How might retaining too much heat be a disadvantage to an organism?

Which of the following does not make up ground substance of connective tissue? hyaluronic acid elastic fibers glycosaminoglycan proteoglycan

Polar zones are cold and tend to be dry because of a pressure system of cold. low high

How would you best describe the role of gene expression in cells a- cells destroy the dna of genes that they do not use b- when cells divide in mitosis, they pass on only the genes that are required. c- to become specialized, cells need to control the production of proteins coded for in their dna d- all genetic information in a cells dna is fully expressed at all times.