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ATI TEAS 7

Biology

1. Homologous structures are those that:

Correct answer: C

Rationale: Rationale: - Option A is incorrect because structures with the same function but different origins are analogous structures, not homologous structures. - Option B is incorrect because structures with different functions but the same origin are also not homologous structures; they are considered to be vestigial structures. - Option D is incorrect because structures that are identical in both appearance and function are not necessarily homologous; they could be the result of convergent evolution. Homologous structures are those that share similarities in appearance and function due to being inherited from a common ancestor. These structures may have undergone modifications over time to adapt to different functions in different species, but their fundamental similarities can be traced back to a shared evolutionary history.

2. The hormone responsible for the "fight-or-flight" response in stressful situations is produced by the:

Correct answer: C

Rationale: The correct answer is C: Adrenal gland. The adrenal gland is responsible for producing the hormone known as adrenaline, which triggers the 'fight-or-flight' response in stressful situations. This response prepares the body to either confront the stressor or flee from it. The thyroid gland (A) is responsible for producing hormones that regulate metabolism, growth, and development. The pituitary gland (B) controls several other endocrine glands and produces a variety of hormones. The pancreas (D) is responsible for producing insulin and glucagon, which regulate blood sugar levels but are not directly involved in the 'fight-or-flight' response.

3. Which of the following structures is responsible for preventing the backflow of blood from the left ventricle into the left atrium?

Correct answer: D

Rationale: The correct answer is D, the mitral valve. The mitral valve, also known as the bicuspid valve, is located between the left atrium and the left ventricle. Its main function is to prevent the backflow of blood from the left ventricle into the left atrium during ventricular contraction. The aortic valve (A) is responsible for preventing the backflow of blood from the aorta into the left ventricle, the pulmonary valve (B) prevents backflow from the pulmonary artery into the right ventricle, and the tricuspid valve (C) prevents backflow from the right ventricle into the right atrium. Therefore, the mitral valve is specifically responsible for preventing backflow in the left side of the heart, making it the correct answer in this case.

4. The critical angle is defined as the minimum angle of incidence in a denser medium for which light undergoes:

Correct answer: A

Rationale: The critical angle is the minimum angle of incidence at which light is totally internally reflected rather than refracted. When light travels from a denser medium to a rarer medium at an angle greater than the critical angle, it undergoes total internal reflection. This phenomenon is crucial in applications like fiber optics and mirages. Continued refraction (option B) occurs when light enters a medium at an angle less than the critical angle. Specular reflection (option C) refers to the reflection of light at a smooth surface. Increased dispersion (option D) involves the separation of light into its constituent colors due to varying refractive indices, which is not directly related to the critical angle. Therefore, the correct answer is A - total internal reflection.

5. Stretch marks occur when

Correct answer: C

Rationale: Stretch marks occur when the dermis layer tears due to rapid stretching. During periods of rapid growth or weight gain, the skin may stretch beyond its capacity, causing the dermis layer to tear and resulting in the formation of stretch marks. Inflammation or clogged sebaceous glands do not directly cause stretch marks, making options A, B, and D incorrect. It is important to understand the physiological process behind stretch marks to identify the correct answer.

6. What are chromosomes made of?

Correct answer: B

Rationale: Rationale: Chromosomes are structures found in the nucleus of cells that contain genetic material. They are made up of DNA (deoxyribonucleic acid), which carries the genetic information, and proteins that help in the organization and packaging of the DNA. While RNA is involved in various cellular processes, it is not a major component of chromosomes. Carbohydrates are not a significant component of chromosomes. Therefore, the most accurate answer is B) DNA and proteins.

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