1. Plant cells have cellulose cell walls whilst animal cells do not.

2. Plant cells do not have plasma membranes, unlike animal cells which do.

3. Mature plant cell has one large vacuole whilst animal cell has many small vacuoles.

Select the correct answer using the code given below:

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Ans: c

Explanation:

Cells is the fundamental, structural and functional unit of life. All the plants and animals are made of cells. Some forms of life, however, are made of only a single cell, such as the many species of bacteria and protozoa. Cells, whether living on their own or as part of a multicellular organism, are usually too small to be seen without a light microscope.

All cells are surrounded by a structure called the cell membrane — which, much like the walls of a house, serves as a clear boundary between the cell’s internal and external environments. The cell membrane is sometimes also referred to as the plasma membrane.

Plant cells have certain distinguishing features, including chloroplasts, cell walls, and intracellular vacuoles. Photosynthesis takes place in chloroplasts; cell walls allow plants to have strong, upright structures; and vacuoles help regulate how cells handle water and storage of other molecules.

PLASMA MEMBRANE OR CELL MEMBRANE :

• This is the outermost covering of the cell that separates the contents of the cell from its external environment. The plasma membrane allows or permits the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials. 
• The cell membrane, therefore, is called a selectively permeable membrane. It is found in both plant and animals cells.
• The plasma membrane is flexible and is made up of organic molecules called lipids and proteins. However, we can observe the structure of the plasma membrane only through an electron microscope. 
• The flexibility of the cell membrane also enables the cell to engulf in food and other material from its external environment. Such processes are known as endocytosis. Amoeba acquires its food through such processes. 

Hence, statement 2 is incorrect.

Cell Wall:

• Plant, fungi and bacteria, in addition to the plasma membrane in their cell, have another rigid outer covering called the cell wall. The cell wall lies outside the plasma membrane. The plant cell wall is mainly composed of cellulose. Cellulose is a complex substance and provides structural strength to plants.
• Cell walls permit the cells of plants, fungi and bacteria to withstand very dilute (hypotonic) external media without bursting. In such media the cells tend to take up water by osmosis. Because of their walls, such cells can withstand much greater changes in the surrounding medium than animal cells.

Hence, statement 1 is correct.

Vacuoles 

• Vacoules are storage sacs for solid or liquid contents. Vacuoles are small sized in animal cells while plant cells have very large vacuoles. The central vacuole of some plant cells may occupy 50-90% of the cell volume. Most mature plant cells have a large central vacuole that helps to maintain the turgidity of the cell and stores important substances including wastes. Plant cells use vacuoles to adjust their size and turgor pressure. Vacuoles usually account for changes in cell size when the cytoplasmic volume stays constant.

Hence, statement 3 is correct.

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