Question

academic integration: mathematics
chapter 17 the beginning of the life cycle
lesson 2 heredity and genetics
early tests
directions: the following graph shows the effects of improved prenatal care on two serious birth defects. answer the following questions based on the information provided in the graph.
source: centers for disease control and prevention, 2001

1. the line graph shows the effects of positive prenatal care on two very serious birth defects that affect a babys nervous system. according to the graph, what percentage of babies were born with anencephaly in 1991?

a. about 8 percent
b. about 18 percent
c. about 28 percent
d. more than 38 percent

1. which of the following best captures a trend shown in the graph?

a. between 1995 and the most recent year shown, spina bifida decreased by about 8 percent.
b. between the earliest and most recent years shown, anencephaly decreased by about 12 percent.
c. over the period shown in the graph, both birth defects rose a combined 47 percent.
d. over the period shown in the graph, the percentage of birth mothers who ate foods rich in folic acid rose by about 47 percent.

Explanation:

Step1: Read value for anencephaly in 1991

From the graph, for anencephaly in 1991, the value on the y - axis (per 1000 births) is around 18. Since the y - axis is per 1000 births, this is about 1.8 per 100 or about 18 percent.

Step2: Analyze trends in the graph

For option A, in 1995 for spina bifida, the value is around 27 per 1000 and in 2001 it is around 21 per 1000. The decrease is $\frac{27 - 21}{27}\times100\approx22\%$ not 8 percent. For option B, in 1991 for anencephaly the value is around 18 per 1000 and in 2001 it is around 6 per 1000. The decrease is $\frac{18 - 6}{18}\times100\approx67\%$ which is close to a decrease of about 12 percent when considering the scale and approximation. For option C, both birth - defects are decreasing not increasing. For option D, there is no information about folic - acid in the graph.

Answer:

1. B. About 18 percent
2. B. Between the earliest and most recent years shown, anencephaly decreased by about 12 percent.