Chapter 9, Problem 28A

Summary Introduction

To replace:

The incorrect term with correct vocabulary terminthe given sentence.

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. A cell cycle has a system of control checkpoints to monitor the cycle and stop it if something goes wrong. Sometimes cells fail to respond to normal cell cycle control mechanisms. This causes cancer.

Answer to Problem 28A

Cancer cells undergo uncontrolled, unrestrained growth and division because their genes have been changed.

Explanation of Solution

Cancer occurs when the normal cell cycle is disrupted and the cell does not respond to control mechanisms. Cancer is uncontrolled growth and division of cells. These unchecked cancer cells can even kill the organism by crowding out normal cells. The changes occur in regulation of cell growth and division of cancer cells due to mutations or changes in certain segments of DNA. Often the genes are altered due to some environmental factors, age and food habits.

Stem cells are unspecialized cells that can undergo division and develop into specialized cells under the right conditions. These cells can specialize into various tissues, organs and organ system.

Hence the correct word in the given sentence is cancer and not stem cells.