What system receives oxygen and gets rid of carbon dioxide?
a. heart
b. muscular system
c. veins
d. respiratory system

Draw the structure of dna nucleotide with adenine as nitrogenous base

The normal shape of an enzyme is as shown in structure a. if the enzyme’s shape changes to that shown in structure b, what are two consequences of this change?

Pentane with molecular formula c5h12, exists in three isomeric forms. one shows linear carbon chains, another has one -ch3 groups present on the third carbon atom, and the third has two -ch3 groups present on the second carbon atom. what types of isomers are these? a. geometric isomers b. structural isomers c. halotropic isomers