Nokea
What causes stretch marks?
- A. The epidermis layer becomes inflamed
- B. The dermis layer becomes inflamed
- C. The dermis layer tears due to rapid stretching
- D. Sebaceous glands become clogged
Correct Answer: C
Rationale: Stretch marks occur when the dermis layer tears due to rapid stretching of the skin. This tearing leads to the appearance of stretch marks, which are often red or purple at first and then fade to a silvery-white color over time. Inflammation of the dermis or clogging of sebaceous glands are not directly related to the formation of stretch marks. Therefore, choices A, B, and D are incorrect as they do not describe the actual cause of stretch marks.
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Which hormone, produced by the pancreas, is released in response to low blood sugar levels and stimulates the release of glucose into the bloodstream?
- A. Insulin
- B. Glucagon
- C. Cortisol
- D. Thyroxine
Correct Answer: B
Rationale: Glucagon is the hormone produced by the pancreas that is released in response to low blood sugar levels. It acts to stimulate the release of glucose into the bloodstream by promoting the breakdown of glycogen in the liver. Insulin, conversely, is released in response to high blood sugar levels and promotes the uptake of glucose by cells. Cortisol is a steroid hormone produced by the adrenal glands that regulates metabolism and the immune response. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism but is not involved in responding to low blood sugar levels.
A routine urinalysis is a common diagnostic test. What does a urinalysis typically evaluate?
- A. Blood sugar levels
- B. Presence of white blood cells (indicating possible infection)
- C. Kidney function
- D. All of the above
Correct Answer: D
Rationale: A routine urinalysis evaluates multiple components of urine, including blood sugar levels, the presence of white blood cells indicating a possible infection, and kidney function. Blood sugar levels are assessed to monitor for conditions like diabetes. The presence of white blood cells is checked to detect possible urinary tract infections. Kidney function is evaluated by assessing markers like creatinine and protein levels. Therefore, all of the above options are typically evaluated in a urinalysis, making choice D the correct answer.
What accurately describes the Linnaean system of classification?
- A. It focuses on evolutionary relationships between organisms.
- B. It uses dichotomous keys for identification.
- C. It groups organisms based on shared functions.
- D. It emphasizes a hierarchical ranking system.
Correct Answer: D
Rationale: The Linnaean system of classification, developed by Carl Linnaeus, is based on a hierarchical ranking system where organisms are grouped into categories based on shared characteristics. This system organizes organisms into a hierarchy of increasingly specific categories, from broad to narrow, such as kingdom, phylum, class, order, family, genus, and species. The emphasis on a hierarchical ranking system allows for systematic organization and classification of a wide variety of organisms based on their similarities and differences, making it easier to study and understand the diversity of life forms. Choice A is incorrect because the Linnaean system is not primarily focused on evolutionary relationships but rather on shared characteristics for classification. Choice B is incorrect because dichotomous keys are tools used for identifying organisms, not the fundamental basis of the Linnaean system. Choice C is incorrect as the Linnaean system categorizes organisms based on shared characteristics, not shared functions.
What term describes the point where parallel rays of light converge or appear to diverge after passing through a lens or reflecting off a mirror?
- A. Aperture
- B. Focal length
- C. Refractive index
- D. Lens thickness
Correct Answer: B
Rationale: The correct answer is 'Focal length.' Focal length is the term used to describe the point where parallel rays of light converge or appear to diverge after passing through a lens or reflecting off a mirror. It is a critical parameter in optics that determines the magnification and image formation in optical systems. Aperture refers to the opening through which light enters a camera or telescope, not the convergence point of light rays. Refractive index is a measure of how much light is bent, not the point where rays converge. Lens thickness is the physical dimension of a lens and does not indicate the convergence point of light rays. Therefore, 'Focal length' is the most appropriate choice in this context.
What is the difference between isometric and isotonic muscle contractions?
- A. Isometric involves movement, while isotonic does not.
- B. Isotonic involves shortening of muscle, while isometric maintains length.
- C. Isometric uses more energy, while isotonic uses less.
- D. Isotonic involves smooth muscle, while isometric involves skeletal muscle.
Correct Answer: B
Rationale: The correct answer is B. Isometric contractions occur when the muscle generates tension without changing its length, while isotonic contractions involve the muscle changing length to move a load. In isotonic contractions, the muscle shortens to move a load, whereas in isometric contractions, the muscle contracts to hold a position without movement. Choice A is incorrect because isometric contractions do not involve movement, while choice C is incorrect as isotonic contractions typically require more energy due to movement. Choice D is incorrect because the type of muscle involved (smooth or skeletal) is not the defining factor between isometric and isotonic contractions.