Every living organism needs a constant energy supply. Outline the need for energy in living organisms.
Fig. 4.1 shows ATP. Name A and B.
Describe how the structure of ATP is related to its role as energy currency.
$\textit{Thermus thermophilus}$ is a bacterium from geothermal environments. It respires aerobically even though oxygen is poorly soluble in water at high temperatures. Explain how aerobic respiration may be affected by a decrease in oxygen availability.
One strain of $T.\ thermophilus$, HB8, possesses the enzyme nitrate reductase, which allows nitrate to act as the final electron acceptor in the electron transport chain (ETC). Suggest an advantage to the bacterium of this adaptation.
A mutant form of HB8 (HB8 mutant) was produced by introducing an insertion mutation into the gene that codes for the enzyme nitrate reductase. An investigation was carried out into population growth of HB8 and HB8 mutant under aerobic and anaerobic conditions. In each experiment, a flask containing bacterial culture medium was incubated. Table 4.1 shows the flask arrangements. The number of bacteria of each strain per $\text{cm}^3$ was determined after 20 hours. The findings are shown in Fig. 4.2.
Compare the growth of the two strains of bacteria in aerobic and anaerobic separate cultures.
Compare the growth of the two strains of bacteria in aerobic and anaerobic conditions in mixed cultures.
Suggest an explanation for the results shown in flask 6.