Chapter 22, Problem 17A

Summary Introduction

Introduction :

The leaves of plants are involved in photosynthesis and the structures of the leaves are such that it is well adapted to this function. The leaves have a flattened area that is termed as blade, it involves in providing a large surface area. The blades of the leaves are attached to the stem with the help of a stalk that is termed as petiole. The internal structure of a leaf consists of tightly packed cell found below the upper epidermis. This portion of the cell is highly exposed to the light; so, most of the photosynthetic process takes place in this cell. This cell has many chloroplasts and made up of palisade mesophyll tissue. Below the palisade layer spongy mesophyll tissue is found, that are rectangular in shape, and loosely packed. The oxygen, water vapor, and carbon dioxide pass through the space on the spongy mesophyll.

Answer to Problem 17A

Correct answer :

The correct answer is option (B) gases.

Explanation of Solution

Explanation/justification for the correct answer :

Option (B) gases. The spongy mesophyll tissue is found below the palisade layer that is rectangular in shape, and loosely packed. The oxygen, water vapor, and carbon dioxide pass through the space on the spongy mesophyll. So, the correct answer is option (B).

Explanation for incorrect answer :

Option (A) chlorophyll. The spongy mesophyll cells have a very low number of chloroplasts in the cells. It is not found in the gap space of spongy mesophyll cell. So, this is an incorrect option.

Option (C) Cells. The cells of spongy mesophyll are not tightly packed. They have space between them. These spaces are filled with gases. So, this is an incorrect option.

Option (D) vascular tissue. The spongy mesophyll cells are involved in photosynthesis in the leaves, whereas the vascular cells are involved in transportation process. So, this is an incorrect answer.