VCE Biology Question Thread

[vaish_vj]

I wouldn't say it's incorrect, as the presence of memory cells does indeed produce a faster and greater response (through the production of a faster and greater amount of antibodies, if we're talking about B cells). However, perhaps the answer they are looking for is the 'actual' function of a memory cell which is to retain immunological memory of a specific antigen.

thankyouuu 

[biy]

Whats the difference between pathogens, antigens and antibodies? Thanks

[grannysmith]

Whats the difference between pathogens, antigens and antibodies? Thanks

Pathogens are disease-causing agents. They have antigens on them which immune cells detect. Antigens are foreign bodies which cause the production of antibodies by B plasma cells. Antibodies are antigen-specific proteins which attach to said antigens. In turn, the pathogen is either neutralised (covered in antibodies so they are made redundant) or agglutinated (basically stuck together with other pathogens which halts their movement and function) and they are more easily detected by phagocytes to be phagocytosed.

[biy]

Thanks grannysmith.
More questions:

What is the difference between the first line and second line defence? Is it right to say that the major difference is that the first line defence are body surface barriers such as skin, mucus, cillia etc.. Whereas second line defence mechanisms are internal barriers?

Also i know how the first line can be non-specific, as it acts as a barrier for all types of pathogens. But how exactly is the second line of defence non-specific? Also what types of leucocytes are involved?

Where are blood cells made? Is it true that all blood cells are produced from the stem cells in the bone marrow, then T cells move to the thymus to mature and develop? Whereas the B cells remain in the bone marrow to mature?

What do B lymphocytes and T lymphocytes do?

Are monocytes just immature macrophages? If so, is there any role that monocytes play before maturing into macrophages?

What does it mean the neutrophils, eosophils and basophils are granulocytes? What does the term granulated mean, is it just that they release digestive enzymes that destroy pathogens?

Do B lymphocytes produce antibodies or do plasma B cells produce them?

Do all pathogens contain antigenic markers on their surface? Even viruses?

What does the lymph nodes actually do? I read that they are second line defence tissues/organs that have mucus on them that trap and filter foreign pathogens?

Does the spleen produce antibodies? If so, as above stated do the plasma B cells play a role in this too, are they located in the spleen?

Sorry for the influx of questions guys, I haven't done the immune system before so most of this stuff is new to me and my teacher gets frustrated when I ask her these 'basic' questions... I hope AN community doesn't mind <3

[BakedDwarf]

Which companies produce the best biology practice exams (let's say, top 3)? This is because I want to do some unit 3 practice exams soon.

[grannysmith]

Thanks grannysmith.
More questions:

What is the difference between the first line and second line defence? Is it right to say that the major difference is that the first line defence are body surface barriers such as skin, mucus, cillia etc.. Whereas second line defence mechanisms are internal barriers?
Yep

Also i know how the first line can be non-specific, as it acts as a barrier for all types of pathogens. But how exactly is the second line of defence non-specific? Also what types of leucocytes are involved?
The leucocytes involved don't have receptors to specific antigens - that is, the same response is made for all types of antigens. Also, things like complement proteins don't target specific antigens - they act generally. The leucocytes involved include neutrophils, macrophages, dendritic cells, natural killer cells (and eosinophils/basophils but you don't need to know these).

Where are blood cells made? Is it true that all blood cells are produced from the stem cells in the bone marrow, then T cells move to the thymus to mature and develop? Whereas the B cells remain in the bone marrow to mature?
Yep

What do B lymphocytes and T lymphocytes do?
They provide specific responses to specific antigens. They're like your tailor-made, special unit commandos.

Are monocytes just immature macrophages? If so, is there any role that monocytes play before maturing into macrophages?
Don't need to know this, but yes. They probably have other functions but definitely not required knowledge.


What does it mean the neutrophils, eosophils and basophils are granulocytes? What does the term granulated mean, is it just that they release digestive enzymes that destroy pathogens?
It just means they have these granules in their cytoplasm. If you look at them under a microscope or something you'd probably be able to see them.

Do B lymphocytes produce antibodies or do plasma B cells produce them?
The naive B cell differentiates into plasma cells and memory cells. The B plasma cells are what produce the antibodies.

Do all pathogens contain antigenic markers on their surface? Even viruses?
They would, although same sneaky pathogens may change continually change their surface antigens to avoid detection by the immune system (pretty sure the HIV virus does this).

What does the lymph nodes actually do? I read that they are second line defence tissues/organs that have mucus on them that trap and filter foreign pathogens?
They contain an abundance of lymphocytes which filter the lymph fluid. Yep.

Does the spleen produce antibodies? If so, as above stated do the plasma B cells play a role in this too, are they located in the spleen?
No, the spleen is a primary lymphoid organ which store lymphocytes and filters blood.

Sorry for the influx of questions guys, I haven't done the immune system before so most of this stuff is new to me and my teacher gets frustrated when I ask her these 'basic' questions... I hope AN community doesn't mind <3

[biy]

Thanks grannysmith, your assistance is greatly appreciated. I mean it

Regarding the B lymphocytes, does a B cell differentiate into plasma B cells and B memory cells? When does it do this and why? Does it differentiate when a helper T cell binds to the B cell, as it gives it the basic shape of the antigen?

Also with dendritic cells, do they actually engulf pathogens, degrade them and present parts of them on their membrane surface? Are they called phagocytes for engulfing pathogens? And why do they put these pathogenic particles on their surface?

[StupidProdigy]

Thanks grannysmith, your assistance is greatly appreciated. I mean it

Regarding the B lymphocytes, does a B cell differentiate into plasma B cells and B memory cells? When does it do this and why? Does it differentiate when a helper T cell binds to the B cell, as it gives it the basic shape of the antigen?

Also with dendritic cells, do they actually engulf pathogens, degrade them and present parts of them on their membrane surface? Are they called phagocytes for engulfing pathogens? And why do they put these pathogenic particles on their surface?

The resident bio expert is gonna get worn out if you keep asking him all these questions 

awesome stuff though grannysmith!

[vox nihili]

Thanks grannysmith.
More questions:

What is the difference between the first line and second line defence? Is it right to say that the major difference is that the first line defence are body surface barriers such as skin, mucus, cillia etc.. Whereas second line defence mechanisms are internal barriers?

Also i know how the first line can be non-specific, as it acts as a barrier for all types of pathogens. But how exactly is the second line of defence non-specific? Also what types of leucocytes are involved?

Where are blood cells made? Is it true that all blood cells are produced from the stem cells in the bone marrow, then T cells move to the thymus to mature and develop? Whereas the B cells remain in the bone marrow to mature?

What do B lymphocytes and T lymphocytes do?

Are monocytes just immature macrophages? If so, is there any role that monocytes play before maturing into macrophages?

What does it mean the neutrophils, eosophils and basophils are granulocytes? What does the term granulated mean, is it just that they release digestive enzymes that destroy pathogens?

Do B lymphocytes produce antibodies or do plasma B cells produce them?

Do all pathogens contain antigenic markers on their surface? Even viruses?

What does the lymph nodes actually do? I read that they are second line defence tissues/organs that have mucus on them that trap and filter foreign pathogens?

Does the spleen produce antibodies? If so, as above stated do the plasma B cells play a role in this too, are they located in the spleen?

Sorry for the influx of questions guys, I haven't done the immune system before so most of this stuff is new to me and my teacher gets frustrated when I ask her these 'basic' questions... I hope AN community doesn't mind <3

As I constantly say here, I don't think that you do yourselves any favours merely asking a tonne of questions. You should always try to answer the question yourselves first and then asking whether your answers were correct. This is a really important skill to develop in Biology and for the 1000th time I'd encourage everyone to develop it!

[heids]

As I constantly say here, I don't think that you do yourselves any favours merely asking a tonne of questions. You should always try to answer the question yourselves first and then asking whether your answers were correct. This is a really important skill to develop in Biology and for the 1000th time I'd encourage everyone to develop it!

Why can I only upvote once??

[Sine]

Can someone have a look and evaluate my descriptions?


Humoral Reponse - (against bacteria, toxins and extracellular viruses.

Activation
•Antigen binds to antibody forms Antibody-Antigen Complex
•B-cell processes antigen & presents it on MHC II
•Th binds to anitgen on MHC II 
•Stimulates B-cell to proliferate and differentiate into Plasma and memory- B cells which remain in lymph tissue to detect future antigens.
•Plasma cells produce vast amounts of specific Antibodies.
•B-cells Under goes Clonal expansion.
 
Cell mediated Response- (Infected eukaryotic cells, viruses, cancerous & transplanted cells.

Activation
•Macrophages present Antigen on MHC II 
•Th binds, Interleukins are released by the macrophage
•Tc binds to Antigen on MHC 1
•Tc produces specific memory Tc cells which go to Antigen infected cells.
•They release enzymes which lyse the cell.

[warya]

Don't the memory Tc cells stay in case of future infection and effector Tc fight present infection?

[biy]

Hey everyone

I keep getting confused with antibodies, antigens and MHC markers. Can someone please distinguish them for me? I have not done immune system before so any help would be greatly appreciated. <3

[Rishi97]

Hey everyone

I keep getting confused with antibodies, antigens and MHC markers. Can someone please distinguish them for me? I have not done immune system before so any help would be greatly appreciated. <3

Antibodies are proteins that bind with antigens that enter the body. This process is called agglutination and the antigen then becomes inactive.
Antigens are substances that cause an antibody to respond. They are like pathogens that enter the body from the external environment.

[vox nihili]

Hey everyone

I keep getting confused with antibodies, antigens and MHC markers. Can someone please distinguish them for me? I have not done immune system before so any help would be greatly appreciated. <3

Antigen: induces the production of antibodies
Antibody: effector molecules of the immune system; do lots of things. Produced by B-cells, bind antigens
MHC Markers: complex of surface molecules that bind antigens and "present" them on the surface of cells. T-cells can bind to the MHC complex with the right antigen bound