Helen is an 80 year old woman with stiff and painful joints caused by loss of articular cartilage from normal wear and tear. she suffers from:

During old age, the joints become weak, as the loss of bone and its associated structure occurs at a higher rate than its formation.

Osteoarthritis is a condition, in which the protective cartilage present on the end of the bones are degraded or wear down over a period of time. The condition of osteoarthritis result in pain, inflammation and stiffness of the joints.

Hence, in this case, Helen is suffering from the condition of osteoarthritis, which occurs normally in old age.

post-impressionism is a predominantly french art movement that developed roughly between 1886 and 1905, from the last impressionist exhibition to the birth of fauvism. post-impressionism emerged as a reaction against impressionists' concern for the naturalistic depiction of light and colour.

explanation:

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.