B7 - Ecology Flashcards
Why is sodium carbonate solution added to the milk sample in the decay practical?
It makes the solution slightly alkaline. This is required as when the lipase releases fatty acids, the solution becomes acidic
What is decomposition?
Decomposition is the breaking down and digestion of biological waste by decomposers
What three factors affect the rate of decay of biological material?
Temperature
Availability of oxygen
Availability of water
Describe how temperature affects the rate of decay of biological material
A higher temperature results in a faster rate of decay because the enzymes decomposers secrete break down biological material in warm conditions. HOWEVER, if the temperature is too extreme, the enzymes will denature and the decomposer may die
At low, cold temperatures, enzymes will function at a slow rate, so decomposition rate will be slow. This is why food is stored in a fridge
Describe how water availability affects the rate of decay of biological material
Rate of decay is faster if the biological material is moist. This is because many of the chemical reactions in decay require water. This means that gardeners, for example, do not allow a compost heap to dry out
Describe how the availability of oxygen affects the rate of decay of biological material
Rate of decay is faster in regions of good oxygen supply. This is because decomposers carry out aerobic respiration
State two uses of decay
As compost
In biogas generators
Describe how decay can be used as compost
Decomposed matter is used to naturally fertilise and improve soil as compost. Once the compost is spread onto the soil, it is broken down by microorganisms and detritivores. This ensures the cycling of materials that can be absorbed by plants or crops for growth
Describe how decay can be used in biogas generators
In anaerobic decay, methane gas is produced. The generator contains inlets for animal and plant waste material. This decomposes. Methane gas is then combusted as a fuel for cooking, heating or to power a turbine to produce electricity. Carbon dioxide that is produced as a bi-product of the combustion is released into the atmosphere and may be used by plants in photosynthesis. The generator also contains outlets for decomposed material that can be used as fertiliser for crops
Explain why a widespread use of biogas as a fuel may be beneficial for global biodiversity
Carbon neutral energy sources help to maintain stable levels of CO2 in the atmosphere, which may reduce the rate of global warming. This may benefit global biodiversity as it will reduce the extinction of species as a result of being unable to survive in a different climate
Suggest why milk left at room temperature becomes sour after a few days
Bacteria in the milk begin the decay process. These bacteria secrete enzymes to produce acidic molecules that make the sour milk taste acidic
What is the IV, DV and CV of the decay investigation?
IV - Temperature of water bath/electrical heater
DV - Time taken for the indicator to change colour
CV - Volumes of different solutions
How can the investigation of the decay of milk be improved?
- Use a clean test tube for the milk solution each time the experiment is repeated. This is because any traces of lipase from the previous experiment will trigger the reaction, resulting in unreliable results
- Share data with other groups of scientists and calculate a mean to reduce the effect of stopping the stopwatch too soon or too late
Decay is a slow process.
What is one disadvantage of the milk decay practical?
The decay is modelled using the enzyme lipase. This means only approximate results are retrieved
Describe how to investigate the effect of temperature on the rate of decay of fresh milk by measuring the pH change
Place 5cm³ of lipase solution into a test tube using a pipette
Place 5cm³ of milk into a different test tube and add five drops of the indicator cresol red/phenolphthalein to the milk
Pour 7cm³ of sodium carbonate solution to the milk test tube. This makes the solution alkaline, so it should turn pink or purple
Place both test tubes into a water bath set at 20 degrees Celsius and place a thermometer into the test tube containing the milk sample. Wait until the test tubes equilibrate to the conditions
Use a pipette to transfer 1cm³ of lipase solution to the test tube containing milk and stir using a glass rod
Start a stopwatch. The lipase will start to break down the fat molecules in the milk, releasing fatty acids that causes the solution to become acidic. As a result, the pH drops
At this point, the indicator will change colour. Stop the stopwatch at this time and record how long the colour change took in a table
Repeat the experiment at a range of different temperatures and carry it out three times at each temperate.
Calculate a mean time taken for the colour change to occur and calculate the rate of decay using the equation rate = 1000/time
Describe how plants are involved in the water cycle
Plants take in water for photosynthesis
Plants lose water by evaporation through transpiration
Plants form water through respiring
When plants die, decomposers release water from them. Decomposers also release water through respiration when breaking down biological matter
State the roles of microorganisms in cycling materials through an ecosystem
Role of plants in cycling carbon and water -> photosynthesis, respiration, transpiration & decay
Role of decomposers in cycling carbon and water -> aerobic respiration for decay and anaerobic respiration in biogas generators
Role of animals in cycling water -> aerobic respiration and excretion
Role of humans and human activity in cycling carbon -> combusting fossil fuels, and aerobic respiration
Is precipitation freshwater or saltwater? Explain your answer
What are the different forms of precipitation?
Freshwater. Salt cannot be evaporated
Global warming is causing ice caps to melt. Describe some of the biological consequences of melting ice caps
More extreme weather events
Sea levels may rise
Habitats will be destroyed
Reduced biodiversity
Describe how living things are involved in the cycling of carbon
Carbon is removed from the atmosphere by green plants and algae during photosynthesis
When plants and algae respire, some carbon is returned to the atmosphere
When plants are eaten by animals, some carbon becomes part of the fats and proteins in their bodies. When animals respire, some carbon is returned to the atmosphere
When plants and animals die, decomposers secrete enzymes to break them down. This uses aerobic respiration and so releases carbon dioxide into the atmosphere
Other animals and microorganisms such as detritus feeders also feed on dead remains. When they respire, carbon is returned to the atmosphere
The combustion of wood and fossil fuels by humans also releases carbon dioxide into the atmosphere
Describe the water cycle
Energy from the sun evaporates water from the land and sea, turning it into water vapour. Water vapour also comes from transpiration in plants
The warm water vapour is carried upwards as warm air rises and at high altitude it cools and condenses to form clouds
Water falls from the clouds as precipitation onto land, where it provides fresh water for plants and animals
It then drains into the sea and the process starts again
What is the importance of the carbon and water cycles to living organisms?
Carbon cycle returns CO2 to the atmosphere. This is important for plants to photosynthesise
Water cycle provides fresh water for plants and animals on land before draining into the sea
For hard application questions,
Think: where have I seen these key words? Do they link across topics?
Understand that: In 6 markers, you should if in doubt write down EVERYTHING you know that is RELEVANT to the question focus
Remember: The questions are linked if in parts. You may have to use information they provide you in setting the scene of the question in your answer
THE QUESTIONS LINK. THINK ABOUT HOW THE CONTEXT RELATES TO THE Q THEY R ASKING. FOR GRAPH EXPLAN QUESTIONS USE DIFF PARTS OF THE GRAPH. IT IS EASIER THAN YOU THINK
In evaluation questions , use your own knowledge and provide a justified conclusion
Give three examples of environmental changes that may affect the distribution of species in an ecosystem
Temperature
Availability of water
Composition of atmospheric gases
Give three reasons for changes in environmental factors that affect the distribution of species in an ecosystem
Seasonal changes
Geographical changes
Human interaction
What is biodiversity?
Biodiversity is the variety of all the different species of organisms on Earth, or within an ecosystem
Explain the importance of good levels of biodiversity
Ensures stability of ecosystems by reducing dependence of one species on another for food, shelter and maintenance of the physical environment (tree roots provide soil stability).
Ensures the future of the human species on Earth (pollinators are needed for food crops)
Many human ____ are reducing ____ and only recently have measures been taken to try to stop this
Activities
Biodiversity
Why have humans’ use of resources and waste production increased?
Rapid growth in human population
Increase in the standard of living
Unless waste and chemical materials are properly handled, more pollution will be caused
What is a trophic level?
A trophic level is the position a species occupies in a food chain
Describe the four trophic levels
- Producers = plants/algae that make their own food
- Primary consumers = herbivores that eat plants/algae
- Secondary consumers = carnivores that eat herbivores
- Tertiary consumers = carnivores that eat other carnivores
What is an apex predator?
A carnivore with no predators
Describe the role of decomposers
Decomposers break down dead plants/animal matter by secreting enzymes into the environment
Small soluble food molecules then diffuse into the microorganism
What do pyramids of biomass represent?
Relative amount of biomass in each level of a food chain
What is biomass?
Biomass is the mass of living tissue/material of organisms in an area
How do you calculate efficiency of biomass transfer between trophic levels?
Efficiency = (biomass transferred to next level/biomass available at previous level) x 100
Explain how biomass is lost between different trophic levels
Not all ingested material is absorbed -> some egested as faeces and bones aren’t eaten
Some absorbed material are lost as waste (excretion) -> C02 in respiration and urea in urine
Large amounts of glucose used in respiration to release energy
What % of incident light energy do producers transfer for photosynthesis?
About 1%
What % of biomass from one trophic level is transferred to the level above it?
About 10%
How does the efficiency of biomass transfers affect the number of trophic levels?
The less efficient the transfers, the fewer trophic levels and the fewer organisms in higher trophic levels
What is food security?
Having enough food to feed a population
Describe the 6 biological factors which are threatening food security
Increasing birth rate so more people to feed
New pests and pathogens that affect farming that destroy and damage crops/livestock
Environmental changes affecting food production
Costs of agricultural inputs such as fertilisers and pesticides
Changing diets in developed countries mean scarce food resources are transported around the world
Conflicts can affect water and food availability due to difficulty transporting
Explain how the efficiency of food production from animals can be improved
Restrict energy transfer from animals to environment so that there is more energy for growth by limiting movement and controlling surrounding temperature
Feed animals high protein foods to increase growth
Give disadvantages of intensive farming methods
Diseases spread more quickly between animals
Overuse of antibiotics/can build up in food chain
Increased use of fossil fuels for regulating temperature
Why is it important to prevent fish stocks from continuing to decline?
Stocks may not be high enough for breeding to continue
So certain species may disappear altogether in some areas
Explain how fish stocks can be conserved at a sustainable level
Control of net sizes (make smaller) and bigger mesh sizes -> younger fish not caught so can survive long enough to reproduce
Introduction of fishing quotas -> fewer fish caught so remaining fish can reproduce
What is a disadvantage of introducing fishing quotas?
Quotas lead to dead fish being thrown back into the sea
Why are modern biotechnology techniques useful in food production?
Enable large quantities of microorganisms cultured for food
What is mycoprotein?
Protein rich food suitable for vegetarians
It is not a fungus. It is produced by a fungus
Explain how mycoprotein is produced
Fungus Fusarium is grown on glucose syrup in aerobic conditions
The biomass (mycoprotein) is harvested and purified
Describe an advantage of using genetically modified (GM) crops
Could provide more food to encourage food security, or food with improved nutritional value
For example, golden rice which has beta carotene to make vitamin A for better vision
Give an example of how GM bacteria can be used
A GM bacteria can produce human insulin
When harvested and purified this is used to treat people with diabetes
Explain why Fusarium needs glucose and oxygen
Explain why a fermenter used for growing Fusarium to make mycoprotein is sterilised before use
Suggest two possible advantages of getting more food from mycoprotein, with less from farming animals
(I) For aerobic respiration, which releases energy for growth
(II) Kills microorganisms which compete for food/oxygen and make toxins
(III) Quicker/cheaper, suitable for vegetarians, more efficient/less methane
