scientists compare the dna of different organisms to understand evolutionary relationships what is this type of evidence called

ATI TEAS 7

TEAS 7 science practice

1. Scientists compare the DNA of different organisms to understand evolutionary relationships. What is this type of evidence called?

A. Morphological evidence (comparing body structures)
B. Biochemical evidence (comparing molecules like proteins)
C. Geographic distribution evidence (where organisms live)
D. Genetic evidence (comparing DNA sequences)

Correct answer: D

Rationale: A) Morphological evidence involves comparing body structures of organisms, which can provide information about evolutionary relationships based on physical similarities and differences. However, DNA comparison is a more direct and accurate method for understanding evolutionary relationships. B) Biochemical evidence involves comparing molecules like proteins, which can also provide insights into evolutionary relationships. However, DNA comparison is considered more reliable due to the direct relationship between DNA sequences and genetic information. C) Geographic distribution evidence refers to where organisms live and how their distribution may provide clues about evolutionary history. While this can be informative, it is not as direct or specific as comparing DNA sequences. D) Genetic evidence involves comparing DNA sequences of different organisms to understand their evolutionary relationships. DNA comparison is a powerful tool in evolutionary biology because it provides direct information about genetic similarities and differences, offering precise insights into evolutionary relationships.

2. Which of the following equations represents a redox reaction?

A. 2H2 + O2 → 2H2O
B. Zn + 2HCl → ZnCl2 + H2
C. 2NaCl → 2Na + Cl2
D. CH4 + 2O2 → CO2 + 2H2O

Correct answer: B

Rationale: A redox reaction involves the transfer of electrons between reactants. In option B, Zn loses electrons to form Zn2+ while H+ gains electrons to form H2. This exchange of electrons demonstrates a redox reaction, making choice B the correct answer. In options A, C, and D, there is no clear transfer of electrons between the reactants, indicating that they are not redox reactions. Option A represents a synthesis reaction, option C represents a decomposition reaction, and option D represents a combustion reaction. These types of reactions do not involve the transfer of electrons between reactants, unlike a redox reaction.

3. When magnesium metal reacts with hydrochloric acid, hydrogen gas is produced. What evidence suggests a chemical reaction is occurring?

A. A change in color
B. The formation of a gas
C. Dissolving in a liquid
D. No change in temperature

Correct answer: B

Rationale: The formation of a gas is evidence of a chemical reaction occurring. In this case, when magnesium metal reacts with hydrochloric acid, hydrogen gas is produced, indicating a chemical change is taking place. The production of gas is a clear indication of a chemical reaction, as new substances are being formed. A change in color might suggest a physical change, dissolving in a liquid could be a physical or chemical change depending on the context, and no change in temperature does not necessarily indicate a chemical reaction, as some reactions are endothermic or release small amounts of heat that may not be easily noticeable.

4. What is the function of the cell membrane?

A. To protect the cell and control what enters and exits
B. To store energy
C. To produce proteins
D. To synthesize lipids

Correct answer: A

Rationale: The cell membrane, also known as the plasma membrane, serves as a protective barrier for the cell, separating the internal environment of the cell from the external environment. It is selectively permeable, meaning it controls the passage of substances in and out of the cell. This regulation of what enters and exits the cell is crucial for maintaining the cell's internal environment and ensuring proper functioning. Options B, C, and D are incorrect because storing energy, producing proteins, and synthesizing lipids are functions carried out by other cellular structures such as mitochondria, ribosomes, and endoplasmic reticulum, respectively, not the cell membrane.

5. Which statement is TRUE about valence electrons?

A. They are located in the innermost electron shell.
B. They have the highest binding energy to the nucleus.
C. They are most likely to participate in chemical bonding.
D. They have no influence on the element's chemical properties.

Correct answer: C

Rationale: Valence electrons are the outermost electrons in an atom's electron cloud and are crucial in forming chemical bonds with other atoms. These electrons determine the reactivity and chemical properties of an element, making option C the correct statement. Option A is incorrect as valence electrons are found in the outer shell, not the innermost shell. Option B is incorrect because valence electrons have lower binding energy compared to inner electrons. Option D is incorrect since valence electrons play a significant role in an element's chemical behavior.