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. Why do Neon (Ne) and Helium (He) belong to Group 18 (Noble Gases)?

A. Electromagnetism
B. Gravity
C. Strong nuclear force
D. Weak nuclear force

Correct answer: A

Rationale: Neon (Ne) and Helium (He) belong to Group 18 (Noble Gases) because they have complete and stable outer electron shells. The stability of these outer electron shells is due to the balance of attractive forces between the positively charged protons in the nucleus and the negatively charged electrons in the outer shell. This balance is maintained by the electromagnetic force, which is responsible for holding atoms together and determining their chemical properties. Gravity (Choice B) is a force of attraction between objects with mass and is not responsible for the stability of electron shells. The strong nuclear force (Choice C) and weak nuclear force (Choice D) are forces that act within the nucleus of an atom and are not directly related to the stability of outer electron shells in determining an element's group in the periodic table.

3. Which of the following best describes eosinophils?

A. A type of granulocyte that secretes histamine to stimulate the inflammatory response.
B. The most abundant type of white blood cell that secretes substances toxic to pathogens.
C. A type of granulocyte found under mucous membranes that defends against multicellular parasites.
D. A circulating granulocyte with high phagocytic activity and aggressiveness.

Correct answer: C

Rationale: Eosinophils are best described as a type of granulocyte found under mucous membranes that defends against multicellular parasites. They release toxic substances to combat parasitic infections and play a significant role in allergic reactions and asthma. Histamine secretion to stimulate inflammation is more characteristic of basophils, while high phagocytic activity and aggressiveness are features of neutrophils, not eosinophils. Describing eosinophils as the most abundant type of white blood cell that secretes toxic substances to pathogens is inaccurate since eosinophils specifically target multicellular parasites, not a broad range of pathogens.

4. When water boils, it changes from a liquid to a gas. This is an example of a:

A. Chemical reaction
B. Physical change
C. Nuclear reaction
D. Biological process

Correct answer: B

Rationale: This is a physical change because boiling water involves a change in state from liquid to gas without altering the chemical composition of the water molecules. In a chemical reaction, new substances are formed by breaking and forming chemical bonds, which is not the case during boiling. A nuclear reaction involves changes in atomic nuclei, which are not occurring during boiling. A biological process refers to activities related to living organisms, which is not applicable to the change from liquid to gas in boiling water.

5. Which of the following is an example of a decomposition reaction?

A. 2H2 + O2 → 2H2O
B. CaCO3 → CaO + CO2
C. 2Na + Cl2 → 2NaCl
D. N2 + 3H2 → 2NH3

Correct answer: B

Rationale: A decomposition reaction involves a single compound breaking down into two or more simpler substances. In option B, CaCO3 breaks down into CaO and CO2, making it an example of a decomposition reaction. Options A, C, and D involve different types of chemical reactions such as synthesis, combination, and combustion, respectively. Option A represents a synthesis reaction, where two elements combine to form a compound. Option C demonstrates a combination reaction, where two elements combine to form a compound. Option D is an example of a synthesis reaction, where two reactants combine to form a single compound. It is important to recognize the specific characteristics of each type of chemical reaction to identify the correct example of decomposition reaction, where a compound breaks down into simpler products.