Chapter 9, Problem 5A

Summary Introduction

Introduction:

A cell grows until it reaches its size limit, then it either stops growing or divides. Most cells undergo division. Cell division helps a cell to reproduce and makes the organism grow and heal certain injuries. Most cells are less than 100μm in diameter. The ratio of surface area to volume is the key factor that limits the size of a cell.By remaining small cells have a higher ratio of surface area to volume and they can sustain themselves more easily.

Answer to Problem 5A

Correct answer :

The correct answer is option B. 3:1

Explanation of Solution

Explanation/justification for the correct answer:

Option B. 3:1- Surface area of a cell refers to the area covered by the plasma membrane through which the nutrients and wastes must pass through. Volumerefers to the space taken up by the contents of the cell. To calculate the surface area of the cube, we have to multiply length times width times the number of sides. To calculate the volume we have to multiply length times width times height.

  $\text{Length of the given cube=2cm}$

  ${\text{Surface area=2×2×6=24cm}}^{\text{2}}$

  ${\text{Volume of cube=2×2×2=8cm}}^{\text{3}}$

  $\text{Ratio of surface area to volume=24:8=3:1}$

Hence this is the correct option.

Explanation for incorrect answer:

Option A. 2:1−To calculate the surface area of the cube, we have to multiply length times width times the number of sides. To calculate the volume we have to multiply length times width times height.

  $\text{Length of the given cube=2cm}$

  ${\text{Surface area=2×2×6=24cm}}^{\text{2}}$

  ${\text{Volume of cube=2×2×2=8cm}}^{\text{3}}$

  $\text{Ratio of surface area to volume=24:8=3:1}$

Hence, this is not the correct option.

Option C. 4:1- To calculate the surface area of the cube, we have to multiply length times width times the number of sides. To calculate the volume we have to multiply length times width times height.

  $\text{Length of the given cube=2cm}$

  ${\text{Surface area=2×2×6=24cm}}^{\text{2}}$

  ${\text{Volume of cube=2×2×2=8cm}}^{\text{3}}$

  $\text{Ratio of surface area to volume=24:8=3:1}$

Hence this is not the correct option.

Option D. 6:1- To calculate the surface area of the cube, we have to multiply length times width times the number of sides. To calculate the volume we have to multiply length times width times height.

  $\text{Length of the given cube=2cm}$

  ${\text{Surface area=2×2×6=24cm}}^{\text{2}}$

  ${\text{Volume of cube=2×2×2=8cm}}^{\text{3}}$

  $\text{Ratio of surface area to volume=24:8=3:1}$

Hence this is not the correct option.