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BIOLOGY MODEL ANSWERS > Module 4 > Flashcards

Module 4 Flashcards

1
Q

Malaria

A
  • caused by proctoctists - plasmodium vivax
  • carried by vector- female anopheles mosquito
  • also transmitted by blood transfusions and across the placenta
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2
Q

Life cycle of malaria

A
  • person with malaria has gametes of P.vivax in blood
  • person bitten by female anopheles mosquito and gametes in blood go to its stomach
  • gametes fuse and zygotes of P.vivax develop in its stomach
  • develop into infective stages and migrate to salivary glands
  • mosquito bites uninfected person and injects saliva containing infective P.vivax
  • infective stages enter hosts liver and divide by mitosis
  • these enter the blood to feed on haemoglobin in red blood cells and make more gametes
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3
Q

HIV

A
  • HIV causes AIDS
  • HIV +VE = inactive version of virus present so no symptoms of aids, can go unknown for a long time ( in which it may be transmitted)
  • active version destroys t helper cells
  • lowers ability to destroy pathogens
  • increased likelihood of contracting aids related diseases ( e.g pneumonia )
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4
Q

Why HIV/AIDS higher in sub-Saharan africa

A
  • poverty
  • less education about means of transmission
  • more promiscuity/ people working in the sex industry
  • lower condom availability
  • religious reasons for not wearing condoms
  • countries promoted denial of existence
  • fewer medicinal facilities for screening
  • less screening of blood for transfusions
  • more infected mothers have to breast feed- no alternative
  • more cases of rape
  • more intravenous drug abuse
  • more use of shared needles
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5
Q

Tuberculosis

A
  • caused by bacteria: Mycobacterium tuberculosis and M. bovis
  • transmitted by droplet infection ( coughs and sneezes )
  • usually in lungs
  • also transmitted through milk or meat of infected cattle
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6
Q

what conditions make tuberculosis more likely?

A
  • overcrowded living conditions
  • poor ventilation
  • weakened immune system
  • poor diet
  • homelessness
  • living or working with people who have just migrated from areas with high TB prevalence
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7
Q

why hasn’t TB been eradicated

A
  • LEDCs cant afford vaccines/ antibiotics
  • vaccine not 100% effective
  • bacteria have become antibiotic resistant
  • people don’t finish long antibiotics course
  • lack of education
  • people drink unpasteurised milk (LEDCs)
  • migration of carriers with no symptoms
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8
Q

Phagocytosis

A
  • phagocytes engulf and digest pathogens
  • receptors on phagocyte cell surface membrane bind to antigen on pathogen cell surface membrane
  • produces a phagosome
  • lysosymes fuse with phagosome releasing lysins into it
  • pathogen is digested into amino acids, fatty acids etc
  • products absorbed into cytoplasm by diffusion
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9
Q

structure and function of antibodies

A
  • 4 polypeptide chains held together by disulphide bonds. Y shaped molecule
  • constant region to bind to phagocytes
  • variable region complementary in shape to antigen to bind to pathogen
  • more than one variable region allows attachment to more than one antigen and more than one pathogen for agglutination
  • hinge region allows flexibility of branches of Y shaped molecule to move closer or further to bind to multiple antigens
  • causes neutralisation by blocking binding sites
  • light and heavy chains
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10
Q

role of antibodies

A
  • bind to antigens on pathogens cell surface membranes
  • neutralises pathogens
  • antibodies cover binding sites on pathogen
  • prevents entry to host cell
  • agglutination of pathogens
  • multiple variable regions allow antibody to clump pathogens together
  • clump too large to enter host cell and increases likelihood of being consumed by phagocyte
  • antitoxins neutralise toxins
  • opsonins allow phagocytes to bind to them ( binded to pathogen ) to perform phagocytosis
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11
Q

immune response: T lymphocytes - cellular response

A
  • macrophages engulf and digest pathogens, incorporate pathogens antigens into their cell surface membrane- antigen presenting cells
  • helps select specific t lymphocytes with receptors complementary in shape to antigen ( clonal selection )
  • once correct are selected, divide by mitosis in clonal expansion
  • t helper cells release cytokines which are specific shapes and bind to complementary receptors on B lymphocytes stimulating them to divide by mitosis and differentiate. also stimulate macrophages to carry out more phagocytosis
  • t killer kill infected host cells by secreting protease enzyme into them
  • t memory cells stay in blood in case secondary infection by the same pathogen. allow a faster secondary response as they recognise the antigen and make clones and differentiate to form new t cells more quickly than in primary response
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12
Q

Immune response - B lymphocytes ( humoral response )

A
  • specific B lymphocytes with receptors complimentary in shape to the antigen or invading pathogen are selected- clonal selection
  • cytokines released by t helper hells stimulate B lymphocytes to divide by mitosis in clonal expansion and then to differentiate into plasma cells and B memory cells
  • plasma cells produce and secrete antibodies which are complimentary in shape to the antigen, these cause agglutination or neutralisation of the pathogens.
  • B memory cells stay in the blood in case there is a secondary infection by the same pathogen. They allow a faster secondary response because they recognise the antigen and can make clones and change to form new antibodies so new antibodies are made more quickly than in the primary response.
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13
Q

Examples of cell signalling in the immune response

A
  • pathogens antigens communicate to the body that they are foreign
  • infected cells with foreign antigens on surface communicate to lymphocytes to be selected in clonal selection and to T killer cells that they need to be killed
  • macrophages engulf and incorporate pathogens antigens on their cell surface membrane communicate to t lymphocytes to be selected in clonal selection
  • t helper cells release cytokines ( interleukins ) which bind to receptors on B cells and stimulate them to divide by mitosis and differentiate
  • macrophages also release interleukins
  • macrophages release chemicals that attract neutrophils by chemotaxis
  • ( many cells release interferon, inhibits virus replication and stimulates t killer activity)
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14
Q

Primary and secondary immune response

A

Primary

  • time delay to trigger immune response after first infection
  • no B memory cells so slow antibody production and few produced

Secondary

  • shorter delay. Quicker response
  • B memory cells are specific to the antigen of the pathogen have remained in the blood after being produced in the primary response. They can clone and differentiate to make plasma cells which make more antibodies more quickly. They give immunity to a disease.
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15
Q

Groups who should be immunised

A
  • elderly/ young children
  • weak immune systems/ young children have had little time to build up natural immunity to many diseases
  • people with HIV/AIDS
  • weak immune system is can’t produce many antibodies themselves
  • Pregnant women
  • foetus has undeveloped immune system
  • Health workers
  • more likely to be at risk of getting a disease
  • People with chronic diseases like TB or autoimmune diseases
  • poor health and bodies may be unable to withstand further disease
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16
Q

Why some people choose not to get immunised

A
  • too busy or can’t be bothered to go to the doctors
  • media scare stories
  • concerns about side effects
  • allergic to vaccine
  • fear of needles
  • religious reasons
  • cost too expensive
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17
Q

Why governments want people to be vaccinated as side from direct health benefits

A
  • prevention of disease can save lost days at work by many which could harm the economy
  • costs less to immunise people than to treat them
  • health service wouldn’t be able to cope if large numbers of people became infected
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18
Q

Why elderly and others encouraged to get a vaccine for influenza every year

A
  • vaccine is changed every year
  • as there are new strains of the virus each year as it has mutated from the previous year
  • new strains have different antigens
  • old antibodies from previous year aren’t complementary to the new antigen and the new vaccination will encourage new antibodies to be made
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19
Q

How governments vaccinate people to control a disease

A

Herd vaccination
-vaccinate all at risk
-stops infection spreading if a large enough proportion is vaccinated
Ring vaccination
-requires people to report victims
-vaccinate all people living with or near the victim
-contains spread within ring

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20
Q

Why it has not been possible to produce an effective malaria vaccine

A
  • different strains of the proctoctist each year as it has mutated from previous year
  • new strains have different antigens
  • multiple stages in life cycle, each has different antigens so needs different vaccines
  • plasmodium concealed in liver cells and RBCs so only exposed to immune system for a short period of time
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21
Q

Why we will never know how accurate estimates of numbers of species are

A
  • we will not be certain we have found all species on earth
  • we are constantly discovering new species
  • evolution and speciation are continuing
  • many species are endangered / becoming extinct
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22
Q

Why estimates of species are lower than true number

A
  • not all species discovered yet
  • many microscopic species are hard to see
  • sampling might miss rare species
  • organisms may be mistakenly identified as one when they are 2 different species
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23
Q

Sampling plants

A
  • set area to be sampled
  • use belt transect to sample
  • use 50x50 cm quadrats
  • at regular 5m intervals
  • identify plant species using keys
  • record presence / absence
  • estimate % cover
  • use point frame
  • repeat with several transepts to show repeatability
  • use simpsons index to calculate biodiversity
  • can display on a kite diagram
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24
Q

Sampling animals

A
  • set grid to be sampled
  • use random numbers to make grid coordinates to locate areas to be randomly sampled
  • appropriate method of capture ( sweep nets, pooters, pitfalls )
  • identify each species with a key
  • count each species
  • repeat in each habitat with the same technique
  • use simpsons index to calculate biodiversity
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25
Q

Why classification systems change over time

A
  • scientific knowledge changes as new discoveries are made
  • technological developments led to new discoveries
  • e.g microscopes, new DNA tech
  • differences in opinion amongst scientists
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26
Q

Animal features

A
  • eukaryotes
  • multicellular
  • heterotrophic feeders
  • no cell walls
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27
Q

Plant features

A
  • eukaryotes
  • multicellular
  • autotrophs
  • cellulose cell wall
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28
Q

Fungi features

A
  • eukaryotes
  • mostly multicellular
  • saprophytic
  • chitin cell walls
  • reproduce with spores
  • hyphae that form mycellium
29
Q

Proctoctist features ( misfits )

A
  • eukaryotes
  • mostly single celled
  • auto/heterotrophic
  • don’t fit into any other kingdom !!
30
Q

Prokaryote features ( bacteria )

A

-prokaryotes ( no nucleus, naked DNA, no membrane bound organelles, smaller ribosomes, respiration in mesosmes, small, peptidoglycan cell wall / murein )

31
Q

Why appearance of fungi made classification hard for early taxonomists

A
  • don’t move freely ( like plants )
  • hyphae resemble roots
  • digest food ( like animals ) rather than photosynthesising
32
Q

How eubacteria different to archaebacteria and eukaryotes

A
  • different cell membrane structure
  • different flagella structure ( not 9+2)
  • naked DNA ( not associated with histones )
  • different mechanism for DNA replication and RNA synthesis
33
Q

Causes of variation

A

Genetic
- combination of alleles inherited not same as any other individual ( unless asexual reproduction or identical twins )
-mutations
Environmental
-the environment ( scars / root growth in response to water )
Most is a combination of both

34
Q

Forms of variation

A

Continuous

  • no defined categories/ distinct groups
  • there is a range so any value is possible
  • caused by genes ( multiple ) and environment
  • quantitative

Discontinuous

  • discrete categories with no intermediates
  • caused by one or a few genes
  • no / little environmental effects
  • qualitative
35
Q

How any species has evolved to have any characteristic

A
  • by natural selection
  • random mutations create alleles and cause individuals to have [characteristic]
  • this creates intraspecific genetic variation
  • [selective pressure] acts as a selection pressure (causing competition between individuals)
  • individuals with beneficial mutation for [characteristic] have an advantage and will be more likely to survive and reproduce to pass on the mutated allele to its offspring (inheritance)
  • over many generations, the frequency of the allele for [characteristic] increases and the population becomes well adapted to its environment.
36
Q

speciation

A
  • a population becomes separated or isolated
  • allopatric separation- geographic separation prevents interbreeding between individuals of the 2 populations ( river/ mountain)
  • sympatric separation- reproductive barriers prevent interbreeding between individuals of the population ( e.g sexual organs become incompatible, biochemical changes prevent fertilisation )
  • mutations occur at random in one population
  • may be different selection pressures in different environments
  • mutation may be beneficial, survival more likely, genes passed on ( natural selection ) in one population, many small changes in the population over many generations
  • populations become different so cant interbreed and have become new species.
37
Q

compare selective breeding with evolution

A
  • both result from changes in allele frequencies
  • selective breeding is faster than evolution
  • both require selection of parents
  • to pass alleles to offspring
  • selective breeding involves artificial selection
  • man selective agent in selective breeding
  • environment provides selective pressure in evolution
  • selective breeding for benefit of man
  • selective breeding may be detrimental to organism
38
Q

how fossils provide evidence for evolution

A
  • show that organisms have changed over time
  • carbon dating can be used to work out how old
  • oldest rocks contain simplest species
  • fossil record shows many organisms no longer exist but were intermediates between oldest common ancestors and modern species
39
Q

molecular evidence for evolution

A
  • DNA from fossils can show similarities between organisms if they have a similar base sequence- implies they share a common ancestor
  • similar cytochrome C ( respiration protein ) primary structure shows similarities- implies they share a common ancestor
40
Q

other evidence for evolution

A
  • many modern animal species share a physiological similarity- the pentadactyl limb ( 5 fingered ) suggesting a shared common ancestor
  • we can see evolution in action ( e.g bacteria becoming resistant to antibiotics )
41
Q

implications for humans of bacteria being antibiotic resistant

A
  • resistant bacteria are harder to treat- there is potential of an epidemic to start
  • developing new antibiotics takes years and is expensive
42
Q

implications for humans of insects being pesticide resistant

A
  • anopheles mosquitos have become resistant to pesticides on mosquito nets, no longer effective protection from being bitten and infected with the malaria parasite ( plasmodium vivax )
  • insects not killed by insecticide spray on crops, reduced crop yield
  • pesticides can bioaccumulate in food chains and harm organisms higher up in the chain ( DDT damages bird eggs )
43
Q

what humans have done to reduce biodiversity and therefore why we need to conserve species

A

we have caused a loss in biodiversity and extinction of some species by:

  • hunting/ over fishing
  • killing pests which threaten food supplies
  • pollution
  • deforestation/ habitat destruction for land for buildings or farm land for one crop species
  • inadvertent introduction of new predators and competitors to native species
44
Q

ecological reasons for conservation of plants and animals

A
  • habitat for other organisms ( plants )
  • part of foodchain in ecosystem
  • native species
  • populations may be nationally significant in maintaining existence in country
  • maintain biodiversity
  • genetic resource for selective breeding
45
Q

economic reasons for conserving plants and animals

A
  • wood used e.g for furniture making ( trees )
  • tourist attraction ( plants or animals )
  • source of medicine or scientific research ( plants )
46
Q

aesthetic reasons for the conservation of plant and animal species

A
  • people enjoy looking at them

- landscape maintenance ( reduce flooding etc )

47
Q

ethical reasons for the conservation of plant and animal species

A

moral responsibility to protect species as they have a right to existence

48
Q

consequences of global climate change on biodiversity 1

A
  • species with narrow gene pools ( e.g selectively bred domesticated plant and animal species ) lack genetic variation necessary to cope with changes in environment ( e,g increasing temp and rainfall caused by climate change )
  • if species cant evolve they must migrate or become extinct ( obstacles = human settlements, natural barriers)
49
Q

consequences of global climate change on biodiversity - changes in patterns of agriculture

A
  • farmers need to grow different crops as old crops don’t thrive in new climatic conditions. could mean a reduced yield or inability to meet consumer demand
  • land may be lost due to rising sea levels so farming land is lost
  • warmer temperatures mean longer growing seasons which means higher yield
  • warmer temperatures means more evaporation so more precipitation, could be good in areas that experience drought as it may boost crop yield but could cause flooding and yield loss in other areas
  • rising CO2 levels and higher temperatures increases rate of photosynthesis and increases crop yield
50
Q

consequences of global climate change on biodiversity- changes in patterns of disease

A
  • new crops grown in new areas ( due to climate change ) and will encounter diseases that they have not been exposed to before - so have no resistance
  • longer growing seasons so more time for pests to breed so lower yields
  • diseases migrate e.g those confined to warmer climates can spread to Europe e,g anopheles mosquito carrying the malaria parasite
51
Q

benefits of maintaining biodiversity of animal and plant species for agriculture

A
  • source of food
  • source of genetic variation for selectively breeding domestic populations with populations with beneficial qualities e.g resistance or quicker growth
  • source of natural predators to pests ( reduces need for chemical pesticides )
  • source of natural pollinators for crops e.g bees
52
Q

advantages of in situ conservation

A
  • conserving species in their natural habitat
  • conditions and food etc that they require for survival already present- cheaper than ex situ
  • species already well adapted to habitat
  • no special provisions are needed
  • can create protected nature reserves :
  • can ensure sustainable use of environment inc land and resources
  • allows scientific research in ecosystem
  • permanently protects biodiversity in area and whole ecosystems
  • creates areas of interest for ecotourists
53
Q

disadvantages of in situ conservation

A
  • may be threats to species survival in the area
  • e.g predators or hunting
  • human activity could threaten species in wild e.g hunting or deforestation
  • diseases could threaten survival
  • species could be outcompeted by other species
54
Q

measures to preserve species in the wild

A
  • ban hunting
  • create protected reserves
  • provide breeding sites
  • prevent habitat destruction
  • monitor species e.g. by tagging
  • feeding programmes
  • educate tourists on not feeding wild animas and littering
  • promote ecotourism to generate money to help with preservation
  • create sperm and egg banks in case population falls again
55
Q

advantages of ex situ conservation

A
  • health can be monitored and treated for disease to ensure survival
  • young can be hand reared which reduces young mortality
  • provision of mates for breeding can be manipulated
  • protection from hunting and predation
  • competition reduced between individuals
56
Q

disadvantages of ex situ conservation

A
  • expensive
    -often unsuccessful breeding due to:
    captive stress
    altered breeding cycles
    no compatible mate
    -space is limited
    limiting number of individuals kept limits genetic diversity
    lack of variation can lead to inbreeding
    -difficult to reintroduce into wild as:
    animals tame and not afraid of humans
    may be unable to reintegrate into wild population
    cant find own food
    predators
    habitats destroyed
57
Q

setting up captive breeding programmes

A
  • collect animals from several sites and keep in several locations:
  • different geographical locations show geographical variation- this is maintained
  • increases genetic variation
  • reduced risk of inbreeding
  • less risk of losing all to disease
  • minimise stress during capture
  • zoos have database of related individuals
  • exchange of animals between zoos or exchange sperm from sperm banks as a source of genetic material
  • artificial insemination
  • increases number of animals available to avoid inbreeding
58
Q

botanical gardens- importance of seed banks

A
  • maintain genetic diversity
  • maintain plants for future or currently unknown uses
  • counteract extinction or prevent inbreeding
59
Q

problems with seed banks

A
  • collection of seeds from wild may disturb environment
  • collected samples may not be representative of genetic diversity of species
  • seeds from one area may not survive in another
  • seeds stored for a long time may not stay viable
  • asexually bred plants have no genetic variation so reduce biodiversity
60
Q

advantages of seed banks rather than adult plants to conserve

A
  • most plants produce an excess
  • so collected from wild without damaging wild population
  • little space
  • store large numbers
  • easy and cheap to transport
  • viable for long periods
  • less susceptible to disease or pests
61
Q

how seeds are kept viable

A

-germinate from time to time
-ensure new seeds are produced
-freeze
( keep range of alleles )

62
Q

how genetic variation is ensured in seed banks

A
  • ensure you have many seeds
  • from many areas
  • ensure mixture of genotypes (alleles)
63
Q

Aims for the Convention on Trade in Endangered Species of wild flora and fauna CITES

A
  • conservation of biodiversity
  • regulate and prevent trade in endangered species
  • ensure trade doesn’t endanger wild populations
  • prohibit commercial trade in wild plants
  • allow trade in artificially propagated plants
  • allow some trade in less endangered plants and animals
64
Q

How cites help save endangered species

A
  • countries agree to make poaching illegal
  • ban on trade of endangered species
  • increased cooperation between countries
  • increased awareness of impact of illegal trade
65
Q

aims for rio convention on biological diversity

A
  • conserve biodiversity
  • sustainable use of organisms, habitats, ecosystems
  • share genetic resources
  • share access to scientific knowledge
  • promote ex situ conservation
  • raise profile of biodiversity with governments/ general public
  • international cooperation on biodiversity issues
66
Q

criteria to consider in environmental impact assessment

A
  • size of development
  • which species are present
  • potential damage to area/ organisms
  • potential strategies to minimise impact
67
Q

Role of EIA as part of local planning decision

A
  • measures effect development is likely to have on biodiversity therefore the need for conservation
  • searched for endangered species and measures need for protection
  • ensures laws concerning endangered species are followed
  • may present conditions for planning e.g species translocation
68
Q

aims of countryside stewardship scheme ( environmental stewardship scheme )

A
  • not environmentally sensitive areas
  • farmers paid to enhance and conserve landscapes
  • grants available e.g for hedge laying
  • improve natural beauty and diversity of countryside
  • enhance, restore and re-create targeted landscapes. their habitat and historical features
  • improve opportunity for public access
  • funding to farmers and land managers
  • look after wildlife species, habitats
  • ensure land well managed and retains traditional character
  • protect historic features and natural resources
  • ensure livestock and crops conserved
  • opportunities for people to visit and learn about the countryside

BIOLOGY MODEL ANSWERS (6 decks)

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