Science TEAS Practice Test

Correct Answer: C

Rationale: The correct answer is C: Covalent. In DNA, sugar and phosphate molecules are joined together by covalent bonds. Covalent bonds involve sharing of electrons between atoms, providing a strong and stable connection. This type of bond is essential for the structural integrity of the DNA molecule. A: Hydrogen bonds are important in DNA structure, but they connect the nitrogenous bases, not sugar and phosphate. B: Ionic bonds involve the transfer of electrons between atoms, not sharing, and are not typically involved in connecting sugar and phosphate in DNA. D: "Overt" is not a recognized type of chemical bond; it is an incorrect distractor.

Correct Answer: D

Rationale: The correct answer is D: Adipose. Adipose tissue is a type of connective tissue that stores fat, not a type of muscle tissue. Skeletal, smooth, and cardiac tissues are the three main types of muscle tissue. Skeletal muscles are attached to bones, smooth muscles are found in organs and blood vessels, and cardiac muscles are specific to the heart. Adipose tissue does not have the contractile properties of muscle tissue, making it the correct choice.

Correct Answer: B

Rationale: The correct answer is B: A model. A model is a representation of a natural pattern or occurrence that simplifies complex systems to make them easier to understand and study. Models can simulate natural phenomena that are difficult or impossible to experience directly, allowing scientists to make predictions and test hypotheses. The other choices are incorrect because: A: A theory is an explanation based on evidence and reasoning, not necessarily something difficult to experience directly. C: A law describes a recurring phenomenon but may not involve a representation or simulation of the phenomenon. D: An observation is a direct act of seeing or noting something, not a representation of a complex natural pattern.

Correct Answer: A

Rationale: The correct answer is A: The sinoatrial node. The SA node is known as the heart's natural pacemaker as it initiates electrical impulses that regulate the heart rate. It is located in the right atrium and generates rhythmic electrical signals that stimulate the cardiac muscle to contract. The left ventricle (B), aorta (C), and tricuspid valve (D) do not serve as electrical stimulators of the cardiac muscle. The left ventricle is a chamber that pumps oxygenated blood, the aorta is the largest artery that carries blood away from the heart, and the tricuspid valve controls blood flow between the right atrium and right ventricle.

Correct Answer: C

Rationale: The correct answer is C: Alveoli. Alveoli are tiny sacs in the lungs where gas exchange occurs. Oxygen enters the bloodstream from the alveoli, while carbon dioxide exits the bloodstream to be exhaled. Kidneys (A) filter blood and regulate fluid balance, not involved in gas exchange. Medulla oblongata (B) controls vital functions like breathing and heart rate, but not where gas exchange occurs. Bronchioles (D) are air passages in the lungs, but gas exchange specifically occurs in the alveoli.