homologous structures are similar structures in different organisms that have a common evolutionary origin an example is

ATI TEAS 7

TEAS Test 7 science

1. Homologous structures are similar structures in different organisms that have a common evolutionary origin. An example is:

A. Butterfly wings and bird wings (analogous structures with different origins)
B. The arm of a human, the wing of a bat, and the flipper of a whale
C. The eyes of an octopus and a human (convergent evolution with different origins)
D. The stinger of a bee and the barb of a cactus (unrelated structures)

Correct answer: B

Rationale: Homologous structures are similar structures found in different organisms that share a common evolutionary origin. The arm of a human, the wing of a bat, and the flipper of a whale are all examples of homologous structures. Despite serving different functions, they share a common underlying structure due to their evolutionary relationship, evidencing a shared ancestry. These structures are modified over time to suit the specific needs of each species. Option A (Butterfly wings and bird wings) refers to analogous structures with different origins. Option C (The eyes of an octopus and a human) describes convergent evolution where traits evolve independently. Option D (The stinger of a bee and the barb of a cactus) are unrelated structures.

2. What is the basic structure of an atom?

A. Protons, neutrons, electrons
B. Protons, electrons, ions
C. Neutrons, electrons, ions
D. Protons, ions, molecules

Correct answer: A

Rationale: The basic structure of an atom consists of protons and neutrons located in the nucleus, with electrons orbiting around the nucleus in specific energy levels or shells. Protons carry a positive charge, neutrons carry no charge, and electrons carry a negative charge. This arrangement maintains the overall neutrality of the atom, with the number of protons equaling the number of electrons. Therefore, the correct answer is 'Protons, neutrons, electrons.' Choices B, C, and D are incorrect as they do not accurately represent the fundamental components of an atom. Choice B includes 'ions,' which are charged particles, not fundamental components of an atom. Choice C includes 'ions' and lacks protons. Choice D includes 'ions' and 'molecules,' which are not part of the basic structure of an atom.

3. What is the purpose of genetic counseling?

A. To treat genetic disorders.
B. To diagnose genetic diseases in newborns.
C. To provide information and support to individuals and families with genetic risks.
D. To collect DNA samples for research purposes.

Correct answer: C

Rationale: The purpose of genetic counseling is to provide information and support to individuals and families with genetic risks. Genetic counselors aim to explain the implications of genetic testing, discuss risks and options, and offer emotional and psychological support to help individuals make informed decisions regarding their genetic health. Choice A is incorrect because genetic counseling is not focused on treatment but rather on providing information and support. Choice B is incorrect as genetic counselors do not primarily diagnose genetic diseases in newborns but rather provide guidance and support based on existing diagnoses. Choice D is not the purpose of genetic counseling; genetic counselors do not collect DNA samples for research purposes but instead focus on assisting individuals and families in understanding and managing their genetic risks.

4. What is the action of the triceps reflex?

A. Forces contraction of the triceps and extension of the arm.
B. Forces contraction of the biceps, relaxation of the biceps, and arm extension.
C. Causes the triceps to contract, causing the forearm to supinate and flex.
D. Causes the triceps to relax and the upper arm to pronate and extend.

Correct answer: A

Rationale: The triceps reflex causes the triceps muscle to contract, leading to the extension of the arm. This reflex is a protective response to sudden stretching of the triceps muscle, as seen when a physician taps the triceps tendon during a physical examination. Choice A is the correct answer as it accurately reflects the action of the triceps reflex. Choices B, C, and D are incorrect because they describe actions that are not associated with the triceps reflex. Biceps contraction, forearm supination, flexion, triceps relaxation, and pronation are not part of the triceps reflex arc.

5. What is the relationship between the wavelength (λ) and frequency (f) of a wave with a constant speed (v)?

A. λ = v / f
B. λ = f / v
C. λ = vf
D. λ is independent of f and v

Correct answer: A

Rationale: The relationship between wavelength (λ), frequency (f), and speed (v) of a wave is given by the formula λ = v / f. This formula is derived from the wave equation v = fλ, where v is the speed of the wave, f is the frequency, and λ is the wavelength. By rearranging the equation, we get λ = v / f, indicating that the wavelength is inversely proportional to the frequency when the speed of the wave is constant. Therefore, choice A, λ = v / f, correctly represents the relationship between wavelength and frequency when the speed of the wave is held constant. Choice B, λ = f / v, is incorrect because it represents an inverse relationship between wavelength and speed, which is not the case. Choice C, λ = vf, is incorrect as it implies a direct relationship between wavelength, frequency, and speed, which is not accurate. Choice D, λ is independent of f and v, is incorrect as both frequency and speed affect the wavelength of a wave, as shown by the correct formula λ = v / f.