Nokea
What is the name for the change in enthalpy (heat) associated with a chemical reaction at constant pressure?
- A. Entropy
- B. Enthalpy
- C. Gibbs free energy
- D. Heat of reaction
Correct Answer: D
Rationale: The correct answer is D, Heat of reaction. The heat of reaction, also known as the enthalpy change, is the amount of heat absorbed or released during a chemical reaction at constant pressure. Entropy (A) is a measure of the disorder or randomness of a system and is not specifically related to heat changes in a chemical reaction. Enthalpy (B) is the total heat content of a system and not just the change associated with a reaction. Gibbs free energy (C) is a measure of the energy available to do work in a system at constant temperature and pressure, but it is not the specific term for the heat change in a chemical reaction.
You may also like to solve these questions
What is the formula to calculate acceleration?
- A. Acceleration = Mass/Force
- B. Acceleration = Force/Mass
- C. Acceleration = Time/Distance
- D. Acceleration = Time Change in Velocity
Correct Answer: D
Rationale: Acceleration is defined as the rate of change of velocity with respect to time. The correct formula to calculate acceleration is Acceleration = Time Change in Velocity. This formula specifically represents how much an object's velocity changes over a specified time period, providing a measure of the object's speed change rate. Choices A and B are incorrect as they do not represent the relationship between acceleration and time change in velocity. Choice C is incorrect as it involves time and distance, which are not directly related to acceleration.
What is the primary function of the placenta during pregnancy?
- A. Produce insulin
- B. Facilitate gas exchange between mother and fetus
- C. Excrete waste products from the fetus
- D. All of the above
Correct Answer: B
Rationale: The primary function of the placenta during pregnancy is to facilitate the exchange of oxygen and carbon dioxide between the mother and the fetus. This ensures that the fetus receives oxygen and eliminates carbon dioxide, supporting its growth and development. While the placenta also allows for the transfer of nutrients and waste products between the mother and the fetus, its main role is to ensure proper gas exchange. Therefore, choices A, C, and D are incorrect as the primary role of the placenta is not to produce insulin or excrete waste products from the fetus. Selecting the correct answer, choice B, highlights the crucial role of the placenta in providing oxygen to the fetus and removing carbon dioxide, which are essential for fetal well-being and development.
Homologous structures are those that:
- A. Have the same function but different origins
- B. Have different functions but the same origin
- C. Are similar in appearance and function due to shared ancestry
- D. Are identical in both appearance and function
Correct Answer: C
Rationale: Homologous structures are defined as anatomical features that are similar in appearance and function due to shared ancestry. This means that these structures are inherited from a common ancestor and may have evolved to fulfill different functions in different species. Option A, which mentions structures with the same function but different origins, describes analogous structures, not homologous ones. Option B, which refers to structures with different functions but the same origin, actually characterizes vestigial structures. Option D, stating that structures are identical in appearance and function, does not necessarily imply homology; such structures could result from convergent evolution rather than shared ancestry. Understanding homologous structures provides insights into the evolutionary relationships between different species and supports the concept of common descent.
What is the 'lock-and-key' model?
- A. Protein folding
- B. Enzyme-substrate interaction
- C. Muscle contraction
- D. Blood clotting
Correct Answer: B
Rationale: The 'lock-and-key' model describes the specificity of the interaction between enzymes and their substrates. In this model, the enzyme's active site acts like a lock that can only be opened by the specific substrate molecule, which serves as the key. This specific binding ensures that enzymes catalyze particular reactions and do not interact with other molecules indiscriminately. Protein folding (option A) is the process by which a protein attains its functional three-dimensional structure but is not directly related to the lock-and-key model. Muscle contraction (option C) and blood clotting (option D) are complex biological processes but are not directly associated with the lock-and-key model of enzyme-substrate interaction.
Which hormone, produced by the adrenal glands, is essential for regulating electrolyte balance, particularly sodium and potassium, in the body?
- A. Aldosterone
- B. Epinephrine
- C. Cortisol
- D. Insulin
Correct Answer: A
Rationale: Aldosterone is a hormone produced by the adrenal glands that plays a crucial role in maintaining electrolyte balance, specifically by regulating sodium and potassium levels in the body. Its primary function involves acting on the kidneys to increase the reabsorption of sodium and water while promoting the excretion of potassium. This process is essential for regulating blood pressure, fluid balance, and electrolyte concentrations in the body. Epinephrine is associated with the fight or flight response, cortisol is a stress hormone, and insulin is responsible for regulating blood sugar levels as produced by the pancreas. Therefore, the correct answer is Aldosterone as it directly targets electrolyte balance, particularly sodium and potassium, in the body.