Nokea
What type of bond holds water molecules together?
- A. Covalent bond
- B. Hydrogen bond
- C. Ionic bond
- D. Peptide bond
Correct Answer: B
Rationale: The correct answer is B: Hydrogen bond. Hydrogen bonds are responsible for holding water molecules together. In a water molecule, the oxygen atom is slightly negative, and the hydrogen atoms are slightly positive, creating a partial positive and negative charge. This polarity allows hydrogen bonds to form between adjacent water molecules. Covalent bonds involve the sharing of electrons, ionic bonds involve transfer of electrons between ions, and peptide bonds are specific to linking amino acids in proteins, which are not relevant to water molecule interactions.
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Which of the following meninges is a thin membrane containing numerous nerves and blood vessels that supply nourishment to the underlying brain cells and spinal cord?
- A. Arachnoid mater
- B. Dura mater
- C. Periosteum
- D. Pia mater
Correct Answer: D
Rationale: The pia mater is the correct answer. It is a thin, innermost layer of the meninges that contains numerous nerves and blood vessels, providing nourishment to the underlying brain cells and spinal cord. The arachnoid mater (Choice A) is the middle layer of the meninges and does not contain as many nerves and blood vessels as the pia mater. The dura mater (Choice B) is the tough, outermost layer of the meninges and is not responsible for supplying nourishment. The periosteum (Choice C) is a connective tissue membrane covering bones, not part of the meninges.
What is the main function of the large intestine?
- A. To absorb proteins
- B. To absorb water and form feces
- C. To produce enzymes for digestion
- D. To store fat
Correct Answer: B
Rationale: The main function of the large intestine is to absorb water and form feces from waste material. Choice A is incorrect because the absorption of proteins primarily occurs in the small intestine. Choice C is incorrect as the production of enzymes for digestion mainly takes place in the pancreas and small intestine. Choice D is incorrect as the storage of fat is not a primary function of the large intestine.
In aerobic respiration, how many ATP molecules are produced per molecule of FADH2?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: B
Rationale: The correct answer is B: 2. During aerobic respiration, each molecule of FADH2 produces 2 ATP molecules. FADH2 enters the electron transport chain and contributes to the generation of ATP. Choice A (1), Choice C (3), and Choice D (4) are incorrect because FADH2 specifically yields 2 ATP molecules per molecule in the process of aerobic respiration.
What is the role of platelets in the blood?
- A. Transport oxygen
- B. Fight infection
- C. Produce antibodies
- D. Clot blood
Correct Answer: D
Rationale: Platelets play a crucial role in blood clotting by forming clots to help stop bleeding. While red blood cells transport oxygen, white blood cells fight infection, and immune cells produce antibodies, platelets specifically function to prevent excessive bleeding by forming clots. Therefore, the correct answer is D. Choices A, B, and C are incorrect as they describe functions of other components of the blood, not platelets.
Which of the following statements is true about an allergic reaction?
- A. An allergic reaction, such as hives or wheezing, results from overactive body systems such as the integumentary and respiratory systems.
- B. An allergic reaction is a result of overactive B-cells in the body that release various immunoglobulins.
- C. An allergic reaction is caused by overactive mast cells in the body, which are stimulated by Immunoglobulin E.
- D. An allergic reaction involves substances like histamine, keratin, and collagen.
Correct Answer: C
Rationale: The correct answer is C. Mast cells are responsible for releasing histamine and other chemicals during an allergic response. Choice A is incorrect because hives and wheezing are symptoms of an allergic reaction, not the causes. Choice B is incorrect as B-cells are not directly involved in allergic reactions. Choice D is incorrect as keratin and collagen are not typically involved in allergic reactions, and histamine is released by mast cells.