ATI TEAS 7
Chemistry
1. Electrons occupy specific energy levels around the nucleus, but not in fixed orbits. This concept is captured by the:
- A. Bohr model
- B. Quantum mechanical model
- C. Lewis structure
- D. Octet rule
Correct answer: B
Rationale: Quantum mechanical model. Unlike the Bohr model with its defined electron paths, the quantum mechanical model uses probability distributions to describe electron locations within energy levels.
2. Which term describes the resistance of a substance to being hammered into different shapes?
- A. Viscosity
- B. Ductility
- C. Malleability
- D. Conductivity
Correct answer: c
Rationale: Malleability refers to the resistance of a substance to being hammered or pressed into different shapes without breaking.
3. What is the name of the radioactive isotope commonly used in medical imaging techniques like PET scans?
- A. Uranium-235
- B. Plutonium-239
- C. Potassium-40
- D. Fluorine-18
Correct answer: D
Rationale: Fluorine-18 is the radioactive isotope commonly used in medical imaging techniques like PET scans. It is often used in the form of fluorodeoxyglucose (FDG) to detect areas of increased metabolic activity in the body, such as in cancer cells. Uranium-235 and Plutonium-239 are not typically used in medical imaging, and Potassium-40 is a naturally occurring radioactive isotope found in the human body but is not commonly used in medical imaging techniques.
4. What is the scientific name for the building blocks of proteins?
- A. Residues
- B. Monomers
- C. Macromolecules
- D. Peptides
Correct answer: B
Rationale: Rationale: - Proteins are made up of long chains of amino acids. - Amino acids are the building blocks of proteins and are considered monomers. - Monomers are the individual units that can be linked together to form larger molecules called polymers. - In the context of proteins, amino acids are the monomers that are linked together through peptide bonds to form polypeptide chains, which then fold into functional proteins. - Residues refer to the specific amino acids within a protein after certain modifications or cleavages have occurred, so it is not the correct term for the building blocks of proteins. - Macromolecules are large molecules made up of smaller subunits, such as proteins, nucleic acids, and carbohydrates, but they are not the specific building blocks of proteins. - Peptides are short chains of amino acids linked by peptide bonds, but they are not the fundamental building blocks of proteins.
5. The innate immune system provides a non-specific first line of defense. What are some physical barriers that contribute to the innate immune system?
- A. Antibodies
- B. Phagocytes
- C. Skin and mucous membranes
- D. Memory B cells
Correct answer: C
Rationale: The correct answer is C: "Skin and mucous membranes." The innate immune system consists of physical barriers, such as the skin and mucous membranes, that act as the first line of defense against pathogens. These barriers prevent pathogens from entering the body and play a crucial role in protecting against infections. Antibodies (option A) are part of the adaptive immune response, not the innate immune system. Phagocytes (option B) are cells that engulf and destroy pathogens, which are part of the innate immune system. Memory B cells (option D) are specific to the adaptive immune response and are not considered part of the innate immunity that provides the initial, non-specific defense.
6. Imagine you have an element with atomic number 11 and mass number 23. How many neutrons does it have?
- A. 11
- B. 12
- C. 23
- D. Cannot be determined without additional information
Correct answer: B
Rationale: Rationale: - The atomic number (Z) of an element is the number of protons in its nucleus. In this case, the element has an atomic number of 11. - The mass number (A) of an element is the sum of its protons and neutrons. Given that the mass number is 23 and the atomic number is 11, we can calculate the number of neutrons by subtracting the atomic number from the mass number: Neutrons = Mass number - Atomic number = 23 - 11 = 12. - Therefore, the element with atomic number 11 and mass number 23 has 12 neutrons.
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