TEAS 7 Science Practice Test

Correct Answer: C

Rationale: The correct answer is C: skin. Skin is the primary physical barrier that the body uses to prevent infection. It acts as a protective barrier, preventing pathogens from entering the body. The outer layer of the skin, known as the epidermis, is made up of tightly packed cells that are difficult for pathogens to penetrate. Additionally, skin produces oils and sweat that contain antimicrobial properties, further protecting against infections. Explanation for why other choices are incorrect: A: Mucus membranes play a role in preventing infections in certain areas like the respiratory and digestive tracts, but they are not the primary physical barrier used by the body. B: Stomach acid is a chemical barrier rather than a physical barrier against infections. D: Urine helps to flush out pathogens from the urinary tract but is not the primary physical barrier used by the body.

Correct Answer: B

Rationale: The correct answer is B: sinoatrial node. The sinoatrial node is a cluster of specialized cells in the right atrium responsible for initiating the electrical impulses that regulate the heartbeat. It acts as the heart's natural pacemaker by setting the pace for the heart's contractions. The other choices are incorrect because: A: Sinus venosus is an embryonic structure in the heart, not the natural pacemaker. C: Atrioventricular node is responsible for conducting the electrical signal from the atria to the ventricles, not for generating the initial signal. D: Tricuspid valve is a heart valve that prevents backflow of blood from the right ventricle to the right atrium, not involved in generating electrical signals.

Correct Answer: C

Rationale: The correct answer is C, the law of independent assortment. This law states that alleles for different traits segregate independently of each other during gamete formation. This is due to the random alignment of homologous chromosomes during meiosis. The law of segregation (A) describes how alleles of a gene separate during gamete formation. The law of dominance (B) explains that one allele can mask the expression of another in heterozygous individuals. The law of predictive traits (D) is not a recognized Mendelian law and is therefore incorrect. In summary, the law of independent assortment best describes how alleles from different genes segregate independently during gamete formation.

Correct Answer: D

Rationale: The correct answer is D: insulin production and blood sugar regulation. The liver is not responsible for insulin production; it is produced by the pancreas. The liver does play a role in blood sugar regulation by storing and releasing glucose, but it is not the primary organ for insulin production. The other choices (A, B, C) are functions of the liver: A) nutrient processing involves metabolizing and storing nutrients, B) blood filtration and detoxification involves removing toxins from the blood, and C) cholesterol and lipoprotein production involves synthesizing cholesterol and lipoproteins.

Correct Answer: B

Rationale: The correct answer is B: medulla oblongata. This region of the brain is responsible for controlling and regulating autonomic functions like respiration, digestion, and heart rate. It is located in the brainstem and contains vital centers for these functions. The cerebellum (A) is primarily involved in coordination and balance. The temporal lobe (C) is responsible for auditory processing and memory. The cerebral cortex (D) is involved in higher cognitive functions like thinking and decision-making. Therefore, the medulla oblongata is the correct choice as it specifically controls autonomic functions.