Animal Tissues and their Types: Muscular Tissues

Figure 19 Different types of muscular tissues
Image source: Keshari and Ghimire. 2023. A Textbook of Biology. Vidyarthi Pustak Bhandar, Kathmandu, Nepal.

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Concept of Plant Tissues

Q.N. 1. Define tissue. Give a brief account on the classification of plant tissues. Tissue is defined as a group of cells having a common origin and co-operating with one-another to perform a similar function. Based on their capacity to divide, tissues can be classified as meristematic tissues or meristems and permanent tissues, in plants. 1. Meristems Meristems are groups of young cells which retain the capacity of cell division. They occur in the growing regions of plants. Meristems are categorised as promeristems, primary meristems, and secondary meristems on the basis of origin and development; as apical meristems, intercalary meristems, and lateral meristems based on position; protoderm, procambium, and ground meristems on the basis of functions. 2. Permanent tissues Permanent tissues are the tissues that have their growth have stopped either completely or they do not divide till their dedifferentiation happens. Sometimes, they regain meri...

The Basic Concept on Photosynthesis

Figure 1 Schematic diagramme of photosynthesis Photosynthesis: Definition Q.N. 1. What is photosynthesis? Briefly describe the site of photosynthesis. Also, mention its significance. Photosynthesis is the process by which green plants synthesize their food by using carbon dioxide (CO 2 ) and water (H 2 O) in the presence of sunlight. The chlorophylls in the chloroplast of green plants absorb light energy and that energy is used to convert carbon dioxide and water into organic food material (glucose). It is the conversion of light energy into chemical energy in plants (See Figure 1 ). The overall reaction of photosynthesis is: Light 6CO 2 + 12H 2 O ⟶ C 6 H 12 O 6 + H 2 O + O 2 Chlorophyll glucose The word photosynthesis is derived from two words – ‘photo’ means light and ‘synthesis’ means putting together. Carbon dioxide is obtained from the ...

Anatomy of Plant Stems

Anatomy of Dicot Stem Q.N.1. Describe the anatomy or internal structure of dicot stem. Primary dicot stem consists of epidermis , hypodermis , cortex , endodermis , pericycle , vascular bundles , medullary rays or pith rays , and pith or medulla (see Figure 3 ). 1. Epidermis Epidermis is the outermost layer of the stem. It is composed of elongated, barrel-shaped parenchymatous cells without intercellular spaces . It is covered externally by a cuticle . Stomata and several unbranched multicellular hairs or trichomes are also present . Each stoma has a pair of specialized kidney-shaped cells, guard cells . Epidermis helps in protection of internal tissues, exchange of gases through stomata, reduces the rate of surface transpiration by cuticle, prevents the entry of harmful organisms and heat insulation by epidermal hairs. 2. Hypodermis Hypodermis lies below epidermis. It is made of 3- to 4-layered collenchyma. Collenchyma is green due to chloroplasts in it. It helps...

MBC BIOLOGY

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