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.
What is the full form of DNA and RNA?
Q 2.
Which organelle of the cell in animals helps in osmregulation?
Q 4.
Give examples of cells which are muti-nucleate (i.e. having many nuclei).
Q 5.
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 6.
Name the sac like structure which form the grana?
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.
What is the plasma membrane composed of?
Q 9.
What will happen if a de-shelled egg in a concentrated salt solution for 5 minutes?
Q 10.
Which cell organelle is known as 'protein factory'?
Q 11.
When chromosomes are visible in the nucleus?
Q 12.
Which cell organelle is called 'kitchen of plant'?
Q 13.
Identify cell organelle and write down its name:
A tough, non-living layer, it prevents plant cells from bursting, freely permeable
Q 14.
Identify cell organelle and write down its name:
Present in some animal cells, help in locomotion.
Q 15.
Name the two postulates of the cell theory.
Q 16.
What are the components nucleus?
Q 17.
Identify cell organelle and write down its name:
Jelly like substance containing particles and other organelles. What is it?
Q 18.
Who observed the cells the first time?
Q 19.
Name the biggest cell in human body.
Q 20.
Is plasma membrane permeable or selectively permeable?
Q 21.
What are the function of nucleus?
Q 22.
What is the thickness of cell membrane?
Q 23.
Identify cell organelle and write down its name:
Digestive organelle where macromolecules are hydrolyzed
Q 24.
Who coined the term 'protoplasm'?
Q 25.
What are different types transport of components across cell membrane?
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.
Who is known as Father of Biology?
Q 28.
What are the conditions for osmosis?
Q 29.
Will the temperature have any effect on the process of the osmosis?
Q 30.
What are the functions of Endoplasmic Reticulum (ER)?
Q 31.
Why is mitochondria absent in red blood cells?
Q 32.
Identify cell organelle and write down its name:
A fluid-filled space surrounded by a membrane. Generally contains salts and sugars in plants.
Q 33.
Name the smallest cell in human body.
Q 34.
Define Osmosis. What are different types of osmosis? Give examples of osmosis.
Q 35.
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 36.
Are plastids present in all cells? What are its types?
Q 37.
Which organ of the plant body helps in osmoregulation?
Q 38.
What are chromosomes?
Q 39.
Are there any exceptions to cell theory proposed by Schleiden & Schwann and Virchow? If yes, what are those?
Q 40.
Which of the following cell is better candidate to study lysosomes?
(a) White Blood Cell
(b) Muscle Cell
Q 41.
Identify cell organelle and write down its name:
Powehouse of cell
Q 42.
Who expanded cell theory by suggesting that all cells arise from pre-existing cells?
Q 43.
In which year electron microscope was invented?
Q 44.
Name the book in which Robert Hooke published his observations about cork cells.
Q 45.
Who discovered nucleus in the cell?
Q 46.
Name the world's smallest cell.
Q 47.
Give an example of anucleate cell i.e. cell without nucleus.
Q 48.
Give an example of cells containing two nuclei (Binucleate).
Q 50.
Who discovered Golgi apparatus?
