A level Biology: Post your doubts here!

[anastasia grey113]

Can anyone explain the difference between Out-breeding and Crossbreeding? PLZ

outbreeding is basically done within the same species.
It's the opposite of what we do in artificial selection. Two 'different' breeds of the same species are bred together. They do have the same physical features and chromosome number and their offspring are fertile too but they may be from different locations which cause them to have alleles which greatly differe.

While crossbreeding is what is done when sympatric speciation occurs. Two individuals from related (not the same) species-with possibly different no. of chromosomes-mate to make a hybrid. The offspring is not fertile and the chromosome number of the offspring is the sum of chromosome no. of the parents.

 

[A*****]

Do we have to learn all the geographical distributions for the various diseases (chapter 10) ?

 

[anastasia grey113]

Do we have to learn all the geographical distributions for the various diseases (chapter 10) ?

no it's not required.

 

[A*****]

no it's not required.

But what about this question?

 

[anastasia grey113]

But what about this question?

but you don't need to memorise this becuz the map is already given
just analyse whats given in the map above...n who knows it might be different from the one given in the book..like slightly different

 

[A*****]

but you don't need to memorise this becuz the map is already given
just analyse whats given in the map above...n who knows it might be different from the one given in the book..like slightly different

The map given is only for anopheles and the question asks to compare its distribution with that of malaria...
Anyways, I don't think such questions come too often

 

[Mstudent]

The map given is only for anopheles and the question asks to compare its distribution with that of malaria...
Anyways, I don't think such questions come too often

A***** Anopheles isn't a disease, its a species of mosquito, the vector, and Malaria is the disease. Female Anopheles mosquitoes spread Malaria, the disease, between people.

 

[A*****]

A***** Anopheles isn't a disease, its a species of mosquito, the vector, and Malaria is the disease. Female Anopheles mosquitoes spread Malaria, the disease, between people.

Hahaha I know that
I was only asking that do we have to learn the geographical spread of malaria because the map for its distribution is not given

 

[A*****]

Are these prominent circles nuclei? If yes, then of which cells, epithelial or goblet??

 

[Mstudent]

Are these prominent circles nuclei? If yes, then of which cells, epithelial or goblet??

But what about this question?

What papers are they?

Hahaha I know that
I was only asking that do we have to learn the geographical spread of malaria because the map for its distribution is not given

Damn! Sorry , My bad

 

[A*****]

What papers are they?

Damn! Sorry , My bad

One was from March'17 I think and the other from W15 p22

 

[Mstudent]

Are these prominent circles nuclei? If yes, then of which cells, epithelial or goblet??

Yes & Goblet

But what about this question?

Nothing to do with knowing the map for malaria,
All to do with Prevention methods, in developed countries no malaria present but mosquito is, cause plasmodium cannot thrive in these conditions as better treatment opportunities in these countries and some eradicated the disease

 

[A*****]

Yes & Goblet

Nothing to do with knowing the map for malaria,
All to do with Prevention methods, in developed countries no malaria present but mosquito is, cause plasmodium cannot thrive in these conditions as better treatment opportunities in these countries and some eradicated the disease

Tysmmm...one more thing, where are the epithelial cells then? Have they just become squamous cells and are not visible?

 

[A*****]

What is wrong with the 3rd statement? Is it that even neutrophils can not enter tissue fluid?
And can lymphocytes enter tissue fluid bqz they are smaller than phagocytes, like tissue fluid DOES contain some sort of WBCs...

 

[Mstudent]

What is wrong with the 3rd statement? Is it that even neutrophils can not enter tissue fluid?
And can lymphocytes enter tissue fluid bqz they are smaller than phagocytes, like tissue fluid DOES contain some sort of WBCs...

View attachment 63440

I'm pretty much sure that all WBCs can enter the tissue fluid, by squeezing in, that's why 3 is wrong

Tysmmm...one more thing, where are the epithelial cells then? Have they just become squamous cells and are not visible?

The layer just under the goblet cells is very likely the epithelial layer, and no it can't disappear!

 

[A*****]

I'm pretty much sure that all WBCs can enter the tissue fluid, by squeezing in, that's why 3 is wrong

But the size of a macrophage is about 21 um, too large to even enter the capillary, then how can it leak from a pore?

 

[A*****]

The layer just under the goblet cells is very likely the epithelial layer, and no it can't disappear!

Okay but how can the epithelium be below the goblet cells? I mean that it is the top most layer, so how can it just go downwards?

 

[Mstudent]

But the size of a macrophage is about 21 um, too large to even enter the capillary, then how can it leak from a pore?

No it isn't, macrophages are just large enough to fit into a capillary

Okay but how can the epithelium be below the goblet cells? I mean that it is the top most layer, so how can it just go downwards?

Hehe, no it doesn't go downwards. that must be the mucous membrane that consists of one or more layers of epithelial cells according to wikipedia

 

[A*****]

Mstudent
Can antibodies DIRECTLY kill or destroy pathogens?

 

[A*****]

According to mark scheme, the impulses first reach the apex of the heart and then through the purkyne tissues...then what about those tissues which are above the apex?