Why is it difficult to make accurate predictions about changes in communities of organism

Which element provides strength to the exoskeleton of clams and oysters

Plz ! for many generations farmers in north america have been choosing to cross corn plants with large ears of corn each year this results in the new generation of plants also growing large ears of corn. what is the technique called? a. selective breeding. b. natural selection. c. mitosis. d. asexual budding.

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