1. Explain how choice of crop varieties helps farmers to achieve sustainability in agriculture. 2. The diagram shows an irrigation system in a developing country.
Explain how and why this irrigation system is sustainable.

Define the apical impulse and describe its normal location, size, and duration. which abnormal conditions may affect the location of the apical impulse? explain the mechanism producing normal first and second heart sounds. describe the effect of respiration on the heart sounds. describe the characteristics of the first heart sound and its intensity at the apex of the heart and at the base. describe the characteristics of the second heart sound and its intensity at the apex of the heart and at the base.