ACT Science Practice Test 90

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.

A polymorphism is the persistent occurrence of different appearances for a particular trait in a species. All humans have slight differences in their genotypes (genetic code) that result in different phenotypes (observable characteristics). Genetic polymorphisms are persistent variations in gene sequences at a particular location in chromosomes, such as those accounting for different blood types. Variations that cannot be observed with the naked eye require techniques such as capillary electrophoresis (the separation of genetic or protein material based on charge characteristics using an electric field).

The label on a vial of blood from a hospital patient was lost. The sample just tested positive for a disease of the blood protein hemoglobin that is very common in the hospital population. The sample was traced to a room with 4 patients who were subsequently tested to determine the source of the initial vial.

Tests and Results

Smears of the blood from the unidentified patient (P) and from the 4 newly tested patients (1–4) were observed under the microscope for the appearance of the blood cells. Results are shown in Table 1.

Table 1

Patient Blood smear findings

P Sickle cells

1 Target cells

2 Sickle cells

3 Normal blood cells

4 Sickle cells

Serum was isolated from the blood of Patient P and from Patients 1–4 and placed in separate tubes. A buffer was added to each vial to establish a pH of 8.6. One at a time, samples from each tube were injected into the capillary electrophoresis device set at 7.5 kilovolts (kV) to separate the types of hemoglobin present into peaks. The hemoglobin proteins composing a peak had similar charge characteristics. Figure 1 shows the peaks that resulted from all 5 samples.

Figure 1

1. Are the data in Table 1 consistent with the hypothesis that Patient 4 and Patient P are the same person?

F. Yes; Patient 4 has the same blood cell appearance as Patient P.
G. Yes; Patient 4 has different blood cell appearance as Patient P.
H. No; Patient 4 has the same blood cell appearance as Patient P.
J. No; Patient 4 has different blood cell appearance as Patient P.

2. What is the most likely reason that the serum samples were treated with a buffer to bring pH to 8.6 ?

A. Hemoglobin protein breaks down at that pH.
B. All bacteria and viruses are destroyed at that pH.
C. Capillary electrophoresis separation of hemoglobin functions best at that pH.
D. Capillary electrophoresis separation of hemoglobin does not function at that pH.

3. Sickle cell anemia is caused by certain hemoglobin genotype combinations of 3 different alleles. The HbA allele is responsible for normal hemoglobin, the HbS allele is responsible for one variant that results in sickle cells, and the HbC allele is responsible for a different variant also resulting in sickle cells. Based on Table 1, the genotype of Patient 4 could be which of the following?

I. HbA HbA



F. II only
G. I or III only
H. II or III only
J. I, II, or III

4. According to Figure 1, the pattern of protein peaks produced by serum from Patient P most closely resembles the pattern produced by the serum sample from:

A. Patient 1.
B. Patient 2.
C. Patient 3.
D. Patient 4.

5. Based on Figure 1, the hemoglobin proteins in which of the following 2 peaks were most likely closest in charge characteristic?

F. W and X
G. W and Z
H. X and Y
J. X and Z

6. During the capillary electrophoresis, all the hemoglobin proteins started with some quantity of charge before migrating from left to right in Figure 1. Therefore, the proteins resulting in peaks furthest to the left must have been the most:

A. negative, as opposite charges attract each other.
B. negative, as opposite charges repel each other.
C. positive, as opposite charges attract each other.
D. positive, as opposite charges repel each other.

To help design a carnival game, bowling balls at rest on the ground are launched along a track by a constant force spring apparatus as shown in Figure 1.

Figure 1

To win the game, the ball must pass Point Y but not Point Z. A total of 5 trials were done to determine the best design. For each combination of ball friction coefficient, μ, and ramp angle, θ, Point W was put at a distance, d, from Point X such that the ball will just barely reach Point Z before rolling back toward the ramp.

The ball's kinetic energy (KE) at Points X and Y along with its potential energy (PE) at Point Y are shown in joules (J) in Table 1 for each trial. The mechanical energy (ME) of the ball at any given point is the sum of its kinetic and potential energies. It should remain constant provided no energy is lost in the form of heat from friction or drag forces.

7. Which of the following ranks Points X, Y, and Z from where the bowling ball had the slowest velocity to where the bowling ball had the fastest velocity during any trial?

F. Point X, Point Y, Point Z
G. Point X, Point Z, Point Y
H. Point Z, Point X, Point Y
J. Point Z, Point Y, Point X

8. In Trial 4, at the point immediately before climbing the ramp, the bowling ball's ME was closest to which of the following?

A. 0 J
B. 11.6 J
C. 24.2 J
D. 29.1 J

9. Based on the results of Trials 1–3, if an additional trial is performed with μ = 0.2 and θ = 50°, PE at Point Y will most likely be:

F. greater than 12.6 J.
G. between 9.8 J and 12.6 J.
H. between 6.7 J and 9.8 J.
J. less than 6.7 J.

10. The results of Trials 3–5 indicate that as the coefficient of friction increases, the minimum distance of Point W from Point X required for the bowling ball to barely reach Point Z:

A. only increases.
B. only decreases.
C. remains the same.
D. varies, but with no general trend.

11. The law of conservation of energy states that the total amount of energy in an isolated system remains constant. In which of the trials, if any, was mechanical energy transformed to heat energy?

F. Only Trial 1
G. Only Trial 5
H. All trials had mechanical to heat energy transfers.
J. No trials had mechanical to heat energy transfers.