Structure of cell

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Reference Books
= Teaching Outlines =

Learning objectives

 * 1) All living organisms are made up of cells.
 * 2) Cells are the structural and functional unit of an organism.
 * 3) Cell consists of three distinct parts when observed through compound microscope-cell membrane, cytoplasm and nucleus.

Notes for teachers

 * 1) This unit begins with how the cell was discovered by Robert Hook. This lead to the discovery of different types of microscopes.
 * 2) Every organism is made up of one or more than one cells.The cell is the basic structural, functional and biological unit of all known living organisms. Cells are the smallest unit of life that can replicate independently, and are often called the "building blocks of life". The study of cells is called cell biology. Cells consist of a protoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. Organisms can be classified as unicellular (consisting of a single cell; including most bacteria) or multicellular (including plants and animals). While the number of cells in plants and animals varies from species to species, humans contain about 100 trillion  cells. Most plant and animal cells are visible only under the microscope, with dimensions between 1 and 100 micrometres.
 * 3) The cell was discovered by Robert Hooke in 1665. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that all cells come from preexisting cells, that vital functions of an organism occur within cells, and that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.[5] Cells emerged on Earth at least 3.5 billion years ago.
 * 4) There are different kinds of cells in plants and animals.
 * 5) Cells control every activity that take place in an organism.

Activities

 * 1) Activity No #1Observation of cell
 * 2) Activity No #2 Concept Name - Activity No.

Concept #
- Diffusion

Learning objectives

 * 1) Transport of materials in plant and animal cells takes place through different processes.
 * 2) In diffusion movement of molecules take place from a region of higher concentration to a region of lower concentration.
 * 3) 3.Diffusion is seen in both lower and higher organisms.

Notes for teachers
The air arriving in the alveoli has a higher concentration of oxygen than the “stale” air in the alveoli. The increase in oxygen concentration creates a concentration gradient for oxygen between the air in the alveoli and the blood in the capillaries that surround the alveoli. Oxygen then moves by diffusion, down the concentration gradient, into the blood. The other consequence of the air arriving in alveoli is that the concentration of carbon dioxide in the alveoli decreases (air has a very low concentration of carbon dioxide compared to the blood in the body). This creates a concentration gradient for carbon dioxide to diffuse from the blood into the alveoli.
 * 1) Movement of materials or molecules in all living organisms take place through diffusion.
 * 2) In diffusion movement of molecules take place from a region of higher concentration to a region of lower concentration.
 * 3) Diffusion is the net movement of a substance (e.g., an atom, ion or molecule) from a region of high concentration to a region of low concentration. This is also referred to as the movement of a substance down a concentration gradient. A gradient is the change in the value of a quantity (e.g., concentration, pressure, temperature) with the change in another variable (e.g., distance). For example, a change in concentration over a distance is called a concentration gradient, a change in pressure over a distance is called a pressure gradient, and a change in temperature over a distance is a called a temperature gradient.
 * 4) An example of a situation in which bulk flow and diffusion can be differentiated is the mechanism by which oxygen enters the body during external respiration (breathing). The lungs are located in the thoracic cavity, which is expanded as the first step in external respiration. This expansion leads to an increase in volume of the alveoli in the lungs, which causes a decrease in pressure in the alveoli. This creates a pressure gradient between the air outside the body (relatively high pressure) and the alveoli (relatively low pressure). The air moves down the pressure gradient through the airways of the lungs and into the alveoli until the pressure of the air and that in the alveoli are equal (i.e., the movement of air by bulk flow stops once there is no longer a pressure gradient).

Activities

 * 1) Activity No #1Diffusion

=Activity No # 1 - Demonstration of Diffusion= At the end of this experiment children should be able to know how diffusion take place from one place to another.

Estimated Time
15 minutes

Materials/ Resources needed
An agarbathi, a match box.

Prerequisites/Instructions, if any
Students are asked to note down the time benchwise as soon as they get the smell of the agarbathi.

Process (How to do the activity)

 * 1) Close all the windows and doors of the classroom.
 * 2) Light the agarbathi with the matchstick.
 * 3) Place it in one corner of the classroom.
 * 4) Observations written in an organized format - aim of the experiment, method and questions below are to be answered in the observation.

Developmental Questions (What discussion questions)

 * 1) Did you get the smell as soon as you light the agarbathi?
 * 2) Did all of you smell the agarbathi at the same time?

Question Corner
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=#Activity No #2 Demonstration of Diffusion=

At the end of this experiment children should be able to know how diffusion take place in water. At the end of this experiment children should be able to know how diffusion take place in water.

Estimated Time
15 minutes

Materials/ Resources needed
A glass beaker, water and ujala blue.

Prerequisites/Instructions, if any
Students are asked to observe how the blue colour spreads in water.

Process (How to do the activity)

 * 1) Take a glass beaker with water.
 * 2) Pour 2 to 3 drops of ujala blue into the beaker.
 * 3) Allow the beaker for 2to 3 minutes without shaking.
 * 4) Observations written in an organized format - aim of the experiment, method and questions below are to be answered in the observation

Question Corner
To link back to the topic page the link of the page name from where activity was given''' Back

Materials/ Resources needed
A glass beaker, water and ujala blue.

Prerequisites/Instructions, if any
Students are asked to observe how the blue colour spreads in water.

Process (How to do the activity)

 * 1) Take a glass beaker with water.
 * 2) Pour 2 to 3 drops of ujala blue into the beaker.
 * 3) Allow the beaker for 2to 3 minutes without shaking.
 * 4) Observations written in an organized format - aim of the experiment, method and questions below are to be answered in the observation

Question Corner
To link back to the topic page the link of the page name from where activity was given''' Back

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