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प्रश्न
Explain sclereids with their types.
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उत्तर
Sclereids are dead cells, usually these are isodiametric but some are elongated too. The cell wall is very thick due to lignification. Lumen is very much reduced. The pits may simple or branched. Sclereids are mechanical in function. They give hard texture to the seed coats, endosperms etc., Sclereids are classified into the following types.
- Branchysclereids or Stone cells: Isodiametric sclereids, with hard cell wall. It is found in bark, pith cortex, hard endosperm and the fleshy portion of some fruits.
eg: Pulp of Pyrus. - Macrosclereids: Elongated and rod shaped cells, found in the outer seed coat of leguminous plants. eg: Crotalaria and Pisum sativum.
- Osteosclereids (Bone cells): Rod shaped with dilated ends. They occur in leaves and seed coats.
eg: seed coat of Pisum and Hakea. - Astrosclereids: Star cells with lobes or arms diverging form a central body. They occur in petioles and leaves.
eg: Tea, Nymphae and Trochodendron. - Trichosclereids: Hair like thin-walled sclereids. Numerous small angular crystals are embedded in the wall of these sclereids, present in stems and leaves of hydrophytes.
eg: Nymphaea leaf and Aerial roots of Monstera.
संबंधित प्रश्न
Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.
Name the tissue that transports food in plants.
Identify the type of tissue in the vascular bundle.
Give two functions of collenchyma.
Distinguish between xylem and phloem.
What are tracheary elements? Describe their functions.
What are the functions of phloem?
What is simple tissue? Classify and explain its different types with suitable diagram.
Identify the odd word and explain why it is odd.
Differentiate between cells of Sclerenchyma and Parenchyma
Study the diagram given below and then answer the question that follows:
State the function of the parts labelled 1, 2, 3 and 4.
Write 'True or False' for the following statement:
A vascular bundle conducts prepared food only.
The question has four answers. Choose the correct answer:
Phloem parenchyma, sclerenchyma, sieve tubes, and companion cells are found in
Match the column (A) with the column (B)
| (A) | (B) | ||
| (a) | Parenchyma | (i) | Thin walled, packing cells |
| (b) | Photosynthesis | (ii) | Carbon fixation |
| (c) | Aerenchyma | (iii) | Localized thickenings |
| (d) | Collenchyma | (iv) | Buoyancy |
| (e) | Permanent tissue | (v) | Sclerenchyma |
Fibers are extensively longer ranging from 20 mm to 550 mm ______.
Which of the following is a permanent tissue?
Cells of this tissue are living and show angular wall thickening. They also provide mechanical support. The tissue is ______.
