Arizona State University BIO 130 Understanding Population Growth Models

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• Question 1 2 out of 2 points If a population is steady at its carrying capacity, but then a group of organisms from that species moves in to the same space occupied by the original population,... what will happen to the carrying capacity of the combined population? the carrying capacity will remain the same the carrying capacity will remain the same Right! The carrying capacity is the population size that can be supported by the available resources. If more individuals move in, this will not increase the amount of resources, or the carrying capacity. • Question 2 1 out of 2 points Part 1, Population Dynamics, Question 9: Two of the birth and death rate combinations below represent equivalent growth rates. Choose the two below. Answers: Birth rate = 0.5; Death rate = 0.25 Answers: Birth rate = 0.5; Death rate = 0.25 Birth rate = 0.25; Death rate = 0 • Question 3 2 out of 2 points The slope of a logistic growth plot of an organism (with time on the x-axis and number of organisms on the y-axis) _____________. increases until it reaches a critical value and then levels of increases until it reaches a critical value and then levels of • Question 4 0 out of 2 points Section 1, Population Dynamics, Question 8: What happened to the Simpoid population (model) if Simploids die, but not as quickly on average as they are born? The Simploid population stopped growing and stayed at the same population size from then on. The Simploid population continued to grow but at a slower rate than before. No. There are still more Simploids being born than dying so the population keeps growing, albeit not as quickly as before. • Question 5 1.5 out of 2 points Section 2, Resource Limitation, Question 22: In addition to suitable habitat, what other resources might limit the size of a population for at least some species? Choose all that apply! Answers: Water availability Amount of sunlight available Food availability Answers: Water availability Availability of a required nutrient Amount of sunlight available Food availability ALL options were . Each of those is limiting for some species. For instance, sunlight availability could limit how many plants can grow in an area. Even with lots of food, if one crucial nutrient is in short supply, that could limit a population—and so on. There are many possible limits to population growth. • Question 6 2 out of 2 points Which population of organisms will grow faster, A or B? Population A has a birth rate of 0.4 and a death rate of 0.2 Population B has a birth rate of 0.6 and a death rate of 0.5 A A A will grow the fastest because it has the highest overall growth rate (overall of 0.2, which is the birth rate - death rate). • Question 7 0 out of 2 points Part 2, Resource Limitation, Question 30: When does the logistic growth model predict that a population will grow nearly exponentially? When the carrying capacity (K) is much smaller than the current population size (N) When the carrying capacity (K) is much larger than the current population size (N) Remember the logistic growth equation: dN/dt = rN(1-K/N). So, when K is much larger than N, then N/K will be a very small number, so the value in the parentheses will be very close to 1. In this case, the equation is approximately dN/dt = rN (the exponential growth equation). • Question 8 2 out of 2 points Part 1, Population Dynamics, Question 16: You are evaluating the fastest way to clean up an oil spill using bacteria (who grow exponentially when eating oil). If your oil spill clean-up organization claims that there is no difference in effectiveness between using faster-growing bacteria and increasing the initial amount of bacteria, what will you tell them? That's not true. With exponential growth, a population's size increases according to its growth rate, so even with fewer initial individuals, a higher intrinsic growth rate can lead to a larger population size in a shorter amount of time. That's not true. With exponential growth, a population's size increases according to its growth rate, so even with fewer initial individuals, a higher intrinsic growth rate can lead to a larger population size in a shorter amount of time. If two populations are growing exponentially, the one with the higher intrinsic growth rate will eventually grow larger than the one with the lower growth rate. • Question 9 2 out of 2 points If a population of organisms is limited by resources necessary for survival and reproduction, such as its food source, its growth is characterized as ______________. logisti c logisti c , this is logistic growth. The population will continue to grow until it reaches its carrying capacity, and then it will level of. • Question 10 0 out of 2 points Part 2, Resource Limitation, Question 21: When Simploid population was limited by the number of available burrows in the model, what was the carrying capacity of Simploids in the area? about 750 about 200 Nope. The limiting resource is the number of burrows, and there are about 200 burrows—so the carrying capacity for Simploids is about 200. [Show More]

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