ATI TEAS 7
Chemistry
1. What is the pH of a solution with a hydrogen ion concentration of \(1 \times 10^{-9}\) M?
- A. 5
- B. 7
- C. 9
- D. 11
Correct answer: c
Rationale: The pH is calculated as the negative logarithm (base 10) of the hydrogen ion concentration. In this case, \(-\log(1 \times 10^{-9}) = 9\).
2. Which part of the neuron insulates and speeds up the transmission of nerve impulses along the axon?
- A. Dendrite
- B. Myelin sheath
- C. Synapse
- D. Cell body
Correct answer: b
Rationale: The correct answer is B: Myelin sheath. The myelin sheath is a fatty substance that surrounds the axon of a neuron, acting as an insulator to speed up the transmission of nerve impulses. It does this by creating gaps called nodes of Ranvier where the nerve impulses jump from one node to the next, allowing for faster signal conduction. Dendrites are branch-like extensions that receive signals from other neurons, the synapse is the junction between two neurons where neurotransmitters are released, and the cell body contains the nucleus and organelles of the neuron, but it is the myelin sheath that specifically insulates and speeds up the transmission of nerve impulses along the axon.
3. How does the amplitude of a wave relate to its intensity or loudness?
- A. They are inversely proportional.
- B. They are directly proportional.
- C. They have no relationship.
- D. Amplitude affects frequency, not intensity.
Correct answer: B
Rationale: Higher amplitude corresponds to larger displacement from equilibrium and translates to higher intensity or perceived loudness in sound waves.
4. Dandruff is caused by
- A. Excessive sebum production (This can contribute to oily dandruff)
- B. Bacterial infection (This can cause scalp folliculitis, not dandruff)
- C. Overgrowth of a specific type of fungus on the scalp
- D. Lack of proper skin hydration
Correct answer: C
Rationale: Dandruff is primarily caused by an overgrowth of a specific type of fungus called Malassezia on the scalp. This fungus feeds on the natural oils produced by the hair follicles, leading to an inflammatory response in some individuals, resulting in flaking and itching. Excessive sebum production can contribute to oily dandruff by providing more food for the fungus. Bacterial infections, such as scalp folliculitis, can cause symptoms similar to dandruff but are not the primary cause. Lack of proper skin hydration can contribute to dry scalp conditions but is not the main cause of dandruff.
5. A book slides across a table. What determines the magnitude of the frictional force acting on the book?
- A. Only the mass of the book
- B. Only the normal force from the table
- C. Both the mass of the book and the normal force from the table
- D. Neither the mass of the book nor the normal force from the table
Correct answer: C
Rationale: Both the mass of the book and the normal force from the table. Friction is proportional to both the normal force and the coefficient of friction, which depends on the materials in contact. Since the normal force depends on the weight of the object (mass x gravity), both factors are important.
6. What type of bone is the kneecap (patella)?
- A. Long bone
- B. Short bone
- C. Flat bone
- D. Irregular bone
Correct answer: B
Rationale: The correct answer is B: Short bone. The kneecap, or patella, is classified as a short bone because it is roughly cube-shaped and is composed of spongy bone enclosed by a thin layer of compact bone. Short bones provide support and stability with limited motion, making them ideal for protecting joints like the knee. Long bones are typically elongated, flat bones are thin and curved, and irregular bones have complex shapes. Understanding the classification of bones can help in identifying their functions and structural characteristics.
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