Compound-Tissues

Tissues in Plants – [with 27 MCQs]

Overview

The group of similar function-performing cells is called tissue. Plants do not have complex organs and organ systems so here tissues perform major life tasks. Like animals’ plants also need support against gravity. The collenchyma provides support to baby plants.

The osmosis is performed by the epidermis, cortex and pith. They also maintain the internal hydrostatic pressure keeping the plant rigid and helping in resistance to bending.

Vascular bundles i.e., xylem and phloem are tough tissues that supply water and food respectively in the whole plant. In addition to this, they are also responsible for secondary growth.

The secondary xylem and secondary phloem are the tissues that increase the girth and thickness of plants. The parenchymatous tissues are rapidly growing tissues on the wound or damaged area of the plant and form callus.

Definition

Plant tissue is a collection of similar cells carrying out an organized function for the plant. Each plant tissue is specialized for a distinct purpose and can be combined with other tissues to develop organs such as leaves, flowers, stems, and roots. The following is a quick outline of plant tissues and their functions within the plant.

There are two significant categories of tissues in plants i.e., simple tissues and compound (complex) tissues.

Bottleneck-Effect

Simple tissues

The tissues which are made of single kind of cells are called simple tissues. They are of two types i.e., meristematic tissues and permanent tissues.

Meristematic Tissues

Meristematic-Tissues

Meristematic tissues include a group of cells that have the capability to divide. These tissues are small, cuboidal, largely packed cells that keep dividing to form new cells. These tissues are capable of stretching, expanding, and differentiating into other kinds of tissues as they mature. Meristematic tissues generate permanent tissues. Meristematic tissues can be of 3 types depending upon the area where they exist: Apical meristems, lateral meristems, and intercalary meristems.

  • i. Apical meristems: lie at the peaks (tips) of roots and shoot. When they divide, they cause an increase in the length of the plant. Such growth is called primary growth.
  • ii. Lateral meristems: lie on the lateral sides of roots and shoot. By dividing, they are accountable for the increase in the development of plant parts. This growth is called secondary growth. They are even more of 2 types i.e., vascular cambium (located in between xylem and phloem) and cork cambium (in the outer lateral sides of the plant).
  • iii. Intercalary meristem: This meristem is located in between the areas of permanent tissues. The intercalary meristem is usually present at the base of the node, the base of the internode, or at the base of the leaf. They are accountable for the development of leaves and internodes.
Permanent Tissues

Permanent tissues stem from meristematic tissue. The cells of these tissues do not have the capability to divide. They are further categorized into the following types:

  1. Epidermal Tissues

Epidermal-Tissues

Epidermal tissues are composed of a single layer of cells and they cover the plant body. They act as a barrier between the environment and internal plant tissues. In roots, they are likewise responsible for the absorption of water and minerals. On stem and leaves, they secrete cutin (the coating of cutin is called the cuticle) which prevents evaporation. Epidermal tissues likewise have some specialized structures that carry out particular functions; for instance, root hairs and stomata.

Simple Permanent Tissues:

These tissues are comprised of cells that are structurally and functionally similar. These are of three types:

  1. Parenchyma
  2. Collenchyma
  3. Sclerenchyma

Permanent-Tissues

1.Parenchyma

The parenchyma tissue is made up of living cells which vary in thin morphology and physiology but usually having a thin wall and a polyhedral shape and concern with the vegetative activities of the plant. They have intercellular spaces in between them. They act as storage for food and water.

Further Reading:  Transpiration in Plants
Types of Parenchyma:

Aerenchyma:

In hydrophytes, the intercellular space in between cells becomes wide and filled with air. Such a parenchymatous tissue having big air areas is called Aerenchyma. These help in gaseous exchange and provide buoyancy to plant.

Chlorenchyma:

When parenchyma is richly provided with chloroplasts, it is called chlorenchyma. They are found in leaf mesophyll, sepals, phylloclade, phyllodes, cladodes, and so on. It is photosynthetic in function and possesses chlorophyll.

2.Sclerenchyma Cells

They have thick secondary cell walls usually impregnated with lignin, an organic compound that makes the walls hard and tough. The majority of the sclerenchyma cells are non-living. Their main function is to provide support to the plant parts. There are 3 types of sclerenchymatous cells.

(i) Fibers (Tracheids): These are long and round and they might exist as solid bundles in the xylem or as bundle caps.

(ii) Sclereides: These are much shorter than fibers and are found in seed coats and nutshells and provide a defense.

(iii) Vessels (Tracheae): Long tubular structures, join end to end to form long water-carrying pipe in the xylem.

3.Collenchyma Cells

Collenchyma cells have protoplasts and typically lack secondary walls. They have angular thickening in their main walls. They are generally grouped in hairs or cylinders. Collenchyma cells provide assistance to young herbaceous parts of the plant. Young stems, for instance, typically have a cylinder of collenchyma simply below their surface area. Collenchyma cells are elastic, elongate with the growth of stems and leaves.

Compound (Complex) Tissues

A plant tissue made up of more than one kind of cell is called a compound or complex tissue. Xylem and phloem tissues, found only in vascular plants, are examples of compound tissues.

Compound-Tissues

Xylem

Its main function is the conduction of water and mineral salts from the root to the top of the plant. Primary xylem elements originate from the procambium of the apical meristem. Secondary xylem components originate from the vascular cambium of the lateral meristem.

The xylem elements are of 4 types: xylem tracheids, vessels, fibers, and parenchyma.

  1. Xylem Tracheids:

These are lignified and dead cells with bordered pits. They assist in the conduction of water in pteridophytes and gymnosperms and offer mechanical assistance to plants.

  1. Xylem Vessels:

The cells are long and tubular with a lignified cell wall. The cross wall (end wall) at both ends dissolves and form a pipe like a channel. They help in the ascent of sap in angiosperms.

  1. Xylem Fibers:

Long and narrow sclerenchymatous fibers with the tapering end. The wall is heavily lignified leaving a really narrow lumen.

  1. Xylem Parenchyma:

They are thin-walled living cells present in both primary and secondary xylem. They store food products.

Phloem

The dead matter in them is referred to as bast. Its main function is the conduction of food material from leaves to other plant parts. The phloem components are of 4 types: Sieve tubes, Companion cells, Fibres, and parenchyma.

  • Sieve Tubes:

These are living but do not have a nucleus at maturity. The cell wall is thin and comprised of cellulose. The transverse walls of the sieve tube form a sieve plate. They help in the conduction of food material.

  • Companion Cells:

The cells are living, thin-walled, narrow, and present attached to the lateral side of the sieve element. They are missing in pteridophytes and gymnosperms. They support the sieve tube in the transport of food. They are absent in all monocots and some dicots.

  • Phloem Fibers (bast fibers):

These are sclerenchymatous fibers having a thick wall and narrow lumen. They provide mechanical support to the plant.

  • Phloem Parenchyma

The chief function of parenchyma is to store food products and other substances like mucilage, tannins, and resins.

Other Ways to Classify Plant Tissue

Another method to categorize plant tissue is based upon its function. Particular tissues are only utilized for the purposes of photosynthesis and development. These tissues can be described as vegetative tissue. The more specific organs of the plant, such as flowers, fruits, and seeds, are all reproductive tissue.

This method of classifying plant tissues is frequently utilized by those, who are interested in plant genes and reproduction, as these forms of the plant are often greatly various, genetically speaking than the vegetative parts of the plant. Plants have a life-cycle that displays the alternation of generations, in which the internal portions of the flower are really little, multicellular organisms varying genetically from the parent plant. For this reason, some researchers choose to see these issues as separate.

Further Reading:  Water Absorption in Plants
Functions of plant tissues
  • Plant tissues have various functions relying on their structure and location.
  • Help provide mechanical strength to organs.
  • They help in providing flexibility and versatility to the organs.
  • They help the tissues to bending easily in different parts of a plant like- leaf, stem, and branches without harming the plant.
  • The xylem and phloem tissues help in the transportation of products throughout the plants.
  • They divide to produce new cells and help in the development of the plants.
  • They help in different cellular metabolisms like photosynthesis, regeneration, respiration, metabolism, and so on.

27 MCQs on Tissues in Plants

1. What is a plant tissue?

  • A. A group of organs
  • B. A collection of different cells
  • C. A single type of cell
  • D. An individual cell
  • Answer: B

2. What major life tasks do plant tissues perform?

  • A. Digestion and circulation
  • B. Support against gravity and osmosis
  • C. Oxygen transport and energy production
  • D. Sensory perception and reproduction
  • Answer: B

3. What provides support to young plants against gravity?

  • A. Xylem
  • B. Phloem
  • C. Collenchyma
  • D. Parenchyma
  • Answer: C

4. Which tissues are responsible for maintaining internal hydrostatic pressure in plants?

  • A. Epidermal tissues
  • B. Collenchyma
  • C. Xylem
  • D. Parenchyma
  • Answer: D

5. What are vascular bundles responsible for in plants?

  • A. Gaseous exchange
  • B. Secondary growth
  • C. Water and food supply
  • D. Photosynthesis
  • Answer: C

6. How are simple tissues categorized in plants?

  • A. Apical and lateral
  • B. Meristematic and permanent
  • C. Epidermal and parenchymal
  • D. Xylem and phloem
  • Answer: B

7. Which type of meristem is responsible for secondary growth in plants?

  • A. Apical meristem
  • B. Intercalary meristem
  • C. Lateral meristem
  • D. Epidermal meristem
  • Answer: C

8. What is the main function of meristematic tissues?

  • A. Water absorption
  • B. Food storage
  • C. Cell division and differentiation
  • D. Mechanical support
  • Answer: C

9. Where is intercalary meristem usually located?

  • A. At the tips of roots and shoots
  • B. Between permanent tissues
  • C. At the base of nodes and internodes
  • D. At the base of leaves
  • Answer: B

10. Which type of cells originate from meristematic tissues?

  • A. Parenchyma
  • B. Sclerenchyma
  • C. Collenchyma
  • D. Permanent tissues
  • Answer: D

11. What is the main function of epidermal tissues?

  • A. Conduction of water
  • B. Food storage
  • C. Protection and absorption
  • D. Mechanical support
  • Answer: C

12. What type of permanent tissues are structurally and functionally similar?

  • A. Epidermal tissues
  • B. Simple permanent tissues
  • C. Collenchyma
  • D. Complex tissues
  • Answer: B

13. What is the primary function of parenchyma tissue?

  • A. Mechanical support
  • B. Food and water storage
  • C. Conduction of water
  • D. Protection against pathogens
  • Answer: B

14. What is the name given to parenchymatous tissue with large air spaces in hydrophytes?

  • A. Aerenchyma
  • B. Chlorenchyma
  • C. Collenchyma
  • D. Sclerenchyma
  • Answer: A

15. Which type of sclerenchymatous cells provide mechanical support to plant parts?

  • A. Fibers
  • B. Sclereids
  • C. Vessels
  • D. Parenchyma
  • Answer: A

16. What is the chief function of collenchyma cells?

  • A. Water conduction
  • B. Mechanical support to young plant parts
  • C. Food storage
  • D. Photosynthesis
  • Answer: B

17. What is the term for a plant tissue made up of more than one type of cell?

  • A. Meristematic tissue
  • B. Simple tissue
  • C. Complex tissue
  • D. Compound tissue
  • Answer: D

18. What is the main function of xylem tissue in plants?

  • A. Conduction of water and mineral salts
  • B. Conduction of food material
  • C. Mechanical support
  • D. Protection against pathogens
  • Answer: A

19. What is the primary function of sieve tubes in phloem tissue?

  • A. Food storage
  • B. Conduction of water
  • C. Mechanical support
  • D. Conduction of food material
  • Answer: D

20. Which cells in phloem are living but lack a nucleus at maturity?

  • A. Sieve tubes
  • B. Companion cells
  • C. Phloem fibers
  • D. Parenchyma
  • Answer: A
Further Reading:  Epidermis: Origin, Structure, Cells, and Function of Epidermis

21. What type of phloem cells support the sieve tubes in food transport?

  • A. Sieve tubes
  • B. Companion cells
  • C. Phloem fibers
  • D. Phloem parenchyma
  • Answer: B

22. Which tissues store food products and other substances in plants?

  • A. Epidermal tissues
  • B. Parenchyma
  • C. Xylem
  • D. Phloem fibers
  • Answer: B

23. How is plant tissue classified based on function?

  • A. Vegetative and reproductive
  • B. Simple and compound
  • C. Meristematic and permanent
  • D. Epidermal and parenchymal
  • Answer: A

24. What is the alternation of generations in plant tissues related to?

  • A. Oxygen production
  • B. Genetic diversity
  • C. Food conduction
  • D. Mechanical support
  • Answer: B

25. What is the primary function of vegetative tissue in plants?

  • A. Conduction of water
  • B. Photosynthesis and growth
  • C. Reproduction
  • D. Food storage
  • Answer: B

26. In what part of the plant are the more specific organs like flowers, fruits, and seeds found?

  • A. Epidermal tissues
  • B. Xylem
  • C. Reproductive tissue
  • D. Meristematic tissue
  • Answer: C

27. What are the various functions of plant tissues?

  • A. Photosynthesis and respiration
  • B. Digestion and circulation
  • C. Support, flexibility, and transportation
  • D. Sensory perception and energy production
  • Answer: C

 

Summary

The tutorial on plant tissues provides a comprehensive overview of the diverse cell types and structures that contribute to the growth and function of plants. It delves into the distinction between simple and compound tissues, covering meristematic and permanent tissues in detail.

The importance of meristematic tissues in generating permanent tissues is highlighted, with a focus on apical, lateral, and intercalary meristems. The tutorial explores the characteristics and functions of simple permanent tissues, including parenchyma, collenchyma, and sclerenchyma. Specific types of parenchyma, such as aerenchyma and chlorenchyma, are elucidated.

The discussion extends to complex tissues like xylem and phloem, crucial for the conduction of water, minerals, and food throughout the plant. Each component of xylem, including tracheids, vessels, fibers, and parenchyma, is examined. Similarly, the different elements of phloem, such as sieve tubes, companion cells, fibers, and parenchyma, are explained.

The tutorial concludes with alternative classifications of plant tissues based on function, distinguishing between vegetative and reproductive tissues. The diverse functions of plant tissues, ranging from mechanical support to cellular metabolism, are emphasized. Overall, the tutorial serves as a comprehensive guide to understanding the intricate world of plant tissues and their vital roles in the growth and development of plants.