2015 AP Biology free response 8

- [Voiceover] An individual
has lost the ability

to activate B cells and mount
a humoral immune response.

Part A, propose one direct
consequence of the loss

of B-cell activity on
the individual's humoral

immune response to the initial exposure

to a bacterial pathogen.

So, just as a reminder what B cells are,

and what a humoral immune response are,

a humoral immune response is
one that involves antibodies.

And B cells are the ones that
will recognize an antigen,

something that the body
doesn't want in its body,

and then in response to
that, those antigens,

it will produce, it will
one, it'll proliferate,

it'll differentiate into plasma cells

that produce antibodies
which are essentially

these macro molecules that
tag the antigens for cleanup,

and then it can differentiate
into memory B cells.

So that next time, when
that same antigen shows up

it can mount a faster response.

So part A, propose one direct
consequence of the loss

of B-cell activity on
the individual's humoral

immune response to the initial exposure

to a bacterial pathogen.

So there won't be a humoral response.

So I could say,

No, no antibodies,

bodies will

be produced,

so no humoral immune response.

So there

will be

no humoral immune response.

Humoral immune,

immune response

to the initial exposure.

To initial,

initial exposure.

So you're not going to have
any tagging of these antigens

that then can be cleaned
up by other immune cells.

None of that's going to happen.

Part B, propose one direct
consequence of the loss

of B-cell activity on the
speed of the inidividual's

humoral immune response
to a second exposure

to the bacterial pathogen.

Well you have no memory B cells.

No memory B cells

and no antibodies.

Antibodies.

Specific or, I could say,

for second exposure to pathogen.

For second

exposure

to pathogen.

So no humoral response.

So no

humoral response.

And overall immune
response will be slower.

The whole point of B
cells and the antibodies

is that the second time it shows around,

it gets tagged very quickly.

It gets recognized very quickly.

And then the immune system can respond.

Well now you're not going to have that.

You're not going to have this
in the secondary exposure,

that quick recognition of the antigen.

So you're not going to
have humoral response,

and you could say, overall,

overall immune response,

immune response will be slower.

Immune response

is going to be slower and less effective.

Slower and

less effective.

Alright, let's think about part C.

Describe one characteristic
of the individual's

immune response to the bacterial pathogen

that is not affected
by the loss of B cells.

Well the B cells are all about

the humoral immune response.

It's about tagging things with antibodies,

having the memory B cells around

so that the next time
you get the pathogen,

the second exposure, you
have a quicker response.

But it's not the only
part of our immune system.

Our immune system has,
still, many facets to it.

One, you're still going
to have the cell mediated

immune response.

Still have

cell mediated,

mediated immune response.

Immune response.

And these are things like phagocytes

that will go and engulf,

that will engulf the pathogens.

Phagocytes.

Phagocytes, you have T cells

that can recognize the antigen

and similarly try to go
about destroying the antigen.

So you still have the cell
mediated immune response.

You also have things like the skin,

things that just block pathogens

from entering your body.

And that's considered part
of your immune system.

Still have

skin protection.

And you can go into more detail

but these are still the types of things

that the body has,

even if it lost its B cell capability

in order to prevent
pathogens from entering,

in the case of skin,

and also still once the pathogens get in,

to still recognize them and engulf them

or destroy them in some way.