What is the difference between nitrogen 14 and nitrogen 15

What can be said about farmers in highly developed countries? a) they have little or no negative impact on the environment. b) they practice subsistence agriculture. c) they are able to incorporate polyculture into their farming practices. d) they utilize organic farming techniques on a regular basis. e) they rely on large amounts of energy from fossil fuels.

Immature bone cells, or osteoblasts, manufacture a protein called osteoid as well as several hormones. because of this, we would expect osteoblasts to contain numerous a) nuclei. b) ribosomes. c) lysosomes. d) golgi bodies.

Which of the following requires the use of energy and the of transport proteins to move a molecule across a cell membrane?