Study of Tissues and Diversity in Shapes and Sizes of Plant and Animal Cells

Do you know how water reaches the leaves and upward parts of plants from the roots? There are special tissues xylem, and the phloem, responsible for carrying out transportation functions over long distances. Do you know plants are made of different types of tissues? xylem and phloem are also known as complex permanent tissues as they are made of more than one type of cell.

To know more about this experiment, continue reading this article.

Table of Content 

• Aim

• Apparatus required

• Theory 

• Procedure

• Observation

• Result

• Precautions

• Lab Manual Questions 

• Viva Questions

• Practical Based Questions 

• Conclusion

• FAQs

Aim

To study the different tissues and diversity in shapes and sizes of plant and animal cells such as palisade cells, parenchyma, sclerenchyma, collenchyma, guard cells phloem, xylem, squamous epithelium, blood cells, and muscle fibres through the preparation of permanent/temporary slides.

Apparatus Required 

 Permanent slide of 

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

• V.S of the shoot apex and root apex

• T.S of Cucurbita stem/ Mentha

• Macerated material of Vitis/Bougainvillea, Tridex

Things required for maceration technique 

• Safranin

• Glycerine 

• Tiny twigs of plants 

• Microscope 

• Wire gauge 

• Burner 

• Knife 

• Cheesecloth 

• Thread 

• Tripod Stand 

• Needles 

• Glass rod 

• Cotton blue 

• Beaker 

• Slides 

Theory 

Tissues are defined as a group of cells having a common origin, similar structure, and functions that also work together as a unit. There are various types of tissues in plants. 

There are two main divisions of plant tissues - Meristematic tissues and permanent tissues.

Meristematic tissues retain the capability to divide, whereas permanent tissues lose the complete capacity to divide. Meristematic tissues are three types - 

• root and shoot apical meristems, 

• intercalary meristems and 

• lateral meristems.

Permanent tissues are two types - Simple permanent and complex permanent tissues. Simple permanent tissues are of three types - 

• Parenchyma

• Collenchyma

• Sclerenchyma

There are two types of complex permanent tissues 

• Xylem

• Phloem 

All tissues have different characteristic features. They can be recognised based on their characters under the microscope.

Procedure

The steps of the procedure are explained below:

1. Pick some plant material of younger branches of thickness equal to the size of a hairbrush of woody plants.

2. Cut the plucked branch into smaller pieces of at least 0.5 cm in length. 

3. Now place these pieces of twigs into a beaker containing water to boil. 

4. Boil this sample for 10-15 minutes till the sample settle into the base of the beaker. 

5. Boiling is done to remove air from the sample. 

6. Now transfer the sample into a beaker containing maceration fluid. 

7. Boil this sample for 10-15 minutes. This boiling is done to make the sample soft and pulpy.

8. Tie muslin clothes to the mouth of the beaker and then rinse this sample continuously with tap water to remove traces of maceration fluid. 

9. After rinsing add some staining material such as cotton blue for phloem and safranin for xylem to the sample. 

10. Then drop some parts of this sample onto the glass slide along with a drop of glycerine. 

11. Split this sample using two needles. 

12. Place a coverslip on this sample and then observe under the microscope. 

13. Draw your observations in your notebook and match them with the standard diagram.

The following slides would be analyzed: 

• T. S of Nerium Leaf - seen for spongy and palisade tissue

• T. S of lotus petiole, and leaf - seen for aerenchyma

• V. S of root and shoot apex - seen for meristem

• T. S of Mentha stem - seen for simple tissue.

Observations

• Chlorenchyma - These are also types of parenchyma cells that contain chloroplast. These are also of two types- palisade parenchyma and spongy parenchyma. Here spongy parenchyma cells are loosely aligned and palisade parenchyma is tightly bound. These cells are columnar and compactly arranged.

• Aerenchyma - These cells have a large amount of air space. 

• The epidermis is the outermost layer of plant tissues. The epidermis is also made of parenchyma cells.

• Stomata are the pores in the epidermis of leaves in some plants, stomata are present on both surfaces of the epidermis, and in some plants, stomata are present only on one of either surface.

• Then slides are observed under a microscope for different characteristics and positions of cells and tissues.

• Sclerenchyma tissues are pointed, and elongated and intercellular space will be absent.

Result

Different cells and tissues of plants are observed under the microscope.

Precautions

• Every instrument should be handled very carefully. 

• A boiled sample should be taken out with very caution.

• Tissues should be studied very carefully in the microscope.

• Handle plant tissues very carefully. 

• All tissues or specimens should be stained very carefully. 

• Place the coverslip very carefully without any air bubbles.

Lab Manual Questions

1. To observe palisade parenchyma, which part of the plant should be taken?

Ans: Upper part of the leaf should be taken for this. Because palisade parenchyma tissues are present in the upper epidermis of the leaf.

2. What type of cells has angular thickening?

Ans: Collenchyma cells have angular thickening; they are used to give mechanical support to plants. 

3. Where is angular collenchyma located?

Ans: Angular collenchyma is present in the Cucurbita genus.

Viva Questions

1. What do you mean by secondary growth?

Ans: Secondary growth is the growth that occurs due to the division of lateral secondary meristems.

2. Why do aerenchyma tissues have large air spaces?

Ans: These tissues have larger air spaces, these spaces store gases and also provide buoyancy to plant tissues. 

3. What are the types of complex permanent tissues?

Ans: Complex permanent tissues are of two types - xylem and phloem. 

4. Write the composition of sclerenchyma cells.

Ans: Sclerenchyma cells are made of lignin and cellulose. 

5. Which plant does not have companion cells?

Ans: Companion cells are not found in gymnosperms. 

6. Why do monocots not show secondary growth?

Ans: Monocots do not show secondary growth because they do not have cambium and have closed vascular bundles. 

7. What are conjoint vascular bundles? 

Ans: Conjoint vascular bundles are arranged how vascular bundles are arranged, here xylem and phloem are arranged on the same radius. 

8. What is periderm?

Ans: Periderm is the outermost protective layer of plants. It is secondary in origin. 

Practical Based Questions

Q1. What is maceration fluid?

1. Soften plant tissues 

2. Harden plant tissue 

3. Both of the above 

4. None of the above 

Ans: 1. Soften plant tissue

Q2. Which substances are needed to prepare maceration fluid?

1. Nitric acid, 

2. chromic acid, and 

3. potassium dichromate 

4. All of the above

Ans: 4. All of the above

Q3. Which stain should be used to observe xylem tissues?

1. Methylene blue

2. Safranin

3. Ziehl Nielsen stain 

4. None of the above

Ans: 2. Safranin

Q4. Which stain should be used to observe phloem tissues?

1. Glycerine 

2. Methylene blue

3. Safranin

4. None of the above

Ans: 1. Glycerine

Q5. Why are twigs boiled?

1. To remove water

2. To remove air

3. To remove 

4. None of the above

Ans: 2. To remove air

Q6. The study of tissues is known as?

1. Cytology

2. Histology

3. Chronology

4. None of the above

Ans: 2. Histology 

Q7. What is the shape of mesophyll cells?

1. Cylindrical

2. Rectangular

3. Irregular

4. None of the above

Ans: 1. Cylindrical 

Q8. Which of the following is complex tissue?

1. Parenchyma

2. Chlorenchyma

3. Xylem 

4. All of the above

Ans: 3. Xylem 

Conclusion

In this article, we have studied an experiment on tissues and the diversity in the shapes and sizes of plant and animal cells. We have seen that plant tissues have different shapes and sizes. Because of their function and structural role, these different cells and tissues have different shapes and sizes. We have also seen certain precautions taken while carrying out the procedure.