BIO 101 1st Edition Final Exam Study Guide Chapter 12 Chapter 12 1 If the Earth has a finite amount of carbon atoms how is it possible that there has been an increase in carbon dioxide in the atmosphere Its just the rearranging of atoms 2 What is the relationship between the carbon cycle and the food web When plants and animals die their bodies wood and leaves decay bringing the carbon into the ground Some become buried miles underground and will become fossil fuels in millions and millions of years 3 Why can t animals take in nitrogen directly from the atmosphere to meet their nutritional needs It has to undergo nitrogen fixation first 4 How does atmospheric nitrogen become available for plants to use It has to undergo nitrogen fixation a process whereby soil bacteria convert N2 to compounds that plants can take up such as nitrates and ammonium Then the plants can absorb the nitrogen 5 Why are big fierce animals rare They take more accommodations to live than the smaller animals If there were a lot of fierce animals they would continuously fight for the top dog position One species would prevail or they would divide the land and not cross the barrier 6 Why is energy transfer from one trophic level to the next very inefficient Most of it is lost as heat These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 7 Why would you expect that there will be a greater biomass of plants than herbivores in any ecosystems If there were more animals than plants the animals would not be able to survive 8 Explain the statement Energy flow is one way but nutrient flow is a cycle o o Energy flow is one way Energy input from sun autotrophs heterotrophs Energy is transformed from one form to another Light energy heat energy Light energy chemical energy heat energy Nutrient flow is a cycle because nutrients can be recycled into the ecosystem 9 What variables in an environment influence the primary productivity in an area The amount of sunlight that penetrates the total volume The ocean has the lowest rate of production because the sunlight only penetrates a small fraction of it Amount of water Amount of sunlight Availability of nutrients Appropriate temperatures 10 What are the differences between ecosystems communities and populations Ecosystem All the life living in a particular area together with all the nonliving components of that environment including water minerals and physical factors such as light and air Community Consists of all the populations living in a particular place Population Group of individuals of the same species living in the same place at the same time 11 Explain why estuaries and rainforests have high primary productivity but deserts and oceans have low primary productivity They have more plants to absorb the sunlight coming in with the ocean there is nothing to absorb the sunlight thus causing it to have low primary productivity 12 What are the possible outcomes if two species try to occupy the same niche in the same community One will either take over the entire niche or they will split the niche and not cross into the other s section 13 What factors may affect the carrying capacity of a species in an environment Is the carrying capacity a fixed number and why or why not The carrying capacity is not a fixed number in an environment Once the population grows too large some will die off because they cannot find food to support the large numbers Then once many of them die the population will rise again It is a rise and fall cycle of population Can be increased by new technological advances 14 How do you define a biome and what main characteristics classify each biome Biome a major terrestrial or aquatic life zone characterized by vegetation type in terrestrial biomes and the physical environment in aquatic biomes Terrestrial amount of available sunlight is often the most important factor in determining how much life can be sustained in a given area Aquatic Light cannot penetrate deeply into water so most photosynthesis occurs near the surface 15 What is the relationship between the greenhouse effect and global warming The greenhouse effect raises the temperature of the earth causing global warming 16 What is a keystone species and how is it related to biodiversity Key stone species A species whose absence would create significant change in a community This species would soon be replaced by another creating a very significant change in the ecosystem they live in 17 What are some biological offenses against invasive species Other organisms can attack the invader For example Asian rats have become invasive and the mongoose eats them to reduce the population