Nokea
Which of the following statements describes a chemical property of water?
- A. Water has a pH of 1.
- B. A water molecule contains 2 hydrogen atoms and 1 oxygen atom.
- C. A water molecule contains 2 oxygen atoms and 1 hydrogen atom.
- D. The chemical formula for water is HO.
Correct Answer: B
Rationale: The correct answer is B because a water molecule consists of two hydrogen atoms and one oxygen atom, which is a fundamental chemical property of water. The pH of water is not a property of the water molecule itself but rather a measure of its acidity or alkalinity. Choice C is incorrect as it describes a different molecule, not water. Choice D provides an incorrect chemical formula for water, which is H2O.
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What type of molecules are enzymes?
- A. Water molecules
- B. Protein molecules
- C. Tripolar molecules
- D. Inorganic molecules
Correct Answer: B
Rationale: The correct answer is B: Protein molecules. Enzymes are biological catalysts made up of proteins. They function by facilitating and speeding up chemical reactions in living organisms. Therefore, enzymes are primarily composed of protein molecules, not water, tripolar, or inorganic molecules. Choice A (Water molecules), Choice C (Tripolar molecules), and Choice D (Inorganic molecules) are incorrect because enzymes are specifically classified as proteins due to their structure and function in biological systems.
Which of the following blood vessels contains the least oxygenated blood?
- A. Aorta
- B. Vena cava
- C. Pulmonary artery
- D. Femoral vein
Correct Answer: C
Rationale: The correct answer is C: Pulmonary artery. The pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation. This blood is considered the least oxygenated in the body as it has just returned from circulating through the body's tissues and is in need of oxygen replenishment. Choice A, the aorta, is incorrect as it carries oxygenated blood from the heart to the rest of the body. Choice B, the vena cava, carries deoxygenated blood from the body back to the heart. Choice D, the femoral vein, also carries deoxygenated blood back to the heart from the lower extremities.
An atom has 5 protons, 5 neutrons, and 6 electrons. What is the electric charge of this atom?
- A. Neutral
- B. Positive
- C. Negative
- D. Undetermined
Correct Answer: C
Rationale: The correct answer is 'Negative.' An atom becomes negatively charged when it has more electrons than protons. In this case, the atom has 6 electrons and 5 protons, resulting in a net negative charge. Choice A 'Neutral' is incorrect because the atom is not balanced in terms of protons and electrons. Choice B 'Positive' is incorrect because having more electrons than protons results in a negative charge. Choice D 'Undetermined' is incorrect, as the charge can be determined based on the relative number of protons and electrons.
Which of the following best describes a function carried out by the circulatory system and the integumentary system working together?
- A. Removal of excess heat from the body
- B. Hormonal regulation of blood pressure
- C. Transport of oxygen in the body
- D. Production of red blood cells in the bone marrow
Correct Answer: A
Rationale: The correct answer is A: Removal of excess heat from the body. The circulatory system, which includes blood vessels and the heart, works with the integumentary system, which consists of the skin, to regulate body temperature by removing excess heat. This process involves blood vessels near the skin's surface dilating to release heat and constricting to conserve heat, a mechanism crucial for maintaining homeostasis. Option B, Hormonal regulation of blood pressure, is incorrect as it does not accurately describe the collaborative function of these systems in regulating body temperature. Option C, Transport of oxygen in the body, is incorrect as it focuses on a different function of the circulatory system. Option D, Production of red blood cells in the bone marrow, is incorrect as it pertains to the skeletal and hematopoietic systems, not the circulatory and integumentary systems working together to regulate body temperature.
What type of chemical bond connects the oxygen and hydrogen atoms in a molecule of water?
- A. Static bond
- B. Aquatic bond
- C. Ionic bond
- D. Covalent bond
Correct Answer: D
Rationale: The correct answer is D, Covalent bond. Covalent bonds are formed between oxygen and hydrogen atoms in a water molecule. In a water molecule, each hydrogen atom forms a covalent bond with the oxygen atom, sharing electrons to achieve a stable configuration. Static bond (choice A) and Aquatic bond (choice B) are not valid types of chemical bonds. Ionic bond (choice C) involves the transfer of electrons between atoms of different electronegativities, which is not the case between oxygen and hydrogen in a water molecule.