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paper 2 biology

Kholoud sabbaji English 200 cards

how can organisms be effected by food chain

Cards in this deck (200)

  1. 1—s
  2. 2describe what is meant by competitionliving organisms require a supply of materials from their surroundings like water or they can get if from other living organisms the problem with that is these resources are often in short supply and so living organisms have to compete with each other.
    - plant compete for light and space and also for water and mineral ions from the soil
    - animals compete for food and water but also for partners and territory
  3. 3describe what is meant by interdependenceall the different species in a community depends on each other because animals depends on living organisms for food ex lions eat zebras and other animals get their food by eating plants.
    some living organisms provide shelter ex. a tree shelters animals from the sun.
    plants can also depend on animals ex. plants depends on bees spreading their pollen or birds that disperse seeds in their faeces.
    we can understand that if a species disappears from a community this can effect the whole community.
    in most communities the populations of different species remain constant scientists call this a STABLE COMMUNITY, in a stable community the population of organisms will balance each other and with the abiotic resources like water
  4. 4what is meant by habitatthe environment in which an organism lives and could contain many different species
  5. 5what is meant by populationtotal number of organisms of the same species living in the same geographical area
  6. 6what is meant by communitypopulation of different species(all the living organisms) that live in the same habitat
  7. 7what is meant by bioticliving part of an environment
  8. 8what is meant by abioticthe non living part of an environment which includes the amount of water and minerals in the soil
  9. 9what is meant by ecosystemboth the abiotic and biotic part of an environment and how they interact
  10. 10describe the biotic factorsthey are 4
    - availability of food
    - new predator can cause the population of a prey species to fall and could effect existing predators like in competing for the same prey
    - competition between species
    - new pathogens
  11. 11describe the abiotic factorsthey are 7
    - light intensity needed for photosynthesis and that can effect animals food
    - temperature causing the change of distribution of a species and plant species might disappear
    - water distribution
    - ph and minerals in the soil depending on the acidity or if it is alkaline the plant might not grow under a certain ph soil, however minerals are needed for proteins synthesis in amino acids
    - wind intensity and direction, strong wind can cause the plant to lose water and so some plants are adapted by growing in sand which reduces the wind intensity
    - carbon dioxide(needed for photosynthesis) and oxygen(aerobic respiration), the oxygen in air is constant but oxygen in water can fall ex. in hot days harmful to organisms as fishes
  12. 12describe the structural adaptations to cope with the hot and dry conditions of the desertcamels are adapted to hot and dry conditions of the desert many of these are structural adaptations.
    - they have a hump on their back which is a store of fats, fat is a thermal insulator and so by storing the fat is one place this allows heat loss from other parts of the camel's body and reduces water loss from sweating
    metabolic reactions can be used to produce water from the fat
    - they have a thick coat on the upper surface of their body this insulates the top of the camel from the heat of the sun and again reduces water loss from seating
    - inside of the camel's mouth is leathery and so they can chew desert plants that often have thorns and these plants can be a good source of water
    - long eyelashes to keep dust away from their eyes
    - they can close their nostrils to keep dust out of their nose
    - wide feet which prevents them to sink into the sand
    functional adaptations
    - they produce concentrated urine and dry faeces which reduces water loss
    - they can tollerate very large changes in their body temperature to cope with the intense heat of the desert
  13. 13what is meant by structural adaptationsadaptations of body shape or structure
  14. 14what is meant by functional adaptationsadaptations to the body functions of an organisms
  15. 15what is meant by behavioural adaptationsadaptations to the animal's lifestyle
  16. 16what is an example of a behavioural adaptationskangaroo rat which lives in the desert, they are nocturnal and so they avoid the heat of the daytime because during the day they live in burrows underground which keeps them cool and protects them from predators
  17. 17describe the adaptation of an arctic fox in cool conditionsstructural adaptations
    - very thick fur which provides insulation and reduces heat loss
    - fur in the soles of their feet this reduces heat loss to the ice and snow
    - very small ears which reduces the surface area of the fox reducing heat loss
    - its coat provides effective camouflage which helps to hunt its prey
  18. 18describe adaptations in plants ex. cactus- very small leaves to reduce the water loss
    - no leaves only spines also protect from animals
    - extensive and shallow roots which allows cacti to catch much water as possible after rainfall
    - store water in the stem this means that they can survive months without rain
  19. 19what is meant by extremophilessome organisms are adapted to live in very extreme conditions
    ex deep sea vent the conditions are extremely harsh ex very high temperature and pressure however we can find bacteria living in these sea beds and these bacteria are extremophiles they can also live in very high concentration of salts
  20. 20how can organisms be effected by food chainboth the food chains begin with a green plant called the 'producer' because every food chain starts with the producer and in most of the food chains the producer is a green planthow can organisms be effected by food chain
  21. 21describe how number of predators and prey change over timethe number of predators and preys rise and falls in cycles, which is only true in a stable community
    using the example rabbits and foxes
    - we have a warm summer with lots of grass for the rabbit to eat, that means that more of the rabbit's offspring survive and the population will increase
    - the foxes have now more rabbits to eat and kill so after some time the foxes population will increase however because there are more foxes more rabbits will be eaten so now the population of rabbits falls
    - foxes have now fewer rabbits to kill and eat so after sometime the population of foxes also falls
    - at this point because the number of foxes has fallen more rabbits will survive and reproduce so the population of rabbits increases again and again because the foxes have more rabbits to eat and kill after some time the fox population will increase again.    describe how number of predators and prey change over time
  22. 22why are 'producers' important in food chain? what is their role?they synthesise complex molecules.
    source of all the biomass in a community
  23. 23what is meant by biomassmolecules like glucose produced by photosynthesis using light from the sunlight.
    these molecules pass down the food chain to the other organisms
  24. 24why are producer so importantbecause they are the source of biomass which are molecules like glucose that are passed down the food chain.
    producers are used to synthesise complex molecules
  25. 25what is meant by primary consumersorganisms that eat the producers
  26. 26what is meant by secondary consumersan animal that eats the primary consumer
  27. 27what is meant by a tertiary consumeran animal that eats the secondary consumer
  28. 28what is meant by predatorconsumers that both kill and eat other animals
  29. 29what is meant by a preythe animal that has been eaten by the predator
  30. 30what is meant by a stable communitywhen the biotic and abiotic factors balance together
  31. 31how to use quadrats and transects to determine the abundance and distribution of species in an ecosystemg
  32. 32how do we determine the number of organisms in an areawe use a technique called sampling and we have 2 ways:
    - random sampling
    - sampling along a transect
  33. 33describe random samplingused to compare the numbers of organisms in different areas and to do this we use a quadrat which is a wooden or plastic square that we place on the ground and count the number of organisms inside the quadrat and this can be used to sample plants or slow moving animals.
    the quadrat is places in random locations across the area by using random numbers to select different locations.
    we count the number of organisms in the quadrat and now we move it in another random location in the area and count the number of organisms there.
    we keep doing this until we sampled a large number of random locations to get valid results.
    now we do the same in an another location that we want to compare with the one before and we use the same procedure.
    random sampling is usually used to compare different locations and to confirm an hypothesis.
    random sampling is also used to estimate the TOTAL population in an area with this formula    describe random sampling
  34. 34describe sampling along a transectused to investigate whether the number of species change as we move across an habitat.
    a transect is a line such as a tape or a rope and we place it across the habitat we are looking at , we then use a quadrat to count the number of organisms at intervals on the transect we also repeat the process to get valid data
  35. 35describe the processes that takes place in the carbon cycle- starts with the carbon dioxide in the atmosphere
    the only way that the carbon enters the carbon cycle is by photosynthesis in which carbon dioxide is combined with water to make glucose
    carbon dioxide returns back to the atmosphere by aerobic respiration.
    - the carbon dioxide is in the atmosphere
    - plants and algae takes in the carbon dioxide from the atmosphere in photosynthesis
    - the carbon dioxide is used to make carbohydrates, fats and proteins which make up the cells
    - plants and algae respire so some of the CO2 is released back to the atmosphere
    - at the same time plants and algae can be eaten by animals and these animals can be eaten by other animals and at this point the carbon that was in the plant becomes part of the animal's carbohydrates, fats and proteins
    - just like plants animals respire and so some of the carbon is released back to the atmosphere as carbon dioxide, animals also releases waste products such as faeces and eventually they will die so now we have carbon dioxide in waste product and dead remains
  36. 36describe the role of decomposersextremely important as the cycle materials through an ecosystem, as well as returning CO2 to the atmosphere they also release mineral ions to the soil.
    cannot function effectively under certain condition such as lack of oxygen and if this happens the carbon in dead remains can slowly be converted in fossil fuels and combusting fossil fuels is releasing a large amount of CO2 back to the atmosphere    describe the role of decomposers
  37. 37describe the stages of the water cycle- almost all the water on earth is found in oceans which is SALT water
    - energy from the sun causes this water to evaporate from the surface of the sea
    - the water vapour travels through the air and COOLS down
    - when it cools the water vapour CONDENSES to form clouds
    - the water in clouds then falls down to the ground as PRECIPITATION (rain and snow)
    - this water does not contain salt and as it touches the ground some of it evaporates back into vapour and some of it passes through rocks forming AQUIFERS and rivers, this water eventually drains back into the sea
  38. 38what is the role of organisms in the water cycle- plants take up water in their roots which moves up the plant through the xylem and passes out through the stomata as vapour process called transpiration
    - animals take in water through drinking and in their food and they release it in their urine, faeces and when they exhale.
  39. 39describe the conditions required for decomposition- temperature, takes place faster in warmer temperatures and that is because the decomposers use enzymes to break down the plant material and we know that enzymes work faster in warmer conditions.
    decomposers are usually warmer anyways because they release energy when they carry our aerobic respiration, however it is so important that the compost does not get too hot if so the enzymes will get denature and the decomposers could even die
    - amount of water, decomposers work faster if the compost is moist because many of the chemical reactions of decay require water
    - oxygen, decomposers carry out aerobic respiration which requires a good supply of oxygen
  40. 40what is meant by anaerobic decaye
  41. 41what is the compostthe decomposed material by bacteria and fungi
  42. 42what is the adaptations to let the oxygen be in abundance- compost bin that has holes in the walls to allow oxygen to enter
    - using gardening fork to mix their compost regularly which breaks down large clumps and increases the surface area
  43. 43what happens if there is no oxygen?the decomposing organisms carry out ANAEROBIC DECAY which produces a mix of gasses like methane this is called BIOGAS used to provide fuel for homes often using plant materials.
    the BIOGAS is only produced under ANAEROBIC conditions.
  44. 44evaluate the impact of environmental change on the distribution of a specieswe know that the distribution of a species depends on the biotic and abiotic factors.
    we can talk about the temperature ex. red fox, water ex. cacti and gasses in the atmosphere. ex. lichen found in larger amount where the air is unpolluted.    evaluate the impact of environmental change on the distribution of a species
  45. 45what is meant by biodiversitythe variety of the different species of organisms on earth, which can also refer to a single ecosystem.
  46. 46what is meant by deforestationtropical forests contain lots biodiversity, however large areas of these forests are destroyed to provide land
  47. 47how is deforestation reducing biodiversityr
  48. 48why is biodiversity important for an ecosystemthe species depends on each other for food and shelter and help to maintain the environment for example with decomposers.
    an ecosystem is more stable when we have a high level of biodiversity and so lots of species and so it is less dependent on one species
  49. 49what are the effects of humans in biodiversitynegative effect.
    ex. deforestation
  50. 50how is the land used- rice fields
    - grazing cattle
    - to grow crops used to make biofuels
    - for buildings
    - farms, quarries, landfills    how is the land used
  51. 51how can waste product by humans be reduced by biodiversity- water pollution, human produce large amounts of sewage containing urine and faeces which in some countries is released to the waterways but in the UK sewage is treated before being released however in some cases sewage is accidentally released into river.
    causes the oxygen levels to fall
    - fertilisers from farms could also pollute rivers and streams.
    both the fertilisers and the sewages cause the oxygen levels to fall killing aquatic organisms
    - toxic chemicals released to rivers from factories which again kills animals from the river
    - air pollution can kill plants and animals reducing biodiversity
    - land pollution which destroys habitats for plants and animals and could release toxic chemicals polluting the soil, or chemicals could be dumped into the land killing microorganisms
  52. 52what is the human activity doing- reducing the biodiversity in aquatic ecosystems
    - polluting the air ex. burning coal releases acidic gasses leading to acidic rain releasing also smoke
  53. 53how is the amount of land reduced by humansd
  54. 54how the destruction of peat dogs reduces biodiversity and releases co2it contains large amount of dead materials mean that decay is very slow and so peat dogs contain a very large amount of co2 however these habitats are being destroyed.
    peat is used to produce cheap compost and in some countries is burned for energy and the destruction of it is reducing the area for habitats reducing the biodiversity.
    ones the peat has been extracted it starts to decay releasing large amounts of co2 to the atmosphere which contributes to the climate change.
    the stop of buying peat is dangerous because the alternatives are really expensive which could increase the price of food
  55. 55what is meant by global warmingthe increasing of the average temperature of the earth
  56. 56what are the biological consequences of global warming- loss of habitats of arctic organisms
    - animals such as birds and insects they extend their range in cooler conditions
    - migration patterns might change
    - effects the flowering of plants
  57. 57what is meant by peer-reviewchecking process done by scientists before scientific papers are published, helps to detect false claims and makes sure that researches are valid which is NOT done in the popular medias which can lead to inaccurate informations
  58. 58what is causing global warming- carbon dioxide due to burning fossil fuels
    - methane produced by bacteria or released by cows
    both of them are greenhouse gasses and so they trap heat in the atmosphere leading to global warming
  59. 59how can we reduce the loss of biodiversity- breeding programs for endanger species
    - protecting and regenerating large areas of wetland
    - farmers leaving a strip of land around fields(field margins) where plants and animals can live
    - hedgerows between fields where different species of animals and plants live
    - government with maintaining biodiversity by for example reducing deforestation or co2 emissions
    - contribution of individuals by recycling waste materials
  60. 60what is meant by trophic levelss
  61. 61how does decomposers break down plantss
  62. 62describe what is a pyramid of biomassd
  63. 63explain why biomass is lost between the topic trophic levelsd
  64. 64efficiency of biomass transfer calculatione
  65. 65what are the biological factors effecting food securityd
  66. 66how to improve the efficiency of food productiond
  67. 67explain the advantages of modern farming techniquesf
  68. 68explain the disadvantages of modern farming techniquesd
  69. 69why some people have some ethical objections to some farming methodss
  70. 70why is it important to maintain fish stocks at sustainable levelss
  71. 71describe the roles of fishing quotase
  72. 72describe the net sizes in maintaining fish stockss
  73. 73describe the role in biotechnologyd
  74. 74TOPIC 33
  75. 75what is meant by variationall the differences in the characteristics of individuals in a population
  76. 76describe the causes of GENETIC variation-mutations which are variations in the DNA that take place all the time not effecting the phenotype but could INFLUENCE it.
    mutation could lead to a new phenotype beneficial in the environmental changes which can lead in a change of species
  77. 77what is meant by natural selectionthe first lives were very simple like single cells , all the species have evolved from these life forms and this process is called evolution by natural selection.
    - we know that there is a massive amount of genetic variation in a population ex rabbits, they will ALL have a slightly different combination of alleles , if the environment changes ex. becomes colder some rabbits with the right alleles are more likely to survive and so REPRODUCE creating offsprings more likely to have that allele and so more likely to survive in that environment and those rabbits will become more common among the population of rabbits
  78. 78what is meant by evolutionchange in the inherited characteristics of a population over the time
  79. 79what is selective breeding- domestic dogs have been selectively breed to have a gentle nature
    - food crops to be resistant to diseases
    - cows to produce more milk or meat
    - plants to produce large flowers
    firstly we take a mixed population of cows and select the larges male and female and breed these together and we know that sexual reproduction produces variation in the offspring and so a mixture of larger animals and smaller animals we then select the larger female offspring and largest male offspring and breed them together and we keep doing this for many generations until all the offsprings are large
  80. 80what is the impact of selective breedingr
  81. 81explain the disadvantages of selective breedingif we breed together closely related animals or plants we can get inbreeding which can cause diseases in the offspring or inherited defects
  82. 82what is meant by genetic engineeringgenes from humans are cut out to be transferred to a different organism for example a bacteria.
  83. 83how is genetic engineering used in medicineex. insulin which is a hormone involved in the regulation of blood glucose in humans and people with diabetes type 1 needs the insulin to be injected and for this bacteria have been genetically modified to contain the insulin gene and so bacteria now produce the human insulin which can be purified and used for type one diabetes.
  84. 84how is genetic engineering used in agriculturetransferring genes into plants to produce modified crops which will produce greater yield then normal crops by for example making them disease resistant or insect attack which won't harm the crop
  85. 85how is genetic engineering carried out- we identify the gene that we want to transfer(animal, human or plant)
    - we use enzymes to isolate this gene
    - we transfer the gene into a small circle of DNA called PLASMID originally coming from a bacteria useful for the transferring on DNA from and organism to another
    - instead of a PLASMID we could also use a VIRUS
    - because they will transfer the DNA from one organism to another they are called VECTORS
    - finally the desired gene is transferred into the cells of the target organism
    key facts:
    we transfer the gene in early stages of the organism's development ex. early embryo stages and this is to make sure that ALL the cells receive the transferred gene and so the organism develops with the characteristics that we want
  86. 86genetic modificationcurrently being explored as a way to treat inherited disorders in humans called GENE THERAPY but we don't know the potential side effects to other genes
  87. 87how are plants cloned- by cutting
    - by tissue culture
  88. 88how are plants cloned by cuttingworks if we want FEW clones of a plant
    - small piece of a plant Is removed and the end is dipped into rooting powder which contains plant's hormones which encourages the plant to develop roots.
    we now produce genetically identical clone of the starting plant    how are plants cloned by cutting
  89. 89how are plants cloned by tissue cultureif we want multiple clones
    - we take the plant that we want to clone and we divide it into hundreds of tiny pieces containing small numbers of cells then incubated with plant hormones which stimulates the plant to grow and develop into clones.
    key facts:
    conditions must be sterile because we don't want to introduce microorganisms like bacteria and fungi.
    useful in commercial plants nurseries and it allows to produces thousands of genetically identical plants quickly and cheaply and gardens can be certain of the characteristics of the plant(because clones).
    it is also extremely useful to preserve rare species    how are plants cloned by tissue culture
  90. 90advantage of cloning plantsbecause they are genetically identical to the original plant we know EXACTLY what are its characteristics. ASEXUAL reproduction ONLY.
  91. 91how animals can be cloned- transplants
    - adult cell cloning
  92. 92how animals can be cloned by transplants- we start with a sperm and an egg cell from horses with characteristics that we want
    - fertilisation produces a fertilised egg and we allow that egg to develop into an early stage embryo
    - we use a glass rod to split this embryo into 2
    - finally we transplant these embryos into a host mother, the embryos will grow and develop producing 2 identical offspring    how animals can be cloned by transplants
  93. 93how animals can be cloned by adult cells cloningTHIS TIME WE ARE CLONING FROM AN ADULT and so we know the characteristics that the offspring will have
    - we remove a cell from the animal that we want to clone ex. a skin cell
    - we remove the nucleus which contains the genetic informations from the animal
    - we take an unfertilised egg cell from same species and we remove the nucleus from the unfertilised egg and throw it away and now the unfertilised egg contains no genetic material
    - we now insert the nucleus of the adult body cell into the empty unfertilised egg cell
    - now the egg cell contains only the genetic informations from the animal we want to clone
    - we give the egg an electric shock which makes the egg cell divide to form an embryo which contains the same genetic informations as the adult's skin cell that we started with
    - when the embryo has developed it is inserted into the womb of an adult female to continue its development, the host mother then gives birth to clones,
    key facts:
    the clone looks nothing like the host mother because the clone contains none of her genetic material
  94. 94what is a problem with animal transplantbecause we start with a sperm and an egg(sexual) we cannot be certain that the offsprings will have the characteristics that we want and we can overcome that by using ADULT CELLS CLONING.
    when we are cloning from an adult we know the future characteristics of the offspring
  95. 95how CHARLES developed the theory of evolution by natural selection- in species we can see a wide range of genetic variation for any characteristics
    - individuals with characteristics more suited to the environment are more likely to survive and breed
    - the characteristics that have enabled these individuals to survive are passed on to the next generation
  96. 96why Darwin's theory was gradually accepted- lots of people believed that GOD made all of the animals and plants that lived on earth and the theory of Darwin challenged that idea
    - also many scientists felt that he didn't have enough evidence to back up its theory.
    - at that time people didn't understand why characteristics are inherited because genetics wasn't understood until 50 years after Darwin's theory
  97. 97describe what Lamarck suggested and why is it incorrect- he suggested that when a characteristics is regularly used it becomes more developed and this characteristic is then passed to the offspring
    - it was incorrect because now we know that changes that occur in an organism's lifetime CANNOT be passed onto offspring
  98. 98how Wallace contributed to the understanding of evolution- he was working on evolution at the same time as Darwin, he was interested in warming colourations in animals and how they evolved
    - he individually proposed a theory of evolution by natural selection
    - they released they both developed the same theory and so they joined their findings publishing them
  99. 99how is a new species formedWallace was so interested in NEW species forming process called SPECIATION
    he noticed that closely related species were often separated by geographical barriers like wide rivers.
    ex. we have an island with one species of an animal, ALL of these animals can interbreed and so any beneficial mutation spreads through the whole population
    - suddenly the river changes course and it separates the populations of snails into 2 groups. The river is a geographical barrier
    - because the 2 populations of the same species are now separated there is no interbreeding between the 2 groups and over time natural selection will favour different alleles on the 2 sides of the island ex. food sources might differ
    - because there is no interbreeding any mutation cannot spread between the 2 populations, this means that over the time and generation the 2 populations will begin to change
    - we can also imagine that the river changes course again and the 2 populations now can mix, however at this point the phenotype of the 2 populations is so different that they can no longer reproduce    how is a new species formed
  100. 100describe the work of Gregor Mendel- he realised that characteristics are not blended during inheritance and he said the characteristics are determined by inherited units which do not change when passed, with our actual understandings we know that units are the genes.
    - he also released that some characteristics could be masked and reappear in later generations we call these recessive alleles
  101. 101why the importance of his discovery was not recognised until after his death- many scientists still held onto the idea that characteristics are blended when inherited
    - after his death scientists discovered how chromosomes behave when division and so scientists rediscovered Mendel's theory because they realised that the units behaves in the same way as chromosomes and so have been renamed as genes and they must be located in the chromosomes
    - in 1950 scientists discovered the structure of DNA and its functions
  102. 102what is meant by fossils ?remains of organisms from millions of years ago found in rocks
  103. 103how are fossils formed- parts of organisms have not decayed
    - when an organism decays if parts of an organism are slowly replaced by minerals
    - they can preserve traces of an organism
  104. 104what are the problems with fossils- many early forms of organisms were soft-bodies and so they didn't have a form or a skeleton and so they rarely form fossils or many of them have been destroyed, and so because we have very few fossils formed in early life and scientists cannot be sure about the starting of the life on Earth.
  105. 105extinctno remaining individuals of that species are still alive
  106. 106how can a species become extinct- catastrophic events
    - environmental changes
    - new disease or new predator that could kill the species
  107. 107how bacteria becomes resistant- bacteria reproduce rapidly (30 minutes) and so they evolute rapidly
    - certain strains of bacteria are no longer killed by antibiotics and that is because those bacteria have EVOLVED and are now antibiotic-resistant ex.MRSA.
    when a bacteria is a pathogen it is possible that a MUTATION could make a bacterium RESISTANT to antibiotics.
    when we use an ANTIBIOTIC to kill the bacteria some of them will die, however the antibiotic resistant ones will live and reproduce and over time the population of the resistant strains RISES and spreads
  108. 108how can we reduce the rate of resistant bacteria- doctors should not prescribe antibiotics INAPPROPRIATELY
    - patients should complete their course of antibiotics making sure ALL of the bacteria is killed
    - restricting the use of antibiotics in farming
  109. 109describe how organisms are classified based on the characteristics- developed by Linnaeus
    - 2 kingdoms, animal and plant
    - each kingdom into smaller categories :
    - kingdom
    - phylum
    - class
    - order
    - family
    - genus
    - species    describe how organisms are classified based on the characteristics
  110. 110describe the 3 domain classifications system- archae which are primitive bacteria found in extreme conditions
    - true bacteria which lives in the human digestive system
    - eukaryota including animals plants and fungi and protists like amoeba
  111. 111describe the relationships between organisms making evolutionary treesto make an evolutionary tree we can use CLASSIFICATION DATA ex their DNA and for the extinct ones we can use fossils which can present problems because many fossils are INCOMPLETE.
    from this diagram we can se that species 1 is closely related to species 2 whereas species 3 is distantly related , however all of them have a common ancestor    describe the relationships between organisms making evolutionary trees
  112. 112how can we name(binomial name) an organismtheir genus and their species this is called the BINOMIAL NAME
  113. 113TOPIC 22
  114. 114describe the differences between sexual and asexual reproduction- animals and plants carry out SEXUAL reproduction which involves the fusion of the male and female GAMETES process called FERTILISATION, in sexual reproduction there is a MIXING of genetic information process called MEIOSIS and so the offspring receives genetic informations from the male and female parents.
    Because every gamete is different we can see variations in the offspring
    - aphid is and example of ASEXUAL reproduction , these is only ONE parent and so does not involve gametes and so there is no mixing of genetic informations and the offsprings are GENETICALLY IDENTICAL scientists call these offsprings CLONES, it does not involve meiosis BUT it only involves MITOSIS
  115. 115describe the process of MEIOSISgametes contains single chromosomes , the chromosomes are not paired and so 23 chromosomes, MEIOSIS only takes place in reproductive organs and so testes and ovaries
    - we first have a cell in human reproductive organ and so 23 chromosomes PAIRS, in the first stage all of the chromosomes are copied
    - the cell now divides in 2
    - both of these cells divide one more time forming gametes and as you can see the gametes are single not paired.
    we can see that meiosis has HALVED the number of chromosomes and produces 4 gametes from 1 original cell and each of these 4 are genetically DIFFERENT from each other and so they all have different ALLELES
  116. 116describe what fertilisation doesnow that we have produced the gametes by meiosis we will now see what happens to them
    - we have a gamete from a male and one from a female and in SEXUAL reproduction they all join together with a process called FERTILISATION, and after that the cell now has the normal number of chromosomes.
    we now see that with MEIOSIS the number of chromosomes have HALVED but with FERTILISATION the number of chromosomes has RESTORED    describe what fertilisation does
  117. 117what happens after fertilisation- the new cell divides by MITOSIS producing identical cells , these identical cells together are called EMBRYO and as it develops the cell differentiate forming different cell typeswhat happens after fertilisation
  118. 118advantages of sexual reproduction- gives a species survival advantages by natural selection ex.
    if the environment changes this variation means that some of the offsprings may survive
    - selective breeding
    inside the mosquito malaria reproduces by sexual reproduction
    fungi can also reproduce sexually creating variations of the offspring
    flowering plants reproduce sexually producing seeds
  119. 119disadvantages of sexual reproductions
  120. 120advantages of asexual reproduction- effective in time and energy , is useful in favourable conditions
    in the human host the malaria reproduces by asexual reproduction
    many species of fungi reproduce asexually through spores.
    some plants reproduce asexually ex strawberry runner , when a runner touches the soil it can develop into a new plant genetically identical to the parent
    daffodils can reproduce asexually by bulb division, the parent plant has an underground bulb that produces buds and these buds produce an offspring
  121. 121disadvantages of asexual reproduction- very risky, because they are genetically identical there is a risk they could all die if the conditions are unfavourable
  122. 122describe the structure of DNA- genetic material, contained in the chromosomes in the nucleus
    - determine our inherited features
    - 2 strands each strand is a polymer, the 2 strands wrap around each other forming a double helix structure.
    a gene is a small section of DNA on a chromosome , each gene codes for a specific SEQUENCE of amino acid to make a SPECIFIC protein.
    both chromosomes in a pair have the same genes    describe the structure of DNA
  123. 123what is meany by genomeentire genetic material of an organism
  124. 124why is a genome important- search for genes linked to diseases
    - understand and treat inherited diseases
    - trace human immigration patterns in the past
  125. 125describe the STRUCTURE of DNADNA is a polymer of molecules called NUCLEOTIDES
    - phosphate group
    - sugar molecule
    - base, the only one that changes and we have 4 different bases, and so DNA contains 4 different types of NUCLEOTIDES :
    - A
    - C
    - G
    - T    describe the STRUCTURE of DNA
  126. 126what is meant by complementary strandsthe DNA strands are COMPLEMENTARY and so the same bases always pair on opposite strands:
    - C with G
    - A with T    what is meant by complementary strands
  127. 127describe the stages of protein synthesis2 stages
    - TRANSCRIPTION : the base sequence of a gene is copied into a complementary template molecule, this template is called mRNA(messenger) which is a single stranded molecule
    the mRNA now passes out of the nucleus and into the cytoplasm.
    - TRANSLATION: the mRNA molecule attaches into a ribosome and amino acids are brought to the ribosomes by tRNA(carrier), the ribosomes read the triplet of bases on the mRNA and uses this information to join the correct amino acids int the correct order.
    ones the chain of the protein is complete it now folds into a UNIQUE shape which enables the protein for its function
  128. 128explain the amino acids- 20 different amino acids
    - the specific order of amino acids determines the shape of the protein which determines its function
    - the order of amino acids in a protein depends on the sequence of bases in a gene for that protein
    - the DNA is read by the cell as TRIPLETS of bases and each triplet encodes for a specific amino acid    explain the amino acids
  129. 129describe why a change in DNA might lead to a change in the protein synthesis by a genea change in a base is called MUTATION, but a change in base won't change the amino acid sequence because sometimes different base triplets can sometime encode for the same amino acid and so in this case the mutation has no effect on the function of the protein.
    however sometimes the change in a base sequence leads to a different mutation that in this case will change the sequence of the amino acid and this change will alter the shape and function of the protein.
    this kind of mutation can have a DRAMATIC effect on the function of a protein ex. the active site of an enzyme might change its shape and so cannot longer attach to the substrate, or if the protein is collagen then it may lose its strength    describe why a change in DNA might lead to a change in the protein synthesis by a gene
  130. 130describe the type of mutation in the chromosome- the chromosome also contain non coding parts of the DNA these regions have the function to turn on and off the gene and so tells the gene when to produce proteins, a MUTATION in this region can effect how genes are turned on and off ex. a gene turns off when it should turn on or it will produce a protein that is not meant In that moment and this could have significant effects on a cell ex. uncontrolled mitosis leading to cancer
  131. 131what is meant by dominant and recessive allelesdominant: allele that will show in the phenotype even if there is only 1 copy present
    recessive: allele that will only show in the phenotype if 2 copies are present
  132. 132homozygous2 copies of the same alleles
  133. 133heterozygous2 different alleles
  134. 134what is an allelesdifferent version of a gene
    because we have 2 copies of chromosomes we also have 2 copies of each gene
  135. 135genotypetells us the alleles present in that chromosome
    ex. EE, ee.
  136. 136phenotypetells the characteristics caused by the person's alleles
  137. 137describe the disorder cystic fibrosisdisorder of cell membranes , controlled by a single gene with 2 alleles.
    - the normal cell membrane function C which is the DOMINANT one
    - the defective cell membranes c which is the RECESSIVE one.
    we understand that in order to have cystic fibrosis the person has to have 2 copies of the recessive allele and so they have to inherit defective alleles from both parents.
    key fact:
    a person with one defective allele and a normal allele does not have cystic fibrosis but they are a CARRIER of the alleles
  138. 138Punnet Square of a carrier and an unaffectedPunnet Square of a carrier and an unaffected
  139. 139Punnet Square of 2 carriersPunnet Square of 2 carriers
  140. 140describe the disorder polydactylyex extra finger or toes , caused in this case by a DOMINANT allele and that means if a person with 1 copy of polydactyly allele and 1 normal allele will have polydactyly and you cannot be a carrier
  141. 141Punnet SquarePunnet Square
  142. 142solutions of inherited disordersembryo screening : embryos are tested to see if the have the alleles for inherited disorders, embryos that does not have it are implanted to the woman that will then develop.
  143. 143issues with embryo screening- expensive
    - large number of embryo created but small amount is actually implanted and that means some healthy embryos are destroyed which is considered unethical
    - in the future this can be used to produce offsprings with desirable features also considered unethical
    - scientists might correct faulty alleles and use this to treat inherited disorders
  144. 144family treesgive one piece of evidence that cystic fibrosis is caused by a recessive allele
    - if we look at person 11 we can see that they have cystic fibrosis however neither of their parents have cystic fibrosis 7 and 8.
    person 7 and 8 MUST be carriers and the cystic fibrosis must be recessive.
    If cystic fibrosis was dominant at least one of the parents must have cystic fibrosis    family trees
  145. 145family treesfamily trees
  146. 146describe the inheritance of sex22 of the chromosome pairs contain the gene which determines inherited characteristics only however 1 of the pairs contain genes that determine sex.
    in this case the 2 sex chromosomes are different, this tells us that these chromosomes came from a male, a male has the sex chromosomes XY. the sex chromosomes from a female are the same and they are XX    describe the inheritance of sex
  147. 147Punnet SquarePunnet Square
  148. 148TOPIC 11
  149. 149what is meant by homeostasisAUTOMATIC CONTROL SYSTEM.
    regulation of the INTERNAL CONDITIONS of a cell or organism to maintain the OPTIMUM conditions for function in response to INTERNAL or EXTERNAL CHANGES.
  150. 150what is meant by internal conditions- blood glucose concentration
    - water levels
    - temperature
  151. 151describe an automatic control systeminvolving nervous system and hormones
    - receptor, detect changes in the environment which is a STIMULUS which could be internal or external conditions.
    the receptor now passes the information to a coordination centre
    - coordination centre ex. the brain, pancreas, spinal cord.
    which receives and processes the informations from the receptor cells.
    the coordination centre now sends the informations to the effector
    - effector ex. a muscle or a gland which will carry out a response restoring the optimum level
  152. 152describe how the nervous system is related to its function- central nervous system which is the brain and spinal cord
    - other nerves running to and from the CNS.
    - receptors detect a stimulus and send electrical impulses down neurones to the CNS
    - the CNS is the coordination centre this now sends electrical impulses down other neurones to effectors
    - the effectors bring about a response
  153. 153structure of reflex arc- stimulus is detected by a receptor , electrical impulses now pass through a sensory neurone to the CNS
    - at the end of the sensory neurone there is a junction called SYNAPSE and at the synapse a chemical is released and this chemical now diffuses through a relay neurone in the CNS where it triggers an electrical impulse, this electrical impulse now passes through the relay neurone and reaches another synapse and ones again a chemical is released this chemical trigger an electrical impulse in the motor neurone, the electrical impulse now passes through the motor neurone to an effector which could be a muscle contracting or a gland secreting hormones which will carry a response
  154. 154why is it importantkey fact:
    in the case of reflexes there is no decision made by the CONSCIOUS part of the brain and this makes reflexes rapid and automatic and because they are rapid and fast they protect us from danger
  155. 155what is the role of the nervous systemit enables humans to react to their surroundings and coordinate their behaviours and this is done by REFLEX ARC
  156. 156describe the functions of the different parts of the brainthe brain controls COMPLEX behaviours and to do that the brain contains billions of interconnected neurones
    - cerebral cortex
    - medulla
    - cerebellum
  157. 157describe how scientists investigate brain functionthere are 3 ways:
    - they look at patients with brain damage by looking at where the damage is taking place they can try to link that part to the specific function
    - we can electrically stimulate different parts of the brain and look at the effects on the person's behaviour and that also allows us to narrow down specific regions to their function
    - we can use MRI scanning to look at which parts of the brain are most active during different activities
  158. 158cerebral cortexlanguage, memory, consciousnesscerebral cortexcerebral cortex
  159. 159medullahearth rate and breathing ratemedullamedulla
  160. 160cerebellumcoordinate balance and movementscerebellumcerebellum
  161. 161why is it so difficult to investigate the brain- brain protected by the skull so it is very tricky to access
    - the structure is very complex and so it is really difficult to work out exactly which part carry out specific function
    - delicate and so easy to damage
  162. 162the eyeit is a sense organ because it contains receptors which are sensitive to light intensity and colour
  163. 163different parts of the eye- cornea
  164. 164cornealight passes through the transparent front of the eye , it starts the focussing of the light rayscornea
  165. 165pupilallows the light to pass into the eyepupil
  166. 166iriscoloured part of the eye which controls the size of the pupil.
    if we have low light intensity this drop in light intensity is sensed by the receptors in the retina and these send electrical impulses to the brain which sends electrical impulses to specific muscles in the iris , these muscles contract allowing more light to enter causing the pupil to become larger.
    REFLEX ACTION    iris
  167. 167lenswhich focuses the light rays onto the back of the eye, the lens can also change its shape allowing us to focus on distant and near objects and this is called ACCOMMODATIONlens
  168. 168retinalight rays from the lens are now focused on the retina and so on the back of the eye which contains receptors for light that allows us to detect the light intensity and colours.
    these receptors cells in the retina now send electrical impulses down the optic nerve to the brain    retina
  169. 169optic nervereceives the electrical impulses from the receptors in the retina and passes that to the brainoptic nerve
  170. 170sclerawhite part of the eye and this protects the eyesclera
  171. 171ciliary muscles and suspensory ligamentswork with the lens and together they allow us to focus on near or distant objectsciliary muscles and suspensory ligaments
  172. 172reflex actiondoes not involve the conscious part of the brain
  173. 173how the eye focuses on near objectslight from near objects needs to be focused a LARGE amount and so in this case the ciliary muscles CONTRACTS and the ligaments LOOSEN and so the lens is THICKER and the light is refracted STRONGLY, and so as you can see the rays are focused on the retina again
  174. 174how is the focusing carriedby the cornea(fixed lens) and the lens(near or distant)
  175. 175what is meant by accommodationthe ability of changing the shape of the lens to focus on near or distant objects
  176. 176what does accommodation involvethe lens is surrounded by circular muscle called ciliary muscles connected to the lens by fibres called suspensory ligamentswhat does accommodation involve
  177. 177describe the process of accommodationby contracting or relaxing the ciliary muscles can change the thickness of the lens.
    - when the ciliary muscle contract the suspensory ligaments LOOSEN and so the lens is now THICKER and refract rays STRONGLY
    - when the ciliary muscles relaxes the suspensory ligaments are PULLED TIGHT and so the lens is pulled THIN and SLIGHTLY refracts light
  178. 178how the eye focuses on distant objectsthe light from distant objects only needs to be focused a SMALL amount and so in this case ciliary muscles relaxes and the ligaments are pulled tight and the lens is pulled thin and because of that the light rays are only slightly refracted because the light rays are now focused in a POINT in the retinahow the eye focuses on distant objects
  179. 179why can people be longsighted or shortsightedbecause the rays does not focus CORRECTLY on the retina
  180. 180long-sighthyperopia, they cannot focus on nearby objects because the eyeball is usually too short and so the light is focused on a point BEHIND the retina, however in some other cases ex. ELDERY the lens becomes LESS ELASTIC and so cannot become thick enough to focus on near objectslong-sight
  181. 181long sight treatmentsconvex lenses, these partially focuses the light before entering the eyelong sight treatments
  182. 182short sightmyopia, cannot focus on distant objects usually become the eyeball is too long and so the light will be focused in a point IN FRONT OF the retina and this can cause the lens to become TOO thick.short sight
  183. 183short side treatmentsconcave lens, to partially UNFOCUS the light before it enters the eyeshort side treatments
  184. 184other treatments- instead of glasses people could use HARD or SOFT CONTACT LENSES which sits on the eyeball refracting the light in the same way as glasses
    - laser surgery can be used to change the shape of the cornea and so the refraction of the light
    - replacing of the lenses in the eye with artificial lenses
  185. 185how is our body monitoring the temperaturethe brain is monitoring the temperature but specifically the thermoregulatory centre which is in the brain
  186. 186describe the thermoregulatory centrecontains receptors which are sensitive to the temperature of the blood
    ex. the skin contains receptors that sends electrical impulses down the sensory neurones to the thermoregulatory centre
  187. 187what happens when the body temperature gets too highc
  188. 188what happens when the body temperature gets too high- sweat glands will release sweat on the surface of the skin
    - the sweat will evaporate which takes energy from the body cooling it down or the body could cool itself down by flushing, under the surface of the sin we have blood capillaries which are supplied with blood deeper in the skin and if it gets too hot the capillaries dilates process called VASODILATION, because the blood vessels have dilated heat could be transferred out of the body and so the temperature returns to its normal level
  189. 189what happens when the body temperature gets too lowin this case blood vessels supplying the capillaries CONSTRICT becoming narrower process called VASOCONSTRICTION in which less blood now flows through the capillaries and less heat is lost from the body
  190. 190other ways of responseby shivering in which our skeletal muscles contract and to generate energy for this contraction the muscle cells increase their rate of respiration releasing HEAT that warms our body.
    if our body temperature falls too low we stop sweating and in both cases the thermoregulatory system detects a change in the body temperature and the body responses to reverse this change to the normal body temperature
  191. 191what is meant by the endocrine systemconsists of a number of glands which secrete hormones which are chemicals carried in the bloodstream but each hormone only acts on a specific target organ where it produces an effect, tent to produce a slower effect then the nervous system and the effect is long lasting
  192. 192pancreasinvolved in controlling the concentration of glucose in the bloodpancreas
  193. 193ovariesreleasing hormones involved in puberty and reproductionovaries
  194. 194testesreleasing hormones involved in puberty and reproductiontestes
  195. 195thyroid glandproduces hormones involved in growth and the regulation of the body's basal metabolic ratethyroid gland
  196. 196adrenal glandsthey release the hormone adrenaline which produces in time fear and stressadrenal glands
  197. 197pituitary glandsrelease a number of different hormones into the blood depending on the conditions , they act ON other glands and can trigger a range of different effects in the bodypituitary glands
  198. 198how is the hormone insulin used to control the blood glucose concentrationa change in the glucose levels could be detected by the pancreas but specifically by the hormone insulin which will travel in the bloodstream around the body and triggers the body cells to take up glucose from the blood and the liver and muscle cells to store excess glucose as a storage molecule called glycogen
  199. 199why is important to regulate the concentration of glucose in the bloodglucose is needed in respiration to release energy and so It is really important that the concentration of glucose in the blood is kept constant and the blood concentration is monitored by the PANCREAS.
  200. 200when could an increasing of glucose happenafter a rich meal of carbohydrates however it is sensed by the pancreas

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Flashcards on paper 2 biology, created by Kholoud sabbaji on 28/05/2023.
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