The water cycle is referred to as a continuous cycle because it repeats everyday. It's a cycle with no end.
Microscopes have been used for centuries in order to see specimen scientists cannot see with their unaided eye. Antón VanLeeonhoeuk is given credit for designing the first lenses for microscopes in the 16th century. He looked at “animacules” which we would now call bacteria and protists. Robert Hooke first coined the term cell, as he looked at cork and thought it looked like cells that monks slept in. Improvements were made in the following centuries, and Ernest Leintz in the 1800s creates a way to have differing magnification lenses on one microscope. Continuing into the 1900s and 2000s there are now electron scanning microscopes, ultraviolet microscopes, atomic force microscopes, and electron tunneling microscopes—all which allow scientists to have better resolution and to see smaller and smaller things. Microscope technology will continue to improve as scientists discover more ways to magnify the microscopic world.
Answer:
guard cells
Explanation:
they control the opening and closing of the stomata
Answer: Land, Water,Urbanization, and smog and acid rain.
Explanation:
Smog and acid rain are produced through similar sources, primarily vehicle and industry emissions. Though both result from human-caused air pollutants, there are chemical distinctions between the two. Though there are regulations in effect to reduce both types of pollution, they remain a threat to both human health and the environment.Smog Causes A combination of three components -- nitrogen oxides, volatile organic compounds (VOCs) and sunlight -- causes smog. Nitrogen dioxide interacts with sunlight to create nitrogen oxide and a free oxygen molecule. This interaction produces ozone, which typically turns back into nitrogen dioxide, and the cycle repeats. The addition of VOCs interrupts the cycle, however. VOCs are produced by various sources, such as paint, cleaning products and refrigerants. The VOCs prevent the breakdown of ozone, allowing it to gather near the surface of the Earth, where even more nitric oxides are produced by vehicle and industry emissions, creating the dense smog seen in large cities such as Los Angeles and Beijing.Smog Hazards The presence of ozone in the form of smog can have several negative health effects. Respiratory systems can be irritated, reducing overall lung function and triggering asthma attacks. Evidence reported by the Environmental Protection Agency also suggests exposure to ozone reduces immune system responses, especially in the lungs. These effects subside over time, but little is known about the long-term effects of repeated exposure. Vegetation also suffers from smog, as plants that take up too much ozone can be damaged in ways such as discoloration and a loss of leaves that cuts photosynthesis efficiency by up to 50 percent.
