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Here is a term paper on the ‘Functions of Specialised Cells, Tissues and Organs in Human Body’ for class 9, 10, 11 and 12. Find paragraphs, long and short term papers on the ‘Functions of Specialised Cells, Tissues and Organs in Human Body’ especially written for school and college students.
Term Paper # 1. Relationship between the Structure of a Cell and Its Function:
In unicellular organisms, one cell must be able to carry out all the functions of a living organism. In multicellular organisms, cells are usually modified to carry out one main function. The appearance of the cell will vary depending on what that main function is.
The following are examples of this relationship:
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A. Root Hair Cell:
Function:
The absorption of water and mineral ions (salts) from the soil.
How it is Adapted to this Function?
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The outer part of its cell wall (i.e. the part in direct contact with the soil) is in the form of a long, tubular extension (the root hair).
This Root Hair:
(i) Is able to form very close contact with the water film surrounding many soil particles
(ii) Greatly increases the surface area of the cell available for uptake of water and ions.
B. Xylem Vessels:
Functions:
(i) To conduct water and ions (dissolved salts) from the roots to the stem, leaves, flowers and fruits.
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(ii) To provide support for the parts of the plant above the ground.
How they are Adapted to these Functions:
(i) Conduction:
Xylem vessels are long narrow tubes, stretching from the roots, through the stem, to the leaves. They are stacked end-to-end like drain pipes.
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(ii) Support:
(a) The walls of xylem vessels are strengthened by the chemical lignin. As the lignin in the walls builds up, it eventually kills the xylem vessels. There is therefore no layer of cytoplasm to restrict the flow of water and dissolved salts.
(b) Xylem vessels are part of the vascular bundles which run through the stems of plants like steel reinforcements in concrete pillars. They help to resist bending strains caused by the wind.
C. Red Blood Cells:
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Function:
To carry oxygen around the body.
How they are Adapted to this Function?
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(i) The cytoplasm in red blood cells contains the pigment haemoglobin. Haemoglobin combines with oxygen in the lungs to become oxy-haemoglobin.
(ii) The cells are small (7 µm × 2 µm) and there are many of them, so they have a very large surface area for oxygen absorption.
(iii) They have a biconcave shape, making their surface area for absorption even larger.
(iv) They are flexible, allowing them to be pushed easily through small blood vessels (capillaries).
D. Muscle Cells:
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Function:
To cause movement when they contract. (Contraction brings about a decrease in length of the cell. Muscles can do work only when they contract, never when they relax.)
How they are Adapted to this Function?
(i) They are long and thin, allowing many to work side-by-side for greater force, or to form a contractile network.
(ii) Each cell (or ‘fibre’) contains many smaller fibrils – each capable of contracting.
(iii) Their cytoplasm contains many mitochondria (visible only with an electron microscope) which are responsible for releasing energy within a cell and necessary here to bring about contraction.
Term Paper # 2. How Cells Combine to Improve their Efficiency?
One cell working on its own would achieve very little in an individual plant or animal, so we usually find many similar cells lying side-by-side and working together, performing the same function.
Definition of Tissue:
Many similar cells working together and performing the same function are called a Tissue.
Examples of Tissues:
(i) Xylem tissue in the vascular bundles of a plant.
(ii) Muscular tissue in the intestine wall of an animal.
Different types of tissue often work together to achieve a combined function.
Definition of Organs:
Several tissues working together to produce a particular function form an Organ.
Examples of Organs:
(i) The leaf of a plant – an organ for the manufacture of carbohydrates during photosynthesis.
(ii) The eye of an animal – the organ of sight.
Several different organs may be necessary in order to carry out a particular function.
Definition Organ Systems:
A collection of different organs working together to perform a particular function is called an Organ System.
Examples of Organ Systems:
(i) The sepals, petals, stamens and carpels (i.e. the flowers) of a plant – for reproduction
(ii) The heart, arteries, veins and capillaries in an animal, i.e. the circulatory system.
Definition of Organism:
An Organism is a collection of organ systems working together.
The increasing order of cell organisation found within any living organism is:
