To calculate the variance, subtract your actual fixed overhead cost from your standard overhead cost. If the actual cost is higher than the fixed cost, the cost variance is unfavorable. For example, your standard fixed overhead cost is $3 per unit.
The major role of hemoglobin is to carry oxygen from the lungs to the tissues and return carbon dioxide (CO2) from the tissue to the lungs.
Hemoglobin transports oxygen from the lungs or gills to the rest of the body (i.e. the tissues) where it releases the oxygen for cell use. It also has a variety of other roles of gas transport and effect-modulation which vary from species to species, and are quite diverse in some invertebrates.