[Biology Class Notes] on Study of Tissues and Diversity in Shapes and Sizes of Plant and Animal Cells Pdf for Exam

Aim of the Experiment

To study the one-of-a-kind tissues and variety in sizes and shapes of animal and plant cells such as guard cells, palisade cells, parenchyma, sclerenchyma, collenchyma, phloem, xylem, squamous epithelium, mammalian blood smear, and muscle fibers via the training of permanent/brief slides.

Theory

What is Tissue?

A tissue is an ensemble or cluster of similar cells that perform a shared function that is similar in shape and size.  

Tissues Can be Classified as –

a) Parenchyma

b) Collenchyma

c) Sclerenchyma

a) Meristematic tissue – 

b) Permanent tissue – It can be further classified as- Simple permanent tissue, complex permanent tissue, and special or secretory tissue

 

What is a Cell?

Before moving further, it is necessary to define a cell in a single line. Simply, a cell is a basic building block or structural, functional, and biological unit of all living organisms. 

 

Requirements

 

A. Permanent Slides of:

• T.S of Nerium Leaf, T.S of Lotus leaf, T.S of Lotus stem/petiole

• V.S of root apex and shoot apex

• T.S of Mentha/Cucurbita stem

• Macerated material of Tridax, Vitis/Bougainvillea

 

B. Things Required for Maceration Technique

 

Requirements for Maceration Fluid

• Chromic acid should be dissolved with an equal quantity of 10% nitric acid.

• Preparation of chromic acid is done by adding 100ml of concentrated H2SO4 gradually in 10ml of water.

• Now add K2Cr2O7 (potassium dichromate) – 50gm

• The stock solution is ready. 10ml of this solution is diluted up to 100ml for the preparation of the working solution of the maceration liquid.

 

Procedure 

• Bring some fine green fresh and younger branches from a locally accessible woody plant. Thickness must be of a toothpick.

• Snip the twigs into smaller bits of 0.5cm long.

• Put the pieces of twigs to the beaker holding water. Boil it for 10-15minutes till the sample settles  down at the base.

• This way the air inside the sample will be removed.

•  Then transfer the material into a beaker having the maceration fluid. Boil it until it turns pulpy and soft for at least to 10-15 minutes.

• Put muslin cloths to the beaker’s mouth. With tap water, rinse the material continuously to remove the traces from the maceration fluid.

• Now add some drops of safranin to the material to stain the xylem or the phloem – cotton blue.

•  place the stained material in a drop of glycerine into a glass slide.

• Split the cells using two needles.

• Plant a coverslip onto the slide and observe under a microscope.

• Sketch and Compare your observation with the diagram given.

 

Analyze the Following Slides:

• For palisade and spongy tissue – T.S of Nerium Leaf

• For Aerenchyma – T.S of Lotus petiole. Lotus leaf

• For meristem – V.S of root and shoot apex

• For simple tissues – T.S of Menthe stem or Cucurbita

 

Observation:

• Chlorenchyma is parenchyma cells with chloroplasts. They may have spongy or loosely arranged cells or palisade – columnar cells compactly aligned.

• If there is a presence of large intercellular spaces into the cells it is aerenchyma.

• The protective tissue or the epidermis is the parenchyma tissue forming the outer covering of leaves, stem, or root.

• Observe the section of the leaf.

• Mesophyll of the leaf is covered by lower and upper epidermis.

• Lower epidermis produces small pores known as stomata. In some plants, both the lower and upper epidermis of the leaf show stomata.

• Tissues are observed for their characteristics, position in the different parts of the material of the plant.

• Sketch diagrams to display the tissue type and their locations.