Question

1 which statement best explains why most biological macromolecules contain carbon? a the long chains formed by carbon can be combusted with oxygen as a source of energy. b carbon exists across the universe and is produced in the interior of stars during their life cycles. c carbon can share electrons with up to four different atoms and form three types of bonding patterns. d the chemical and physical characteristics of carbon - containing molecules change as they move through the carbon cycle.

Explanation:

Carbon has 4 valence electrons. It can form single, double, or triple bonds (three types of bonding patterns) with up to four different atoms. This allows it to form long chains and complex structures which are the basis of biological macromolecules like carbohydrates, lipids, proteins, and nucleic acids.

• Option A: While some carbon - containing molecules (like glucose) can be a source of energy, this is not the main reason for carbon being in most biological macromolecules. The key is its bonding ability, not just energy - related combustion.
• Option B: The origin of carbon (in stars) does not explain its prevalence in biological macromolecules. The bonding properties are more relevant.
• Option D: The carbon cycle describes the movement of carbon - containing molecules in the environment. But it does not explain why carbon is the backbone of biological macromolecules. The bonding capacity of carbon is the reason.

Answer:

C. Carbon can share electrons with up to four different atoms and form three types of bonding patterns.