NIOS Class 12 Biology Chapter 5 Solutions provide detailed answers to the terminal exercises, helping students revise effectively. This chapter focuses on important biological concepts that build a base for advanced study. Each solution is explained in a simple manner to aid clarity and exam readiness.
Students can use these solved exercises as a guide for self-study and quick revision, making their preparation for the NIOS Class 12 Biology exam stronger.
NIOS Class 12 Biology Chapter 5 Solutions
1. What is a tissue?
A tissue is a group of cells with a common origin, structure, and function.
2. State one main structural characteristic and the special activity of the following tissue:
Meristem, sclerenchyma, xylem, phloem, epithelium, muscle, and nervous tissue.
- Meristem: Vacuoles are small or absent. Growth in length.
- Sclerenchyma: Consists of thick-walled cells. Supporting tissue.
- Xylem: Long cells with pointed ends. Conducts water.
- Phloem: Thin cell walls. Translocate food.
- Epithelium: Closely packed cells with no intercellular spaces in between. Helps in absorption and secretion.
- Muscle: Composed of long excitable cells containing parallel microfilaments of
- contractile proteins. Helps in movements.
- Nervous Tissue: The Main cell body has projections and the transmission of nerve impulses.
3. In what way do the following tissues differ from the one stated:-
- (i) Connective tissue from epithelial tissue
- (ii) Bone from blood
- (iii) Phloem from xylem
- (iv) Squamous epithelium from columnar epithelium
- (v) Tracheids from wood fibres
Ans:
(i) Connective tissue from epithelial tissue
| Connective tissue | Epithelial tissue |
| Connective tissues consist of a matrix and cells. | Epithelial Tissue is made of closely packed cells with no intercellular spaces. |
| Connective tissues bind, supporting, and transporting in function. | Epithelial tissues are absorption and secretion in function. They also have protoplasmic projections, such as cilia, for locomotion. |
| Both matrix and cells are different in different types of connective tissues. | Structure and number of layers differ for different epithelial tissues. |
(ii) Bone from blood
| Bone | Blood |
| Bone is a supporting connective tissue. | Blood is a fluid connective tissue |
| Bone matrix is composed of ossein. | Plasma forms the matrix. |
| Matrix also contains salts of calcium, phosphorus and magnesium. | Matrix contains a large number of proteins, such as Fibrinogen, Albumin, and Globulin |
| Cells present are osteocytes | Cells present are Red Blood Cells, White Blood Cells, and platelets. |
(iii) Phloem from xylem
| Phloem | Xylem |
| Phloem conducts synthesized food from the leaves to other parts | Xylem conducts water and salts |
| Conduction is multidirectional | Conduction is unidirectional, upwards from the roots to the leaves |
| Xylem is composed of Tracheids, Vessels, Fibres, and Xylem Parenchyma | Phloem is composed of the Sieve tube elements. Companion cells, Phloem fibre, and Phloem Parenchyma |
(iv) Squamous epithelium from columnar epithelium
| Squamous epithelium | Columnar epithelium |
| Flattened cells with irregular margins and a centrally placed nucleus | Long column-like cells, each with a nucleus at the basal end |
| Found in the air sacs of lungs, kidney tubules, and the lining of blood capillaries. | Found in the lining of the stomach and intestine |
| Exchange of gases in lungs, absorption in kidneys, and exchange of materials in blood capillaries in functions. | Secretion and absorption in function. |
(v) Tracheids from wood fibres
| Tracheids | Wood Fibres |
| Dead cells | Dead cells |
| Long cells with pointed ends and thick lignified walls. | Long cells with very thick lignified walls |
| Pores are present | Pores are absent |
4. Name the different levels of organisations in animals (such as humans), giving one example of each.
The different levels of organisations in humans are as follows.
- Cellular level: Red blood cells.
- Tissue level: Epithelium
- Organ: Liver
- Organ system: Digestive system
- Organism: Humans
