Nokea
What action would result in an increase in the rate of a chemical reaction?
- A. Adding more of the reactants
- B. Decreasing the temperature of the reactants
- C. Using a mortar and pestle to grind a solid reactant to a powder
- D. Sealing the reaction in an airtight container
Correct Answer: C
Rationale: Grinding a solid reactant to a powder increases the surface area exposed to other reactants, leading to more frequent collisions and a faster reaction rate. This process enhances the chances of successful collisions, hence accelerating the reaction. The other options do not directly impact the rate of a chemical reaction in the same manner. Adding more of the reactants provides more reactant particles to collide, promoting a higher reaction rate. Decreasing the temperature of the reactants generally slows down reactions by reducing the kinetic energy of the particles. Sealing the reaction in an airtight container may affect the equilibrium but not necessarily the reaction rate.
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Which of the following processes causes most of the carbon dioxide from the blood to move into the alveoli?
- A. Diffusion down a concentration gradient
- B. Active transport using energy or passive transport using carrier proteins
- C. Conversion to carbon monoxide
- D. Conversion to carbon dioxide
Correct Answer: A
Rationale: The correct answer is A: Diffusion down a concentration gradient. In the alveoli, carbon dioxide moves from an area of higher concentration in the blood to an area of lower concentration in the alveolar air sacs. This movement occurs through simple diffusion, which does not require energy or carrier proteins. Active transport (B) requires energy input from the cell, while conversion to carbon monoxide (C) or conversion to carbon dioxide (D) are not processes involved in the movement of carbon dioxide from the blood to the alveoli.
Which of the following structures is present in both prokaryotic and eukaryotic cells?
- A. Cell membrane
- B. Chromoplast
- C. Golgi apparatus
- D. Endoplasmic reticulum
Correct Answer: A
Rationale: The correct answer is the cell membrane (choice A). The cell membrane is a vital structure present in both prokaryotic and eukaryotic cells. It plays a crucial role as a selectively permeable barrier, controlling the movement of substances into and out of the cell. On the other hand, chromoplasts, Golgi apparatus, and endoplasmic reticulum are specific organelles found only in eukaryotic cells. Chromoplasts are responsible for pigment synthesis, Golgi apparatus is involved in protein processing and packaging, and endoplasmic reticulum is crucial for lipid synthesis and protein folding. Therefore, the cell membrane is the correct choice as it is the common feature shared by both prokaryotic and eukaryotic cells.
Which of the following is an example of a biological macromolecule?
- A. Monosaccharide
- B. Protein
- C. Nucleic acid
- D. Amino acid
Correct Answer: B
Rationale: The correct answer is B, 'Protein.' Proteins are biological macromolecules composed of amino acid chains. They play vital roles in cellular functions, including catalyzing reactions, providing structural support, and acting as signaling molecules. Monosaccharides are simple sugars, nucleic acids are genetic materials such as DNA and RNA, and amino acids are the fundamental units that make up proteins.
In experimental design, which group can be measured against the experimental group as a standard of comparison?
- A. Control
- B. Responding
- C. Manipulated
- D. Variable
Correct Answer: A
Rationale: The control group is a critical component in experimental design as it serves as a reference point for comparison with the experimental group. The control group does not receive the experimental treatment but is subjected to all other conditions. By comparing the outcomes of the experimental group with those of the control group, researchers can evaluate the impact and efficacy of the experimental treatment.
Which of the following nucleotides is only found in RNA?
- A. Adenine
- B. Uracil
- C. Guanine
- D. Thymine
Correct Answer: B
Rationale: The correct answer is B: Uracil. Uracil is a nucleotide base that is specifically found in RNA. In DNA, thymine replaces uracil. Adenine, guanine, and cytosine are nucleotides present in both RNA and DNA. Understanding the unique nucleotide composition of RNA and DNA is essential in molecular biology to comprehend the genetic information flow and transcription processes accurately. RNA uses uracil instead of thymine, which is a key distinction between the two nucleic acids.