Nokea
Which of the following ions binds to the troponin complex, initiating muscle contraction?
- A. Sodium
- B. Potassium
- C. Phosphorus
- D. Calcium
Correct Answer: D
Rationale: The correct answer is calcium (D). Calcium ions bind to the troponin complex, initiating muscle contraction. When calcium binds to troponin, it causes a conformational change in the troponin-tropomyosin complex, exposing the binding sites on actin for myosin. This interaction allows muscle contraction by facilitating the sliding of actin and myosin filaments past each other, leading to muscle contraction.
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Which of the following organic molecules contains both an amine and a carboxyl group?
- A. Lipids
- B. Cellulose
- C. Chitin
- D. Proteins
Correct Answer: D
Rationale: Proteins are composed of amino acids, which contain both an amine (NH2) and a carboxyl (COOH) functional group. The amine group is found at one end of the amino acid molecule, while the carboxyl group is located at the other end. When amino acids join together through peptide bonds, the amine of one amino acid reacts with the carboxyl group of another, forming a protein chain. Therefore, the correct answer is proteins.
Which of the following substances is responsible for donating H+ ions to act as a buffer when blood pH rises?
- A. Carbon Monoxide
- B. Oxygen
- C. Carbon Dioxide
- D. Carbonic Acid
Correct Answer: D
Rationale: Carbonic acid is a pivotal buffer in blood that plays a key role in maintaining pH balance. When blood pH rises, indicating increased alkalinity, carbonic acid releases hydrogen ions (H+) to counterbalance the excess base, thereby preventing significant changes in pH levels. This mechanism highlights the essential function of carbonic acid in regulating the acid-base equilibrium in the blood.
Which of the following is a function of bone?
- A. Detoxification of alcohol
- B. Production of otoliths
- C. Storage of minerals
- D. Secretion of hormones
Correct Answer: C
Rationale: Bones serve as a crucial storage site for essential minerals like calcium and phosphorus. These minerals are indispensable for various physiological functions in the body, such as muscle contraction, nerve transmission, and blood clotting. Bones act as a reservoir for these minerals, releasing them into the bloodstream as needed to maintain appropriate mineral levels. Therefore, the correct answer is C, storage of minerals.
A patient goes to the doctor with a cold and sore throat and asks for antibiotics. The doctor refuses to prescribe antibiotics because the illness is caused by which of the following pathogens?
- A. Protist
- B. Fungus
- C. Virus
- D. Bacteria
Correct Answer: C
Rationale: The correct answer is C: Virus. Antibiotics are ineffective against viral infections, such as colds and sore throats caused by viruses. They are only effective against bacterial infections. In this case, the doctor refuses to prescribe antibiotics because the patient's illness is viral, not bacterial. It is important to differentiate between viral and bacterial infections to ensure appropriate treatment and avoid unnecessary use of antibiotics, which can contribute to antibiotic resistance.
Which of the following processes uses an electrochemical gradient to produce ATP?
- A. Chemiosmosis
- B. Cell division
- C. Fermentation
- D. Photosynthesis
Correct Answer: A
Rationale: Chemiosmosis is the process where ATP is produced as protons flow down their electrochemical gradient across a membrane, typically during cellular respiration or photosynthesis. Cell division and fermentation do not produce ATP via an electrochemical gradient.