Which one of the following is the 'energy currency' for cellular processes?
- A.Glucose
- B.ATP
- C.ADP
- D.Pyruvic acid
Correct answer
Explanation
The correct answer is B, ATP. Adenosine triphosphate stores energy in its phosphate bonds and releases it wherever the cell needs it, so it is called the energy currency of the cell.
ATP is made mainly in the mitochondria during cellular respiration, which is why mitochondria are called the powerhouse of the cell; in plants it is also made in chloroplasts during photosynthesis. When the last phosphate group is removed, ATP becomes ADP (adenosine diphosphate) and releases energy that drives muscle contraction, active transport, nerve impulses and the building of new molecules. Respiration then adds a phosphate back to ADP, so the cycle repeats continuously.
Option A is wrong because glucose is the fuel that is broken down to make ATP, not the currency the cell spends directly. Option C is wrong because ADP is the low-energy form left after ATP is used. Option D is wrong because pyruvic acid is an intermediate formed when glucose is split in glycolysis.
Exam tip: ATP = energy currency; mitochondria = powerhouse; ATP → ADP + phosphate releases energy.
Practice Questions
View allWhich one of the following is the correct reactivity order of metals reacting with dilute HCl?
- A.Mg > Al > Zn > Fe
- B.Mg < Al < Zn < Fe
- C.Mg > Zn > Fe > Al
- D.Fe > Mg > Al > Zn
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This is the order in which these metals stand in the reactivity series, and it matches how vigorously they release hydrogen from dilute hydrochloric acid.
Read the full explanation →Deficiency of iron causes
- A.Anaemia
- B.Scurvy
- C.Rickets
- D.Cholera
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Iron is needed to make haemoglobin, so too little iron means too little haemoglobin and a reduced ability of the blood to carry oxygen.
Read the full explanation →Consider the following statements regarding waves : 1. If the particles of a medium move along the direction of motion of the wave, the wave is called a longitudinal wave. 2. If the particles of a medium move perpendicular to the direction of motion of the wave, the wave is called a transverse wave. 3. Transverse waves may involve change in the shape of the medium, whereas longitudinal waves involve change in the density of the medium. Which of the statements given above is/are correct ?
- A.1 and 2 only
- B.1 only
- C.2 and 3 only
- D.1, 2 and 3
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All three statements correctly describe how particles move in the two kinds of mechanical waves. In a longitudinal wave, such as sound in air, the particles vibrate back and forth along the direction in which the wave travels.
Read the full explanation →In paper manufacturing, degumming of the raw material is done using
- A.sulphuric acid
- B.bleaching powder
- C.caustic soda
- D.nitric acid
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In paper making the raw plant material is cooked with caustic soda, which dissolves the gums, resins and lignin that bind the cellulose fibres together.
Read the full explanation →When a piece of pure silicon is doped with aluminium, then
- A.the conductivity of the doped silicon piece will remain the same
- B.the doped silicon piece will become n-type
- C.the doped silicon piece will become p-type
- D.the resistivity of the doped silicon piece will increase
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Aluminium has three valence electrons, one fewer than silicon, so each aluminium atom leaves a hole that acts as a positive charge carrier.
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