University of California, Los Angeles

• LIFESCIENC 30B

• Homework 2 Solutions January 26, 2017 Rubric 4 problems were graded in the following scale for a total of 10 points. 4.1.Exercise 7: (2 points) • 2 points: Have 3 graphs (Trajectory + Time Series for both V and X) AND a description of the trend of the graph as the value of a changes • 1 point: Either the description is missing or one of the graphs is missing • 0 point: Blank answer 4.1.Further Exercise 2: (2 points) • 2 points: Able to state that the trajectory will never reach the limit cycle attractor along with a detailed explanation OR state that the trajectory will reach the limit cycle attractor but demonstrate a good effort to explain their answer • 1 point: Missing a detailed explanation • 0 point: Blank answer 4.2.Further Exercise 1: (4 points) Part a: (2 points) • 2 points: Able to identify negative feedback loop • 1 point: Any other kind of answer • 0 point: Blank answer Part b: (2 points) • 2 points: A detailed explanation that will address either sensitivity of the system or time-delay • 1 point: An explanation that somewhat lacks in effort (e.g. state a solution without much explanation) 1 LS 30B Homework 2 Solutions Jan 26, 2018 • 0 point: Blank answer 4.4.Exercise 8: (2 points) • 2 points: Produce a graph with two nullclines + four test points (along with their respective vectors) + some sort of mathematical calculations (even some numbers or algebraic expressions are fine) • 1 point: Produce a graph with two nullclines + four vectors but missing some sort of mathematical calculations (numbers or algebraic expressions) • 0 point: Unable to produce a graph 2 LS 30B Homework 2 Solutions Jan 26, 2018 Chapter 4.1. Exercise 4.1.7. Simulate the model X0 = V V 0 = −X − (aV 3 − V ) for three different positiv