Nokea
Which of the following is NOT a characteristic of a chemical reaction?
- A. Formation of new substances
- B. Release or absorption of energy
- C. Change in color
- D. Change in temperature
Correct Answer: C
Rationale: A change in color is not always a characteristic of a chemical reaction. While some chemical reactions may result in a change in color, it is not a universal characteristic of all chemical reactions. The formation of new substances, release or absorption of energy, and change in temperature are commonly associated with chemical reactions. Therefore, the correct answer is C, as it does not always occur in every chemical reaction.
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Which vitamin is essential for blood clotting?
- A. Vitamin A
- B. Vitamin C
- C. Vitamin K
- D. Vitamin D
Correct Answer: C
Rationale: Vitamin K is essential for blood clotting as it plays a crucial role in the synthesis of clotting factors in the liver. Deficiency in vitamin K can result in impaired blood clotting and excessive bleeding. Vitamin K is necessary for the activation of proteins that are involved in the blood clotting process, making it a vital nutrient for maintaining proper hemostasis. Vitamin A (Choice A) is important for vision and immune function, Vitamin C (Choice B) is crucial for collagen synthesis and antioxidant protection, and Vitamin D (Choice D) is essential for calcium absorption and bone health. However, when it comes to blood clotting specifically, Vitamin K is the key vitamin involved.
What is the difference between the atomic number and the mass number of an atom?
- A. The atomic number is the number of protons in the nucleus, while the mass number is the total number of protons and neutrons in the nucleus.
- B. The atomic number is the number of electrons in an atom, while the mass number is the total number of protons and neutrons in the nucleus.
- C. The atomic number is the number of neutrons in the nucleus, while the mass number is the total number of protons and electrons in an atom.
- D. The atomic number is the number of protons and neutrons in the nucleus, while the mass number is the total number of electrons in an atom.
Correct Answer: A
Rationale: The atomic number of an atom represents the number of protons in its nucleus, which defines the element's identity. On the other hand, the mass number corresponds to the total sum of protons and neutrons in the nucleus. Therefore, the key distinction between the atomic number and the mass number lies in the fact that the atomic number specifically counts the protons, whereas the mass number encompasses both protons and neutrons. Choice B is incorrect because the atomic number is not related to the number of electrons but rather to the number of protons. Choice C is incorrect because the atomic number is not the number of neutrons but the number of protons. Choice D is incorrect because the atomic number does not include neutrons; it is solely the number of protons.
What is the term for the pressure exerted by blood against the walls of blood vessels?
- A. Heart rate
- B. Blood pressure
- C. Cardiac output
- D. Stroke volume
Correct Answer: B
Rationale: Blood pressure is the term for the pressure exerted by blood against the walls of blood vessels. It is measured in millimeters of mercury (mmHg) and consists of two numbers: systolic pressure (the top number) and diastolic pressure (the bottom number). Heart rate (A) is the number of times the heart beats per minute, cardiac output (C) is the volume of blood pumped by the heart per minute, and stroke volume (D) is the volume of blood pumped by the heart in one contraction. Understanding blood pressure is crucial in assessing cardiovascular health and the risk of various conditions like hypertension.
What is the building block of DNA?
- A. Amino acid
- B. Nucleotide
- C. Phosphate group
- D. Fatty acid
Correct Answer: B
Rationale: - Amino acids are the building blocks of proteins, not DNA.
- Nucleotide is the correct building block of DNA. A nucleotide consists of a sugar (deoxyribose in DNA), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine).
- The option 'C) Phosphate group' is incorrect as it is only part of a nucleotide, not the complete building block of DNA.
- Fatty acids are not the building blocks of DNA; they are a type of lipid molecule.
What are the finger-like projections that increase the surface area for absorption in the small intestine called?
- A. Crypts of Lieberk¼hn
- B. Goblet cells
- C. Villi
- D. Paneth cells
Correct Answer: C
Rationale: A) Crypts of Lieberk¼hn are small pits in the lining of the small intestine that contain cells involved in the production of intestinal juices, but they do not increase the surface area for absorption.
B) Goblet cells are specialized cells that secrete mucus to protect the lining of the digestive tract, but they do not increase the surface area for absorption.
C) Villi are finger-like projections in the small intestine that increase the surface area available for nutrient absorption. Each villus contains blood vessels and lacteals (lymphatic vessels) that help absorb nutrients from digested food.
D) Paneth cells are specialized cells found in the small intestine that secrete antimicrobial substances, but they do not increase the surface area for absorption.