ACT science practice test 83

Directions: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

You are NOT permitted to use a calculator on this test.

Table 1 lists two genes found in Sesamum indicum (sesame), the possible alleles of each gene, and the possible genotypes for each gene.

Table 1


Table 2 lists various sesame genotypes and the phenotype associated with each genotype. Each gene affects only one of the phenotype traits listed.

Table 2


Table 3 lists four sesame plant crosses, the genotypes of the parents, and the percent of offspring that had each phenotype for the traits listed in Table 2. In each cross, each parent donated one allele to each offspring at each gene.

Table 3


1. Based on Table 2, which of the 2 genes affects leaf texture?

A. P
B. L
C. Neither
D. Both

2. Based on Table 2, a sesame plant with 2 recessive alleles for each of the 2 genes will have which of the following phenotypes?

F. 1 pod and normal leaves
G. 3 pods and normal leaves
H. 3 pods and wrinkled leaves
J. 1 pod and wrinkled leaves

3. Based on the information provided, all of the offspring of Cross 3 had 3 pods because each received:

A. allele p from its female parent and allele p from its male parent.
B. allele L from its female parent and allele l from its male parent.
C. allele l from its female parent and allele L from its male parent.
D. allele P from its female parent and allele P from its male parent.

4. In Cross 3, what percent of the offspring had genotype pp?

F. 0%
G. 25%
H. 50%
J. 100%

5. Based on the information provided, a sesame plant with 3 pods and normal leaves could have which of the following genotypes?

A. PPll
C. ppll
D. ppLl

To determine the effect of ambient ultraviolet radiation (UVR) on the chlorophyll production, growth rate, and cell death of Antarctic phytoplankton, scientists conducted experiments on phytoplankton communities exposed to natural levels of solar radiation.

Experiments were conducted during three different periods of time. Experiment 1 took place February 1–6, Experiment 2 February 7–12, and Experiment 3 February 13–20. A meteorological station automatically recorded solar radiation for the duration of the study (see Figure 1).

The experiments involved sampling surface seawater, placing them in bottles submersed in incubators, and exposing them to either natural solar radiation (UVR) or radiation filtered to exclude ultraviolet radiation (PAR).


Figure 1

Every two days, duplicate samples were taken from each location to determine chlorophyll amounts and phytoplankton cell death (see Table 1 and Figure 2). Net population growth rates were calculated for diatoms and flagellates from the cell abundances obtained at the beginning and end of the experiments (see Figure 3).

Table 1



Figure 2


Figure 3

6. Based on the data in Table 1, how much chlorophyll was measured in Experiment 3 for the sample exposed to UVR after 4 days?

F. 1
G. 1.3
H. 3
J. 4

7. Based on the information presented in Table 1, UVR seems to have what effect on the amount of chlorophyll measured?

A. UVR seems to inhibit the production of chlorophyll.
B. UVR seems to stimulate the production of chlorophyll.
C. UVR seems to have no effect on the production of chlorophyll.
D. It cannot be determined what the effect of UVR is on chlorophyll.

8. According to the data shown in Figure 3, which cells showed the least growth in Experiment 3?

F. Diatoms shielded from UVR
G. Diatoms exposed to UVR
H. Flagellates shielded from UVR
J. Flagellates exposed to UVR

9. Based on the information presented in Table 1, if Experiment 1 had been continued for another 2 days, the amount of chlorophyll measured in the samples that were not exposed to UVR would most likely be closest to what amount?

A. 0
B. 17
C. 3
D. 36

10. Based on the results displayed in Figure 2, it can be assumed that ultraviolet radiation (UVR) has what effect on the life of the diatoms and flagellates found in phytoplankton?

F. The presence of UVR leads to fewer dead diatoms and more dead flagellates.
G. The presence of UVR leads to more dead diatoms and fewer dead flagellates.
H. The presence of UVR leads to fewer dead cells for both diatoms and flagellates.
J. The presence of UVR leads to more dead cells for both diatoms and flagellates.