Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    Offline

    2
    ReputationRep:
    Can someone explain/summarise the biological and the phylogenetic species concept please?
    Offline

    5
    ReputationRep:
    (Original post by Cdp3)
    Can someone explain/summarise the biological and the phylogenetic species concept please?
    Biological is just the idea of the two organisms being able to breed together to produce fertile offspring. Though the zebra and horse can mate and produce a 'Zorse', the chromosome numbers mean that the the Zorse is infertile and can't reproduces, so they are therefor classed as different species.

    Phylogenetic is based on evolutionary relationships through history. The closer the common ancestor, the more genetically related the organisms are likely to be to one another. This concept has it's issues as there's no clear say so as to classifying species.
    Offline

    2
    ReputationRep:
    (Original post by Mila230)
    Does anyone know what siRNA is and if we have to know about in the exam? I saw a couple of questions on it but can't find them anymore.
    Thank you
    Stretch and challenge on page 171
    Offline

    2
    ReputationRep:
    (Original post by EvasiveRose)
    Yes- its a good idea. Just done a past paper where you got marks for mentioning the names of animals. It would be good to learn specific examples for innate and learned behaviour too
    Would you be able to write down the examples you know?? Thanks
    Offline

    15
    ReputationRep:
    (Original post by Student23478)
    Yeah. Do we need to know examples for interspcfifc competition intra and predator prey relationships? So for predator prey you've for lynx predator and snowshoe then you've got the grey and (other coloured ) rabbits for inter what about intra eg??
    Yes, the spec says you need to know examples, and it's come up before.

    For interspecific, I would personally advise using the mink/water vole or red/grey squirrel comparisons, as they're specific species you can name.

    Intraspecific competition happens within all species, so you can basically name any species you like provided you can apply it - for instance, you could talk about plants competiting for nutrients of the soil, as well as light and water, or you could use the example of lions defending territory and hunting for their own pack against outsiders of the group.
    Offline

    1
    ReputationRep:
    (Original post by raach.14)
    Where in the text book is the chain termination method?
    I can't remember the exact page, but it's under genome sequencing in my CGP OCR textbook
    Offline

    2
    ReputationRep:
    (Original post by loperdoper)
    Yes, the spec says you need to know examples, and it's come up before.

    For interspecific, I would personally advise using the mink/water vole or red/grey squirrel comparisons, as they're specific species you can name.

    Intraspecific competition happens within all species, so you can basically name any species you like provided you can apply it - for instance, you could talk about plants competiting for nutrients of the soil, as well as light and water, or you could use the example of lions defending territory and hunting for their own pack against outsiders of the group.
    What example could you give for habituation? And taxes ?
    Offline

    2
    ReputationRep:
    Describe how artifical selection can be used to produce bread wheat,Triticum Aestivum.
    I understand the diary cow bit but the stuff on the other two looks complicated.
    Offline

    15
    ReputationRep:
    (Original post by Student23478)
    What example could you give for habituation? And taxes ?
    For taxes, I only know the one given in the textbook. Taxes is where woodlice will start moving when taken out of a dark/damp area, and they will keep moving until they reach the dark/damp area.

    Habituation: rabbits by a busy roadside learn to not run away from cars as they drive past, although they will still run away from other stimuli
    Offline

    2
    ReputationRep:
    Can someone look at the markscheme for 1bii on jan 2013 is it me or are the f1 genotype supposed to be the other way around???
    Offline

    15
    ReputationRep:
    (Original post by cr7alwayz)
    Describe how artifical selection can be used to produce bread wheat,Triticum Aestivum.
    I understand the diary cow bit but the stuff on the other two looks complicated.
    (bread wheat is triticum aestivum, so it's only asking for one other thing)
    Artificial selection is selecting wheat in order to give it a higher yield. It's selected to have a larger yield, all of similar heights to make harvesting easier. Artificial selection is just the simple "pick the best, breed, pick those best, breed"
    Offline

    2
    ReputationRep:
    (Original post by loperdoper)
    For taxes, I only know the one given in the textbook. Taxes is where woodlice will start moving when taken out of a dark/damp area, and they will keep moving until they reach the dark/damp area.

    Habituation: rabbits by a busy roadside learn to not run away from cars as they drive past, although they will still run away from other stimuli
    Nah, the woodlouse one is kinesis. It is non-directional. When woodlouse in unfavourable condition, it increases rate of random movement

    Taxes is the directional one. For example, if you shine a torch at an animal, it runs away from the light source

    You can also do something like birds learning to ignore scarecrows for habituation one :yes:

    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by loperdoper)
    (bread wheat is triticum aestivum, so it's only asking for one other thing)
    Artificial selection is selecting wheat in order to give it a higher yield. It's selected to have a larger yield, all of similar heights to make harvesting easier. Artificial selection is just the simple "pick the best, breed, pick those best, breed"
    Do we need to about polyploidy, the different species and their genomes?
    Offline

    15
    ReputationRep:
    (Original post by Prince edmund)
    Nah, the woodlouse one is kinesis. It is non-directional. When woodlouse in unfavourable condition, it increases rate of random movement

    Taxis is the directional one. For example, if you shine a torch at an animal, it runs away from the light source

    You can also do something like birds learning to ignore scarecrows for habituation one :yes:

    Posted from TSR Mobile
    Oh, whoops. I always mix them up "/

    (Original post by cr7alwayz)
    Do we need to about polyploidy, the different species and their genomes?
    I'm not quite sure what that is?
    Offline

    2
    ReputationRep:
    monophyletic and paraphyletic groups difference?
    Offline

    1
    ReputationRep:
    Also, when does independent assortment of chromosomes occur in meiosis? My textbook says Metaphase 1 and 2, but I don't see how that's correct if cytokinesis and nuclear envelope formation doesn't occur until telophase? How can the chromosome be 'sorted' into separate cells, if they haven't even begun to be pulled apart yet?
    Cheers
    Offline

    2
    ReputationRep:
    (Original post by LMottram)
    Also, when does independent assortment of chromosomes occur in meiosis? My textbook says Metaphase 1 and 2, but I don't see how that's correct if cytokinesis and nuclear envelope formation doesn't occur until telophase? How can the chromosome be 'sorted' into separate cells, if they haven't even begun to be pulled apart yet?
    Cheers
    Independent assortment of chromosomes = metaphase 1

    Independent assortment of chromatids = metaphase 2

    They're randomly arranged at the equator, just before being pulled to opposite poles by the spindle fibres

    How they line up at the equator determines which cell they go into innit
    Posted from TSR Mobile
    Offline

    1
    ReputationRep:
    (Original post by Prince edmund)
    Independent assortment of chromosomes = metaphase 1

    Independent assortment of chromatids = metaphase 2

    They're randomly arranged at the equator, just before being pulled to opposite poles by the spindle fibres

    How they line up at the equator determines which cell they go into innit
    Posted from TSR Mobile
    Oo right Blonde moment, thanks fam
    Offline

    2
    ReputationRep:
    (Original post by loperdoper)
    I would check the spec and see what they've said, but the end of f215 papers often is a series of questions where you make comparisons between two things - so I wouldn't be surprised if "what's the difference between DNA and (t/m)RNA" came up or similar.

    It wouldn't be a bad idea to be aware of the structure of tRNA/mRNA, at least.
    "Can someone look at the markscheme for 1bii on jan 2013 is it me or are the f1 genotype supposed to be the other way around???" Could you explain this please im sure it's the other way round ?
    Offline

    3
    ReputationRep:
    Is it even worth asking for predictions after f214?
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: June 3, 2016
Poll
Are you going to a festival?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.