Final answer:
To calculate the surface area and volume of a sphere, the only number you need to know is the sphere's radius. Formulas for volume and surface area are 4/3 π r³ and 4 π r², respectively.
Step-by-step explanation:
To find the surface area and volume of a sphere, you must know the sphere's radius (r). The formula for the volume of a sphere is V = 4/3 π r³, which tells you that the expression 4³/3 is related to the volume. On the other hand, the formula for the surface area of a sphere is A = 4 π r². You do not need to know the circumference or the area of a great circle, as these can be derived from knowing the radius. Furthermore, when comparing cells or other objects in terms of surface area and volume, the surface area-to-volume ratio is critical, particularly in fields such as biology, where cell sizes are discussed.