Tutor profile: Adam R.
Subject: Microsoft Excel
Explain a few useful functions for summarizing data in Excel?
Some of the more useful functions for organizing and summarizing data in excel include the following functions: IF: this function allows you to perform logical tests, and return editable answers based on the test. This is especially useful if you want to create new organizational columns based on the dataset or even return calculations that can be customized to specific questions (for example: for a budget spreadsheet, you could use the IF function to specify the appropriate taxes due based on location). In addition to the IF function, the COUNTIF and SUMIF allow for even more versatility as they allow for the summation or counting of values that meet a specific criteria. LEFT & RIGHT / CONCATENATE: these functions are useful for splitting up and joining information. The LEFT and RIGHT functions allow you to select a certain number of characters from either the left or right side of a cell and copy it to a new cell. This is useful for extracting information such as ID numbers or names. CONCATENATE is useful for joining information like names, locations, and unique identifiers. VLOOKUP: this is extremely useful as it allows you to search for a value in a table and will return information from another column that relates to that value. It is great for combining data from different lists into one, or comparing them for missing or matching items. UNIQUE: this is a new function that allows one to return a list of unique characters/variables in a range. For example, in a large mark-recapture dataset, once could return a table containing the name of each unique individual in the dataset. PivotTables: basically essential for organizing large datasets to compare and contrast information, filter data, and create meaningful figures and tables prior to further analysis.
Subject: Environmental Science
What is an environment?
An environment can be defined as everything that surrounds us, though, in most contexts, it refers to a single system of interacting living (biotic) and non-living (abiotic) components. An example of an environment could be a lake system, with biotic components including all of the living things that inhabit the lake and areas around (fish, plankton, bacteria, deer, etc...) and non-living things that compose the area (substrate types, water quality, soil types, drainage type, etc...) as well as the energy flow between them.
How does the introduction of an invasive species affect an ecosystem?
Invasive species can affect an ecosystem in both direct and indirect ways. Direct impacts of invasive species introduction include competition for food or for habitat, which put direct pressure on native species. Indirect impacts include the potential to transmit diseases to and between native species that they had not been previously exposed to. This exposure can cause native species to be especially vulnerable as they have not been exposed to these stressors before. Invasive species often do well in new environments due to the fact that they often don't "fit" into the native environment. This means they, initially, don't experience the same types of pressures/predation as native species, allowing them to increase in population quickly. Without controls in place to limit/control invasive species, their presence may impact habitat quality and availability, available resources, lower biodiversity, and possibly impact the integrity of the ecosystem.
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