Biology Question?

[ashley g]

Sensors in the blood detect levels of __ to control breathing rate.
a). carbon dioxide
b). oxygen
c). hemoglobin
d). red blood cells

I'm assuming oxygen, but it just seems too easy.

And which of the following is false regarding cytotoxic T-cells?
a). They bind to and destroy cells that carry Class I MHC glycoproteins
b). They may attack bacteria in the blood and lymph
c). They contribute the body's cell-mediated response to pathogens
d). They may attack cancer cells

I think it's either b or c, but I can't decide between the two.

[scottsdalehigh64]

I'll deal with the first question. The primary sensors that determine the rate of respiration are in the floor of the fourth ventricle of the brain. They monitor the pH of the cerebrospinal fluid (CSF) which is created in the choroid plexus from the blood. When the pH of the CSF goes down, the respiratory center causes the rate of respiration to rise, driving off carbon dioxide and returning the blood and CSF to normal pH.

The answer to the second question is b.

[kenny]

It's carbon dioxide.

second of which i couldnt tell you

[kenny]

It's carbon dioxide.

second of which i couldnt tell you