Nokea
Which of the following constituents of blood is a biconcave disc that is round and flat without a nucleus?
- A. Plasma
- B. Platelet
- C. RBC
- D. WBC
Correct Answer: C
Rationale: The correct answer is C, RBC (Red Blood Cell). Red blood cells are biconcave discs that lack a nucleus, allowing them to carry oxygen efficiently. Plasma (A) is the liquid component of blood that carries various substances. Platelets (B) are cell fragments important for blood clotting. White blood cells (WBCs) (D) are part of the immune system and have a nucleus.
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What is the smallest bone in the human body?
- A. Stapes (Middle ear bone)
- B. Patella (Kneecap)
- C. Phalanges (Finger bones)
- D. Ribs
Correct Answer: A
Rationale: The correct answer is A: Stapes (Middle ear bone). The stapes, located in the middle ear, is indeed the smallest bone in the human body. Despite its small size, the stapes is vital for hearing as it transmits and amplifies sound vibrations, contributing significantly to auditory perception. Choices B, C, and D are incorrect. The patella (kneecap) is the largest sesamoid bone in the human body, not the smallest bone. Phalanges are the bones in fingers and toes, not the smallest bone overall. Ribs are long bones that protect the chest cavity, not the smallest bone in the body.
Epithelial tissue, which covers surfaces, is further classified based on the number of cell layers. Simple epithelium has:
- A. No layers
- B. One layer
- C. Two to several layers
- D. Many tightly packed layers
Correct Answer: B
Rationale: Simple epithelium consists of a single layer of cells. This type of epithelium is found in areas where absorption, secretion, and filtration occur, as it allows for efficient exchange of substances across the epithelial barrier. Simple epithelium is well-suited for diffusion and filtration processes due to its thin nature, enabling substances to pass through easily. Choice A, 'No layers,' is incorrect as epithelial tissue always consists of at least one cell layer. Choice C, 'Two to several layers,' describes stratified epithelium, not simple epithelium, which has only one layer. Choice D, 'Many tightly packed layers,' is more characteristic of stratified epithelium, where multiple layers of cells are present. Therefore, the correct answer is B: 'One layer.'
Which of the following best describes the term homeostasis?
- A. The ability to maintain a constant body temperature
- B. The ability to maintain a stable internal environment
- C. The ability to increase body temperature when cold
- D. The ability to regulate blood glucose levels
Correct Answer: B
Rationale: The correct answer is B, 'The ability to maintain a stable internal environment.' Homeostasis refers to the body's ability to regulate and maintain a stable internal environment, which includes variables like body temperature, pH levels, and fluid balance. It involves processes that help keep the body's internal conditions within a narrow range, despite external changes. While maintaining body temperature is a component of homeostasis, it is not the complete definition of the term. Choice C, 'The ability to increase body temperature when cold,' is incorrect as homeostasis aims to maintain stability rather than promoting temperature increases in response to external conditions. Choice D, 'The ability to regulate blood glucose levels,' is also incorrect as this is a specific function related to glucose homeostasis, which is a part of overall homeostatic processes but not the sole definition of homeostasis itself.
Where is the primary site for nutrient absorption from digested food in the human digestive system?
- A. Esophagus
- B. Large intestine
- C. Small intestine
- D. Stomach
Correct Answer: C
Rationale: The small intestine is the primary site for nutrient absorption in the human digestive system. It is where the majority of digestion and absorption of nutrients from food occurs. The walls of the small intestine are lined with tiny finger-like projections called villi, which increase the surface area available for absorption. Nutrients such as carbohydrates, proteins, fats, vitamins, and minerals are absorbed through the walls of the small intestine and into the bloodstream to be transported to cells throughout the body for energy and other functions. The esophagus is a muscular tube that connects the throat to the stomach and plays a role in swallowing, not nutrient absorption. The large intestine primarily absorbs water and electrolytes from the remaining indigestible food matter after the absorption of nutrients in the small intestine. The stomach mainly functions in the mechanical and chemical breakdown of food through muscular contractions and the secretion of digestive enzymes.
Through which structure do the kidneys reabsorb water, salts, and nutrients and return them to the body?
- A. Renal artery
- B. Renal vein
- C. Nephron
- D. Glomerulus
Correct Answer: C
Rationale: The question has been corrected to specify the structure responsible for reabsorbing water, salts, and nutrients in the kidneys. The correct answer is the nephron, which is the functional unit of the kidney that performs filtration and reabsorption processes. The renal artery brings blood into the kidney for filtration, the renal vein carries filtered blood away from the kidney, and the glomerulus is a part of the nephron where filtration occurs. Therefore, the nephron is the structure that reabsorbs substances and returns them to the body.