A level Biology: Post your doubts here!

[geek101]

Can someone please explain the full process of an immune response? as in the order of how everything happens and which cells reach the pathogen first?

Primary response
1) the pathogen invades the body
2) it damages or weakens body cells
3) the weakened body cells produce proteins called histamines
4) the phagocytes in the blood are attracted to these proteins...(chemotaxis)
5) the phagocytes (macrophages) engulf the pathogen by phagocytosis and display the non self antigens on its surface
6) the T helper cells with the complementary receptors goes and recognizes the antigens of the pathogen, and secretes chemicals which cause the bone marrow to form T Killer cells, and secretes cytokines (hormone-like)
7) B lymphocytes with the complementary surface receptors are activated due to these cytokines and divide by mitosis to produce B-memory cells and Plasma cells.
8) The B memory cells further divide to produce more memory cells and plasma cells.
9) the plasma cells release anitbodies with the variable region (antigen binding site) complementary to the antigens of the pathogen. These antibodies destroy the pathogens.
10) The T killer cells (cytotoxic T cells) with the specific complementary receptors release chemicals such as hydrogen peroxide or punch holes in the infected body cells to remove and kill any remaining weakened body cells, and the remaining debris.
11) The memory B and memory T cells remain circulating in the blood.
Secondary response:
The memory cells which are in the blood on the encounter of the pathogen with the antigens complementary to their receptors, divide rapidly producing plasma cells which secrete antibodies (more than the primary response) and the pathogens are destroyed in a short time.

Correct me if im wrong

 

[rogue94]

so are epithelium and endothelium the same? what are the difference?

Epithelia line the outside of the body, since alveolar walls are in contact with air so its epithelium. Endothelia line the inside of the body such as blood vessels. Sometimes endothelium is referred to as a type of epithelium. However, you must not use these terms interchangeably in your exam, because it may be penalised.
This difference is also in transport in plants: endothelium (in root, with Casparian strip) and epithelium (out of which root hairs extend).

 

[eyamwir]

Epithelia line the outside of the body, since alveolar walls are in contact with air so its epithelium. Endothelia line the inside of the body such as blood vessels. Sometimes endothelium is referred to as a type of epithelium. However, you must not use these terms interchangeably in your exam, because it may be penalised.
This difference is also in transport in plants: endothelium (in root, with Casparian strip) and epithelium (out of which root hairs extend).

OHHH! NOW I GET IT thanks a lot! :')

 

[geek101]

what do we have to learn about the xylem vessels?? and can anyone explain the loading and unloading of sucrose including the roles of companion cell n sieve tube in detail??? reaaly need ur help on this thanksss

this is posted by a member on the previous few pages you can see it there...good luck!

 

[Soldier313]

Primary response
1) the pathogen invades the body
2) it damages or weakens body cells
3) the weakened body cells produce proteins called histamines
4) the phagocytes in the blood are attracted to these proteins...(chemotaxis)
5) the phagocytes (macrophages) engulf the pathogen by phagocytosis and display the non self antigens on its surface
6) the T helper cells with the complementary receptors goes and recognizes the antigens of the pathogen, and divides to form T memory cells and T helper cells that produce cytokines (hormone-like)
7) B lymphocytes with the complementary surface receptors are activated due to these cytokines and divide by mitosis to produce B-memory cells and Plasma cells.
8) The B memory cells further divide to produce more memory cells and plasma cells.
9) the plasma cells release anitbodies with the variable region (antigen binding site) complementary to the antigens of the pathogen. These antibodies destroy the pathogens.
10) The T killer cells (cytotoxic T cells) with the specific complementary receptors release chemicals such as hydrogen peroxide or punch holes in the infected body cells to remove and kill any remaining weakened body cells, and the remaining debris.
11) The memory B and memory T cells remain circulating in the blood.
Secondary response:
The memory cells which are in the blood on the encounter of the pathogen with the antigens complementary to their receptors, divide rapidly producing plasma cells which secrete antibodies (more than the primary response) and the pathogens are destroyed in a short time.

Correct me if im wrong

is it T memory cells or did you mean T-killer cells??

 

[rogue94]

what does carcinogen do?

It causes cancer, by switching off the tumor supressor genes and activating proto-oncogenes to form oncogenes (genes that have the potential to cause cancer). This activation is as a result of mutation/change in DNA/damage to DNA. Also, apoptosis (programmed cell death) is inhibited. As a result, uncontrolled cell division/growth occurs to form an irregular mass of cells, which is known as a tumourous growth. The tumor may be malignant (can spread to other organs/tissues). An example of carcinogens is benzpyrene. Sometimes tar is referred to as carcinogenic, which means that it contains carcinogens.

 

[shan5674]

An opsonin is any molecule that targets an antigen for an immune response. However, the term is usually used in reference to molecules that act as a binding enhancer for the process of phagocytosis, especially antibodies, which coat the negatively-charged molecules on the membrane.
which pastpaper did you see this in ?

W09-P22 are we meant to know all of that?

 

[geek101]

is it T memory cells or did you mean T-killer cells??

my bad...ur right, T killer cells. thank you.

 

[Amaryllis]

what do we have to learn about the xylem vessels?? and can anyone explain the loading and unloading of sucrose including the roles of companion cell n sieve tube in detail??? reaaly need ur help on this thanksss

for loading of sucrose:
- the hydrogen ions in the companion cell are pumped outusin ATP as source of energy
-this create a high level of H+ ions outside companion so move back down their conc. gradient with sucrose molecules from mesophyll cells through co-transporter(against conc. gradient of sucrose)
- sucrose molecules move from companion cells into the sieve tube through plasmodesmata

 

[Peter Check]

CAN ANYONE SHOW ME THE VARIOUS POINTS THROUGH A CARDIAC CYCLE(like which valve closes where) IN A GRAPHICAL REPRESENTATION OF THE CARDIAC CYCLE(like the on i uploaded)

 

[raamish]

http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w10_qp_21.pdf

5c) shouldnt the third answer be j?

 

[Peter Check]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_21.pdf

5c) shouldnt the third answer be j?

yes, I think I solved this once, it was j

 

[Almostdoctor]

What's bulk transport?

 

[geek101]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_21.pdf

5c) shouldnt the third answer be j?

i dont think so, J is the nucleolus, this is where the ribosomes are manufactured. while transcription is the formation of the mRNA molecule..this takes place in the nucleoplasm (nucleus) >> H.

 

[Almostdoctor]

What's bulk transport?

Ok nvm got it...it's got to do with endo/exocytosis

 

[KurayamiKimmi]

W09-P22 are we meant to know all of that?

well i dont think so -i think it's enough to knowantigen-antibody- neutrophils -macrophages-B and T lymphocytes and their actions

 

[soccerprinc3]

Primary response
1) the pathogen invades the body
2) it damages or weakens body cells
3) the weakened body cells produce proteins called histamines
4) the phagocytes in the blood are attracted to these proteins...(chemotaxis)
5) the phagocytes (macrophages) engulf the pathogen by phagocytosis and display the non self antigens on its surface
6) the T helper cells with the complementary receptors goes and recognizes the antigens of the pathogen, and secretes chemicals which cause the bone marrow to form T Killer cells, and secretes cytokines (hormone-like)
7) B lymphocytes with the complementary surface receptors are activated due to these cytokines and divide by mitosis to produce B-memory cells and Plasma cells.
8) The B memory cells further divide to produce more memory cells and plasma cells.
9) the plasma cells release anitbodies with the variable region (antigen binding site) complementary to the antigens of the pathogen. These antibodies destroy the pathogens.
10) The T killer cells (cytotoxic T cells) with the specific complementary receptors release chemicals such as hydrogen peroxide or punch holes in the infected body cells to remove and kill any remaining weakened body cells, and the remaining debris.
11) The memory B and memory T cells remain circulating in the blood.
Secondary response:
The memory cells which are in the blood on the encounter of the pathogen with the antigens complementary to their receptors, divide rapidly producing plasma cells which secrete antibodies (more than the primary response) and the pathogens are destroyed in a short time.

Correct me if im wrong

thanks alot!! i've been having trouble with that for quite some days xD

 

[soccerprinc3]

CAN ANYONE SHOW ME THE VARIOUS POINTS THROUGH A CARDIAC CYCLE(like which valve closes where) IN A GRAPHICAL REPRESENTATION OF THE CARDIAC CYCLE(like the on i uploaded)View attachment 11313

i hope this diagram helps...there's alot of irrelevant data on it but just look at the stuff thats on our syllabus

 

[raamish]

How are liver and rbcs connected in the division of the maralial parasites in the body of humans???

 

[shan5674]

well i dont think so -i think it's enough to knowantigen-antibody- neutrophils -macrophages-B and T lymphocytes and their actions

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w09_qp_22.pdf

then could you explain to me how to answer Q1 - b? and C too please