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osmosis and guard cells class 9 biology in urdu
osmosis and guard cells class 9 Biology in Hindi
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00:00Assalamu alaikum today our topic of discussion is osmosis and guard cell.
00:08What is osmosis? Water molecules always move from low solute concentration to high solute
00:17concentration. This is called osmosis. Then what is guard cell? To understand guard cell,
00:27it is important to know the structure of the leaf. For example, we have taken a leaf,
00:32we have cut a small section of it and shown it by enlarging it. So, the uppermost part of the leaf
00:40is called epidermis. Epi means outer, dermis comes from derma which means skin. That is,
00:51the uppermost layer is called epidermis and there are two epidermis present in the plant.
00:57The uppermost layer is called upper epidermis and the lowest layer is called lower epidermis.
01:03And in epidermis, guard cells are present. And it is always in the form of a pear,
01:12a beam-shaped structure is present in epidermis. This is called a guard cell. And between two guard
01:21cells, there is a small pore, a small opening. This is called stromata as shown here. So,
01:30guard cells are present in the upper epidermis and lower epidermis. And the upper epidermis
01:37and lower epidermis are the upper layers of the plant leaf.
01:42Here, the guard cell is shown by enlarging it. During the day, when the stromata opens,
01:52the structure of the guard cell is like this. These are two guard cells. It is always in the
01:57form of a pear. This is a guard cell and this is a guard cell. And between these two,
02:02the structure of the guard cell is like this. This is a guard cell and this is a guard cell.
02:13So, the guard cell is green in color and chloroplasts are present in it.
02:20We read about chloroplasts in detail at the back. Chloroplasts have a green pigment present
02:28in it, which is called chlorophyll. And chlorophyll are responsible for photosynthesis. The photosynthesis
02:35process is taking place in chlorophyll. So, plants in the presence of sunlight make their
02:43food. This process is called photosynthesis. So, in the presence of sunlight, carbon dioxide
02:52plus water react in the presence of sunlight. And after this, glucose is made. Glucose is
03:02a solute. And with this, oxygen is made. As a by-product, plants are made. Because oxygen
03:12is not needed in the plant, plants extract it through stromata. When photosynthesis is
03:24taking place during the day, glucose is being made in the guard cell. So, glucose is a solute.
03:33And here, the concentration of solute will increase as compared to the surrounding.
03:38So, water always moves from low solute concentration to high solute concentration. So, as more as possible, water will enter the guard cell.
03:45Because of this, guard cells will expand. And this way, its stromata remains open during the day.
03:53Through this stromata, plants exchange gaseous, which is CO2. So, this is the process of exchanging
04:00carbon dioxide. So, plants take carbon dioxide from their environment. And where do they
04:07take water from? So, the roots of the plants are in the guard cell. So, the plants take
04:14water from the guard cell. So, this is the process of exchanging gaseous. So, this is
04:21the process of exchanging gaseous. So, this is the process of exchanging gaseous. So,
04:28this is the process of exchanging gaseous. So, this is the process of exchanging gaseous.
04:35So, this is the process of exchanging gaseous. So, this is the process of exchanging gaseous.
04:42So, this is the process of exchanging gaseous. So, this is the process of exchanging gaseous.
04:49So, this is the process of exchanging gaseous. So, this is the process of exchanging gaseous.
04:56So, this is the process of exchanging gaseous. So, this is the process of exchanging gaseous.
05:03So, this is the process of exchanging gaseous. So, this is the process of exchanging gaseous.
05:10So, this is the process of exchanging gaseous. So, this is the process of exchanging gaseous.
05:17So, when photosynthesis is not happening, glucose is also not formed.
05:24So, water will move out of the guard cell.
05:30So, here is an isotonic condition.
05:34So, as much solute is inside the guard cell, so much is in its surrounding.
05:39So, as much water is entering inside the guard cell, so much is coming out.
05:47Because of this, these cells become flaccid.
05:51Because of this, stomata also become closed.
05:55As shown in this diagram.
05:57As shown in this diagram.
05:59As shown in this diagram.
06:01As shown in this diagram.
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