Nokea
If Silicon (Si) has an atomic mass of 28.1 AMU (atomic mass units), which of the following is the most likely number of neutrons an atom of Silicon would have?
- A. 28.1
- B. 14
- C. 28
- D. 14.2
Correct Answer: B
Rationale: Silicon has an atomic number of 14, indicating it has 14 protons. The atomic mass of 28.1 AMU accounts for both protons and neutrons in the nucleus. By subtracting the atomic number from the atomic mass, we can estimate the number of neutrons in the atom. Thus, 28.1 - 14 = 14 neutrons. Choice A is incorrect as it represents the total atomic mass, not the number of neutrons. Choice C is incorrect; it is the atomic number (protons) rather than the number of neutrons. Choice D is incorrect as it is a value that does not reflect the number of neutrons in the silicon atom.
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Find the lowest coefficients that will balance the following combustion equation: __C H + __O2 → __CO2 + __H2O
- A. 1:5:5:2
- B. 4:10:20:8
- C. 2:9:10:4
- D. 2:5:10:4
Correct Answer: C
Rationale: To balance the combustion equation CxHy + O2 → xCO2 + y/2 H2O, we need to balance the carbon and hydrogen atoms. The balanced equation for the given combustion is: 2C H4 + 9O2 → 2CO2 + 4H2O. This means that the correct coefficients are 2:9:10:4, which corresponds to choice C. Choice A (1:5:5:2) does not balance the equation correctly, choice B (4:10:20:8) has excessive oxygen and does not balance the equation, and choice D (2:5:10:4) does not provide the correct ratio of oxygen to balance the equation.
What are the two primary functions of the respiratory system?
- A. Delivering nutrients and removing CO2
- B. Delivering O2 and removing CO2, maintaining blood pH
- C. Maintaining blood pH and delivering nutrients
- D. Delivering O2 and nutrients to the cells
Correct Answer: B
Rationale: The correct answer is B. The respiratory system's primary functions include delivering oxygen (O2) to the body's cells for cellular respiration and removing carbon dioxide (CO2), thereby aiding in the maintenance of blood pH. These functions are crucial for gas exchange and the overall metabolic processes within the body. Choice A is incorrect as the respiratory system primarily delivers O2, not nutrients, and removes CO2, not delivering it. Choice C is incorrect as while the respiratory system helps maintain blood pH by removing CO2, it does not primarily deliver nutrients. Choice D is incorrect as it combines the functions of delivering O2 and nutrients, which are distinct roles of different systems in the body.
What is a monohybrid cross, and what is the ratio of dominant to recessive gene manifestation?
- A. A cross involving two traits, 9:3:3:1
- B. A cross involving one trait, 3:1
- C. A cross involving two traits, 1:2:1
- D. A cross involving one trait, 1:1
Correct Answer: B
Rationale: A monohybrid cross is a genetic cross involving one trait. The ratio of dominant to recessive gene manifestation in the offspring is typically 3:1 when both parents are heterozygous. This ratio is the genotypic ratio, not just the phenotype ratio, where the dominant allele is present in 3 out of 4 offspring, and the recessive allele is present in 1 out of 4 offspring. Choice A is incorrect because it describes a dihybrid cross ratio. Choice C is incorrect as it represents the genotypic ratio for a monohybrid cross involving incomplete dominance. Choice D is incorrect as it does not reflect the typical ratio for a monohybrid cross.
Which of the following is an example of a pivot joint?
- A. Hip
- B. Neck
- C. Shoulder
- D. Elbow
Correct Answer: B
Rationale: The correct answer is B: Neck. A pivot joint, as found in the neck, allows for rotational movement around a single axis. This type of joint is essential for movements like shaking your head 'no' or looking left and right. Choices A, C, and D are incorrect because the hip, shoulder, and elbow joints are examples of ball-and-socket joints, which allow for a wide range of motion in multiple directions, not just rotational movement around a single axis like a pivot joint.
What is the pathway of deoxygenated blood in our body?
- A. From the lungs to the left ventricle
- B. From the body to the right atrium, then to the right ventricle, and finally to the lungs
- C. From the left atrium to the body
- D. From the aorta to the right atrium
Correct Answer: B
Rationale: The correct pathway of deoxygenated blood in our body involves blood returning from the body, entering the right atrium, then passing to the right ventricle, and eventually reaching the lungs for oxygenation. This sequence ensures that deoxygenated blood is pumped to the lungs, where it receives oxygen and releases carbon dioxide before circulating back to the body. Choices A, C, and D are incorrect because they do not follow the actual path of deoxygenated blood in the circulatory system.