Question:
Why can't single cells grow very large? Or Big organisms like human beings are multi-cellular? Why can't such big organisms be a single large cell?
Answer:
Cell is the fundamental unit of life. All metabolic activities (necessary for life) takes place inside the cell. All raw materials required for these metabolic activities enter through the cell surface via cell membrane. Greater the surface are, large amount of raw material can enter (this is the case of uni-cellular micro-organisms). As the size of cell grows larger, the Surface Area to Volume (SA/V) ratio decreases, it means raw material required for the cell to survive will not be sufficient. Thus, SA/V ratio limits the size of the cell. Therefore big organisms like human beings are mulch-cellular.
The Fundamental Unit of Life
Q 1.
Name the sac like structure which form the grana?
Q 2.
Identify cell organelle and write down its name:
Called 'suicide bags' of a cell.
Q 4.
What is the full form of DNA and RNA?
Q 5.
Give examples of cells which are muti-nucleate (i.e. having many nuclei).
Q 6.
What are the function of nucleus?
Q 7.
Identify cell organelle and write down its name:
Slipper or oval shaped, its inner membrane is multi-folded and has lot of chemical activity
Q 8.
Identify cell organelle and write down its name:
Membrane-bound vesicles arranged approximately parallel to each other. Active in synthesis, modification, sorting, and Secretion of cell products
Q 9.
Who discovered nucleus in the cell?
Q 10.
Who discovered Golgi apparatus?
Q 11.
Identify cell organelle and write down its name:
A tough, non-living layer, it prevents plant cells from bursting, freely permeable
Q 12.
Identify cell organelle and write down its name:
Powehouse of cell
Q 13.
Give an example of anucleate cell i.e. cell without nucleus.
Q 14.
Put dried raisins in plain water and leave them for some time. Then place them in concentrated solution of sugar or salt. What do you observe in both cases?
Q 15.
What is the energy currency of the cell called?
Q 16.
What are the components nucleus?
Q 17.
What is the function of nucleoplasm?
Q 18.
Why can't single cells grow very large? Or Big organisms like human beings are multi-cellular? Why can't such big organisms be a single large cell?
Q 19.
Name the cell organelles involved in synthesis, packaging and movement of protein (or other macromolecules) inside a cell.
Q 21.
Define Passive Transport.
Q 22.
What are the conditions for osmosis?
Q 23.
Which organelle of the cell in animals helps in osmregulation?
Q 24.
Identify cell organelle and write down its name:
Detoxify drugs and poisons specially in liver cells.
Q 25.
In which year electron microscope was invented?
Q 27.
Are plastids present in all cells? What are its types?
Q 28.
Which cell organelle is called 'kitchen of plant'?
Q 29.
What are chromosomes?
Q 30.
Who discovered Virus?
Q 31.
Why is mitochondria absent in red blood cells?
Q 32.
Identify cell organelle and write down its name:
Appear brown dots either present freely in cell or bound to a membrane and make proteins.
Q 33.
Name the smallest cell in human body.
Q 34.
Name the longest cell in human body.
Q 35.
Who proposed fluid-mosaic model of cell or plasma membrane?
Q 36.
Is plasma membrane permeable or selectively permeable?
Q 37.
What would happen if the plasma membrane ruptures or breaks down?
Q 38.
Why are lysosomes known as suicide bags?
Q 39.
What is osmoregulation?
Q 40.
Which cell organelle is called 'control center'?
Q 41.
Are there any exceptions to cell theory proposed by Schleiden & Schwann and Virchow? If yes, what are those?
Q 42.
Which of the following cell is better candidate to study lysosomes?
(a) White Blood Cell
(b) Muscle Cell
Q 43.
Identify cell organelle and write down its name:
Jelly like substance containing particles and other organelles. What is it?
Q 44.
Identify cell organelle and write down its name:
A fluid-filled space surrounded by a membrane. Generally contains salts and sugars in plants.
Q 45.
Identify cell organelle and write down its name:
Thread like structures made up of in DNA and proteins. Converts to chromosomes when cell is dividing.
Q 46.
Identify cell organelle and write down its name:
Present in some animal cells, help in locomotion.
Q 47.
Identify cell organelle and write down its name:
A structure involved in production of ribosomes, present inside a nucleus.
Q 48.
Name the book in which Robert Hooke published his observations about cork cells.
Q 49.
Define Osmosis. What are different types of osmosis? Give examples of osmosis.
Q 50.
What is plasmolysis?
