In old age, people often suffer from stiff and inflamed joints. What is this condition called? What are the possible reasons for these symptoms?

Q. SHORT ANSWER TYPE
Some people in old age complain of stiff joints. What do you think could be a possible reason for it ?

Q. Some people in old age complain of stiff joints. What do you think could be a possible reason for it?

Q. (a) Why are colour blindness and thalassemia categorised as Mendelian disorders? Write the symptoms of these diseases seen in people suffering from them.
(b) About 8% of human male population suffers from colour blindness whereas only about 0.4% of human female population suffers from this disease. Write an explanation to show how it is possible.