Instructions: Respond to the following questions. You are allowed to use your book, your notes, and your classmates as sources to answer any question, but written responses must be in your own words (please explain it yourself!). The quiz is due as a printed hard copy at the beginning of lecture . No excuses. No electronic copies will be accepted.
1. Use your understanding of the basic B-cell immune response, and the data in Fig. 5.12 (right), to explain how the process of cellular evolution occurs via natural selection in B- cells. Be sure to identify the presence of each tenet of natural selection. Type your answer and use no more than 150 words in your answer.
Figure 1. Obesity and the presence of influenza antibodies over a 12-month period. a) The x-axis shows BMI (20-40), and the y-axis shows the percent decline of ELISA antibody titers. b) the x-axis shows three different influenza strains (A/Brisbane/59, A/Brisbane/10, and B/ Brisbane/60), while the y-axis shows a decrease in ELISA titer after 12 months.
Background & Question: Body Mass Index (BMI) is an indicator of healthy weight. BMI Categories:
Underweight = <18.5 Normal weight = 18.5-24.9 Overweight = 25-29.9
Obesity = BMI of 30 or greater
ELISA- A test that determines how much protein is present.
Antibody titers is a test that determines the presence and the amount of antibodies in the blood.
Influenza- Common cold
Strains- different species
2. Using your background information and what you have learned in lecture, interpret panel a) and panel b) from Figure 1. (i.e. explain what the data illustrate and reasonable conclusions you can draw from the data)
3. In the mid-1800s, California sea lions were hunted to near extinction for their blubber. A starting population of hundreds of thousands of sea lions was reduced to approximately 50-100 individuals on Guadalupe Island off of Baja California by the end of the century. However, after being federally protected, the population has increased to approximately 300,000 or more individuals distributed across several breeding colonies along the California coast. Despite their successful recovery, this species experienced what is called a genetic bottleneck. Look up information about genetic bottlenecks online and then answer these questions:
a. Scientists attempted to do a paternity study to determine if the offspring of “alpha males” (the males that get to mate with most of the females) were more likely to survive to sexual maturity than the offspring of non-dominant male sea lions (who will sneak into an alpha male’s territory and mate with his harem of females until he gets chased off…sneaky, huh?). Since sea lions return to their natal breeding colony later in life, they assumed it should be possible to find and identify offspring and fathers. However, after a genetic fingerprinting study, the scientists discovered that they couldn’t differentiate between individuals or assign paternity. Explain why this was the case based on the background information above and your understanding of the material in chapter 5. Maximum of 50 words.
b. Populations that experience genetic bottlenecks are at great risk of “crashing” to extinction if their environment changes (in a negative way for which they are not adapted). Why don’t those populations mutate in response to the environmental change and then undergo natural selection, driving adaptation and allowing persistence of the species? (maximum of 50 words)