Which of the following is true of valves in veins?
a) they are associated with venous sinuses
b) they are most abundant in limbs
c) they contract to propel blood forward
d) they prevent blood pressure in veins from dipping below that of arteries

Study the diagram of a desert food chain . what would most likely happen if the kangaroo rats were killed off and removed from the food chain ?

Approximately 90% of all cases of polycystic kidney disease are inherited in an autosomal dominant fashion. the disease is typically related to mutations to genes (pkd1 and pkd2). pkd genes can be found on chromosome 16. the disease occurs in approximately 1: 800 to 1: 1000 people. here is a hypothetical example. the dominant allele d will cause the development of pkd. the recessive allele is known as d. what genotypes would correspond to suffering from pkd? dd, dd what genotypes would correspond to being normal (not suffering from pkd)? dd consider that 1: 1,000 people have pkd in your population of 325million. consider that pkd is inherited in an autosomal dominant fashion. show you math for all of the following questions: what is the genotypic frequency for dd? what is the genotypic frequency for dd? what is the genotypic frequency for dd? what is p? what is q? how many people in your population would have pkd?

Drag each label to the correct location in the equation. not all tiles will be used. the density of mercury is 13.6 grams per cubic centimeter. complete the steps for converting 13.6 g/cm3 to kg/m3. (1 kg = 1,000 g, 1 m3 = 106 cm3)