Urea (NH2)2CO carries amine (ammonia) generated by the catabolism of amino acids. Assume the natural abundance of 14N is 100%. Citrulline (Exam Images Sheet) is synthesized with 15N in both nitrogen atoms (assume 100%). The citrulline enters into the urea cycle. Approximately what percentage of nitrogen in the urea produced in one turn of the cycle contains a 15N, assuming the naturally occurring nitrogen isotope is 100% 14N?

In which phase(s) do the molecules take the shape of the container?

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

Which statement correctly identifies the scientific question and describes why the question is scientific? question 1 refers to the supernatural.question 2 reflects a moral or social value.question 3 refers to something that can be measured.question 4 reflects a question that can’t be observed.