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. How does AIDS impair the immune system?

A. AIDS targets and destroys Helper T-Cells, preventing the activation of Cytotoxic T-Cells or B-Cells.
B. IgE stimulates mast cells to release excessive histamine.
C. IgE inhibits mast cells from releasing sufficient histamine.
D. Helper T-Cells deceive the body into attacking itself.

Correct answer: A

Rationale: AIDS targets and destroys Helper T-Cells, which play a crucial role in coordinating the immune response. By affecting these cells, AIDS prevents the activation of other important immune cells like Cytotoxic T-Cells or B-Cells. This disruption in the immune system's communication and response mechanisms leads to immune system failure and increased vulnerability to infections. Choices B and C are incorrect because they refer to the role of IgE in allergic reactions, which is not directly related to how AIDS impairs the immune system. Choice D is also incorrect as Helper T-Cells being destroyed in AIDS is not about deceiving the body into attacking itself, but rather the direct impact on immune system function.

3. What is the unit of force in the SI system?

A. Newton (N)
B. Kilogram (kg)
C. Meter (m)
D. Second (s)

Correct answer: A

Rationale: The unit of force in the SI system is the Newton (N). It is defined as the amount of force required to accelerate a mass of one kilogram at a rate of one meter per second squared. In the SI system, force is measured in Newtons, not in kilograms, meters, or seconds. Choice B, Kilogram (kg), is incorrect because kilograms are units of mass, not force. Choice C, Meter (m), is incorrect because meters are units of length, not force. Choice D, Second (s), is incorrect because seconds are units of time, not force.

4. Which of the following is NOT a function of the skeletal system?

A. Support and structure
B. Production of red blood cells
C. Storage of minerals like calcium
D. Insulation of the body

Correct answer: D

Rationale: The skeletal system's primary functions include support and structure, protection of internal organs, movement facilitation, production of blood cells, and storage of minerals like calcium. Insulation of the body is not a function of the skeletal system. Insulation, typically involving fat under the skin, helps regulate body temperature but is not a direct function of the skeletal system. Choice B, the production of red blood cells, is a function of the skeletal system as it occurs in the bone marrow within the bones. Choices A and C are also correct functions of the skeletal system.

5. Which macromolecules are composed of nucleotides and store information and energy?

A. Lipids
B. Proteins
C. Carbohydrates
D. Nucleic acids

Correct answer: D

Rationale: The correct answer is D: Nucleic acids. Nucleic acids, such as DNA and RNA, are composed of nucleotides and are responsible for storing genetic information and energy (e.g., ATP). Lipids, proteins, and carbohydrates are distinct macromolecules with varying functions and structures. Lipids primarily serve as energy reservoirs, structural components, and cell signaling molecules. Proteins play crucial roles in cellular functions like enzyme activity, structural support, and intracellular signaling. Carbohydrates are mainly utilized as an energy source and for structural purposes within cells.