Question

Different types of healthy tissues have different mitotic indices—the rate of dividing cells to the total number of cells in a sample. Which of the tissues from the activity has the highest mitotic index (percentage of dividing cells)? Explain why you think this type of cell divides more quickly than the other tissues.

Answer 1

Epidermal or meristematic tissues are likely to have the highest mitotic indices due to their functions requiring frequent cell renewal and growth. These tissues constantly replace lost or damaged cells or expand for organismal growth. In contrast, nerve or muscle tissues have low mitotic indices as they have cells that do not divide frequently post-development.

Step-by-step explanation:

The tissue with the highest mitotic index is likely to be one that has cells which divide frequently, such as epidermal tissue or meristematic tissue. Epidermal tissue cells cover surfaces of the body and are constantly being shed and replaced, requiring frequent cell division. Likewise, meristematic tissues in plants are regions where active cell division occurs for growth, particularly in root and shoot tips. Tissues like muscle and nerve have nearly lifelong cells, which means they have a low mitotic index.

The reason some tissues have higher rates of cell division, and hence a higher mitotic index, lies in their function and need for renewal. Epidermal tissue, for example, forms a barrier that is subject to abrasion and damage, necessitating rapid turnover of cells for repair and maintenance. Meristematic tissues are critical for plant growth and differentiation into various specialized tissues.

In contrast, tissues composed of cells that do not divide or divide infrequently, such as nerve or muscle tissues, have a low mitotic index. These cells often remain in the GO phase of the cell cycle for a lifetime, reflecting their longevity and low turnover. For such tissues, their specialized functions do not require frequent cell division once development is complete.

Answer 2

Cells of skin, for instance, have highest mitotic index.

Step-by-step explanation:

Many cells are capable of dividing rapidly. For example, in plants, the cells near the root tip in the apical meristem divide rapidly to push through the soil because the root cap detects the gravity and direct rapid division and growth of cells near the tip.

If we take muscle, skin, kidney, and lung as examples that are given in real question, skin cells have the highest mitotic index because they need to get replaced most frequently.