AS Biology f212 26th May 2011

June 2009: markscheme answer for B LYMPHOCYTE - 7 marks

- HUMORAL response
- b cell has antigen receptor (antibody) on its surface
- specific to only ONE ANTIGEN

- CLONAL SELECTION of appropriate b cell
by macrophages / T helper cells / cytokines / interleukins (by the way-- what is the difference between cytokines and interleukins?

-CLONAL EXPANSION - selected cell divides by mitosis

-specialise/differentiate into plasma cells (produce antibodies which are specific to ANTIGEN) and memrory cells (long lived / remain in body circulation / provide immunological memory / provides secondary response to subsequent exposure of same antigen)

Reply 582

ok does any1 have the past paper for jan 2011 or does anyone know what page of this thread is the link to it on?

Reply 583

Original post by broken_glass_heart

Disease can be caused by INFECTION with PATHOGENS or PARASITES.

PATHOGEN = AN ORGANISM THAT CAN CAUSE DAMAGE TO THE ORGANISM IT INFECTS (THE HOST)

PARASITE = AN ORGANISM THAT LIVES ON OR IN ANOTHER ORGANISM (THE HOST) AND CAUSES DAMAGE TO THE ORGANISM

So basically- pathogen causes damage to host ...... and parasite is a pathogen that lives in the host??

Reply 584

EternalDoom

15

How do bacteria lead to food spoilage? - 3 marks

Reply 585

INFECTIOUS DISEASE ARE DISEASES THAT CAN BE PASSED BETWEEN INDIVIDUALS, E.g. malaria, HIV and TB

Reply 586

mRNA function (2 marks)
Carries GENETIC info out of nucleus
Transfers it to the ribosome (site of translation)
For protein synthesis

(it says 'ignore transcription')

Reply 587

EternalDoom

15

Original post by giraffegiraffe

mRNA function (2 marks)
Carries GENETIC info out of nucleus
Transfers it to the ribosome (site of translation)
For protein synthesis

(it says 'ignore transcription')

What are transcription and translation? Could you explain them briefly?

Reply 588

MALARIA IS CAUSED BY PARASITE PLASMODIUM

PLASMODIUM IS A EUKARYOTIC, SINGLE-CELLED PARASITE
TRANSMITTED BY MOSQUITOS (FEED ON BLOOD)
MOSQUITOS ARE VECTORS (DONT CAUSE DISEASE, JUST SPREAD IT).
Mosquitos spread the infection by transferring the parasite from one host to another

Reply 589

Why are there different malarial vaccines

-different strains of Plasmodium
-different antigens
Due to mutation/variation

-more than 1 stage in the life cycle (within human)and different stages have different antigens

-need different vaccine for each strain/stage

Reply 590

lilpg

Original post by EternalDoom

How do bacteria lead to food spoilage? - 3 marks

dou have to know this

not specified on the spec ..??

Reply 591

PLASMODIUM infects the LIVER, RBC'S and DISRUPTS BLOOD SUPPLY to vital organs.

Reply 592

Original post by broken_glass_heart

MOSQUITOS ARE VECTORS (DONT CAUSE DISEASE, JUST SPREAD IT).
Mosquitos spread the infection by transferring the parasite from one host to another

yup dont forget to say female anopheles

Reply 593

amina khan

7

Original post by giraffegiraffe

June 2009: markscheme answer for B LYMPHOCYTE - 7 marks

- HUMORAL response
- b cell has antigen receptor (antibody) on its surface
- specific to only ONE ANTIGEN

- CLONAL SELECTION of appropriate b cell
by macrophages / T helper cells / cytokines / interleukins (by the way-- what is the difference between cytokines and interleukins?

-CLONAL EXPANSION - selected cell divides by mitosis

-specialise/differentiate into plasma cells (produce antibodies which are specific to ANTIGEN) and memrory cells (long lived / remain in body circulation / provide immunological memory / provides secondary response to subsequent exposure of same antigen)

Interleukins are a type of cytokine, so there isn't a difference i don't think. just doubled checked it in my textbook and thats all it said. :smile:

Reply 594

EternalDoom

15

Original post by lilpg

dou have to know this

not specified on the spec ..??

it came up on a past paper but can't find it :s

They secrete enzymes and toxins, changes appearance of food, cant remember 3rd point

Reply 595

H.I.V infects human WBC's
HIV can only reproduce INSIDE CELLS of the infected organism (due to lack of equipment such as enzymes to replicate on its own)
After reproducing in cells, it KILLS WBC's & leaves.
This leads to AIDS

AIDS - ACQUIRED IMMUNE DEFICIENCY SYNDROME.
AIDS = Immune system deteriorates and then fails due to loss of WBC's
Sufferer is more vulnerable to other infections

Reply 596

ibysaiyan

16

i am back open to questions =]

Reply 597