Ecology Flashcards
1
Q
What is a ‘habitat’?
A
- the environment in which an organism lives
2
Q
What is a ‘population’?
A
- the total number of organisms of the same species living in the same geographical area
3
Q
What is a ‘community’?
A
- the populations of all of the different species that live in the same habitat
4
Q
What is an ‘ecosystem’?
A
- the interaction of a community of biotic parts with the abiotic parts of their environment
5
Q
What is the difference between ‘biotic’ and ‘abiotic’?
A
biotic = living organisms
abiotic = non-living parts
6
Q
What do organisms need to survive and reproduce?
A
- organisms require a supply of materials from their surroundings and from the other living organisms there
7
Q
What 4 main factors do plants in a community or habitat often compete for?
A
- light
- space
- water
- mineral ions
8
Q
What 4 main factors do animals often compete with each other for?
A
- food
- water
- mates
- territory
9
Q
What is the term for how within a community, each species depends on other species for certain things; if one species is removed, it can affect the whole community?
A
interdependence
10
Q
What makes a community be stable?
A
- a stable community is one where all the species and environmental factors are in balance => population sizes remain fairly constant
11
Q
Give 4 examples of factors that species depend on other species for?
A
- food (eg. lions depend on gazelles to eat)
- shelter (eg. animals may depend on trees to provide shelter from the Sun)
- pollination (eg. flowers depend on bees)
- seed dispersal (eg. flowers depend on birds to disperse seeds in their faeces)
12
Q
How would a change in the availability of food affect organisms in a community?
A
- availability of food falls => the populations of species would also fall as they have less food to eat => less likely to survive and live on to reproduce
- availability of food increases => the populations of species would also increase
13
Q
How would the arrival of a new predator affect organisms in a community?
A
=> population of a prey species will fall
=> more competition for existing predators that eat the same food as the new predator => less food
14
Q
How does the level of competition affect organisms in a community?
A
- if a species is outcompeted, its population can fall => may even become extinct if numbers are insufficient to breed
15
Q
How would the arrival of new pathogens affect organisms in a community?
A
- if an infectious disease emerges and spreads, it can wipe out a population of a species
16
Q
How does changing light intensity affect plants?
A
- if the light intensity is too low, the rate of photsynthesis falls => plants will grow more slowly => animals may not have enough food
17
Q
How does changing temperature affect plants?
A
- if temperature changes significantly, the distribution of a species may change (eg. animals could migrate or plant species may disappear from that area)
18
Q
How do moisture levels affect organisms in a community?
A
- both plants and animals need water to survive => if there are low levels of moisture, plants that are not adapted may die
19
Q
How does soil affect plants?
A
- many plants cannot grow on soil which is too acidic or too alkaline
- plants also need certain mineral from the soil
20
Q
How does wind intensity and direction affect plants?
A
- stronger winds may cause plants to lose water via transpiration
21
Q
How do the carbon dioxide levels affect plants?
A
- a higher carbon dioxide concentration means plants can photosynthesise more
22
Q
How do the oxygen levels in water affect aquatic animals?
A
- aquatic animals need dissolved oxygen from the water for respiration
23
Q
What is the difference between the 3 types of adaptations?
A
- structural adaptations relate to the physical body shape or body structure
- functional adaptations relate to the body functions of an organism
- behavioural adapatations relate to the animal’s lifestyle or behaviour (things that the animal does)
24
Q
How are camels STRUCTURALLY adapted to the hot and dry conditions of a desert?
A
- camels have a hump on their back which is a store of fat, a thermal insulator (by storing the fat in one place, this allows heat loss from the other parts of the camel’s body => reduces water loss from sweating) + metabolic reactions can be used to produce water from the fat
- thick coat on the upper surface of their body => insulates the top of the camel from the heat of the Sun => reduces water loss from sweating
- the inside of a camel’s mouth is leathery => allows camel to shew desert plants (which often have thorns)
- camels have long eyelashes => keep dust out of their eyes
- camels can close their nostrils => keep dust out of their nose
- camels have wide feet => prevents the camel from sinking into the sand
25
How are camels FUNCTIONALLY adapted to the hot and dry conditions of a desert?
- camels produce CONCENTRATED URINE and DRY FAECES => reduce water loss
- camels can tolerate very large changes in their body temperature => helps them to cope with the intense heat of the desert
26
What are different ways that some animals BEHAVIOURALLY adapted to survive in both hot and cool conditions?
- some animals are NOCTURNAL (mainly active at night when it is cooler) => avoid the heat of the daytime + these animals may also live in burrows underground during the day => keep cool and protects them from predators
- some animals, eg. polar bears, hibernate during the winter to avoid the cold (the animal becomes inactive and all the body processes slow down)
- some animals, eg. some birds, migrate south to warmer climates
27
How are some animals STRUCTURALLY adapted to survive the cold climate?
- very thick fur => provides insulation and reduces heat loss to the air
- fur on the soles of their feet, eg. the Arctic fox => reduces heat loss to the ice and the snow
- very small ears => reduces the overall surface area of the animal, eg. the Arctic fox => reducing heat loss
- white coat => effective camouflage (helps the animal to hunt its prey)
28
How are cacti adapted to live in the dry desert?
- very small leaves => reduce surface area for water loss (or even no leaves at all, only spines which also protect the cacti from animals)
- extensive and shallow roots => absorb maximum water after rainfall
- cacti can store water in their stems => survive many months without rain
29
What are 'extremophiles'?
- organisms that live in environments with extreme conditions, eg. bacteria that live in deep sea vents
30
Give 3 examples of extreme conditions that an extremophile may be able to survive in?
- high temperature
- high pressure
- high salt concentration
31
What do food chains represent?
- feeding relationships within a community
32
What do all food chains begin with?
- all food chains begin with a PRODUCER which synthesise complex molecules (biomass)
- this is usually a green plant or alga which makes glucose by photosynthesis
33
What is the general food chain?
producer => primary consumer (prey) => secondary consumer => tertiarry consumer => apex predator
34
What are transects and quadrats used for?
- a range of experimental methods using transects and quadrats are used by ecologists to determine the distribution and abundance of species in an ecosystem
35
What is random sampling used for?
How is random sampling done? What is a quadrat?
What can we sample with this method?
- used to compare the numbers of organisms in different areas
- by using a quadrat (a wooden/plastic square)
- we throw the quadrat randomly and then count the number of organisms inside wherever it lands
=> we can use random sampling to sample plants or slow-moving animals
36
How can we increase the validity of random sampling?
- throwing the quadrat a large number of times
37
How can we increase the accuracy of random sampling?
- using a smaller quadrat
38
In random sampling, what is the equation to estimate the total population size of a species?
(total area / area sampled) x number of organisms of that species counted in sample
39
What is sampling along a transect used for?
What is a transect? How is sampling along a transect done?
- to investigate how the numbers of species change as we move across a habitat
- a transect is simply a line (eg. a tape measure of a piece of rope)
- we use a quadrat to count the organisms at intervals on the transect
40
How can we increase the validity of sampling along a transect?
- move the tape measure of rope further along in the horizontal direction => repeat the whole process
41
What is the method to measure to population size of a common species in a habitat?
1) Place two tape measures at a right angle. (20m in length)
2) Use a bag filled with numbers 1-20.
3) The first student picks a number out of the bag and moves to this number along one of the tape measures.
4) A second student picks another number out of a second bag which has been filled with humbers 1-20. The student then moves to this number along other tape measure.
5) A third student places a quadrat (0.5m x 0.5m) at the point where the two numbers picked out intercept as a co-ordinate, eg. (12,8).
6) The students record the number of flowers, eg. daisies, in the first quadrat. The students return their numbers back to the two bags.
7) the students repeat this process nine more times for a total of ten samples.
8) Estimate the total population of flowers, eg. daisies, in the whole field by using the equation; say the total number of common species counted was 300 => (400m² / 2.5m²) x 300 = 48000 total flowers
42
What is the method to investigate the effect of a factor on the distribution of this species.
- we are going to investigate the effect of light intensity on the distribution of daisies
1) Place a transect (eg. tape measure) at the tree (providing shelter and reducing the light intensity) and going outwards.
2) Place a quadrat at the base of the tree and count the number of daisies inside. Also, measure the light intensity by using a light meter or app.
3) Move the quadrat 1m down the tape measure and count the number of daisies inside. Repeat this process until you reach the end of the tape measure.
=> you will notice that as we move the quadrat further away from the tree, the number of daisies increases (light is an abiotic factor as plants need light for photosynthesis)
=> however, the tree is also absorbing water and mineral ions from the soil so light may not be the only abiotic factor
43
What is the importance of the carbon and water cycles?
- all materials in the living world are recycled to provide the building blocks for future organisms
44
How is carbon cycled?
- the carbon cycle starts with carbon dioxide in the atomosphere
=> this carbon dioxide enters the carbon cycle by the only way of photosynthesis in plants and algae
=> some of the carbon returns back to the atmosphere as carbon dioxide by aerobic respiration
=> plants and algae can be eaten by animals => these animals can be eaten by other animals (still respiring and releasing some of the carbon back to the atmosphere as carbon dioxide)
=> the animals release waste products, such as faeces + eventually, all animals and plants die to form their dead remains => decomposed by microorganisms (when these bacteria or fungi respire, some of the carbon is returned to the atmosphere again)
=> if decomposers cannot function properly, the carbon in dead remains can slowly be converted to fossil fuels (releases carbon when combusted)
45
What do decomposers return to the soil?
mineral ions
46
How is water cycled?
- almost all of the water on earth is found in the oceans
=> energy from the Sun causes the salt water to evaporate from the surface of the sea
=> water vapour now travels into the air and cools down
=> condenses to form clouds
=> the water in clouds then falls to the ground as precipitation (fresh water)
- once this water hits the ground, some of it simply evaporates back into the atmosphere
=> some of the water passes through rocks and formes aquifers
=> most of the water forms rivers or streams (eventually drain back into the sea)
- water is continuously evaporated and precipitated
47
What is the role of plants in the water cycle?
- plants take up water in their roots => moves up the plant in the xylem => passes out of the leaves through stomata as water vapour (transpiration)
48
What is the role of animals in the water cycle?
- animals take in water through drinking and in their food => release water in their urine, in their faeces, and when they exhale
49
What is the role of gardeners and farmers in decomposition?
- they try to provide optimum conditions for rapid decay of waste biological material
50
What is the compost used for after it has been produced by the decomposers?
- used as a natural fertiliser for growing garden plants or crops
- compost is very rich in the minerals that plants need to grow (the decomposers return the mineral ions back to the soil)
51
How does temperature affect decomposition?
Why do compost heaps tend to be quite warm naturally?
- decomposition takes place faster at warmer conditions (the decomposers use enzymes to break down the plant materials and the enzymes work most efficiently at specific temperatures)
- compost heaps tend to be quite warm anyway because decomposers release energy when they carry out aerobic respiration
52
Why is it important that gardeners and farmers must control the temperature of a compost heap?
- if the temperature gets too high, the enzymes in the decomposers can denature => decomposers can die
53
Why is it important that gardeners and farmers control the amount of water in compost heaps?
- decomposing microorganisms work faster if the compost is moist (many of the chemical reactions in decay require water)
54
Why is it important that gardeners and farmers control the availability of oxygen in compost heaps?
How can farmers increase the availability of oxygen?
- aerobic respiration in decomposers requires oxygen
=> farmers can use compost bins which have holes in the walls to allow oxygen to enter
=> farmers can use a gardening fork to mix their compost regularly to allow more oxygen to pass into the centre + mixing the compost also breaks up large clumps => increasing the surface area for decomposers to act on
55
What happens if there is insufficient oxygen for decomposers to carry out aerobic respiration?
=> anaerobic decay
=> produces a mixture of gases, including methane (biogas)
=> biogas generators can be used to produce methane gas as a fuel
56
What is the method to investigate the effect of temperature on the rate of decay of fresh milk by measuring pH change?
- decomposing bacteria use enzymes to produce acidic molecules when milk is left at room temperature for a couple of days
1) Label a test tube "lipase" and use a pipette to place 5cm³ of lipase solution into the test tube.
2) Label another test tube "milk" and add five drops of the indicator Cresol red. Add 5cm³ of milk and 7cm³ of sodium carbonate solution to the "milk" test tube. (solution should be purple as sodium carbonate solution is alkaline and Cresol red turns purple in alkaline conditions)
3) Place a thermometer into the test tube containing the milk.
4) Place both test tubes into a beaker of water at our first chosen temperature, 20°C.
5) Wait until the temperature of the solutions is the same as the water in the beaker.
6) Use a pipette to transfer 1cm³ of lipase solution to the test tube containing milk, stir the solution. Start a timer. The enzyme lipase will start to break down fat molecules in the milk, releasing fatty acids, and also, causing the milk solution to become acidic.
7) Stop the timer and record the time when the Cresol red changes to yellow (acidic conditions).
8) Repeat the whole experiment at a range of different temperatures (eg. 25°C, 30°C, 35°C, 40°C, 45°C, 50°C).
i.v. = temperature
d.v. = time taken for colour change to yellow
c.v.. = volume of each component
57
How can we increase the accuracy of the decompostion required practical?
- using several people to stop the timer when they believe that the Cresol red has changed colour => calculating a mean
58
What is the impact of a change in temperature on the distribution of species in an ecosystem?
- species that live in hot conditions, eg. a desert, will be more suited to the environment
- eg. the Desert fox lives in Africa and it has large ears which increase the fox's surface area, allowing it to lose heat more easily => the Desert fox would not be found in cooler places => as we move further north, the conditions get colder and we find the Arctic fox, with very small ears
- temperature shows geographic variation
59
What is the impact of a change in availability of water on the distribution of species in an ecosystem?
- in the dry desert, we find plants that are adapted to live here where the water is scarce => cacti are not found in regions where water is more plentiful, eg. a tropical rainforest (we instead find plants that are adapted to live in wetter conditions, such as ferns)
60
How can environmental changes lead to seasonal variation?
- birds and bats migrate south in winter to warmer conditions
- wildebeest follow the rainfall patterns in search of better grazing land
61
How can abiotic factors be inflenced by human activity?
- lichens are extremely sensitive to sulfur dioxide gas (can be produced by burning fossil fuels) => we find the largest numbers of lichens where the air is unpolluted
- human activity can affect the levels of gases dissolved in water (eg. if sewage is allowed into streams, the level of dissolved oxygen can decrease => organisms such as mayfly nymphs cannot live in conditions of low oxygen => population of this species falls)
62
A large amount of untreated sewage entered the river. Many fish died. Untreated sewage contains organic matter and bacteria.
Explain why many fish died. (Exam Q)
- bacteria decay organic matter
- by digestion
- bacteria respire aerobically using oxygen
- which lowers the oxygen concentration in the water, leaving less oxygen for the fish
- so the reduced energy supply causes death of fish
63
What is 'biodiversity'?
- the variety of all the different species of organisms on earth, or within an ecosystem
64
Why is a higher level of biodiversity beneficial and important?
- a great biodiversity ensures the stability of ecosystems by reducing the dependence off one species on another for food, shelter and the maintenance of the physical environment, eg. decomposers break down the remains of dead organisms
- if the population of a species falls, it is less likely to affect the whole ecosystem
65
How is deforestation having a negative effect on biodiversity?
- tropical rainforests contain a very high level of biodiversity
- large areas of these forests are being destroyed to provide land, removing habitats at the same time
66
What are some reasons for deforestation?
- to provide land for rice fields or for grazing cattle
- land is used to grow crops which are then used to make biofuels
67
What is the cause for the increase in demand for resources and therefore, the production of more waste?
rapid growth in the human population and an increase in the standard of living
68
How can pollution occur in water?
What is the negative effect of water pollution?
- untreated sewage can be accidentally released into rivers or streams
- rivers and streams can be polluted with fertilisers from farms
(both fertilisers and untreated sewage cause dissolved oxygen levels in water to fall => kill aquatic animals)
- toxic chemicals can be released into rivers from factories => kill aquatic animals
=> waste from human activity is reducing biodiversity in aquatic ecosystems
69
How can pollution occur in air?
What is the negative effect of air pollution?
- burning fossil fuels, eg. coal, in power stations can release smoke and acidic gases => cause acid rain
=> air pollution can kill plants and animals, reducing biodiversity
70
How can pollution occur on land?
What is the negative effect of land pollution?
- millions of tons of waste are dumped in landfills => destroy habitats for plants and animals
=> toxic chemicals can then leach out of landfills and pollute the soil (toxic chemicals are sometimes simply dumped directly onto the land)
=> kill living organisms, reducing biodiversity
71
What is it important for humans to do to reduce pollution?
- waste and chemical materials should be properly disposed of, in a way that will not harm the environment
72
What are the uses of land?
- humans reduce the amount of land available for other animals and plants by:
=> building
=> quarrying
=> farming
=> dumping waste, eg. landfills
=> reduced biodiversity
73
What is the effect of destroying peatbogs?
- the destruction of peat bogs, and other areas of peat to produce cheap garden compost, reduces the area of this habitat
=> reduces the variety of different plant, animal and microorganism species that live there (biodiversity)
74
What is the effect of the decay or burning of the peat?
- peat can be burned to release energy, eg. to generate electricity => releases carbon dioxide into the atmosphere => contributes to climate change
75
Why is there a conflict with using compost with alternatives for peat?
- the alternatives are more expensive
- if farmers use compost with no peat, it can lead to an increased price of food
76
What is 'global warming'?
What is it caused by?
- a gradual increase in the average temperature of the Earth's atmosphere
- human activity (eg. burning fossil fuels, growing crops in paddy fields, and grazing cows) has increased the levels of carbon dioxide and methane in the atmosphere (the greenhouse gases) => trapping more heat
77
What is 'peer-review'?
Why is it important?
- a process in which scientists examine and check other scientists' work
=> helps to detect false claims
=> makes sure that research publishes in scientific journals is valid
78
Why can reports in the popular media, eg. newspapers, be sometimes oversimplified, inaccurate, or biased in their reports on global warming?
- these reports are not subject to peer review
79
What is the effect of global warming on animals and plants?
- loss of habitats, eg. reduction in Arctic sea ice => populations of Arctic organisms (such as polar bears) will fall
- animals, such as birds and insects, may gradually extend their range northwards towards cooler conditions
- spring plants are flowering earlier in the UK
- we may be able to grow crops, such as grapes, in parts of the UK where we cannot today (in other parts of the world, it may be too hot to grow the crops they need)
80
What are some ways we can reduce the loss of biodiversity?
- breeding programmes for endangered species
- protection and regeneration of rare habitats
- reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
- reduction of deforestation and carbon dioxide emissions by some
governments
- recycling resources rather than dumping waste in landfill
81
How do trophic levels represent the feeding relationships in an ecosystem?
- trophic levels can be represented by numbers, starting at level 1 with plants and algae
- further trophic levels are numbered subsequently
according to how far the organism is along the food chain
Level 1: Plants and algae make their own food and are called producers.
Level 2: Herbivores eat plants/algae and are called primary consumers.
Level 3: Carnivores that eat herbivores are called secondary consumers.
Level 4: Carnivores that eat other carnivores are called tertiary consumers
- apex predators are carnivores with no predators
82
What is the role of decomposers?
- decomposers break down dead plant and animal matter by secreting enzymes into the environment
- small soluble food molecules then diffuse into the microorganism
83
What do pyramids of biomass represent?
- the relative amount of biomass (the living tissue of an organism, including proteins, lipids, and carbohydrates) in each level of food chain
- trophic level 1 is at the bottom of the pyramid
84
Why is dry biomass more reliable than fresh/wet biomass?
- the moisture content of organisms can vary widely and produce inaccurate results
85
Why is biomass lost between the different trophic levels?
- not all of the material that the animal ingests is absorbed (some is egested as faeces)
- some of the absorbed biomass is converted into waste products of metabolism and then released, eg. a large amount of the biomass is used for respiration to release energy, as well as being used to produce carbon dioxide and water, or urea in urine (large amounts of glucose, an example of biomass, are used in respiration)
=> only ~10% of the biomass from each trophic level is transferred to the level above it
86
How can we calculate the efficiency of biomass transfer as a decimal or percentage?
(gain in biomass / total intake) x 100 for a %
87
What is 'food security'?
- food security is having enough food to feed a population
88
What are some biological factors which are threatening food security?
- the increasing birth rate has threatened food security in some
countries (more people need to be fed)
- changing diets in developed countries means scarce food resources are transported around the world from other countries => threatening THEIR food security
- new pests and pathogens that affect farming (pests eat food crops) => reduce the amount of food
- environmental changes that affect food production, such as
widespread famine occurring in some countries if rains fail
- the cost of agricultural inputs (eg. fertilisers, pesticides and food for animals)
- conflicts that have arisen in some parts of the world which affect the
availability of water or food
=> sustainable methods must be found to feed all people on Earth and to increase our long-term food security
89
Why is the disadvantage of using free-range chickens?
- a lot of the biomass is used in respiration, to release energy for MOVEMENT
- these chickens are kept outdoors so the energy is also needed to keep their body TEMPERATURE constant
=> less biomass available
90
How can the efficiency of food production and biomass transfer be increased?
- use intensive/factory farming (animals are raised inside a shed or barn)
=> temperature can be controlled
=> movement is restricted
===> less biomass is lost due to the energy needed for movement or maintenanceof body temperature
=> these animals are also fed high protein foods to increase growth (and in the case of chickens, produce more eggs)
91
What are the advantages of using intensive farming methods?
- more efficient (less biomass is wasted by the animals in respiration)
- food eaten by the animals can be controlled => make sure they get all the nutrients they need + less food is wasted
- produce (eg. eggs or milk) can be more easily harvested
92
What are the disadvantages of using intensive farming methods?
- infectious diseases can spread more easily (animals have to be treated with antibiotics => may increase the risk of strains of bacteria that are resistant)
- stress levels of animals are high as they are kept in crowded conditions => more likely to fight
- unethical (factory farming is unnatural) (engaging in natural behaviour will increase the animals' welfare, eg. by reducing stress)
93
Why is it important to maintain the fish stocks in the oceans?
- breeding may not be able to continue if the populations of mature fish in the oceans decline too much
- certain species may disappear altogether in some areas
94
What are the 2 main strategies that governments are using to maintain fish stocks in the oceans?
- the fishing industry is set strict quotas on the numbers of fish that can be caught for each species => remaining fish can still breed
- the net size must be large enough so that smaller, immature fish are not caught => these fish can then develop into adults and reproduce
95
Why are GM crops beneficial in providing food to meet the demands of the growing population?
- GM crops could provide more food
- or food with an improved nutritional value
96
What is the possible agricultural solution to reduce cases of blindness?
- billions of people around the world depend on rice as a staple food (many of these people are deficient in vitamin A, which is needed for effective vision)
- every year, ~500,000 people go blind due to a lack of vitamin A (the body makes vitamin A from molecules foundd in food)
- natural rice does not contain any of the molecules that the body needs to make vitamin A
=> Golden Rice (rice which has been genetically modified to contain the molecules needed to make vitamin A)
97
How can a fungus be used to meet the protein needs of the growing human population?
- in aerobic conditions, the fungus Fusarium converts the glucose syrup on which it is grown (inside a fermentor) into mycoprotein => this biomass is harvested and purified before being made into products, eg. Quorn products
98
What are 2 advantages of mycoprotein?
- suitable for vegetarians
- very large amounts of mycoprotein can be grown in a relatively small amount of space (very efficient protein source)
99
What is one use for a genetically modified bacterium?
- a bacterium could be genetically modified to produce human insulin => when harvested and pruified, this can be used to treat people with diabetes
