Practice TEAS Science Test

Correct Answer: A

Rationale: The correct answer is A: Ectoderm. During embryonic development, the nervous system originates from the ectoderm layer. The neural plate forms from the ectoderm, which further develops into the neural tube and neural crest cells, giving rise to the brain, spinal cord, and peripheral nervous system. The other choices, B: Endoderm, C: Gastroderm, and D: Mesoderm, do not give rise to the nervous system. Endoderm forms the innermost layer of organs like the gut, Gastroderm is not a recognized germ layer, and Mesoderm gives rise to structures like muscles, bones, and connective tissues, not the nervous system.

Correct Answer: B

Rationale: The correct answer is B: Vitamin D. When skin is exposed to sunlight, it triggers the production of Vitamin D in the body. Sunlight activates a form of cholesterol in the skin, which then converts to Vitamin D through a series of chemical reactions. Vitamin A (Choice A) is not produced by sunlight but is found in foods like carrots. Vitamin K (Choice C) is involved in blood clotting and bone health but is not produced by sunlight. Vitamin E (Choice D) is an antioxidant found in foods like nuts and seeds, not produced through sun exposure.

Correct Answer: C

Rationale: The correct answer is C because an allergic reaction is triggered by the release of histamine and other inflammatory molecules from mast cells, which are stimulated by Immunoglobulin E. This process leads to symptoms such as hives, itching, swelling, and difficulty breathing. Other choices are incorrect because: A: While integumentary and respiratory systems are involved in allergic reactions, they are not overactive systems but rather respond to the allergen. B: B-cells produce antibodies, not immunoglobulins directly related to allergic reactions. D: Histamine is involved in allergic reactions, but keratin and collagen are not typically associated with allergic responses.

Correct Answer: D

Rationale: The correct answer is D: Epiglottis. The epiglottis is a flap of tissue that covers the opening of the windpipe (trachea) during swallowing to prevent food from entering it. Step-by-step rationale: 1. During swallowing, the epiglottis moves down to cover the trachea. 2. This action directs food to the esophagus (B), a muscular tube that carries food to the stomach. 3. The pharynx (A) is a common passageway for both food and air but does not prevent food from entering the windpipe. 4. The larynx (C) is involved in sound production but does not prevent food from entering the windpipe. In summary, the epiglottis is the correct structure as it specifically functions to protect the windpipe during swallowing, while the other choices do not have this specific function.

Correct Answer: C

Rationale: The correct answer is C: Graduated cylinder. To measure the volume of a solid accurately, we need to use a container with volume markings like a graduated cylinder. Step 1: Fill the graduated cylinder with a known amount of water. Step 2: Drop the solid into the water and measure the new water level. Step 3: Subtract the initial water level from the final level to find the volume displaced, which is the volume of the solid. The other choices are incorrect because a triple beam balance measures mass, a measuring wheel is for linear measurements, and using a measuring wheel and formula may not provide accurate volume measurements.