ATI TEAS 7 Science

Correct Answer: D

Rationale: The correct answer is D, both transcription and translation. First, DNA undergoes transcription to produce mRNA, which carries the genetic information. Then, during translation, mRNA is used by ribosomes to synthesize proteins. Replication (A) is the process of copying DNA, not directly related to protein synthesis. Transcription (B) is the step where DNA is transcribed into mRNA. Translation (C) is the process where mRNA is translated into proteins. Therefore, both transcription and translation are essential steps in the flow of genetic information from DNA to protein.

Correct Answer: A

Rationale: The correct answer is A: Nucleosome. Nucleosomes are the basic units of DNA packaging in eukaryotic cells, consisting of DNA wrapped around histone proteins. This structure helps in compacting the DNA to fit inside the nucleus. Choice B (Chromatin) is a broader term for DNA and associated proteins, not a specific packaging structure. Choice C (Histone) refers to the protein component of nucleosomes, not the packaging structure itself. Choice D (Centromere) is a region on a chromosome where the kinetochore forms during cell division, not involved in DNA packaging.

Correct Answer: B

Rationale: The correct answer is B. A decomposition reaction involves a single compound breaking down into two or more simpler substances. In choice B, CaCO3 decomposes into CaO and CO2. This reaction follows the general form AB → A + B, making it a clear example of a decomposition reaction. Choices A, C, and D involve synthesis or combination reactions, where simpler substances combine to form a more complex compound, making them incorrect for this question.

Correct Answer: B

Rationale: Platelets are responsible for blood clotting, which is crucial for preventing excessive bleeding when a blood vessel is injured. They adhere to the site of injury and form a plug to stop bleeding. This function is essential for maintaining hemostasis in the body. Platelets do not carry oxygen like red blood cells (Choice A), fight infection like white blood cells (Choice C), or transport nutrients like plasma (Choice D).

Correct Answer: A

Rationale: The correct answer is A: Covalent bond. In a covalent bond, atoms share electrons to achieve a stable electron configuration. This sharing allows both atoms to fill their outer electron shells and form a strong bond. Ionic bonds (choice B) involve the transfer of electrons, not sharing. Metallic bonds (choice C) occur in metals where electrons are delocalized. Hydrogen bonds (choice D) are weak electrostatic attractions between hydrogen and electronegative atoms, not a result of electron sharing. Thus, the correct answer is A because it accurately describes the sharing of electrons between elements to form a covalent bond.