SB9 Flashcards
Explain mutualism.
It is when both organisms benefit from the relationship i.e. bees and flowers as bees feed on the nectar and pollinate flowers.
Explain parasitism.
A feeding relationship where a parasite benefits and the host is harmed i.e. head lice living on hair and skin (it is adapted via its harp claws to grip on hair and skin).
What are trophic levels?
Feeding level in a food chain i.e. producer, secondary consumer etc
Positives and negatives of fish farming.
Positives: Reduces overfishing of wild fish and produces more fish.
Negatives: parasites and diseases spread easily due to the close proximity between fish in pens (fish need to be treated to be kept healthy). Uneaten food and faeces from fish can sink to the bottom of water, changing conditions and harming wild fish living there.
Explain the process of eutrophication.
Eutrophication is the addition of more nutrients to an ecosystem than it normally has.
1. Heavy rain washes away fertiliser, nitrates and phosphates dissolve in soil water or nitrates and phosphates not taken in by plants get washed into streams/rivers.
2. high nitrate and phosphate concentration in the water encourage rapid plant and algae growth.
3. surface plants block sunlight thus plants in water die + stop producing oxygen.
4. bacteria that break down dead material increase and use more oxygen from the water.
oxygen concentration in the water decreases.
How can the level of polluted water be assessed?
Indicator species
Polluted water have bloodworm & sludge worm
Clean water have stonefly & freshwater shrimps
How can air quality be assessed?
Indicator species i.e. lecanora conizaeoidies lichen is the only lichen that can be tolerate sulphur dioxide pollution
Blackspot fungus is a pathogen of roses and cannot grow well where there is lots of sulphur pollution.
What is the equation for population size?
population size = number of organisms in all quadrats x (total area of where organism lives/total area of quadrats)
What can convert nitrogen gas into something useful for plants and where is it found?
Nitrogen-fixing bacteria can convert nitrogen gas into nitrogen compounds in the soil and leguminous plants such as peas and beans have a mutualistic relationship with this bacteria. : the bacteria is protected inside nodules of plant roots and plants get nitrogen from bacteria.
What is crop rotation?
Planting a sequence of crops in different years to keep their soil fertile so different crops can benefit from the nitrogen from leguminous plants.
What do most methods of food preservation rely on?
- decreasing temperature i.e. freezing food
- reducing water content i.e. salting and then drying meat to make ham
- irradiation of packaged food to kill decomposers
- reducing oxygen content i.e. storing in oil or packaging in unreactive gases like nitrogen
What conditions do decomposers thrive on?
Warm and moist conditions with most of them needing oxygen.
How do you calculate rate of decomposition?
mass lost(g)/number of days
