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OCR Gateway A GCSE Biology > B6: Global challenges > Flashcards

B6: Global challenges Flashcards

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1
Q

what does sampling mean

A
  • to take observations/measurements from a small area, which is representative of a larger area
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2
Q

what are the different ways you can sample animals

A
  • pooters: suck on mouthpiece to draw insect into holding chamber - filter stops organism entering mouth
  • sweep nets: sweep large net in air/grass to catch insects
  • kick sampling: ‘kick’ a river bank to disturb mud + vegetation - hold a net downstream to catch organisms bein released into flowing water
  • tree beating: put large white cloth under tree/bush - shake/beat it and organisms will fall into cloth
  • pitfall traps: dig hole in ground to which insects/invertebrates will fall into - cover with roof so water doesn’t fill the hole
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3
Q

how do you identify unknown organisms

A
  • using identification keys to identify living organisms
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3
Q

what do identification keys do

A
  • ask a series of questions about an organism’s characteristics to identify it
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4
Q

what are the 2 main types of identification keys

A
  • branched key (spider key) - by answering yes / no for each question you can determine an organism’s identity
  • numbered key (or dichotomous key) - the correct answer to a question tells you what question to answer next - eventually after answering a series of questions you’ll identify your organism
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4
Q

what tool can you use to sample plants + how

A
  • a quadrat (square frame divided into a grid)
  • place it on the ground to take a sample + record the type and number of organisms within each section
  • to figure out population, multiply the mean by the total area
  • mean = population / area
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4
Q

what is the equation for estimated population size

A

estimated population size =
1st sample size x 2nd sample size
____________________________________________
number of recaptured marked individuals

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5
Q

how are animal populations estimated

A
  • using the capture-recapture technique which scales up results from a small sample area to estimate population
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5
Q

describe how to use the capture-recapture technique to estimate animal population

A
  • capture organisms from a sample area
  • mark individual organisms, then release back into community
  • at later date, recapture organisms in the original sample area
  • record the number of marked + unmarked individuals
  • estimate the population size using the equation
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6
Q

what are the 2 ways plants can be sampled

A
  • random sampling
  • non random sampling
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6
Q

what is random sampling

A
  • when you randomly sample areas of plant populations
  • mark out a grid on the sample area + use random number generator to determine the coordinates of where to place your quadrat
    > prevents bias (normally tempting to place quadrat in areas that look interesting)
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6
Q

what is non random sampling

A
  • samples are taken along a line to study how the distribution of organisms varies over a distance
    > known as a transect
  • samples can be taken by counting organisms that touch the line, or by placing quadrat at fixed positions along the line
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7
Q

what is biodiversity

A
  • the variety + variability of life on Earth
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8
Q

why is biodiversity important

A
  • species are interconnected, so the removal of one species can affect others
    > could lead to a loss of another species’ food/shelter
  • biodiversity is essential for maintaining a balanced ecosystem
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9
Q

what do humans rely on biodiversity for

A
  • raw materials
    > food, wood + oxygen
  • however humans are the leading cause of loss of biodiversity
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10
Q

how is biodiversity lost

A
  • now over 7 billion ppl on earth which caused increased need for food + materials which is reducing biodiversity through:
    > deforestation
    > agriculture
    > hunting + overfishing
    > pollution
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10
Q

what is the leading cause of loss of biodiversity

A
  • humans
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11
Q

how does deforestation contribute towards the loss of biodiversity

A
  • deforestation reduces number of trees + supported animal species, as their food source / habitat has been lost
    > can affect predator species
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12
Q

why has agriculture increased

A
  • due to higher demands for food for the growing population
  • more land is farmed
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12
Q

how does intensive farming lead to the loss of biodiversity (agriculture)

A
  • removing hedgerows to use large machinery + freeing up extra land for crops
    > reduces number of plant species + destroys animal habitats e.g. mice, hedgehogs
  • using pesticides to kill pests which eat crops / live on livestock
    > reduces number of pest species + removes food source of other organisms - pesticides can accumulate in food chain, killing animals that weren’t targeted
  • using herbicides to kill plants growing where they aren’t wanted
    > reduces plant species + animals species present e.g. removing source of food/shelter
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12
Q

what is deforestation + why is it done

A
  • deforestation is the permanent removal of large areas of forest
  • removing forests:
    > provides wood for building
    > creates space for roads, buildings, and agriculture
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13
Q

how does hunting + overfishing lead to a loss of biodiversity

A
  • overfishing has led to some fish populations decreasing significantly / even being lost from some areas
    > other marine species may also be caught + killed
  • hunting decreases the target species’ population, which removes food for other species
    > this can further reduce biodiversity as the food chain is disturbed
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13
Q

what methods are used to increase biodiversity

A
  • conservation
  • captive breeding
  • seed banks
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14
Q

how have humans increased pollution levels

A
  • the expansion of the human population has resulted in burning of more fossil fuels, increased use of fertilisers and herbicides
    > this has led to increased pollution levels
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14
Q

how does pollution lead to a loss of biodiversity

A
  • when pollutants enter the environment, they have an impact on the number + types of organism
    > the more populated an area, the fewer the number of species that can survive
  • gases are also produced from burning of fossil fuels: CO2, methane, nitrous oxide, sulfur dioxide
    > sulfur dioxide causes acid rain, which results in the death of trees and fish
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14
Q

what does conservation mean + how does it help

A
  • conservation means protecting a natural environment to ensure habitats aren’t lost
    > protecting an organism’s habitat increases their chance of survival, allowing them to reproduce
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15
Q

how can nature reserves + natural parks be actively managed to protect the habitat

A
  • controlled grazing: only allowing animals to graze land for certain period of time, giving plant species time to recover
  • restricting human access: e.g. providing paths to prevent plants from being trampled
  • feeding animals: to ensure more organisms survive to reproduce
  • reintroduction of species: adding new individuals of a species into an area with lower numbers, or where the species has not survived
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15
Q

what are some conservation methods

A
  • protected habitats for species to live in
  • legal protection to stop hunting + trade
  • artificial ecosystems to replace destroyed ones
  • seed banks to store the seeds from rare plants
  • education to make people aware of the problem
  • captive breeding in zoos to increase the population
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16
Q

what is captive breeding

A
  • breeding animals in human-controlled environments such as zoos/aquariums
  • animals given shelter, plenty nutritious food, veterinary treatment + predator-free environment
  • selective breeding partners can be imported from other zoos
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17
Q

what do scientists working on captive breeding programmes aim to do

A
  • create a stable, healthy population of a species
  • gradually reintroduce the species back into its natural habitat
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18
Q

what are some problems associated with captive breeding

A
  • maintaining genetic diversity can be difficult since few breeding partners are available
  • organisms born in captivity may not be suitable for release into the wild
    > e.g. predators bred in captivity may not know how to hunt for food
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18
Q

how can you prevent extinction of species

A
  • as ew species are evolving, others are becoming extinct
  • using seedbanks as a store of biodiversity
  • seeds are carefully stored so that new plants may be grown in the future
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18
Q

what are seedbanks + how do they help increase biodiversity

A
  • seed banks are a way of conserving plants
  • seeds are carefully stored so new plants may be grown in the future
  • a seed bank is an example of a gene bank - a store of genetic material
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19
Q

what are conservation agreements

A
  • to conserve biodiversity, local + international cooperation is required to preserve habitats + individual species
  • many animals naturally move between countries, so global action is required
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20
Q

what are the 2 different types of conservation agreements

A
  • international agreements
  • local agreements
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20
Q

what is the Rio Conventions

A
  • the Rio Earth Summit of 1992 resulted in an international agreement known as the ‘Rio Conventions’
    > these require countries to develop strategies for sustainable development, to reduce greenhouse emissions + combat desertification
  • altogether, the conventions aim to maintain biodiversity - however, individual countries can’t be forced to implement them
20
Q

how do intergovernmental organisations (e.g. IUCN - international union for the conservation of nature) help to secure agreements between nations

A
  • IUCN publishes the ‘Red list’, detailing the current conservation status of threatened animals
  • the CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) treaty regulates the international trade of wild plants + animals + their products, to prevent over exploitation
    > this treaty protects more than 35,000 species
20
Q

what are local agreements

A
  • through Stewardship Scheme, farmers in England are offered government payments to conserve the landscape
  • their aim is to make conservation a part of normal farming practices
    > thus securing the beauty of the landscape + biodiversity found there
21
Q

how is tourism linked to a loss of biodiversity

A
  • large numbers of human visitors in any region can lead to habitats being lost / destroyed, leading to loss of biodiversity
21
Q

how can tourism be beneficial to increasing biodiversity

A
  • tourism brings money that can be used to support natural wildlife by extending + improving habitats + preventing poaching
  • landowners are encouraged to maintain biodiversity, if this decreases, tourists won’t come
21
Q

how does ecotourism ensure that tourism doesn’t have a negative impact on natural environments / local communities

A
  • supports conservation, whilst allowing people to observe wildlife
  • tourists often restricted to certain areas + asked to keep on footpaths
    > ensures animal breeding grounds aren’t disturbed or endangered plants trampled
22
Q

what does Ecotourism aim to ensure

A
  • that tourism doesn’t have a negative impact on the natural environment or local communities
23
Q

how can ecotourism still have negative impact on the ecosystem

A
  • evidence that tourist movements such as repeated use of hiking trails, or vehicles carrying tourists, may contribute to soil erosion + other habitat changes
23
Q

how do scientists monitor pollution

A
  • by regularly taking samples of plants + animals from environment to monitor the type + number of organisms present
  • a decrease in range/number of species indicates that environmental changes have taken place
    > the more polluted an area, the fewer the species present
23
Q

what are indicator species

A
  • organisms that can be used to measure environmental quality
    > their presence (or absence) tells biologists that an area is polluted
24
Q

what is one the most common forms of air pollution + what can it cause

A
  • sulfur dioxide
  • released from combustion of some fossil fuels
  • causes acid rain, which can result in the death of trees + fish
25
Q

what is water pollution caused by

A
  • the discharge of harmful substances into rivers, lakes and seas
25
Q

what indicator species are used to measure air pollution (sulfur dioxide)

A
  • lichens
    > have no root systems - most of their nutrition comes from air
    > rainwater contains just enough nutrients to keep them alive
    > air pollutants dissolved in rainwater, especially sulfur dioxide, can damage lichens + prevent their growth
25
Q

what does a lack of lichens indicate

A
  • high pollution
    > as they die because of air pollutants dissolved in rainwater
25
Q

how can you identify high levels of water pollution

A
  • the higher the level of pollution, the lower the level of dissolved oxygen
26
Q

what species of lichen are found in industrial / rural places

A
  • species of lichens that can cope with high levels of pollution are found in industrial places
  • species of lichens that can only grow in clean air are found away from towns
26
Q

how can you estimate the oxygen content of water

A
  • by identifying the indicator species found living in it, as some require higher oxygen content than others
27
Q

what is food security

A
  • the state of having reliable access to sufficient quantity of affordable + nutritious food
27
Q

what factors have a positive impact on food security + explain

A
  • inc amount of land available for growing crops: more crops can grow to feed larger population
  • decreasing human population: less pressure to grow lots of crops, more food to go around
  • inc CO2 levels: crops can photosynthesis, increasing crop yield
28
Q

what is intensive farming

A
  • the production of high-yield crops + animal products using the minimum amount of space
28
Q

what factors have a negative impact on food security + explain

A
  • changing diet in wealthier countries: people will eat more meat, but meat is more energy intensive to produce than plants
  • global warming: more droughts, inc sea levels, less land for agriculture
  • new pests + pathogens: lower crop yield
  • inc agricultural costs: food more expensive, many can’t afford
28
Q

what are some advantages of intensive farming

A
  • high yields: maximum production achieved per unit of land, pesticides means less food lost to pests
  • efficient energy conversion: movement restricted, minimising wasteful energy loss
  • low cost of production
  • less space needed: more space for natural habitat
  • predators excluded: no energy loss to other organisms in the food web
28
Q

how can intensive farming be achieved

A
  • using fertilisers + pesticides yo aid plant growth
  • maximising animals growth rates
  • minimising labour inputs by using machinery
28
Q

how can food production be increased

A
  • maximising photosynthesis using industrial greenhouses
  • using artificial fertilisers to aid growth
  • using herbicides, insecticides, fungicides - removes competition
  • using genetically modified crops
29
Q

what are some disadvantages of intensive farming

A
  • battery rearing of animals: less humane + cause disease to spread quickly through animal population
  • fertilisers + pesticides: can damage environment + too much can wash into streams + lead to pollution - leads to eutrophication
  • lower quality of food
30
Q

do people agree with intensive farming

A
  • many believe it to be wrong + that the disadvantages outweigh the advantages
31
Q

what is sustainable food production

A
  • the production of food that can be continued indefinitely
31
Q

what is the alternative to intensive farming

A
  • organic farming
    > uses more natural methods to produce crops + rearing animals (avoids artificial fertilisers + pesticides )
    > so reduces harm to environment
    > yields are smaller, but products are more expensive
32
Q

what are some examples of sustainable food production

A
  • fish farming
  • hydroponics
  • biological control
  • crop rotation
32
Q

describe how hydroponics is a practice of sustainable food production

A
  • plants are grown in water containing dissolved minerals (not soil)
    > more plants can be grown in the same space
  • very sustainable
  • advantages: plant grows quickly as they receive minerals needed, greater yield per area of land, pests can be controlled easily
  • disadvantages: cost to set up
32
Q

describe how fish farming is a practice of sustainable food production

A
  • fish are bred + reared in large cages in seas/rivers
    > protects fish from predators + makes them easier to catch
  • very sustainable
  • advantages: allows wild population to recover, easy to catch, cheaper, can be fed ideal diet to maximise yield
  • disadvantages: disease can spread quicky
33
Q

describe how biological control is a practice of sustainable food production

A
  • natural predators that kill pests are introduced; bred in large numbers + released
    > removes competition from pests
  • very sustainable but needs repeating
  • advantages: reduces pest population + no chemicals required
  • disadvantages: needs repeating
34
Q

describe how fertilisers are a practice of sustainable food production

A
  • chemicals high in minerals (N,P,K) are spread over soil
    > inc plant growth + flower and fruit production
  • not very sustainable, chemicals need to be produced
  • advantages: inc yield of crop
  • disadvantages: pollutes environment, eutrophication
35
Q

describe how pesticides are a practice of sustainable food production

A
  • toxic chemicals that kill pests are sprayed on land + animals can be dipped
    > removes competition from pests, stops animal disease
  • not very sustainable, requires chemical production
  • advantages: kills pests + removes competition
  • disadvantages: can damage other organisms, bioaccumulation
36
Q

what is selective breeding

A
  • humans choosing the parents to breed together in the hope the offspring will have the desired characteristics
    > aka artificial selection
36
Q

describe the steps in selective breeding

A
  • desirable feature (trait) is chosen
  • organisms showing high levels of this feature are chosen + bred to produce offspring
  • best offspring are chosen + bred again
  • repeat for many generations
37
Q

what are the uses of selective breeding

A

economic
- high yield: less animals + space, more income
- disease / insect resistant crops
- drought resistance crops
- fast growth
non economic
- pedigree dog breeding

38
Q

what are the disadvantages of selective breeding

A
  • reduces the gene pool (number of diff alleles)
    > reduces variation
    > more prone to disease / mutations
39
Q

what are problems of selective breeding

A
  • takes a long time (many generations)
  • desired trait doesn’t always appear as expected
40
Q

how have scientists eliminated the problems in selective breeding

A
  • by using genetic engineering
41
Q

how is genetic engineering better than selective breeding

A
  • quicker - happens in 1 generation
  • more predictable (accurate) as single genes are targeted
42
Q

what does genetic engineering involve

A
  • taking a gene from one species + putting it into another species
  • it modifies the genome of an organism to introduce a desirable characteristic - genetic modification
  • organisms produced by genetic engineering are called genetically modified (GM) organisms
    > the organism produced is called a transgenic organism
42
Q

why do scientists genetically engineer bacteria

A
  • to produce useful substances such as hormones, vaccines & antibiotics
42
Q

what is genetic engineering

A
  • the process of modifying an organism’s genome to introduce desirable characteristics
43
Q

what are some modern uses of genetic engineering

A
  • finding out where genes are expressed in the body
  • manufacturing useful substances
  • producing crops resistant to bacteria
  • producing crops with a greater yield
44
Q

describe the steps in genetic engineering

A
  • identify the characteristic you want and use a restriction enzyme which cuts out the gene from the DNA at specific base sequences
    > this makes a staggered cut exposing unpaired bases on the ends of DNA strands called sticky ends
  • use the same restriction enzyme to cut open the bacterial plasmid (because it creates sticky ends that are complementary to each other)
  • the gene is attached to the plasmid with a ligase enzyme which joins the sticky ends of the 2 DNA strands
  • the plasmid vectors now containing the DNA are inserted into other cells (host cells) which can use the gene you inserted to produce the desirable characteristic
    > to identify which host cells have successfully received the desired gene, antibiotic resistance markers are used
45
Q

how can antibiotic resistance markers be used to identify the successful host cells

A
  • insert a gene for antibiotic resistance (resistance marker gene) into the plasmid at the same time as inserting the gene coding for the desirable trait
  • transfer the bacteria to an agar plate with the antibiotic + allow bacteria to grow
  • bacteria colonies which grow must contain the antibiotic resistance marker gene + so therefore it will also contain the desired gene
46
Q

what is a transgenic organism

A
  • an organism that contains DNA from a donor organism (‘foreign DNA)
47
Q

what is biotechnology

A
  • the use of biological processes / living organisms to make products
48
Q

what are GM organisms

A
  • genetically engineered plants / animals that have been made to produce a useful characteristic
48
Q

what are some examples of biotechnology

A
  • making alcohol (use bacteria)
  • making cheese / yogurt (use bacteria)
  • antibody production (use GM bacteria)
  • hormone production
  • genetically modified (GM) crops
49
Q

how do you produce a genetically modified organism (GM)

A
  • very similar to the process used to genetic engineer bacteria
    > but has an extra step, during which the engineered bacterium or virus carries the modified gene into a plant or animal cell
    > plasmids, bacteria, and viruses can all be used as vectors to transfer foreign DNA into an organism
49
Q

what are the pros of GM organisms

A
  • inc yield
  • resistance to disease + pests
  • produces essential nutrients
  • longer shelf life
  • better flavour
49
Q

what are some cons of GM organisms

A
  • some believe the process to be unethical + should be banned
  • concerns about the effects of GM crops on wild flowers, insects + whether eating GM crops may harm human health

OCR Gateway A GCSE Biology (7 decks)

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