Which one of the following polymers is made of protein ?
- A.Rubber
- B.Cotton
- C.Wool
- D.Jute
Correct answer
Explanation
The correct answer is C, Wool. Wool is an animal fibre made mainly of the protein keratin.
Polymers are giant molecules built from many small repeating units called monomers. Natural fibres fall into two groups. Animal fibres such as wool and silk are proteins, long chains of amino acids joined by peptide bonds. Wool comes from the fleece of sheep, goats (cashmere, angora), yaks and camels, and its keratin is the same protein found in human hair and nails. Silk, from the cocoon of the silkworm, is made of the protein fibroin. Plant fibres, on the other hand, are made of cellulose, a polymer of glucose.
A is wrong: natural rubber is a polymer of isoprene, a hydrocarbon, obtained from the latex of the rubber tree.
B is wrong: cotton is almost pure cellulose from the seed hairs of the cotton plant.
D is wrong: jute is a cellulose-based fibre taken from the stem of the jute plant.
Exam tip: Protein fibres = wool (keratin) and silk (fibroin); cellulose fibres = cotton, jute, flax; natural rubber = polyisoprene.
Practice Questions
View allConsider the following actions :
1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously
2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive
3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode
In how many of the above actions is the function of accelerometer required?
- A.Only one
- B.Only two
- C.All three
- D.None
Show answer
An accelerometer measures acceleration, including the pull of gravity, and each of the three actions depends on reading it. An accelerometer is a small sensor, today usually a MEMS (micro-electro-mechanical system) chip, that senses changes in speed and the direction of gravity.
Read the full explanation →Consider the following statements :
1. Carbon fibres are used in the manufacture of components used in automobiles and aircrafts.
2. Carbon fibres once used cannot be recycled.
Which of the statements given above is/are correct?
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
Show answer
Carbon fibre is widely used in cars and aircraft for its strength and low weight, and it can be recovered and recycled.
Read the full explanation →Which 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
Show answer
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 →