Improvement in food resources

Introduction

==Tissues== → Group of cells having common origin working together to perform a particular function.

Term Tissue was coined by “Xavier Bachat”.

Study of Tissue is known as “Histology”.

Plant Tissues

1. Dead Tissues are abundant.
2. They require less maintenance energy because they are autotrophic (makes its own food).
3. Differentiation of tissues in meristematic tissues and permanent tissues which are located in different parts based on their dividing capacity.
4. Dividing of meristematic tissues led to growth throughout the life.
5. Organization of plant tissues are simple.
6. Placement in based for their stationary position.

They were divided into two categories :-

1. Meristematic tissues.
2. Permanent tissues.

Meristematic Tissues

They are classified in 3 Groups.

1. Apical Meristem

2. Intercalary meristem

3. Lateral Meristem

   

@@Apical meristem@@

apex → tip

It is further divided into 2 categories.

1. Shoot apical meristem.
2. Root apical meristem.

%%Shoot apical meristem.%%

1. Present at the tips of the shoot/stem.
2. Help to increase the length or the shoots/stem.
3. [Primary Growth]

%%Root apical meristem%%

1. Present at the tips of the roots.
2. Helps to increase the length / height of the roots.
3. [Primary Growth]

@@Intercalary Meristem@@

1. Present in only few plants, such as grasses.
2. Present near the node / at the base of the internode.
3. helps in the elongation of the internode in grasses thereby increases the length of the stem.
4. Helps in the regeneration of leaves after the grazing of herbivores.
5. [Primary Growth]

@@Lateral Meristem@@

1. Helps to increase thickness / girth / width of the stem / root(rarely).
2. [Secondary Growth]
3. Also called [Secondary meristem]
4. [Ring meristem]
5. [Cylindrical meristem]

@@Characteristics of meristematic tissues@@

• they are made of living cells.
• the cells of meristematic tissues have dense protoplasm, and their cell wall is thin.
• the nuclei are large and clearly visible.
• vacuoles are almost absent.
• cells are tightly packed with almost no intercellular spaces.
• they do not store food and exhibits high metabolic activity.
• the cells actively divide to add new cells to the plant.

Permanent Tissues

Meristematic tissues are converted in permanent tissue by giving it a fixed & permanent shape, size, function and location.

• The cells are originating from pre-existing meristematic tissue.
• They do not divide.
• The cells are fully different from each other.
• The cells differ in shape and size.
• Visible intercellular spaces are present.
• Large vacuoles are present in mature cells.
• Metabolic activities occur at low rate.
• Cell wall may be thin or thick.

They are divided into 3 categories.

@@Parenchyma@@

1. It is a living tissue.
2. Most abundant tissue.
3. Cells of this tissue have a thin cell wall made up of cellulose.
4. Cells of this tissue have dense cytoplasm with small nucleus and large vauoles.
5. Intercellular spaces are present between cells.
6. It is present in all organs of plant.
7. Idioblast ( parenchyma ) stores resin, tannin, gums and oil.

%%Modification/types of parenchyma%%

1. Chlorenchyma

   Parenchyma that contains chloroplast that contains chlorophyll that helps in photosynthesis.

   In short, Chlorenchyma → Chloroplast → Chlorophyll → Photosynthesis

2. Aerenchyma

   A type of parenchyma made of rounded cells with large air cavities.

   It is found in aquatic plants

   Function is to provide tendency to float to plants

@@Collenchyma@@

• Cells of this tissue are living, elongated or vary in structure.
• Cells of this tissue are irregularly thickened to the deposition of cellulose, hemicellulose and pectin.
• Intercellular spaces are very little or absent between cells of this tissue.
• sometime, chloroplast is also present.
• 

@@Sclerenchyma@@

Animal Tissues

1. Living Tissues are abundant.
2. They require more maintenance energy because they are heterotrophic (have to move for food).
3. Differentiation of tissues is absent in animal as their growth is uniform.
4. Animal does not show growth after reaching maturity. Reparative growth is present.
5. Organization of plant tissues are complex.
6. Tissue organization is targeted towards high mobility of animals.