Which one of the following statements is NOT correct ?
- A.All proteins are enzymes
- B.Mostly enzymes are proteins
- C.All fats are energy rich compounds
- D.Glucose is a common carbohydrate
Correct answer
Explanation
The correct answer is A, All proteins are enzymes. This statement is false: enzymes are mostly proteins, but most proteins are not enzymes.
Proteins do many jobs in the body. Some are enzymes, which speed up chemical reactions, such as amylase and pepsin. Others are structural, like keratin in hair and collagen in skin and bone; some carry substances, like haemoglobin; some are hormones, like insulin; and antibodies are proteins that defend the body. So being a protein does not make a molecule an enzyme. On the other hand, almost all enzymes are proteins; the main exceptions are ribozymes, which are catalytic RNA molecules.
B is wrong as an answer because it is true that most enzymes are proteins. C is wrong as an answer because fats give about 9 kilocalories per gram, more than twice carbohydrates or proteins. D is wrong as an answer because glucose is the commonest simple sugar and the body's main fuel.
Exam tip: Every enzyme is (almost always) a protein, but not every protein is an enzyme; fats give 9 kcal/g.
Practice Questions
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- A.Refractometer
- B.Galvanometer
- C.Viscometer
- D.Diffractometer
Show answer
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Read the full explanation →Reverberation is a phenomenon associated with a
- A.multiple refraction of sound.
- B.multiple reflection of sound.
- C.single refraction of sound.
- D.single reflection of sound.
Show answer
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Read the full explanation →Which one of the following is NOT a basic property of electric charge ?
- A.Charges can be added
- B.Charge is conserved
- C.Charge on a body is always an integral multiple of an electron or a proton charge
- D.Charges can be created and destroyed in an isolated system
Show answer
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Read the full explanation →Which of the following organelles have their own DNA and ribosomes?
- A.Endoplasmic reticulum and Golgi bodies
- B.Mitochondria and Chloroplast
- C.Endoplasmic reticulum and cytoskeleton
- D.Cell wall and nucleolus
Show answer
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Read the full explanation →Which one of the following types of radiations has the smallest wavelength?
- A.Microwaves
- B.Infra-red
- C.Visible light
- D.X-rays
Show answer
Of the four, X-rays lie farthest towards the short-wavelength, high-energy end of the electromagnetic spectrum. All electromagnetic waves travel at the speed of light in vacuum but differ in wavelength.
Read the full explanation →