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.
Is plasma membrane permeable or selectively permeable?
Q 2.
Which cell organelle is known as 'protein factory'?
Q 3.
Identify cell organelle and write down its name:
A tough, non-living layer, it prevents plant cells from bursting, freely permeable
Q 4.
What is the plasma membrane composed of?
Q 5.
Which cell organelle is called 'kitchen of plant'?
Q 6.
Name the two postulates of the cell theory.
Q 7.
Are plastids present in all cells? What are its types?
Q 8.
What are chromosomes?
Q 9.
Which of the following cell is better candidate to study lysosomes?
(a) White Blood Cell
(b) Muscle Cell
Q 10.
Why is mitochondria absent in red blood cells?
Q 11.
What is the full form of DNA and RNA?
Q 12.
Name the sac like structure which form the grana?
Q 13.
Identify cell organelle and write down its name:
Digestive organelle where macromolecules are hydrolyzed
Q 14.
Name the biggest cell in human body.
Q 15.
Who observed the cells the first time?
Q 17.
What are the conditions for osmosis?
Q 18.
What are the function of nucleus?
Q 19.
Identify cell organelle and write down its name:
A network of flattened cavities surrounded by a membrane, which links with the nuclear membrane. Help in packaging proteins.
Q 20.
Identify cell organelle and write down its name:
Called 'suicide bags' of a cell.
Q 21.
Who proposed the cell theory?
Q 22.
Name the smallest cell in human body.
Q 23.
Give an example of anucleate cell i.e. cell without nucleus.
Q 24.
What are different types transport of components across cell membrane?
Q 26.
What is plasmolysis?
Q 27.
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 28.
Identify cell organelle and write down its name:
Present in some animal cells, help in locomotion.
Q 29.
Who coined the term 'protoplasm'?
Q 30.
Who discovered Golgi apparatus?
Q 31.
When chromosomes are visible in the nucleus?
Q 32.
Will the temperature have any effect on the process of the osmosis?
Q 33.
Which organ of the plant body helps in osmoregulation?
Q 34.
Which cell organelle is called 'control center'?
Q 35.
Identify cell organelle and write down its name:
Powehouse of cell
Q 36.
In which year electron microscope was invented?
Q 37.
Who proposed fluid-mosaic model of cell or plasma membrane?
Q 38.
What is the function of nucleoplasm?
Q 39.
Identify cell organelle and write down its name:
A partially permeable layer prevents cell contents from escaping controls what substances enter and leave the cell. Identify?
Q 40.
Who is known as 'Father of Microscopy'?
Q 41.
What are the components nucleus?
Q 42.
Identify cell organelle and write down its name:
Detoxify drugs and poisons specially in liver cells.
Q 43.
Give an example of cells containing two nuclei (Binucleate).
Q 44.
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 45.
Define Osmosis. What are different types of osmosis? Give examples of osmosis.
Q 46.
Who discovered Virus?
Q 47.
Identify cell organelle and write down its name:
Contains green colour pigment, traps light energy. Present in some plant cells.
Q 48.
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 49.
Name the longest cell in human body.
Q 50.
What would happen if the plasma membrane ruptures or breaks down?
