Nokea
Which of the following is a balanced chemical equation?
- A. H2 + O2 → H2O
- B. 2H2 + O2 → 2H2O
- C. 3H2O → 2H2 + O2
- D. H2O → H2 + O2
Correct Answer: B
Rationale: A balanced chemical equation must have the same number of atoms of each element on both sides of the equation. In option B, 2H2 + O2 → 2H2O, the equation is balanced as there are 2 hydrogen atoms and 2 oxygen atoms on both the reactant and product sides after balancing, satisfying the law of conservation of mass. Option A is unbalanced as there are 2 oxygen atoms on the reactant side but only 1 oxygen atom on the product side. Option C is unbalanced with 3 hydrogen atoms on the reactant side and 2 hydrogen atoms on the product side. Option D is unbalanced with 1 oxygen atom on the reactant side and 2 oxygen atoms on the product side.
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What is the process of breaking down and rebuilding bone tissue called?
- A. Ossification
- B. Remodeling
- C. Calcification
- D. Osteoporosis
Correct Answer: B
Rationale: The correct answer is 'Remodeling.' Remodeling is the process of breaking down and rebuilding bone tissue. Ossification is the process of bone formation, not breaking down and rebuilding bone tissue. Calcification involves the deposition of calcium salts in tissues, but it is not specifically related to breaking down and rebuilding bone tissue. Osteoporosis is a condition characterized by decreased bone density leading to increased bone fragility, not the process of breaking down and rebuilding bone tissue.
Which of the following statements about fungi is FALSE?
- A. They can be unicellular or multicellular
- B. They are all parasitic and cause disease in humans
- C. They play a vital role in decomposition and nutrient cycling
- D. Some are used in food production, like mushrooms
Correct Answer: B
Rationale: A) This statement is true. Fungi can exist in both unicellular (yeast) and multicellular (molds and mushrooms) forms.
B) This statement is false. While some fungi can be parasitic and cause diseases in humans, not all fungi exhibit this behavior. Many fungi are beneficial and play essential roles in ecosystems.
C) This statement is true. Fungi are crucial for decomposition and nutrient cycling in ecosystems. They break down organic matter and recycle nutrients back into the environment.
D) This statement is true. Some fungi, like mushrooms, are used in food production and are consumed by humans.
Which of the following structures in the respiratory system is responsible for gas exchange?
- A. Trachea
- B. Alveoli
- C. Bronchi
- D. Diaphragm
Correct Answer: B
Rationale: The correct answer is B: Alveoli. The alveoli in the lungs are responsible for gas exchange. They have a thin membrane that allows for the exchange of oxygen and carbon dioxide between the air in the lungs and the blood in the capillaries surrounding them. This process is essential for respiration, providing oxygen to the body's tissues and removing carbon dioxide, a waste product of cellular metabolism. Choices A, C, and D are incorrect. The trachea is a passageway that carries air to and from the lungs but is not directly involved in gas exchange. Bronchi are airway passages that further divide into smaller bronchioles leading to the alveoli but do not perform gas exchange themselves. The diaphragm is a muscle involved in the breathing process by aiding in inhalation and exhalation, but it is not the structure responsible for gas exchange in the respiratory system.
What is the smallest bone in the human body?
- A. Stapes (Middle ear bone)
- B. Patella (Kneecap)
- C. Phalanges (Finger bones)
- D. Ribs
Correct Answer: A
Rationale: The correct answer is A: Stapes (Middle ear bone). The stapes, located in the middle ear, is indeed the smallest bone in the human body. Despite its small size, the stapes is vital for hearing as it transmits and amplifies sound vibrations, contributing significantly to auditory perception. Choices B, C, and D are incorrect. The patella (kneecap) is the largest sesamoid bone in the human body, not the smallest bone. Phalanges are the bones in fingers and toes, not the smallest bone overall. Ribs are long bones that protect the chest cavity, not the smallest bone in the body.
What is the acceleration due to gravity near the Earth's surface?
- A. 9.8 meters per second squared (m/s²)
- B. 6.3 meters per second squared (m/s²)
- C. 5.0 meters per second squared (m/s²)
- D. 12.5 meters per second squared (m/s²)
Correct Answer: A
Rationale: The acceleration due to gravity near the Earth's surface is approximately 9.8 m/s². This value is commonly used in physics calculations and represents the rate at which an object accelerates towards the Earth when in free fall. The acceleration due to gravity is a constant value near the Earth's surface and affects the motion of all objects. Choices B, C, and D are incorrect as they do not represent the standard value of 9.8 m/s². Understanding the correct value of acceleration due to gravity is fundamental in physics as it helps in solving various problems related to motion, forces, and energy.