Nokea
What is the function of sodium bicarbonate released by the pancreas?
- A. Sodium bicarbonate neutralizes the acidity of chyme.
- B. Sodium bicarbonate stimulates the protease that digests carbonates.
- C. Sodium bicarbonate inhibits peristalsis.
- D. Sodium bicarbonate stimulates the protease.
Correct Answer: A
Rationale: The correct answer is A because sodium bicarbonate released by the pancreas functions by neutralizing the acidity of chyme in the small intestine. This action helps to create a more alkaline environment, which is crucial for the activity of pancreatic enzymes and the absorption of nutrients. Option B is incorrect as sodium bicarbonate itself does not stimulate a protease to digest carbonates. Option C is incorrect as sodium bicarbonate does not inhibit peristalsis; instead, it aids in digestion. Option D is incorrect as sodium bicarbonate does not directly stimulate the protease but rather helps in maintaining the optimal pH for enzyme activity.
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Why does dipping an apple slice in lemon juice prevent it from browning through an enzymatic reaction?
- A. Lemon juice has a pH that inactivates the enzymes.
- B. Lemon juice has enzymes that reverse the browning.
- C. Lemon juice functions to dilute the brown material.
- D. Lemon juice functions to bleach the brown material.
Correct Answer: A
Rationale: The correct answer is A: Lemon juice has a pH that inactivates the enzymes. Enzymatic browning in apples is caused by the enzyme polyphenol oxidase. When an apple is sliced, the enzyme comes into contact with oxygen in the air, leading to the browning process. Lemon juice contains citric acid, which lowers the pH of the apple's surface, creating an acidic environment that inactivates the polyphenol oxidase enzyme, thus preventing the browning reaction. This acidic environment denatures the enzyme, rendering it unable to catalyze the browning reaction. Therefore, by dipping the apple slice in lemon juice, the enzymatic activity that causes browning is effectively inhibited, maintaining the apple's color and freshness.
Which of the following properties does soap, an emulsifier, have that make it useful for washing dirt off one's hands with water?
- A. Soap's dual polar and nonpolar nature helps bond oil and water.
- B. Soap's acidity causes grime to precipitate into the water.
- C. Soap's rough texture physically scours grime off surfaces.
- D. Soap's enzymatic action helps to dissolve grime into smaller particles.
Correct Answer: A
Rationale: Soap acts as an emulsifier due to its dual polar (hydrophilic) and nonpolar (hydrophobic) nature, allowing it to effectively bond oil and water, making option A the correct choic
Which of the following allows the skull to rotate on the neck?
- A. Vertebral foramen
- B. Spinous process
- C. Atlas
- D. Sacrum
Correct Answer: C
Rationale: The atlas is the first cervical vertebra that supports the skull and allows it to rotate on the neck. The vertebral foramen is an opening in the vertebra for the spinal cord, and the spinous process is a bony projection, not involved in rotation.
Which of the following cells transfers pigment granules to adjust epidermal cells?
- A. Merkel Cells
- B. Keratinocytes
- C. Langerhans cells
- D. Melanocytes
Correct Answer: D
Rationale: Melanocytes are the cells responsible for transferring pigment granules to adjust epidermal cells. Melanocytes produce melanin, the pigment that gives skin its color and provides protection against UV radiation. Once produced, melanin is transferred to neighboring skin cells, primarily keratinocytes, to distribute the pigment throughout the epidermis. Merkel cells are associated with the sense of touch, not pigment transfer. Keratinocytes are the predominant cells in the epidermis that produce keratin, a structural protein for skin, nails, and hair. Langerhans cells are part of the immune system in the skin, helping to recognize and respond to foreign invaders.
What is the atomic number of an atom that has 12 protons and 12 neutrons?
- A. 1
- B. 144
- C. 12
- D. 24
Correct Answer: C
Rationale: The atomic number of an element is determined by the number of protons in its nucleus. In this case, the atom has 12 protons, which directly corresponds to its atomic number. Neutrons have no impact on the atomic number; they contribute to the atomic mass. The atomic number uniquely identifies an element based on the number of protons in its nucleus. Therefore, the correct answer is 12, as it represents the number of protons in the nucleus and defines the element, regardless of the presence of neutrons.