ACT Science Practice Test 4

The oceans of Earth are exposed to various climates and consequently have different physical properties. Deep oceans can be divided into zones based on temperature gradient and penetration of sunlight. Figure 1 shows the zones of a typical deep-water ocean, the depth of the zone boundaries in meters (m), and the overall pressure at those depths in kilopascals (kPa). Figure 2 shows the water temperature in degrees Celsius (°C) in warmer tropical oceans and cooler temperate oceans at varying depths. Sound waves are used to measure water temperature at depth, and readings from two different ocean regions are recorded in Table 1.

Figure 1

Figure 2

Although many forms of bacteria are helpful for human health, they can also cause illness and even death from severe infections. Antibiotics are a class of medicines used to combat bacterial infections. Bacteriostatic activity inhibits bacteria cell division and bactericidal activity kills bacterial cells. Both actions eliminate populations of bacteria over time. Several classes of bacteriostatic and bactericidal antibiotics are described in Table 1.

The effectiveness of several antibiotics against a bacterium known to cause common skin infections was tested. Drugs were introduced to the bacterial culture by themselves or in combination with sulfamethoxazole (forming SMX compounds). The effectiveness of these antibiotics at eliminating the responsible bacterium is shown in Figure 1.

Figure 1

A study was conducted regarding the fossil shells of a particular species of turtle that lives off the coast of the Opulasian Peninsula. Scientists discovered a continuous record of fossilized shells in the seabed off the coast dating back 120,000 years. In addition to examining the fossilized turtle shells, the scientists also examined the shells of living turtles.

From each layer of seabed, the scientists randomly selected five complete, unbroken fossilized shells. Each shell was carefully prepared, measured, and photographed. A bit of each shell was then clipped off and sent to a laboratory for radiocarbon dating to determine the precise age of each shell.

Study 1

All of the living turtles had a distinct band of hexagonal scutes (bony plates) running the length of their shells, from head to tail. The fossilized shells' scutes were not visible to the naked eye; however upon application of a particular dye, a similar band of scutes from head to tail was observed in every shell.

Scutes extending greater than of the length of the shell were labeled major (M), where scutes extending less than or equal to of the length of the shell were labeled minor (m). The pattern of scutes was recorded for each fossil. For each time period, the percent of fossils exhibiting each pattern is given in Table 1.

Study 2

For each shell, the surface area of the shell, the height of the shell's bridge (the part of the shell linking the upper and lower plates), and the total number of scutes were recorded (see Figure 1).

For the shells of each age, the average of each measurement was calculated. The results are presented in Figure 2.

The 4 different blood types in sheep are A, B, AB, and O. The blood type of an offspring is determined by the blood types of its parents. Each parent contributes a single gene to its offspring, forming a pair of genes. The genotype of an offspring refers to the arrangement of the offspring's new gene formed by the combination of the parents' genes.

There are three possible alleles (forms) of this gene: the type-A blood allele (I^A), the type-B blood allele (I^B), and the type-O blood allele (I^O). Both I^A and I^B are dominant to I^O, and I^O is recessive to I^A and I^B. This means that an individual with 1 I^A and 1 I^O will have type-A blood, and an individual with one I^B and one I^O will have type-B blood. When an individual has one I^A and one I^B allele, this individual will have type-AB blood, due to the codominance of the I^A and I^B alleles.

To explore the inheritance patterns of blood types in sheep, researchers conducted 4 analyses. In each analysis, male and female sheep of differing blood types were mated and the resultant blood types of their offspring recorded.

Analysis 1

One thousand males with type-O blood were mated with 1,000 females with type-AB blood. The following blood types were observed in the offspring:

Type A: 50%

Type B: 50%

Analysis 2

Two hundred of the type-A offspring from Analysis 1 were mated with 200 type-O mates from no previous experiment. The following blood types were observed in the offspring:

Type A: 50%

Type O: 50%

Analysis 3

One hundred of the type-A offspring from Analysis 1 parented children with 100 type-B offspring from Analysis 1. The following blood types were observed in the offspring:

Type A: 25%

Type B: 25%

Type AB: 25%

Type O: 25%

Analysis 4

Twenty-five of the type-A offspring from Analysis 3 were mated with type-B mates with Genotype I^BI^B who were not from any previous analysis. The following blood types were observed in the offspring:

Type AB: 50%

Type B: 50%