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

I don't understand how people can come on here saying they are 100% of the answer. I believe this was a suggest question, was it not? Either way, there is often more than 2 points that are valid for a 2 mark question.

I haven't googled the water bear so perhaps you know more about this than me, and having looked around it seems the microscope - in its early stages - has been around since 1595, not to mention the fact the Romans used glass in experiments. That said, unless you are near certain and have some proof to back your case up, I wouldn't scare people so much by saying their answer is 100% wrong.

What did people write for the question to do with ethanol and toxins?

I am no examiner and I may be completely wrong but I think you've just completely misquoted what the question asked. It said explain how pathogens are destroyed after the pathogen binds with the receptor on the phagocyte.

Nowhere was antigen stated. Antigens are presented AFTER the pathogen is destroyed.

That said, you may well be right in saying that cytotoxic T cells secret hydrogen peroxide and possibly antibodies clumping pathogens together for phagocytosis.

But I based my response on the phagocyte's mode of action, I think there is enough you can say there to get the six marks (plus the one mark for the correct sequencing).

1. Pathogen is engulfed by folding of the membrane made possible by the phagocyte's extensive cytoskeleton - endocytosis/phagocytosis.
2. Pathogen held in a vesicle named a phagosome.
3. Lysosomes fuse with phagosome.
4. Secrete digestive enzymes e.g lysins onto pathogen
5. Pathogen is digested
6. Antigen presented on plasma membrane
7. Sequencing of marks 1-6

Of course I may be wrong and I believe it may have been referring to cytotoxic cells and antibodies as well, but I think you can get at least the majority of the marks by describing phagocytosis correctly.

I don't understand how people can come on here saying they are 100% of the answer. I believe this was a suggest question, was it not? Either way, there is often more than 2 points that are valid for a 2 mark question.

I haven't googled the water bear so perhaps you know more about this than me, and having looked around it seems the microscope - in its early stages - has been around since 1595, not to mention the fact the Romans used glass in experiments. That said, unless you are near certain and have some proof to back your case up, I wouldn't scare people so much by saying their answer is 100% wrong.

i did R1 as the same...R2 one the same and second band higher

for valid i wrote-same suger concentration,same number of spins and rate and volume of dna the same

I wrote all that but though it was too short and began to talk about b-cells and antibodies, would I loose marks for including the second bit

It said it was a vertebrate so it is animal

What were the 3 reasons for low income groups being more likely to get TB?

Macrophages dont as far as Im aware. It's the infected cells.

What were the 3 reasons for low income groups being more likely to get TB?

For the phagocytosis question, I wrote about how the phagocyte engulfs the pathogen via endocytosis, this forms a phagosyme inside the cell, lysosomes fuse with the phagosyme, digesting enzymes are released into the vesicles containing the pathogen and they break down the pathogen into harmless substances. But people have out stuff about lymphocytes so maybe I've missed something or read the question wrong. :\

The question about why complementary based pairing is important was hard, asexual selective reproduction was just a myth lol

What were the 3 reasons for low income groups being more likely to get TB?

What were the 3 reasons for low income groups being more likely to get TB?

What were the 3 reasons for low income groups being more likely to get TB?

What were the 3 reasons for low income groups being more likely to get TB?