Article-25

Article-2⃣5⃣

*Self-Practice*

Std.10th -Science Part 2

Topic 2: *Life Process in Living Organisms Part-1*

 ★★★★★★★★★

*Today's exercise*:

1) “Explain the importance of water in our body.

2) "Fibers are also essential nutrients."  Explain this statement.

(Ref: See page 17 in the textbook.)

 ★★★★★★★★★★

 *Learn cells*

*Lord Krishn:* - We have seen how important nutrients are for the survival of the cells and so for the living things.  Ask if you have any more doubts about cells!

*Arjun:* - Hey Vasudeva, as you say, I understand how big a system is working to keep the cells alive. But how many cells do we have in our body?

*Lord Krishn:* - The structure of cells in the human body is very complex. If you are asking about the number of cells, the answer would be "innumerable".   Even though the number is beyond 100 trillion cells.

*Arjun:* - That is, the human body has as many cells as the stars in the sky or more! So how small or large are these cells?

*Lord Krishn:* - Cells come in different sizes.  One drop of blood contains about 40 million red blood cells. Guess how small they will be from this! Cell sizes are measured in micrometers and nanometers. One nanometer is 100 thousandth part of a millimeter.  You may find it amusing to hear that an egg is also a single cell. The Ostrich's egg is the largest cell.

*Arjun:* - It's fun!  But hey Madhav, how many days do cells live?  Do they have life span as that of ours? 

*Lord Krishn:* - The cells in our body live for about 4 days.

*Arjun:* So what happens to dead cells?

*Shri Krishn:* - Cells become old, injured and die. They are digested by the "lysosomes" in the cell and the essential substances are reused.

*Arjun:* - Do these lysosomes also digest injured cells?

*Lord Krishn:* - Yes. In place of the injured cells, new cells are formed by cell division and the wound is gradually healed.

*Arjun:* - Hey Vasudev, what is cell division?

*Shri Krishn:* - Cell division is the process by which a mother cell decided (splits) into two daughter cells. Thus new cells are formed. 

*Arjun:* - Hey Vasudev, I am eager to know how cell devides. Please tell me in detail. 

*Shri krishn:* - Hey Parth, I would like to explain the cell division in detail. But not today, tomorrow!

■■■

...✍

*Shrishail Mathapati,* Kolhapur 

💢Ⓜ💢Ⓜ💢Ⓜ