory farms
-Unethical
- Overcrowding
-Faster spread of diseases
-Antibiotics appear in food chain
What is the flow of nutrients described as?
Cyclic
What is the role of saprobionts?
Feed on remains of dead plants + animals - breaking them down
Secrete enzymes + digest food externally so they can then absorb the needed nutrients ( extracellular digestion)
What is mycorrhize?
When fungi form a symbiotic relationship with the roots of plants
What are hyphae?
Fungi made up of long, thin strands which connect with the plant roots
What do hyphae help increase?
Surface area
Uptake of water
What is guano?
Bird/seabird poo
This returns a high amount of phosphorus ions to the soil
What are natural fertilisers?
Consist of dead +decaying remains of plants + animals as well as animal waste (manure)
What are artificial fertilisers?
Mines from rocks + deposits and converted into different forms and blended together to give appropriate balance of minerals
What are disadvantages of using fertilisers?
Reduced species diveristy
Leaching of ions
Eutrophication
What is leaching?
The process by which nutrients are removed from the soil
Describe the process of leaching
Caused by rainwater dissolving any soluble nutrients and they are carried deep into the soil.
Leached ions can then find their way into waterways
What is eutrophication?
The process by which nutrient concentrations increase in bodies of water
Describe the process of eutrophication
1.Aquatic plants grow exponentially since nitrate level is no longer a limiting factor
2. Algal bloom on water surface prevents light from reaching bottom and plants die
3. Oxygen levels decrease as population of saprobionts increase to decay dead matter - fish die
4. Anaerobic organisms reproduce exponentially and produce toxic waste -> water is putrid
How can the risk of eutrophication be reduced?
- Don’t used fields near waterways
- Use crop rotation so different minerals are removed each year
- Use natural fertilisers
- Don’t use fertilisers in rainy season
