Nokea
What is the role of DNA in heredity?
- A. Provides energy for the cell
- B. Determines the structure and function of proteins
- C. Stores and transmits genetic information
- D. Controls cell division
Correct Answer: C
Rationale: DNA (deoxyribonucleic acid) is a molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all living organisms. It stores genetic information in the form of a code made up of four chemical bases: adenine (A), thymine (T), cytosine (C), and guanine (G). This genetic information is passed down from parents to offspring and is responsible for determining an organism's traits and characteristics. DNA's primary role is to store and transmit genetic information, making option C the correct answer. DNA does not provide energy for the cell (option A), determine the structure and function of proteins (option B), or control cell division (option D).
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Which mineral is crucial for bone strength and is stored in bones and teeth?
- A. Calcium
- B. Iron
- C. Magnesium
- D. Potassium
Correct Answer: A
Rationale: Calcium is crucial for bone strength as it is a major mineral stored in bones and teeth. It plays a vital role in maintaining bone density and strength, making it essential for overall bone health. Calcium is essential for various physiological functions, including muscle contraction, nerve transmission, and blood clotting. Inadequate calcium intake can lead to conditions like osteoporosis, where bones become weak and brittle. Iron (Choice B) is important for transporting oxygen in the blood, but it is not stored in bones and does not play a significant role in bone strength. Magnesium (Choice C) is essential for bone health, but it is not primarily stored in bones and teeth. Potassium (Choice D) is crucial for various physiological functions, such as fluid balance and muscle function, but it is not a major mineral stored in bones and teeth for bone strength.
Which property of matter refers to the measure of the force of gravity acting on an object?
- A. Mass
- B. Weight
- C. Density
- D. Volume
Correct Answer: B
Rationale: The correct answer is 'Weight.' Weight is the measure of the force of gravity acting on an object. Mass refers to the amount of matter in an object, density is the mass per unit volume of a substance, and volume is the amount of space an object occupies. In this context, the question specifically asks for the property related to the force of gravity, making 'Weight' the correct choice. 'Mass' is the measure of the amount of matter in an object, 'Density' is the mass per unit volume of a substance, and 'Volume' is the space occupied by an object, none of which directly measure the force of gravity on an object.
Which hormones are responsible for stimulating the development of sex organs and secondary sex characteristics during puberty?
- A. Growth hormone
- B. Testosterone (in males) and Estrogen (in females)
- C. Insulin
- D. Thyroid hormone
Correct Answer: B
Rationale: Testosterone and estrogen are the primary sex hormones responsible for the development of male and female sex organs, respectively, and the emergence of secondary sex characteristics during puberty. Growth hormone, insulin, and thyroid hormone do not directly influence the development of sex organs and secondary sex characteristics during puberty. Growth hormone primarily regulates growth and metabolism, insulin regulates blood sugar levels, and thyroid hormone controls metabolism and energy levels. Therefore, choices A, C, and D are incorrect for this question.
Which of the following blood vessels carries oxygenated blood from the lungs back to the left atrium of the heart?
- A. Pulmonary artery
- B. Pulmonary vein
- C. Aorta
- D. Inferior vena cava
Correct Answer: B
Rationale: The correct answer is B: Pulmonary vein. The pulmonary vein carries oxygenated blood from the lungs back to the left atrium of the heart. This oxygenated blood is then pumped out to the rest of the body. The pulmonary artery, choice A, carries deoxygenated blood from the heart to the lungs for oxygenation. The aorta, choice C, is responsible for carrying oxygenated blood from the heart to the body's tissues. Choice D, the inferior vena cava, transports deoxygenated blood from the lower body back to the heart.
A car is moving in a circle at a constant speed. Which of the following is NOT true about its motion?
- A. It has a constant centripetal acceleration
- B. Its tangential velocity remains constant
- C. It experiences a force directed towards the center of the circle
- D. It covers the same distance in equal time intervals along its circular path
Correct Answer: B
Rationale: In circular motion at a constant speed, the car has a constant centripetal acceleration (choice A), experiences a force directed towards the center of the circle (choice C), and covers the same distance in equal time intervals along its circular path (choice D). However, the tangential velocity of an object in circular motion at a constant speed changes continuously as it moves around the circle, so it is not constant (choice B). The change in tangential velocity allows the car to maintain its motion in a circular path despite moving at a constant speed. Choice A is incorrect because centripetal acceleration is indeed present to keep the car moving in a circular path. Choice C is incorrect as a force towards the center is required to keep the car in circular motion. Choice D is incorrect because the car covers equal distances in equal time intervals to maintain its circular trajectory.