Question

Vacuole in a plant cell
A. Lacks membrane and contains air
B. Lacks membrane and contains water and excretory substances
C. Is membrane bound and contains storage protein and lipids
D. Is membrane bound and contains water and excretory substances

Answer 1

Hint: Vacuoles are cellular organelles. They are formed by fusion of vesicles. Vacuoles are well developed and functional in plant cells and smaller or absent in animal cells. Generally, these organelles are associated with storage of both liquid and solid substances.

Complete answer:
Vacuoles are membrane bound organelles present in cells. The membrane of the vacuoles is composed of phospholipid molecules and transmembrane proteins. The proteins function to transport molecules of certain shape and size to pass through it.
Vacuoles in plant cells are well-developed structures and take part in storage, while vacuoles of animals do not play any major role in the functioning of the cells.
Plant cell vacuoles are large structures and occupy most of the cell. The membrane surrounding the vacuoles is known as the tonoplast and is filled with cell sap. The vacuoles contain water, minerals, enzymes and excretory wastes.

The functions of vacuoles are listed below:
-Maintains the turgidity of the cell.
-Helps to isolate substances that are harmful
-Contains water that helps to keep the plant cell rigid
-Maintains the acidity of the cell cytoplasm and creates an effective environment for proteins to act.

The vacuoles are not composed of air, or proteins. Therefore, to conclude, we can say that vacuoles are membrane bound cellular organelles that contain water and excretory products.

Hence, the correct answer is option (D).

Note: Vacuoles are cell organelles of plants. They are bound by a phospholipid membrane and are filled with cell sap and function to maintain the turgidity of the cell. Vacuoles are also responsible for storing excretory substances and small molecules. The vacuoles of animal cells are not involved in maintenance of turgid conditions and are mainly involved in endocytosis and exocytosis.