Question:
What are centrosomes? What functions do they perform?
Answer:
Centrosome is a small, star shaped protoplamic organelle and is present near to nucleus. In animal cells, it consists of two small granules called centrioles. These centrioles are orthogonally arranged i.e. lie at right angles to each other. In plant cells, centrioles are absent.
Functions of Centrosomes:
- Initiate cell division
- During cell division, centrioles move to opposite poles of the cell and help in spindle formation.
- They form basal bodies (microtubules like sturtures) which form cillia or flagella.
The Fundamental Unit of Life
Q 1.
Which cell organelle is known as 'protein factory'?
Q 2.
Identify cell organelle and write down its name:
A tough, non-living layer, it prevents plant cells from bursting, freely permeable
Q 3.
Is plasma membrane permeable or selectively permeable?
Q 4.
What is the plasma membrane composed of?
Q 6.
Why is mitochondria absent in red blood cells?
Q 7.
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 8.
Name the two postulates of the cell theory.
Q 9.
Which cell organelle is called 'kitchen of plant'?
Q 10.
What are chromosomes?
Q 11.
What is the full form of DNA and RNA?
Q 12.
Are plastids present in all cells? What are its types?
Q 13.
Which of the following cell is better candidate to study lysosomes?
(a) White Blood Cell
(b) Muscle Cell
Q 14.
Who expanded cell theory by suggesting that all cells arise from pre-existing cells?
Q 15.
Name the biggest cell in human body.
Q 16.
Name the sac like structure which form the grana?
Q 17.
Identify cell organelle and write down its name:
Digestive organelle where macromolecules are hydrolyzed
Q 18.
Who observed the cells the first time?
Q 19.
Give an example of anucleate cell i.e. cell without nucleus.
Q 20.
Give examples of cells which are muti-nucleate (i.e. having many nuclei).
Q 21.
What are the function of nucleus?
Q 22.
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 23.
Name the smallest cell in human body.
Q 24.
Which cell organelle is called 'transport system'?
Q 25.
In which year electron microscope was invented?
Q 26.
Place a de-shelled egg in water for five minutes. What do you observe? (Note: De-shelled egg means,the shell of an egg is removed by dissolving it in dilute hydrochloric acid. The shell is mostly calcium carbonate. A thin outer skin now encloses the egg.)
Q 27.
Identify cell organelle and write down its name:
Called 'suicide bags' of a cell.
Q 28.
Who proposed the cell theory?
Q 29.
Who coined the term 'protoplasm'?
Q 30.
What are different types transport of components across cell membrane?
Q 31.
What are the conditions for osmosis?
Q 32.
Name the cell type that have internal membranes which compartmentalize their functions.
Q 33.
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 34.
Identify cell organelle and write down its name:
Powehouse of cell
Q 35.
Name the cell in human body which cannot reproduce.
Q 36.
Give an example of cells containing two nuclei (Binucleate).
Q 38.
Will the temperature have any effect on the process of the osmosis?
Q 39.
Which organ of the plant body helps in osmoregulation?
Q 40.
What is plasmolysis?
Q 41.
Who is known as 'Father of Microscopy'?
Q 42.
What are the components nucleus?
Q 43.
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 44.
Identify cell organelle and write down its name:
Contains green colour pigment, traps light energy. Present in some plant cells.
Q 45.
Identify cell organelle and write down its name:
Controls cell division and cell development.
Q 46.
Who proposed fluid-mosaic model of cell or plasma membrane?
Q 47.
Who discovered Golgi apparatus?
Q 48.
When chromosomes are visible in the nucleus?
Q 49.
What is the function of nucleoplasm?
Q 50.
Who discovered Virus?
