Question 18
blood contains that allow small amounts of acids or bases to be absorbed without harmful effects.
a)esters
b)buffers
c)enzymes
d)precipitates

I do believe the answer to be; Buffers

Blood contains buffers that allow small amounts of acids or bases to be absorbed without harmful effects. Hence the answer is option B.

Explanation:

The blood of human is of red color because of presence of hemoglobin in 8th which provides red color to it. Iron is considered to be as rich source of hemoglobin so it is advised to take iron when hemoglobin is not present in proper amount in the body.

Hemoglobin is also responsible for the carrying of oxygen throughout the body and carrying back of carbon dioxide from the whole body to the lungs.  

The Benthic zone would most likely be the part of a like wherein it is mostly aphotic in nature. In addition, the benthic zone is usually located at the bottommost layer of the lake wherein it is usually characterised by having sediments that support huge amounts of vegetation on the layer.

So C