How many mL of a 0 M stock solution of HCl should be added to water to create 250 mL of a 50 M solution of HCl?
- A. 31.25 mL
- B. 32 mL
- C. 30 mL
- D. 31.3 mL
Correct Answer: B
Rationale: To prepare 250 mL of a 50 M solution of HCl, the formula V1 x C1 = V2 x C2 is used, where V1 is the volume of the stock solution, C1 is the concentration of the stock solution, V2 is the final volume of the desired solution, and C2 is the final concentration of the desired solution. Given V1 x 0 M = 250 mL x 50 M, solving for V1 results in V1 = (250 mL x 50 M) / 0 M = 32 mL. Therefore, 32 mL of the 0 M stock solution of HCl needs to be added to water to create a 250 mL solution of 50 M HCl. Choices A, C, and D are incorrect because they do not represent the accurate volume required for the dilution calculation based on the given concentrations and volumes in the problem.
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Which locations in the digestive system are sites of chemical digestion? I. Mouth II. Stomach III. Small Intestine
- A. II only
- B. III only
- C. II and III only
- D. I, II, and III
Correct Answer: D
Rationale: Chemical digestion occurs in all three locations in the digestive system - the mouth, stomach, and small intestine. Enzymes in the saliva break down carbohydrates in the mouth, gastric juices in the stomach help break down proteins, and enzymes in the small intestine further break down macronutrients like carbohydrates, proteins, and fats. The mouth initiates the digestion of carbohydrates, the stomach digests proteins, and the small intestine continues the breakdown of carbohydrates, proteins, and fats. Choice A is incorrect because chemical digestion does occur in the mouth. Choice B is incorrect as both the stomach and small intestine are sites of chemical digestion. Choice C is incorrect as the mouth is also a location of chemical digestion, not just the stomach and small intestine.
What is the dermis composed of?
- A. Adipose tissue
- B. Epithelial cells
- C. Connective tissue
- D. Muscle tissue
Correct Answer: C
Rationale: The correct answer is C: Connective tissue. The dermis is primarily composed of connective tissue, which includes collagen and elastin fibers that provide strength and elasticity to the skin. It houses blood vessels, nerve endings, hair follicles, and glands, playing a crucial role in supporting the skin structure and function. Adipose tissue (choice A) is found in the subcutaneous layer beneath the dermis, providing insulation and energy storage. Epithelial cells (choice B) form the outermost layer of the skin called the epidermis. Muscle tissue (choice D) is not a significant component of the dermis but is found deeper in the body associated with movement and support.
Which of the following is LEAST likely to be found in a human cell's genes?
- A. Sequences of amino acids to be transcribed into mRNA
- B. Lethal recessive traits like sickle cell anemia
- C. Mutated DNA
- D. DNA that codes for proteins the cell doesn't use
Correct Answer: D
Rationale: Human cells typically contain genes that code for proteins necessary for the cell's functions. DNA that codes for proteins the cell doesn't use would be an inefficient use of the cell's resources. Therefore, it is less likely to be found in a human cell's genes. Options A, B, and C are more commonly associated with genes found in human cells. Choice A refers to the genetic information needed for protein synthesis, while choice B involves traits that can be present in the gene pool. Mutated DNA (choice C) can also be found in human cells as a result of genetic alterations. However, DNA that codes for proteins not utilized by the cell would be redundant and not typically retained in the genome.
What are the three types of muscle tissues?
- A. Cardiac, smooth, epithelial
- B. Skeletal, cardiac, smooth
- C. Cardiac, smooth, connective
- D. Skeletal, epithelial, connective
Correct Answer: B
Rationale: The correct answer is B: Skeletal, cardiac, smooth. Skeletal muscle tissue is responsible for voluntary movement, cardiac muscle tissue is found in the heart and is responsible for involuntary heart contractions, and smooth muscle tissue is located in organs and is responsible for involuntary movements. Therefore, the three types of muscle tissues are skeletal, cardiac, and smooth. Choices A, C, and D are incorrect because they include types of tissues that are not classified as muscle tissues. Epithelial and connective tissues are different types of tissues that serve other functions in the body, not related to muscle contractions.
What are the four types of cells in the gastric glands of the stomach mucosa?
- A. Endocrine, parietal, chief, mucous cells
- B. Parietal, mucous, goblet, endocrine cells
- C. Chief, parietal, goblet, lymphoid cells
- D. Goblet, lymphoid, parietal, chief cells
Correct Answer: A
Rationale: The correct answer is A: Endocrine, parietal, chief, mucous cells. In the gastric glands of the stomach mucosa, the four types of cells are endocrine (producing hormones), parietal (secreting acid and intrinsic factor), chief (responsible for producing digestive enzymes), and mucous cells (providing protection to the stomach lining). These cells play essential roles in the digestive processes and maintaining the health of the stomach mucosa. Choices B, C, and D are incorrect because they do not accurately represent the types of cells found in the gastric glands of the stomach mucosa. Parietal cells secrete acid and intrinsic factor, chief cells produce digestive enzymes, and mucous cells provide protection, making these the correct choices in the context of gastric gland cellular composition.