Question

Which of the following has dead cells?
A. Parenchyma
B. Sclerenchyma
C. Collenchyma
D. Epithelium

Answer 1

Hint: The plant consists of dermal and vascular cells. The other types of cells or tissues are ground tissues. These are neither dermal or vascular. The major ground tissues are parenchyma, sclerenchyma, and collenchyma. Parenchyma is a filler tissue found in softer parts of the plant. Collenchyma provides structural support to growing stems, and sclerenchyma is present in hard parts of the plant.

Complete answer: Plants are made up of three types of main tissues. These are; dermal tissues that provide coverage and make outer layers of the plant, for example, epithelium. The second is the vascular tissue that provides transportation of nutrients, water, food, etc. throughout the plant, and the last is the filler tissues or support tissues. They are further of three main types; Parenchyma, Collenchyma and Sclerenchyma.
a) Parenchyma is a versatile ground tissue. It makes up filler tissues in softer plant parts. They are made up of living cells and may have meristematic cells even in maturity. They are capable of cell division when provided stimulation. The cells have thin and flexible cell walls made of cellulose. The cells are polyhedral or oval. They also act to store waste products and water in their central vacuoles.
b) Sclerenchyma is a tissue that is present in hard plant parts. They provide stiffness wherever they are present. They are the major supporting tissue in plants. Their cells have cell walls made up of cellulose, hemicelluloses, and lignin. They are present in parts that have grown maximum and have ceased to grow further. The mature sclerenchyma tissue is composed of dead cells that have extremely thick cell walls. Thus, it becomes harder and provides strength to the plants.
c) Collenchyma is made up of cells with irregularly thickened cell walls. They also provide structural support to plants where they are present. They are particularly present in growing shoots and leaves. The cells are living cells having thick cell walls made of cellulose and pectin. The epithelium is made of epithelial cells. These are living and thin-walled cells that make a protective covering over plant parts. It is present on the surface of leaves, stems, etc.
So, the right answer is option B.

Note: The sclerenchyma cells are of two types. These are fibres and sclereids. The sclerenchyma fibres are used extensively in industries. They have great economical importance. They serve as primary source material for many fabrics. For example, flax, hemp, jute, and ramie are derived from sclerenchyma tissue.