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OCR Biology F212 Revision [3rd June 2013] (Now Closed)

Can someone help me with 'discuss current estimates of biodiversity'

What exactly do we need to know?

Thanks

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So the amount of species currently known, around 1.75 million, although some remain unknown due to them being microscopic, unicellular etc. they may be very rare so sampling areas will not be sufficient to find them. And they also may live in habitats that remain unexplored. :smile:

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Reply 301

jamesmact

3

Original post by Liberty.

Ditto

My brain hurts already. I wish it was an afternoon exam! I always need to pee like 3 times in the morning :frown:

Does anyone have like a list of relevant keyword for this unit?

It is an afternoon exam I swear...?

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Reply 302

Prees

Original post by wilkes14

Can someone help me with 'discuss current estimates of biodiversity'

What exactly do we need to know?

Thanks

Posted from TSR Mobile

Just done this! Not sure if you need to remember exact numbers but there's an estimate of 1.73 million species in the world of which 89,000 are in the UK. However it's not accurate as we haven't found all the species, evolution and speciation are still happening so more species are being created all the time and many species are endangered/extinct so it could be less. :smile:

Reply 303

NielsBohrsDad

Hey could somebody help me here.

I already know that evolution is the evolving of new species from older species. its done thru natural selection. And in natural selection genetic variation is needed for evolution to be successful

is this because firstly, with no variation and a selection pressure coming in the entire population could be killed because they're all the same and nothing is selected.

secondly, the adaptations that they have- are these genetic or cause of enviornmental factors? because it says that genetic variation is needed for evolution- so surely the adaptations are written in their genetic codes. and here was me thinking they were developed as a result of environmental factors..

or do you not need to know that detailed. ive just gotten confused all of a sudden.

Reply 304

wndms

1

What is the roles of antibodies? I thought it only binds to pathogens' antigens for agglutination and neutralisation.. but it also binds to Phagocytes? Why?

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(edited 10 years ago)

Reply 305

NielsBohrsDad

Original post by wndms

What is the roles of antibodies? I thought it only binds to pathogens' antigens for agglutination and neutralisation.. but it also binds to Phagocytes? Why?

Posted from TSR Mobile

it binds to phagocytes, during phagocytosis in the secondary defence.
the phagocyte has receptors shaped complimentary to the constant region of an antibody. the antibodies that are free floating bind to the antigen on the surface of a pathogen and then bind to the phagocyte via the phagocytes receptor. they are then ingested etc

Reply 306

Deziah

15

Original post by rival_

Guys how do mosquito's get infected with malaria? Or are they resistant to the parasite(plasmodium)?

Original post by rival_

Guys how do mosquito's get infected with malaria? Or are they resistant to the parasite(plasmodium)?

I learnt it like;
Mosquito will take the parasite's (plasmodium falciparum) gametes when it feeds on an infected person.
Games will fuse in the mosqutio's stomach, forming zygotes.
Infective stages will form.
Infective stages will move to the mosquito's salivary glands.
When the mosquito feeds on somebody uninfected, they will inject the infective stages into the person's blood.
The infective stages will move into the liver cells to replicate, and into the red blood cells to form gametes.

I found it really confusing because the text book described it different to my teacher, and other revision guides described it different to the mark scheme. I didn't understand what I actually needed to know so just learnt all this. D;

Reply 307

wndms

1

How does Tar increases diffusion distances for o2 entering the blood? Help please

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Reply 308

phaseshift

12

Original post by wndms

How does Tar increases diffusion distances for o2 entering the blood? Help please

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Tar coats the alveoli, thereby increasing the distance O2 is required to diffuse across.

Reply 309

imconfused

10

I was looking for past papers older than june 2009 for f212, however couldn't find any? r there any other pp apart e.g. 2008/2007...?
PLEASE HELP :smile:

Reply 310

medicinemedicinemedicine1996

7

Original post by Liamnut

Do you know how proteins are produced?

To say it briefly, a specific part of the DNA (a gene) comes apart, there are two strands, the coding strand and the template strand, free nucelotides (with ribose sugas) bind to their complementary bases on the template strand, the mRNA then pills away and because of the base pairing rules, the mRNA will be identical to the coding strand, except where there is a T on the coding strand, there will be a U on the mRNA. The mRNA then leaves the nucleus through a nuclear pore and goes to a ribosome, either in the rough ER or in the cyctoplasm, the mRNA moves through the ribosome and as it's doing this, tRNA molecules bring the correct amino acid triplets to the ribosome (depending on the base the mRNA has), as the mRNA moves through the ribosome, more amino acid triplets get brought to the ribosome by tRNA molecules until the whole protein is assembled.

ps. It's hard to give an abstract definition of tRNA so I thought I'd just outline it's role in protein synthesis to give you a better understanding.

Alright thank you, it's better to contextualise its role anyway :smile:

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Reply 311

Joe4567

Could some one explain domain and kingdom classification systems, exam style if possible please?

Reply 312

Liamnut

13

Original post by Joe4567

Could some one explain domain and kingdom classification systems, exam style if possible please?

They are part of he same classification system. They're both different taxonomic groups. There are 3 different domains and 5 different kingdoms. If you read earlier in the thread I explain this in more detail. It can also be found in the textbook.

Reply 313

wndms

1

What are the differences between platlets, blood clot and thrombus? So confoozle

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Reply 314

Liamnut

13

Original post by t()m

Thanks I remember now I was making a silly mistake, cheers.

Do we have to remember the formula?

Reply 315

NielsBohrsDad

Guys ive done a few past papers. I use the cgp revision guide and the ocr book. I really need an a but i seem to find no link to what ive learnt from either of my books in most of these questions. How would i best be able to tackle the questions and prepare for the exam itself??

In particular the questions usually asking to suggest.

Also does anybody have any heavy mark exam style questions made with answers preferably so i could practice?!!

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Reply 316

Unsworth

14

Kinky People Can Often Find Great Sex - Kingdom, Phylum, Class, Order, Family, Genus, Species.

Reply 317

Joe4567

Original post by Liamnut

They are part of he same classification system. They're both different taxonomic groups. There are 3 different domains and 5 different kingdoms. If you read earlier in the thread I explain this in more detail. It can also be found in the textbook.