1. Draw and label a diagram of a single molecule of ATP.
Answer
2. What type of reaction resynthesises ATP from ADP and Pi ?
Answer
Condensation reaction.
3. Give one similarity and one difference between ATP and a nucleotide in RNA.
Answer
Similarity: both ATP and a nucleotide in RNA have ribose sugar, a phosphate group, and adenine.
Difference: an RNA nucleotide can have uracil, cytosine, or guanine, but ATP only has adenine. Alternatively, an RNA nucleotide has one phosphate group, whereas ATP has three.
4. Give two functions of ATP.
Answer
The hydrolysis of ATP can be coupled to energy-requiring reactions within cells. The inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds, often making them more reactive.
5. Name the enzyme that produces ATP.
Answer
ATP synthase.
6. Name the products of ATP hydrolysis.
Answer
ADP and phosphate.
7. The cells of a typical human hydrolyse 50–75 kg of ATP every day. The average body mass of a human is also 50–75 kg. At any given time, the mass of ATP in a person's body is considerably less than this. Explain how it is possible for the body to hydrolyse this amount of ATP every day.
Answer
ATP is hydrolysed and reformed many times. The mass of ATP in the body remains constant and is much less than this amount.
8. Give the properties of water, and for each explain their importance to living organisms.
Answer
Water is polar, which allows it to dissolve charged particles and act as a solvent. It is also a metabolite, playing a vital role in hydrolysis and condensation reactions. Its cohesive nature enables transpiration in plants and creates surface tension, which supports small organisms on water surfaces. Water has a high specific heat capacity, meaning it resists temperature fluctuations and helps organisms maintain stable internal and external environments. Finally, it has a high latent heat of vaporization, so when water evaporates it removes heat and provides an efficient cooling mechanism for living organisms.
9. Name each of the ions that has a role in the following: a) pH, b) Haemoglobin, c) Co-transport, d) DNA and ATP
Answer
a) H+, b) Fe2+, c) Na+, d) Phosphate