PCR (polymerase chain reaction) is a relatively new advance (1980's) but it has a great impact in our lives. Specifically, in forensic science, PCR is useful in many sorts of crimes . Up until the PCR method, in order to identify a person forensic scientists would use fingerprints or some other ambiguous methods like teeth marks etc. But now, with PCR, we can compare the genetic material found on a crime scene and compare it with a suspect's genetic material, definitively concluding whether they are the same person or not. The way this works is that we collect a sample from the crime scene with DNA and then PCR amplifies the quantity of DNA in that sample. One of the apparent advantages of this method is that PCR works with even a very small sample, often not even a single cell is required. This makes crime scenes full of information. Hence, succinctly, PCR has helped modern forensic science in that:
1) its results are more definitve than traditional identification methods and subject to less ambiguity
2) it is relatively fast
3) new pieces of evidence can be of value (like some hair cells) and identify the crominal in cases that in older times would be impossible to solve.
Answer:
Underground stem, Aerial stem, and subaerial stem.
Explanation:
Plant stems can be Underground stem, Aerial stem, and subaerial stem due to its presence and strength of the stem. Underground stem are thick stems that run below the ground surface. e.g rhizome. Aerial stems are thin stems that can not stand erect. Examples include watermelon and strawberry etc. Subaerial stems are very thin stems that do not rise up but grow just above the ground. for example, water plantain, flowering rush etc.
The common component of air pollution is particulate matter (PM). This is a complex mixture of extremely small particles and liquid droplets.
The major components of PM are sulphates, nitrates, ammonia, sodium chloride, black carbon, dust particles and water. PM comes from dust , soot, smoke, industry and vehicle exhaust as well as complex chemical reactions with other pollutants.
Burning of fossil fuels produces sulphur dioxide . It is a colorless gas that pollutes the air and can cause health problems affecting the respiratory system.
Earth revolves around the sun, keeping doldrums stationary causes the doldrums to be calm winds. Thus, the correct option is C.
<h3>
Why are the doldrums so calm?</h3>
The Intertropical Convergence Zone, also known as the doldrums or calms by sailors due to its constant lack of wind, is the area where the northeast and southeast trade winds meet. It encircles the Earth near the thermal equator, however its exact location changes with the seasons.
The sunlight beams down directly on the area around the equator, the Doldrums are caused by solar radiation from the sun. Instead of blowing horizontally, this heating causes the air to warm and climb straight up. As a result, there is little or no wind for weeks at a time.
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