Reading: There are 3 types of polar bears : ones with thick coats , ones with thin coats and ones with medium coats. When it is winter the temperature drops rapidly and the bears must be kept warm or they will freeze to death. Many of the bears have had 2 cubs each but due to the extreme temperatures, many mothers only have one cub left. Question l: what physical variation of the polar bear was identified in the reading

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

the answer is c.mitochondria. glad to .

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.