TEAS 7 Science Practice Test

Correct Answer: D

Rationale: Natural selection is the correct answer. It is the mechanism where advantageous traits lead to better survival and reproduction, passing on those traits to offspring. This process drives evolution by selecting for traits beneficial for survival in a given environment. Gene flow involves the transfer of genes between populations, genetic drift is the random change in allele frequencies, and mutation introduces new genetic variations. These mechanisms do not specifically involve the differential survival and reproduction of organisms based on advantageous traits, making them incorrect choices for this question.

Correct Answer: A

Rationale: The correct answer is A. Progesterone is not responsible for the expression of secondary sexual characteristics, such as enlarged breasts. Progesterone's main functions in the female reproductive system are to regulate and prepare the endometrial lining of the uterus for potential pregnancy, inhibit contractions of the uterus as the ovum is released, and stimulate milk production in the breasts. Enlarged breasts are primarily influenced by estrogen, another hormone in the female reproductive system. Thus, A is the correct answer as it does not align with the known functions of progesterone.

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: A

Rationale: The correct answer is A because atomic radius generally increases from top to bottom within a group and decreases from left to right across a period on the periodic table. This trend is due to the increasing number of energy levels (shells) as you move down a group, leading to larger atomic radii. Moving from left to right across a period, atomic radius decreases due to increasing effective nuclear charge pulling the electrons closer to the nucleus. Choices B, C, and D are incorrect as they do not accurately describe the trend of atomic radius across the periodic table.

Correct Answer: C

Rationale: The primary function of the large intestine is to absorb water and compact material into solid waste. This process helps in forming feces for elimination. Absorbing digested material into the blood (Choice A) is mainly done in the small intestine. Nutrient processing and metabolizing (Choice B) occur in various organs like the liver and kidneys, not primarily in the large intestine. Bile production and storage (Choice D) are functions of the liver and gallbladder, not the large intestine.