What is the primary function of carbohydrates attached to the exterior of cell membranes?
identification of the cell
flexibility of the membrane
strengthening the membrane
channels through membrane

The correct option is : a. Identification of the cell

Explanation:

The cell membrane, also called plasma membrane, is a semi-permeable membrane surrounding the cytoplasm of the cell, that protects and separates the interior of the cells from the external environment.

The carbohydrate layer of the cell membrane is known as the glycocalyx. In eukaryotes, the carbohydrates present on the surface of the cell membrane play a important role in the cell-cell recognition and share information.

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.