This reaction is called an exothermic reaction.
Red blood cells carry oxygen throughout the human body
The molecule that makes up proteins is amino acids.
In case of heptane (C7H16) the following structural isomers are possible
shown in figure
a. 1-sec-butylpropane : this is actually 3-methyl hexane
b. 4-methylhexane : this is actually 3-methylhexane
c. 2-ethylpentane : this is actually 3-methyl hexane
d. 1-ethyl-1-methylbutane: 3-methylhexane
e. 3-methylhexane: correct IUPAC
f. 4-ethylpentane: This is actually 3-methylhexane
Hence all represent single isomer