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.
Give examples of cells which are muti-nucleate (i.e. having many nuclei).
Q 2.
What is the thickness of cell membrane?
Q 4.
What is the energy currency of the cell called?
Q 5.
What is osmoregulation?
Q 6.
Identify cell organelle and write down its name:
Called 'suicide bags' of a cell.
Q 7.
In which year electron microscope was invented?
Q 8.
What is the full form of DNA and RNA?
Q 9.
What are the conditions for osmosis?
Q 10.
Why are lysosomes known as suicide bags?
Q 11.
Which cell organelle is called 'control center'?
Q 12.
Name the biggest cell in human body.
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.
Name the sac like structure which form the grana?
Q 16.
Will the temperature have any effect on the process of the osmosis?
Q 17.
What is the function of nucleoplasm?
Q 18.
What is plasmolysis?
Q 19.
What will happen if a de-shelled egg in a concentrated salt solution for 5 minutes?
Q 20.
Who is known as Father of Biology?
Q 21.
Who discovered Golgi apparatus?
Q 22.
Who is known as 'Father of Microscopy'?
Q 23.
What are chromosomes?
Q 24.
Name the cell organelles which their own DNA and Ribosomes.
Q 25.
Name the cell organelles which change energy from one form to another.
Q 26.
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 27.
Who proposed fluid-mosaic model of cell or plasma membrane?
Q 28.
Define Osmosis. What are different types of osmosis? Give examples of osmosis.
Q 29.
Which organ of the plant body helps in osmoregulation?
Q 30.
Identify cell organelle and write down its name:
Present in some animal cells, help in locomotion.
Q 31.
Identify cell organelle and write down its name:
A structure involved in production of ribosomes, present inside a nucleus.
Q 32.
Who expanded cell theory by suggesting that all cells arise from pre-existing cells?
Q 33.
Which cell organelle is known as 'protein factory'?
Q 34.
Which organelle of the cell in animals helps in osmregulation?
Q 35.
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 36.
What is cytoskeleton?
Q 37.
Name the cell organelles involved in synthesis, packaging and movement of protein (or other macromolecules) inside a cell.
Q 38.
Identify cell organelle and write down its name:
Contains green colour pigment, traps light energy. Present in some plant cells.
Q 39.
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 40.
Who observed the cells the first time?
Q 41.
Name the two postulates of the cell theory.
Q 42.
Name the smallest cell in human body.
Q 43.
What is the plasma membrane composed of?
Q 44.
Define Passive Transport.
Q 45.
Which cell organelle is called 'kitchen of plant'?
Q 46.
What are the functions of Endoplasmic Reticulum (ER)?
Q 47.
Who discovered Virus?
Q 48.
What are the function of nucleus?
Q 49.
Are there any exceptions to cell theory proposed by Schleiden & Schwann and Virchow? If yes, what are those?
Q 50.
Why is mitochondria absent in red blood cells?
