Movement of materials to different parts of cytoplasm and nucleus is generally carried out by
- A.Ribosomes.
- B.Mitochondria.
- C.Lysosomes.
- D.Endoplasmic reticulum.
Correct answer
Explanation
The correct answer is D, Endoplasmic reticulum. Its network of membrane tubes and sheets forms channels that carry materials, especially proteins, between parts of the cytoplasm and the nucleus.
The endoplasmic reticulum (ER) is joined to the outer membrane of the nucleus and spreads through the cytoplasm. Rough ER, studded with ribosomes, makes proteins and passes them along its channels; smooth ER makes lipids and helps detoxify drugs and poisons. Because of this transport role, NCERT describes the ER as serving as channels for the movement of materials within the cell.
A is wrong because ribosomes make proteins but do not carry them around the cell.
B is wrong because mitochondria release energy as ATP; they are the cell's powerhouses.
C is wrong because lysosomes hold digestive enzymes and break down waste; they are called suicide bags.
Exam tip: ER = transport channels, ribosome = protein factory, mitochondria = powerhouse, lysosome = suicide bag.
Practice Questions
View allWhich one of the following cell organelles contains DNA?
- A.Golgi apparatus
- B.Mitochondrion
- C.Lysosome
- D.Endoplasmic reticulum
Show answer
Mitochondria carry their own small, circular DNA and their own ribosomes. Mitochondria are the powerhouses of the cell, where aerobic respiration makes ATP.
Read the full explanation →Which set of vegetables is underground stem or modified stem of a plant?
- A.Potato, artichoke, round gourd
- B.Onion, garlic, carrot
- C.Potato, onion, garlic
- D.Potato, garlic, turnip
Show answer
All three are underground modified stems: the potato is a stem tuber, and onion and garlic are bulbs. A stem can be told from a root by its nodes and buds.
Read the full explanation →A sound wave having frequency of 300 Hz is travelling in an unknown medium. Its wavelength is not known. It travels a distance equal to 150 times its wavelength in time t. The value of t is :
- A.0.5 s
- B.1 s
- C.1.5 s
- D.2 s
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A wave moves forward by one wavelength in each cycle, so 150 wavelengths take 150 cycles, and 150 cycles at 300 per second take half a second.
Read the full explanation →A body floats in a liquid if the buoyant force is :
- A.equal to its weight.
- B.less than its weight.
- C.greater than its weight.
- D.zero.
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A floating body is in equilibrium, so the upward buoyant force exactly balances its weight. By Archimedes' principle, a body in a liquid is pushed up by a force equal to the weight of the liquid it displaces.
Read the full explanation →Which of the following are the different parts of a human brain ?
- A.Forefront brain, Standard brain and Hind brain
- B.Fore brain, Median brain and Rear brain
- C.Fore brain, Mid brain and Hind brain
- D.Precursor brain, Mean brain and Hind brain
Show answer
These are the three main divisions of the human brain. The fore brain is the largest part.
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