HI GUYS☺☺☺☺ I NEED YOUR HELP AGAIN.... What are meristematic and permanent tissues ? PLEASE GUYS HELP ME , TOMORROW'S MY TEST , PLEASE ..❤❤❤☺☺☺
Answers
1. These tissues have the capacity to divide.
2. They have thin cellulose wall.
3. They do not have intercellular spaces.
4. They contain dense cytoplasm with prominent nucleus.
5. They contain many small vacuoles in their cytoplasm.
6. They produce permanent tissues.
7. They are responsible for the primary and secondary growth of the plants.
Permanent tissues:
1. These tissues have lost the capacity of division.
2. They have thick cellulose wall.
3. They have large intercellular spaces.
4. They contain thin cytoplasm with normal nucleus.
5. They contain a single large vacuole in their cytoplasm.
6. They are produced by meristemic tissues.
7. These tissues add to the various growths.
Structure and function of simple permanent tissues:
These tissues are of 3-types, such as (a) parenchyma (b) collenchymas (c) scelerenchyma.
(a) Parenchyma:
These are isodiametric and thin-walled. The cells may be oval, circular or polygonal with intercellular space. They are living. These tissues are present in all organs of the plants.
Functions:
1. These tissues are mainly concerned in storage of food.
2. In fleshy stem, they act as water storage tissues.
3. In hydrophytes large air cavities are formed in-between these tissues. These types of tissues are called aerenchyma.
4. In leaf, these tissues contain chloroplasts and help in photosynthesis and are called collenchyma.
5. Sometimes these tissues become meristamic and form cork cambium and cambium in root. Thus, they help in secondary growth.
(b) Collenchyma:
These are oval or elliptical in shape. These are living mechanical cells. The intercellular spaces at the corner of cells are thickened due to deposition of cellulose and pectin. Sometimes these cells contain chloroplasts. These are present below the epidermis i.e. stem, petiole and midrib of most of the dicot plants.
Functions:
1. They provide mechanical support to the organs.
2. These tissues containing chloroplasts help in photosynthesis.
(c) Scelerenchyma:
These are dead tissues. These are thick-walled, elongated and pointed at both ends.
The thickening of wall is due to heavy deposition of lignin. The lumens of these tissues are narrow and empty. These tissues may be present in bundles or singly. These tissues are of two types, such as, sclerenchymatous fibres and stone cells. Fibres are long and tapering at both ends with lignified wall. They are present in hypodermis of monocot stem, pericylce of many dicot, secondary wood, bundle sheath and hypodermis of many leaves.
Stones cells are oval, stellate, spherical or cylindrical with lignified cell wall. The lumen is almost obliterated. They are present in endocarp of coconut and seed coat of leguminous plants.
Functions:
(i) The main function of these tissues is to provide mechanical strength to the plant.
(ii) The jute fibres are produced from sclerenchyma.
Answer:
Meristematic tissues:
1. These tissues have the capacity to divide.
2. They have thin cellulose wall.
3. They do not have intercellular spaces.
4. They contain dense cytoplasm with prominent nucleus.
5. They contain many small vacuoles in their cytoplasm.
6. They produce permanent tissues.
7. They are responsible for the primary and secondary growth of the plants.
Permanent tissues:
1. These tissues have lost the capacity of division.
2. They have thick cellulose wall.
3. They have large intercellular spaces.
4. They contain thin cytoplasm with normal nucleus.
5. They contain a single large vacuole in their cytoplasm.
6. They are produced by meristemic tissues.
7. These tissues add to the various growths.
Structure and function of simple permanent tissues:
These tissues are of 3-types, such as (a) parenchyma (b) collenchymas (c) scelerenchyma.
(a) Parenchyma:
These are isodiametric and thin-walled. The cells may be oval, circular or polygonal with intercellular space. They are living. These tissues are present in all organs of the plants.
Functions:
1. These tissues are mainly concerned in storage of food.
2. In fleshy stem, they act as water storage tissues.
3. In hydrophytes large air cavities are formed in-between these tissues. These types of tissues are called aerenchyma.
4. In leaf, these tissues contain chloroplasts and help in photosynthesis and are called collenchyma.
5. Sometimes these tissues become meristamic and form cork cambium and cambium in root. Thus, they help in secondary growth.
(b) Collenchyma:
These are oval or elliptical in shape. These are living mechanical cells. The intercellular spaces at the corner of cells are thickened due to deposition of cellulose and pectin. Sometimes these cells contain chloroplasts. These are present below the epidermis i.e. stem, petiole and midrib of most of the dicot plants.
Functions:
1. They provide mechanical support to the organs.
2. These tissues containing chloroplasts help in photosynthesis.
(c) Scelerenchyma:
These are dead tissues. These are thick-walled, elongated and pointed at both ends.
The thickening of wall is due to heavy deposition of lignin. The lumens of these tissues are narrow and empty. These tissues may be present in bundles or singly. These tissues are of two types, such as, sclerenchymatous fibres and stone cells. Fibres are long and tapering at both ends with lignified wall. They are present in hypodermis of monocot stem, pericylce of many dicot, secondary wood, bundle sheath and hypodermis of many leaves.
Stones cells are oval, stellate, spherical or cylindrical with lignified cell wall. The lumen is almost obliterated. They are present in endocarp of coconut and seed coat of leguminous plants.
Functions:
(i) The main function of these tissues is to provide mechanical strength to the plant.
(ii) The jute fibres are produced from sclerenchyma.