Sickle-cell disease is a debilitating disease that results from being homozygous recessive for the "sickle-cell allele" of a hemoglobin gene. Why is the allele present and even common in many human populations?

Heterozygote advantage

Explanation:

The sickle cell allele in a heterozygote state confers a kind of resistance to malaria in areas where the disease is endemic while it is deleterious in homozygous condition. Hence, this heterozygote advantage ensures that the recessive allele is present and quite common in the population.

not only is it colder, it also becomes darker, less salty, and more dense.

homeostasis is the tendency towards a relatively stable equilibrium between interdependent elements, especially as maintained by physiological processes. and this is how it applies to the integumentary system. back to top. skin functions in homeostasis include protection, regulation of body temperature, sensory reception, water balance, synthesis of vitamins and hormones, and absorption of materials. when body temperature falls, the sweat glands constrict and sweat production decreases.