Question

13.1. Write a short note on meristematic tissue.

13.2. Draw a well-labelled diagram of nerve cell.

13.3. a) What are the characteristic features of cuboidal epithelial tissue?

b) Write down three functions of blood.​

Answer 1

13.1 Meristematic tissues are the tissues in which the cells divide continuously and help in increasing the length and girth of the plant.

According to their position in the plant, meristems are of three types:

a) Apical Meristems - These are situated at the growing tip of the stems and roots and increase the height of the plant.
b) Lateral Meristems - These are found beneath the bark and in vascular bundles of dicot roots and stems. These are responsible for the growth of cambium and hence increases the girth of the plant.
c) Intercalary Meristems - They are located at the base of leaves or internodes or below the nodes. It increases the length of the plant.

13.2.
13.3. a) The main characteristic features of cuboidal epithelium are

• They are tough and can withstand more impact than squamous or cuboidal epithelium.
• The cells of this type of tissue are adapted for diffusion and secretion. This is one of the specializations found in epithelial tissues.
• They consist of layers of closely packed cube shaped cells.
• Simple cuboidal epithelium is found in organs that are specialized for secretion, such as salivary glands and thyroid follicles, and those that are specialized for diffusion, such as the kidney tubules.

b) The three functions of the blood are as follows:​

• Blood transports nutrients, hormones and vitamins to the tissues and transports excretory products from the tissues to the liver and kidney.​

• The red blood corpuscles $\left(RBCs\right)$ carry oxygen to the tissues for the oxidation of foodstuff and carry carbon dioxide from them to the lungs.​

• The white blood cells $\left(WBCs\right)$ fight disease either by engulfing and destroying foreign bodies or by producing antitoxins and antibodies that neutralise the harmful effects of germs.​