Nokea
What is a characteristic feature of a convex lens?
- A. Converge light rays
- B. Diverge light rays
- C. Focus sound waves
- D. Create virtual images only
Correct Answer: A
Rationale: A convex lens is characterized by its ability to converge light rays. The convex lens is thicker in the middle and thinner at the edges, causing light rays passing through it to converge or come together at a focal point on the opposite side of the lens. This convergence of light rays is what distinguishes convex lenses. Choice B is incorrect as convex lenses do not diverge light rays. Choice C is incorrect as convex lenses do not focus sound waves but rather light waves. Choice D is incorrect as convex lenses can create both real and virtual images, not just virtual images.
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Which type of waves require a medium (solid, liquid, or gas) to propagate?
- A. Transverse waves
- B. Longitudinal waves
- C. Electromagnetic waves
- D. Surface waves
Correct Answer: B
Rationale: Longitudinal waves require a medium (solid, liquid, or gas) to propagate because the particles in the medium move parallel to the direction of the wave. As a result, they rely on the medium for transmission. Transverse waves, on the contrary, do not need a medium and can travel through a vacuum, making choice A incorrect. Electromagnetic waves, represented by choice C, do not require a medium as they consist of oscillating electric and magnetic fields that can propagate through a vacuum. Surface waves, the option in D, involve a combination of both longitudinal and transverse motion and do require a medium to travel, but longitudinal waves are the ones that strictly depend on a medium for propagation.
What tool helps scientists identify and classify organisms based on their shared characteristics?
- A. Binomial nomenclature
- B. Cladistics
- C. Dichotomous key
- D. Domain-based classification
Correct Answer: C
Rationale: A) Binomial nomenclature is a system used to give each organism a two-part scientific name (genus and species) but does not help in identifying or classifying organisms based on shared characteristics. B) Cladistics is a method of classification based on evolutionary relationships and shared characteristics, but it is not a tool used for identifying organisms. C) A dichotomous key is a tool that helps scientists identify and classify organisms based on their shared characteristics by presenting a series of choices leading the user to the correct identification. D) Domain-based classification is a system of grouping organisms into three domains (Bacteria, Archaea, Eukarya) based on molecular and genetic similarities, but it is not a tool used for identifying organisms based on shared characteristics.
Which term refers to the condition where a muscle shortens in length while generating force, leading to movement at a joint?
- A. Isometric contraction
- B. Eccentric contraction
- C. Isotonic contraction
- D. Concentric contraction
Correct Answer: D
Rationale: Concentric contraction refers to the condition where a muscle shortens in length while generating force, leading to movement at a joint. This type of contraction is commonly associated with the lifting phase of an exercise where the muscle is actively shortening against resistance. Isometric contraction (Choice A) involves muscle contraction without a change in muscle length, Eccentric contraction (Choice B) involves the muscle lengthening while generating force, and Isotonic contraction (Choice C) refers to muscle contraction against a constant load with a change in muscle length.
How does the Pauli exclusion principle relate to the structure of the atom?
- A. It defines the maximum number of electrons allowed in each energy level.
- B. It explains why oppositely charged particles attract each other.
- C. It describes the wave-particle duality of electrons.
- D. It determines the arrangement of protons and neutrons in the nucleus.
Correct Answer: A
Rationale: The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers. This principle directly influences the structure of the atom by defining the maximum number of electrons allowed in each energy level. As a result, it helps determine the electron configuration and the arrangement of electrons in different orbitals within an atom. Choices B, C, and D are incorrect as they do not directly relate to the Pauli exclusion principle's specific impact on the electron distribution within an atom.
T cells in the immune system can be categorized into different types. What type of T cell directly kills infected body cells?
- A. Helper T cells
- B. Cytotoxic T cells
- C. Regulatory T cells
- D. Memory T cells
Correct Answer: B
Rationale: Cytotoxic T cells directly kill infected body cells by recognizing specific antigens on the surface of infected cells and releasing cytotoxic substances to induce cell death, eliminating the infected cells. Helper T cells assist in coordinating the immune response, regulatory T cells help maintain immune tolerance, and memory T cells mount a faster and stronger response upon re-exposure to a previously encountered antigen. Therefore, the correct answer is cytotoxic T cells as they play a crucial role in directly targeting and destroying infected cells.