|Aim||To identify parenchyma and sclerenchyma tissues in plants, from prepared slides and to draw their labelled diagrams.|
|Materials Required||Permanent slides of parenchyma tissues, sclerenchyma tissues, striated muscle fiber, nerve cell and compound microscope.|
|Theory||Plant tissues are groups of cells that have similar structures and functions. There are four main types of plant tissues:|
Meristematic tissue: This type of tissue is responsible for plant growth and cell division. It is found in the tips of roots and shoots.
1 . Epidermal tissue: This tissue covers the surface of the plant and protects it from water loss and external damage. It also contains stomata, which are small openings that allow gases to pass in and out of the plant.
2 . Ground tissue: This tissue is responsible for photosynthesis, storage, and support. It is found in the interior of the plant and includes parenchyma, collenchyma, and sclerenchyma cells.
3 . Vascular tissue: This tissue is responsible for the transport of water, minerals, and nutrients throughout the plant. It is divided into two types: xylem, which transports water and minerals from the roots to the leaves, and phloem, which transports food from the leaves to the rest of the plant.
|Procedure||1) Take the prepared slides of parenchyma, collenchyma and sclerenchyma tissues one by one.|
2) Adjust the slide under compound microscope.
3) Initially adjust the slide on 10 X objective and then 45X objective,
4) Draw the diagram of your observation and label appropriately.
|(a) Parenchymatous tissues:||Cells in parenchyma tissue are roughly spherical in shape.|
There are small spaces between the cells in parenchyma tissue.
Parenchyma cells have a large central vacuole and peripheral cytoplasm containing a nucleus.
This type of tissue is typically found in the soft parts of plants, such as leaves, roots, and flowers.
Parenchyma cells are involved in several important functions, including storage and photosynthesis.
|(b) Sclerenchymatous tissues:||Collenchymatous cells have an oval to elongated shape.|
Each cell has a large central vacuole and peripheral cytoplasm containing a prominent nucleus.
The corners of the cells are thickened with cellulose and pectin.
There are no intercellular spaces present in collenchyma tissue.
This type of tissue is typically found in the petiole, leaves, and stems, just below the epidermis.
The main function of collenchyma tissue is to provide mechanical support and strength.
|(c) Collenchymatous tissues:||The cells in sclerenchyma tissue have thick, non-living walls that are heavily thickened with lignin. There are two types of sclerenchyma cells: fibers, which are elongated cells with tapering ends, and sclerae’s (also known as stone cells), which are roughly isodiametric cells with narrow cavities. Sclerenchymatous cells are equipped with pits that act as connections with neighboring cells. The primary role of sclerenchyma is to provide support and structural strength to the plant.|
|Aim||To identify striped, smooth and cardiac muscle fibers and nerve cells in animals, from prepared slides. Draw their labeled diagrams.|
|Materials Required||Prepared slides of striped, smooth and cardiac muscle fibers and nerve cells in animals and compound microscope.|
|Theory||Animal tissues are groups of cells with similar structures and functions that work together to perform specific tasks within an animal’s body. There are four main types of animal tissues:|
Epithelial tissue: This tissue covers the surface of the body and lines organs and cavities. It functions to protect the body from injury, regulate the exchange of materials between the body and its environment, and secrete and absorb substances.
Connective tissue: This tissue provides support and structure to the body. It includes bone, cartilage, adipose (fat), and blood, among others. Connective tissue functions to anchor organs, protect and cushion the body, and transport nutrients and waste products.
Muscle tissue: This tissue is responsible for movement and locomotion. There are three types of muscle tissue: skeletal, cardiac, and smooth. Skeletal muscle is attached to bones and allows voluntary movement, while cardiac and smooth muscles are involuntary and control the contraction and relaxation of organs such as the heart and digestive tract.
Nervous tissue: This tissue is responsible for communication within the body. It includes neurons and supporting cells such as glial cells. Nervous tissue functions to receive and transmit information, integrate information, and coordinate responses to stimuli.
|Procedure||1) Take a prepared slide of striped, smooth, cardiac muscle fibers and nerve cells.|
2) Observe the slide under compound microscope.
3) Adjust the slide first under 10X or low power objective.
4) Once you observe the structure on 10X objective, move it on 45 X objective.
|(a) Striated muscles:||Instead of having a single nucleus, these muscles exhibit multiple nuclei distributed along their long, cylindrical fibers.|
The appearance of dark and light bands in an alternating pattern is a characteristic feature of these muscles.
The cells of these muscles are embedded in connective tissue, which supports and encloses them.
Encircling each muscle cell, there is a membrane known as sarcolemma that plays a vital role in muscle contraction.
|(b) Non-striated muscles or Smooth muscles:||The cells of these muscles have a spindle-like shape and their nucleus is located at the center.|
These muscles lack the characteristic alternating pattern of dark and light bands seen in striated muscles.
Non-striated muscles are under involuntary control and are commonly found in blood vessels and the digestive tract.
|(c) Cardiac muscles:||Cardiac muscle cells are elongated and exhibit branching patterns, each containing a single nucleus.|
Similar to skeletal muscle, they also display alternating light and dark bands.
These muscles are not under voluntary control and are referred to as involuntary muscles.
Cardiac muscle tissue is exclusively found within the walls of the heart.
These muscles are capable of sustained contractions over an individual’s lifetime and play a crucial role in the rhythmic beating of the heart.
|(d) Nerve cell:||Neurons are comprised of a cell body known as cyton, which is relatively large in size.|
The cyton contains a prominent nucleus that controls cellular activities.
Neurons have projections called dendrites that receive signals from other neurons or sensory cells.
Axons are long dendrites that transmit signals away from the cyton to other neurons, muscle cells, or glands.
Nerve endings are attached to muscles, enabling them to communicate with and control muscle function.