How does the prevalence of a disease increase?
The prevalence of a disease may increase if the duration of the disease is very long as is the case with chronic conditions. It may also increase due to a higher incidence rate. Also, improved methods of diagnosis which lead to more cases being detected and the availability of a more effective treatment which prolongs life are other possible reasons.
What is the is the difference between active and passive transport?
Both active and passive transport are processes that move water, oxygen, and nutrients into cells and waste products out. However, there are difference between the two. For one, active transport requires energy in the form of ATP to pump molecules against the concentration gradient. That means from an area of low concentration to an area of high concentration. On the other hand, passive transport is the movement of molecules down the concentration gradient. That means from an area of high concentration to low concentration. Also, passive transport is mainly responsible for diffusion while active transport is responsible for endocytosis and the sodium/potassium pump.
Describe the causes and consequences of osteoporosis ?
Osteoporosis is caused by the loss of bone density that occurs as one ages. Most people reach their peak bone mass by their 20's and from then on bone mass loss is faster than new bone can be made. The affected bones are much more susceptible to fractures and other symptoms may develop such as loss of height and a stooped posture as well.