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.
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 2.
Name the two postulates of the cell theory.
Q 3.
What is the plasma membrane composed of?
Q 4.
Which of the following cell is better candidate to study lysosomes?
(a) White Blood Cell
(b) Muscle Cell
Q 6.
What is the full form of DNA and RNA?
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:
Digestive organelle where macromolecules are hydrolyzed
Q 9.
Name the cell organelles which change energy from one form to another.
Q 10.
Identify cell organelle and write down its name:
Jelly like substance containing particles and other organelles. What is it?
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.
Is plasma membrane permeable or selectively permeable?
Q 13.
Are plastids present in all cells? What are its types?
Q 14.
Name the cell type that have internal membranes which compartmentalize their functions.
Q 15.
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 16.
Will the temperature have any effect on the process of the osmosis?
Q 17.
What are chromosomes?
Q 18.
Identify cell organelle and write down its name:
Present in some animal cells, help in locomotion.
Q 19.
What will happen if a de-shelled egg in a concentrated salt solution for 5 minutes?
Q 20.
Name the sac like structure which form the grana?
Q 21.
Which cell organelle is called 'kitchen of plant'?
Q 22.
What is the thickness of cell membrane?
Q 23.
Who expanded cell theory by suggesting that all cells arise from pre-existing cells?
Q 24.
In which year electron microscope was invented?
Q 25.
Who coined the term 'protoplasm'?
Q 26.
Name the biggest cell in human body.
Q 27.
Which cell organelle is known as 'protein factory'?
Q 28.
What is cytoskeleton?
Q 29.
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 30.
Identify cell organelle and write down its name:
Powehouse of cell
Q 31.
What is the energy currency of the cell called?
Q 32.
Which organelle of the cell in animals helps in osmregulation?
Q 33.
Why is mitochondria absent in red blood cells?
Q 34.
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 35.
Who observed the cells the first time?
Q 36.
Name the smallest cell in human body.
Q 37.
Name the cell in human body which cannot reproduce.
Q 38.
Give an example of cells containing two nuclei (Binucleate).
Q 39.
Give examples of cells which are muti-nucleate (i.e. having many nuclei).
Q 40.
Define Passive Transport.
Q 41.
What would happen if the plasma membrane ruptures or breaks down?
Q 42.
Which organ of the plant body helps in osmoregulation?
Q 43.
Which cell organelle is called 'transport system'?
Q 44.
What are the functions of Endoplasmic Reticulum (ER)?
Q 45.
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 46.
Name the world's smallest cell.
Q 47.
Define Osmosis. What are different types of osmosis? Give examples of osmosis.
Q 48.
What are centrosomes? What functions do they perform?
Q 49.
Who is known as 'Father of Microscopy'?
Q 50.
Identify cell organelle and write down its name:
A fluid-filled space surrounded by a membrane. Generally contains salts and sugars in plants.
