Is this negative feedback or positive feedback? When a human increases physical activity, the amount of fuel burned in its cells also increases, which in turn increases the concentration of dissolved
CO2 in the blood. The CO2 reacts with water in the blood to make a weak acid,
which lowers the pH of the blood, Sensory cells in the medulla of the brain
register this drop in pH and send signals to the diaphragm and heart to
increase respiration. This will clear the CO2 from the bloodstream.

protein makes up the building blocks of organs, muscles, skin, hormones and pretty much everything that matters in your body.

some choices are:

peanut butter

seeds

eggs

yogurt

meats

fish

so pretty much meat, dairy, nuts, and grains.

answer: the correct option is d. enzyme

lactase and carbonic anhydrase are the examples of enzymes.

lactase is an enzyme, which is present in the small intestine of mammals. it in the digestion of the disaccharide, lactose ( milk sugar) by converting it into two monosachharide, which are glucose and galactose.

carbonic anhydrase is present in the red blood cells. this enzyme plays significant role in the transport of co₂. it in the conversion of co₂ and h₂o into carbonic acid, which is then dissociated into bicarbonate ions and hydrogen ions.