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

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Reply 820

kited4

I'll be having words with my teacher for teaching me stuff i dont need to know :wink:

sorry guys!

Reply 821

nevarsan

What are the reasons for maintaining biodiversity? I know that its economical, ethical and ecological reasons but I don't know how to explain them.

Reply 822

TheSnail

Original post by nevarsan

What are the reasons for maintaining biodiversity? I know that its economical, ethical and ecological reasons but I don't know how to explain them.

Economic -
- growth of timber, food and fuel
- source of new medicinces
- ecotourism

Ecological -
- regulation of atmosphere and climate
- purification and retention of fresh water
- formation of fertilised soil
- Detoxification and recylcing of waste
- crop pollination

Ethical -
- all living organisms have the right to survive and live in the way in which they have become adapted. The loss of habitats and biodiversity can prevent many organisms from living where they should.

Aesthetic -
- Studies have shown that patients recover more rapidly from stress and injury when they are exposed to pleasing natural environmental conditions

:smile:

Reply 823

Gotzz

Original post by nevarsan

What are the reasons for maintaining biodiversity? I know that its economical, ethical and ecological reasons but I don't know how to explain them.

Just things like, every living thing has a right to exist, aesthetically pleasing, allows for scientific research, etc.

Reply 824

nevarsan

Original post by g.k.galloway

Thank you

Reply 825

HeyMickey6

What you you put for this question..... I feel it's going to major as it hasn't come up yet :smile:

Discuss the global impact malaria, AIDS/HIV and TB

Reply 826

jadec123

I'm so annoyed- our teacher spent the last 3 lessons going over monoclonal antibodies. IT'S NO WHERE TO BE SEEN ON THE SPECIFICATION OR IN THE TEXT BOOKS :frown:

. We haven't had a stable teacher for the past year either so we basically had to teach ourselves quite a lot of the course while we had supply teachers -_- anyway, good luck for tomorrow everyone. :smile:

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Reply 827

cookiess

Original post by wndms

"Explain how biodiversity may be considered at different levels:habitat, species and genetic"
This is what it says inthe specification, can anybody help me what we are supposed to say? :/

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-variation between species
-genetic variation within species
-different habitat of species

Reply 828

cookiess

Original post by HeyMickey6

What you you put for this question..... I feel it's going to major as it hasn't come up yet :smile:

Discuss the global impact malaria, AIDS/HIV and TB

erm...we don't need to know the global impact unless they give us figures haha...or it's like worth 2 marks and is a suggest question

Reply 829

Simran6275

so what does everyone think will come up for definite tomorrow?

Reply 830

Grammar Kid

Im really sorry if its already answed but im on my phone and i cant search properly but... Im really struggling with the immune responce...

How are phagocytes linked in to the responce?? Abd if anyone would be willing to write out a bullet point list of the immune reponce and whst happends step by step thst would be brilliant!!

Reply 831

cookiess

Original post by nevarsan

What are the reasons for maintaining biodiversity? I know that its economical, ethical and ecological reasons but I don't know how to explain them.

Ecnomical and ecological:
-used for food e.g. animals and plants so we need to maintain biodiversity
-if we chop down trees, reduce Co2 absorbed from atmosphere...e.g. global climate change
-reduction in worms, therefore reduce soil quality and affect crop yield and plants are the basis of in all food chains

ethical:
-belief that human activities shouldn't result in extinction or cause a species to cease to exist
-habitats and huge biodiversity are aesthetically pleasing

Reply 832

wndms

"Explain the relationship between classification and taxonomy"

"Explain the relationship between classification and phylogeny"

Can someone explain this please? I just don't get the actual difference.. although I know their definitions are different.

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Reply 833

Prees

How long do you think it's going to be before there's an abundance of people who haven't done any revision asking for help?

Reply 834

MrMeep2580

Original post by Grammar Kid

Phagocytes engulf pathogens via phagocytosis. They then digest the nutrients and become antigen-presenting cells. in which they present the antigen of that specific pathogen on their cell surface membrane. This then stimulates an immune response.

Immune Response

Antigen presenting cells.
Selection of the correct T lymphocyte. (clonal selection)
Specific to that antigen. (complimentary)
Clonal expansion of that T lymphocyte. (mitosis)
then T lymphocyte differentiates into 3 types of T lymphocytes. (T Killer, T helper, T memory)

T Helper stimulates B lymphocytes via cytokines.
T killer engulfes and destroyes infected cells
T Memory provides immune memory of that specific antigen.

B lymphocytes differentiate to Plasma cells and B memory cells.

Plasma cells produce antibodies to neutralise and aggulinate the antigens.

Reply 835

Fattydelty

Original post by wndms

Can someone distinguish between herd vaccination and ring vaccination? They sounds the same where they just vaccinate a population :colondollar:

help!

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Sure. Ring vaccination is vaccinating every body in a particular area after an outbreak of a disease to prevent it spreading outside this area (like they did inWales with measles earlier this year). Herd vaccination is vaccinating every one (especially the vulnerable) in the country to prevent against spread (like they do with the flu every winter).

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Reply 836

Grammar Kid

Original post by MrMeep2580

words cannot discribe how usefull that is :smile:

thank you!!!

Reply 837

cookiess

Original post by Grammar Kid

Immune response via phagocytes

Phagocytes take two forms. Neutrophils and macrophages
-When a pathogen enters the body, the pathogen is carrying an antigen on the surface of its plasma membrane which acts as a signal ''I am foreign''. This initiates the immune response and antibodies start to be produced.
-antibodies are complementary to the antigen and bind to the antigen. Phagocyte receptors are complementary to the antibodies and are attached to the antibodies.
-Phagocytes then curve inwards and surround the antigen and the antigen is now inside the vacuole of the phagocyte known as the phagosome.
-lysosomes fuse with the phagosome and secrets lysins which digest the pathogen into harmless nutrients which can be absorbed into the cytoplasm of the phagosome
Neutrophils are short lived and die after digesting a few pathogens
Macrophages:
-these are found in the lymphatic system. Infected cells release a chemical called histamine. This makes the capillaries leaky so that tissue fluid flows into the lymphatic system directly to the macrophages in lymph nodes to deal with the pathogen. The macrophages don't deal with the pathogen directly. They form an antigen presenting cell which stimulate the activation of lymphocytes- it speeds up clonal selection.