which statement below correctly describes the movement of molecules in the body andor in relation to the external environment

ATI TEAS 7

ATI TEAS 7 Science Practice Test

1. Which statement below correctly describes the movement of molecules in the body and in relation to the external environment?

A. Osmosis is the movement of a solution from an area of low solute concentration to an area of high solute concentration.
B. Diffusion is the process in which oxygen moves from the lungs into the bloodstream.
C. Dissipation is the transport of molecules across a semipermeable membrane from low to high concentration.
D. Reverse osmosis is the movement of molecules in a solution from high concentration to low concentration.

Correct answer: B

Rationale: The correct answer is B. Diffusion is the process where molecules move from an area of higher concentration to an area of lower concentration. In the context of the lungs, oxygen moves from the alveoli in the lungs to the bloodstream through diffusion. Choice A is incorrect as osmosis involves the movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration. Choice C is incorrect because dissipation does not refer to a specific biological process related to molecule movement. Choice D is incorrect as reverse osmosis is a process where solvent moves from an area of high solute concentration to an area of low solute concentration, not the movement of molecules within a solution.

2. Which of the following is directly transcribed from DNA and represents the first step in protein synthesis?

A. siRNA
B. rRNA
C. mRNA
D. tRNA

Correct answer: C

Rationale: mRNA (messenger RNA) is directly transcribed from DNA in the nucleus during the process of transcription. It serves as a template for protein synthesis during translation in the cytoplasm. mRNA carries genetic information from the DNA to the ribosomes, where it determines the sequence of amino acids in a protein. Thus, mRNA represents the first step in protein synthesis as it carries the code from the DNA to be translated into a protein. Choice A, siRNA (small interfering RNA), is involved in post-transcriptional gene silencing and does not play a role in protein synthesis. Choice B, rRNA (ribosomal RNA), is a component of the ribosome and plays a structural and functional role in protein synthesis but is not directly transcribed from DNA. Choice D, tRNA (transfer RNA), is responsible for bringing amino acids to the ribosome during protein synthesis but is not directly transcribed from DNA.

3. Which of the following is a balanced chemical equation?

A. H2 + O2 → H2O
B. 2H2 + O2 → 2H2O
C. 3H2O → 2H2 + O2
D. H2O → H2 + O2

Correct answer: B

Rationale: A balanced chemical equation must have the same number of atoms of each element on both sides of the equation. In option B, 2H2 + O2 → 2H2O, the equation is balanced as there are 2 hydrogen atoms and 2 oxygen atoms on both the reactant and product sides after balancing, satisfying the law of conservation of mass. Option A is unbalanced as there are 2 oxygen atoms on the reactant side but only 1 oxygen atom on the product side. Option C is unbalanced with 3 hydrogen atoms on the reactant side and 2 hydrogen atoms on the product side. Option D is unbalanced with 1 oxygen atom on the reactant side and 2 oxygen atoms on the product side.

4. What is the difference between a pure substance and a mixture?

A. Pure substances have a fixed composition, mixtures don't.
B. Mixtures have a fixed composition, pure substances don't.
C. Pure substances can be in any state, mixtures are not always solids.
D. Pure substances are always elements, mixtures are always compounds.

Correct answer: A

Rationale: Pure substances have a definite and constant composition, meaning they are made up of only one type of atom or molecule with fixed proportions. This composition does not vary. On the other hand, mixtures are composed of two or more substances physically combined. The components of a mixture can be present in varying proportions, leading to a variable composition. Choice A is correct as it accurately distinguishes between pure substances and mixtures based on the fixed composition of pure substances and the variable composition of mixtures. Choice B is incorrect because mixtures, not pure substances, have variable compositions. Choice C is incorrect as both pure substances and mixtures can exist in different states. Choice D is incorrect because pure substances can be compounds as well, not exclusively elements, and mixtures can contain elements and compounds.

5. What does antidiuretic hormone (ADH) help the kidneys regulate?

A. Acid-base balance
B. Blood pressure
C. Urine output by controlling water reabsorption
D. All of the above

Correct answer: C

Rationale: Antidiuretic hormone (ADH) helps the kidneys regulate urine output by controlling water reabsorption. ADH acts on the kidneys to increase the reabsorption of water, leading to a decrease in urine output. This helps the body conserve water and maintain proper fluid balance. ADH primarily affects urine output by controlling water reabsorption and does not directly regulate acid-base balance or blood pressure. Therefore, choices A and B are incorrect because ADH does not directly influence acid-base balance or blood pressure.