Which one of the following is the first enzyme to mix with food in the digestive tract?
- A.Trypsin
- B.Cellulose
- C.Pepsin
- D.Amylase
Correct answer
Explanation
The correct answer is D, Amylase. Digestion begins in the mouth, where saliva adds salivary amylase to the food as it is chewed.
Salivary amylase, also called ptyalin, starts breaking starch into maltose while food is still in the mouth. That is why a piece of bread or chapati begins to taste slightly sweet if it is chewed for long. The food then passes down the oesophagus to the stomach, where pepsin begins protein digestion in an acidic medium. In the small intestine, pancreatic juice adds trypsin for proteins, lipase for fats and pancreatic amylase for the remaining starch.
Option A is wrong because trypsin acts only in the small intestine, after the stomach. Option B is wrong because cellulose is a plant carbohydrate, not an enzyme, and humans do not even make the enzyme cellulase. Option C is wrong because pepsin acts in the stomach, after saliva.
Exam tip: order of enzymes: salivary amylase in the mouth, pepsin in the stomach, then trypsin, lipase and amylase from the pancreas in the small intestine.
Practice Questions
View allBronze is an alloy of copper and
- A.nickel
- B.iron
- C.tin
- D.aluminium
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Bronze is an alloy of copper and tin, usually about 88 parts copper to 12 parts tin. Adding tin makes copper harder, stronger and easier to cast, and bronze also resists corrosion well.
Read the full explanation →Which one of the following instruments is used for measuring moisture content of air?
- A.Hydrometer
- B.Hygrometer
- C.Hypsometer
- D.Pycnometer
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A hygrometer measures humidity, that is, the amount of water vapour or moisture in the air. The name comes from the Greek "hygros", meaning wet.
Read the full explanation →Which one of the following elements is present in the green pigment of leaves?
- A.Magnesium
- B.Iron
- C.Calcium
- D.Copper
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The green pigment of leaves is chlorophyll, and a magnesium atom sits at the centre of every chlorophyll molecule.
Read the full explanation →Consider 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
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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
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Carbon fibre is widely used in cars and aircraft for its strength and low weight, and it can be recovered and recycled.
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