The human brain and spinal cord are immersed in the cerebrospinal fluid. The fluid is normally continuous between the cranial and spinal cavities. It normally exerts a pressure of 100 to 200 mm of H2O above the prevailing atmospheric pressure. In medical work pressures are often measured in units of […]

A relative of a friend of yours had a spinal cord injury after a bad car accident. The medical team has decided that this patient is a good candidate for a clinical trial using stem cell therapy. Your friend has not had a biology course since high school, so you […]

What is Mendel’s Concept of Dominance? Answer A. The two members of a gene pair segregate from each other into the gametes, so half the gametes carry one member of the pair, half the gametes carry the other member of the pair. B. In a heterozygote, only the trait from […]

Clearly selection pressure will not result in organisms that are better equipped to avoid agents of mass extinction such as the major asteroid impact at the end of the Cretaceous. Yet there is increasing evidence that mass extinctions are selective even though they follow different rules to “background” extinction. What […]