Low-head dams are dangerous structures that basically extend from one side of a riverbank to the other. Low-head dams block the water way partially and the water moving over the dam produces a strong circular current at the lower part of the dam. Low-head dams are dangerous to small boats and paddle craft because the strong circular current below the dam can trap small boats and paddle craft and pull them under the dam.
Answer:
C
Explanation:
The deposition of pesticides in the bond with result to increase in bacteria that breakdown the chemicals for energy. This provides ‘food’ for bacteriophages and then food for algae that will thrive in the pond. They take up oxygen from the pond and make the waters anoxic. The fish will, therefore, be smothered and their numbers will reduce in the pond.
Answer:
- Radial symmetry is advantageous because sessile animals can "sit down", take food, or sense harmful environmental conditions from different directions.
- Bilateral symmetry allows motile animals to move straight forward.
- The major evolutionary advantages of bilateral symmetry include cephalization, the formation of a head and tail area and a more directional motion.
Explanation:
Radial symmetry is advantageous for sessile organisms since it enables the uniform distribution of the sensory receptors around the body. In consequence, sessile organisms can react to environmental stimuli from every direction. On the other hand, bilateral symmetry allows motile organisms the arrangement of a specialized nervous system from the anterior end of the organism (i.e., the 'head'). Moreover, another important advantage of bilateral symmetry is the ability to equalize environmental pressures on both sides of the body, thereby enabling a rectilinear motion.
Answer:
in the wall of the right atrium of the heart.
Explanation:
The sinoatrial node (SA), consisting of spindle-shaped cells, initiates the electrical activity of the heart. From its location in the right atrium in proximity to the superior vena cava, the electrical activity spreads to the atria, whose cells are larger than those of the SA.
The correct answer is - Since 2000, more people are living with HIV, but fewer people are dying from AIDS.
Since the year 2000, the number of people that are living with HIV has been steadily increasing, though it has to be noted that the rise has been gradually slowing down. On the other hand, despite having more living with HIV, the deaths by AIDS have reduced gradually.
The main reason for the increase of people living with HIV is simply that there's more and more people in the world that can contact physically much more easily, so the disease can be transferred much more easily over larger distances. On the other hand, less and less people are dying from AIDS, and the reason for that is the discovering of the disease in its early stage, as well as the development of the medicine and keeping a certain routine in the lifestyle that is healthy.
