1. Bottlenose dolphins (Tursiops truncatus) inhabit almost all tropical and temperate oceans between 45° N and 45°S. Over a two-year period, aerial surveys were carried out to investigate the seasonal distribution of these animals along the mid-Atlantic and eastern coastal waters of the USA. Sightings were recorded using a global positioning system (GPS) while flying parallel to the coast approximately 500 m offshore. The diagram below shows a map of the section of coast surveyed. The bar graph shows the seasonal data for summer and winter at the corresponding latitudes (°N）. A total of 5431 bottlenose dolphins were sighted during these surveys.
(a) State the largest number of dolphins counted in a single summer survey.
(b) Compare the distribution of dolphins in summer and winter.
(c) Suggest one reason for the differences in distribution.
In a different study, researchers investigated the role of water temperature as a possible factor in the distribution of bottlenose dolphins. The rate of metabolism (measured as the rate of oxygen uptake per unit mass) of five captive adults was measured under a range of water temperatures. The rate of metabolism was found to increase significantly when the water temperature fell below a certain value known as the lowest critical water temperature (LCTw). Below this temperature the body uses more energy to combat the cooling effect of the surrounding water. The data for these animals are summarized below.
The graph below summarizes the relationship between LCTw and body mass.
(d) Outline the relationship between body mass and LCTw for male dolphins.
(e) Evaluate the hypothesis that water temperature determines the range and distribution of bottlenose dolphins in the wild.
(f) Explain how an increase in water temperature due to global warming could affect the distribution of bottlenose dolphins along the eastern coast of the USA.
(g) Suggest how research into the range and distribution of bottlenose dolphins could benefit from international cooperation.
2. (a) State two differences in structure between plant and animal cells.
(b) Outline how molecules move across a membrane by simple diffusion.
(c) Explain the role of protein pumps in active transport.