Compound P shows some structural similarities with the hydrophobic tail of a fatty acid. State one structural difference between compound P and a complete saturated fatty acid molecule.

An industrial solvent mixture containing compounds P, Q, and R is accidentally spilled into a soil ecosystem. Soil bacteria are capable of breaking down these organic compounds.

The rate of solvent breakdown can be accelerated by treating the soil with a liquid additive containing inorganic ammonium salts and phosphates.

• Student A concluded that the additive increased the rate of solvent breakdown only by acting as a physical surfactant, dispersing the solvent into smaller droplets and increasing the surface area for bacterial colonization.
• Student B concluded that the additive also directly stimulated the growth and division rate of the bacterial population by providing essential chemical nutrients.

Use the molecular structures in the figure and your knowledge of biological molecule synthesis to provide support for Student B's conclusion.

Suggest one experiment or piece of evidence that would further support Student B's conclusion.

Bacteria capable of metabolizing chlorinated aromatic hydrocarbons (such as compound R) are found in significantly higher proportions in soil samples near chemical waste sites compared to pristine forest soils. Suggest an explanation for this observation.

Listed below are three approaches, A, B and C, that can be used to maintain biodiversity:

• A: ex situ conservation
• B: in situ conservation
• C: preservation

For each of the statements below, indicate which approach or approaches are consistent with the statement by inserting the correct letter or letters (A, B, and/or C):

1. The target species are maintained within their native ecological habitat.
2. Direct conservation actions and active human management of the ecosystem or species take place.