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OCR AS Biology (New Spec) F212: Molecules, Biodiversity, Food and Health

skatealexia

I believe the primary defences are classed as the skin as a barrier, or for example the goblet and cilliated epithelium cells in the trachea... so not sure what you mean there. The other I need to look up.

I understand the primary defense mechanism.
Another question if the release of antibody is secondary defence and non-specific why is it released when the immune response is activated
when macrophages release monokines they stimulate B-cells to differentiate and release antibodies. So that means the release of antibody must be non-specific response and specific response?

Reply 41

nofishing

8

Remarqable M

Can someone please state the steps of sequence in immune response when the pathogen gets past the primary defense?
Is the production of antibodies after the release of T-cells and B-cells or before?
the order of immune response is bit wobbly in the book(OCR).
Edit/Delete Message

As far as I've been taught, Helper T cells release interleukins which stimulate B cells which then reproduce into either plasma cells or memory cells. The plasma cells then make antibodies.

Reply 42

Remarqable M

15

I think I understand it now. I got confused with the term non-specific response and specific response.

Reply 43

Remarqable M

15

I have been revisin today health and disease - I thin this might come 'improving food production', 'microorganisms and food' and 'immunity'. you can use past papers on health and disease from the old spec by going to the paper bank.

Reply 44

Mattjames

can anyone link to the specimen paper? i couldnt find it anywhere :smile:

Reply 45

JackPearson

9

Mattjames

can anyone link to the specimen paper? i couldnt find it anywhere :smile:

http://www.ocr.org.uk/Data/publications/assessment_materials/AS_Level_Biology_SAM_All_units.zip

Reply 46

aimz08

13

Does the CGP revision guide have the 'maintaining biodiversity' part of the syllabus?

Reply 47

skatealexia

14

Here's my evolution, biodiversity, and classification notes if anyone wants them :smile:

.

Evolution (1)..doc241.2KB

Reply 48

Remarqable M

15

what does this mean?

outline the roles of DNA and RNA in living organisms (the concept of protein synthesis must be considered in outline only).

Do we have to know protein synthesis in detail?

Reply 49

BHAM!

Remarqable M

what does this mean?

outline the roles of DNA and RNA in living organisms (the concept of protein synthesis must be considered in outline only).

Do we have to know protein synthesis in detail?

Im not sure this always bugs me because some text books go into more detail than others so i become confused on how much i actually need to know.

Reply 50

sanamalik1992

7

Remarqable M

what does this mean?

outline the roles of DNA and RNA in living organisms (the concept of protein synthesis must be considered in outline only).

Do we have to know protein synthesis in detail?

Well, as it states outline only... I have revised only an outline on protein synthesis, just the basic stages:

Protein synthesis:

1) H-bonds split double helix
2) mRNA is formed
3) mRNA leaves nucleus through nuclear pore
4) mRNA attaches to a ribosome
5) tRNA brings amino acids to ribosome in correct order
6) Amino acids join together by peptide bonds
7) Protein is formed.

Reply 51

aimz08

13

Anyone using CGP :s-smilie:

?

Reply 52

NCIShippo

OP

1

aimz08

Anyone using CGP :s-smilie:

?

Not for Biology - I did for physics - was very useful!

Reply 53

sanamalik1992

7

Diet and Food production

Balanced diet - one that contains all the nutrients required for health in appropriate proportions.
Malnutrition - caused by an unbalanced diet.
E.g Obesity - caused by consuming too much energy.
- excess energy is deposited as fat in the adipose tissues.

CHD - coronary heart disease.
- result of deposition of fatty substances in the walls of the arteries by atherosclerosis.
- deposition >> narrows size of lumen >> restricts blood flow to the heart muscles >> causing oxygen starvation.

Increased risk of CHD:
- Salt - excess salt decreases the water potential of the blood, so more water is held within the blood >> high blood pressure.
- Fat - saturated fats are more harmful than unsaturated ones.
- Cholesterol - made up of saturated fats.

HDL's - High density lipoproteins.
- made up of proteins, lipids and unsaturated fats.
- carry cholesterol from body tissues back to the liver.
- reduce blood cholesterol level, reduce deposition of fatty substances.

LDL's - Low density lipoproteins.
- made up of proteins, lipids and saturated fats.
- carry cholesterol from the liver to the body tissues
- high concentration of LDL's - caused deposition of fatty substances in the walls of the arteries by atherosclerosis.

Plants as food

Humans rely on plants for food, basis of all food chains.
Get nutrition directly from plants and indirectly from animals.

Selective breeding

Plants/Animals:

1) Select plants/animals with characteristics you want.
2) Breed them together
3) Select offspring with best characteristics and breed them together.
4) Continue for many generations for desired traits.

>> Increases productivity of animals
>> Produces plants with a high crop yield.

Disease/Pest resistant:
1) Plants with high level of resistance are bred together
2) Offspring with most resistance are bred together
3) Continue for many generation until you get a plant that is disease/pest resistant.

Fertilisers:
- Increase crop yield by providing minerals
- Replace minerals in soil
- Increase rate of growth and overall size of crops.

Pesticides - kill organisms that causes diseases in crops
>> fewer plants damaged/destroyed.

Antibiotics - to treat infected animals >> reduces spread of disease.
>> increases food production.

Using microorganisms to make food for human consumption:

+ Production of protein is faster
No animal fat/ cholesterol
No animal welfare issues

- Protein need to be isolated
Protein has to be purified to ensure it is uncontaminated
Might not want to eat fungal protein.

Preventing food spoilage by microorganisms:

- Cooking
- Pasteurising
- Freezing
- Irradiation
- Salting, adding sugar.

Reply 54

Scherzando225

9

aimz08

Anyone using CGP :s-smilie:

?

yeah! it's the best :yep:

Reply 55

Remarqable M

15

writin the notes on my lg 501 :smile:

not wastin papers.

Reply 56

definite_maybe

4

I'm doing this exam too, and am stuck on immune systems. I don't understand the role of phagocytes. On one hand they engulf and digest pathogens, with macrophages displaying antigens. They don't require receptors complementary to antibodies for this do they? The macrophages present antigens and antibodies are created, and attach to the antigens. Do these antibodies then connect to receptors on the phagocytes, in order to engulf the pathogen and why are they needed? Can phagocytosis take place without antibodies?

Sorry for the long question. I'm just finding the immune system difficult. Does anybody have a good website or summary for the immune response?

Reply 57

Remarqable M

15

definite_maybe

I'm doing this exam too, and am stuck on immune systems. I don't understand the role of phagocytes. On one hand they engulf and digest pathogens, with macrophages displaying antigens. They don't require receptors complementary to antibodies for this do they? The macrophages present antigens and antibodies are created, and attach to the antigens. Do these antibodies then connect to receptors on the phagocytes, in order to engulf the pathogen and why are they needed? Can phagocytosis take place without antibodies?

Sorry for the long question. I'm just finding the immune system difficult. Does anybody have a good website or summary for the immune response?

Im also confused on this topic so bear with me - phagocytes come into action after the primary defence fails, so the secondary defence is series of attacks that includes phygocytes(2 types) and antibodies - these attacks trigger an immune response where T-cells(2 type) and B-cells are activated. B-cells uses a long range atttacks while T-cells uses short range attacks. T-helper cells originate from the thymus gland they release interleukins to activate B-cells where colonal expansion happens(reproduction )
some b-cell differentiate to make plasma cells(cell surface membrane) where the manufacture of antibodies occurs. the other b-cell differentiate to make B-memory cells(u can think of this as keepin info on the pathogen incase it re-attacks so that immune response is quicker) these circulate in the body.

I don't know if T-helper and T-killer do their job simulataneosly so maybe someone can help us :confused:

Reply 58

nofishing

8

Remarqable M

T-helper cells originate from the bone marrow they release interleukins to activate B-cells where colonal expansion happens(reproduction )

T Cells originate from the Thymus gland.
B Cells originate from the bone marrow.
Not being a know it all but just thought I'd correct you in case it comes up in a question! :wink:

Reply 59

Remarqable M

15

nofishing

T Cells originate from the Thymus gland.
B Cells originate from the bone marrow.
Not being a know it all but just thought I'd correct you in case it comes up in a question! :wink:

thnx, like I said I'm not that solid on immunity. I read on wikipedia that all t-cells originate from hematopoietic stem cells in the bone marrow. Maybe
someone can clarify if what I wrote above is correct?

OCR AS Biology (New Spec) F212: Molecules, Biodiversity, Food and Health

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