Nokea
The chemical equation below is unbalanced. When it is properly balanced, how many molecules of carbon dioxide (CO2) are produced for each molecule of propane (C3H8) in the reaction? 3C3H8 + 5O2 → 3CO2 + 4H2O
- A. One Half.
- B. Two.
- C. Three.
- D. Five.
Correct Answer: B
Rationale: The balanced chemical equation for the combustion of propane is: 3C3H8 + 5O2 → 3CO2 + 4H2O. This equation shows that for every 3 molecules of propane (C3H8) consumed, 3 molecules of carbon dioxide (CO2) are produced. Therefore, when properly balanced, 3CO2 are produced for each molecule of propane used. Thus, the correct answer is B: Two. Choices A, C, and D are incorrect because they do not reflect the correct stoichiometry as determined by the balanced equation.
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What is the control, if any, in this experiment?
- A. There is no control in this experiment
- B. The control is the water
- C. The control is the diet soda
- D. The control is the amount of sunlight provided to the plants
Correct Answer: B
Rationale: The correct answer is B: 'The control is the water.' In a scientific experiment, the control group is used as a baseline comparison to evaluate the effects of the variables being tested. Here, the water serves as the control group against which the effects of other substances like diet soda or different amounts of sunlight can be compared. Choice A is incorrect as every experiment should have a control group for comparison. Choice C and D are incorrect as they are not the standard control in this scenario.
Where would a nonpregnant patient with normal anatomy most commonly have pain in acute appendicitis?
- A. Right upper quadrant.
- B. Left upper quadrant.
- C. Right lower quadrant.
- D. Left lower quadrant.
Correct Answer: C
Rationale: In acute appendicitis, nonpregnant patients with normal anatomy commonly experience pain in the right lower quadrant of the abdomen. The pain usually starts around the umbilicus or epigastric area and then migrates to the right lower quadrant as inflammation progresses in the appendix. This classic migration of pain is known as McBurney's point tenderness and is a key clinical feature in diagnosing appendicitis.
What is the primary purpose of conducting an experiment?
- A. to test a hypothesis
- B. to collect data
- C. to identify a control state
- D. to choose variables
Correct Answer: A
Rationale: The correct answer is A: 'to test a hypothesis.' The primary purpose of conducting an experiment is to test a hypothesis. This process allows researchers to gather empirical evidence to either support or refute a proposed hypothesis. By systematically manipulating variables and observing outcomes, scientists can draw conclusions about the relationships between these variables. Choice B, 'to collect data,' is a common step within an experiment, but the ultimate goal is to test a specific hypothesis. Choice C, 'to identify a control state,' is not the primary purpose but rather a methodological consideration within an experiment to ensure reliable results. Choice D, 'to choose variables,' is a step that is typically done before conducting the experiment and is not the primary purpose of the experiment itself.
What is the process by which simple cells become highly specialized cells?
- A. Cellular complication
- B. Cellular specialization
- C. Cellular differentiation
- D. Cellular modification
Correct Answer: C
Rationale: The correct answer is 'Cellular differentiation'. Cellular differentiation is the process by which simple cells become highly specialized cells. During cellular differentiation, cells acquire specific structures and functions that allow them to perform particular roles within an organism. This process involves the activation and silencing of specific genes, leading to the development of various cell types with distinct characteristics and functions. 'Cellular complication' (Choice A) is incorrect as it does not describe the specific process of cells becoming specialized. 'Cellular specialization' (Choice B) is not the most precise term for the process, as it does not capture the transformation from simple cells to specialized cells. 'Cellular modification' (Choice D) is incorrect as it is a vague term that does not specifically refer to the process of cellular specialization.
What are substances that stimulate adaptive immunity called?
- A. Peptides
- B. Phagocytes
- C. Prions
- D. Platelets
Correct Answer: A
Rationale: Substances that stimulate adaptive immunity are called peptides. Peptides are short chains of amino acids that play a crucial role in activating the immune response by interacting with immune cells such as T cells and B cells. Peptides are important in antigen presentation and recognition, leading to the development of specific immune responses against pathogens. Choice B, phagocytes, are cells that engulf and digest pathogens but are not substances that stimulate adaptive immunity. Choice C, prions, are infectious agents made of misfolded proteins and are not related to stimulating adaptive immunity. Choice D, platelets, are cell fragments involved in blood clotting and have no direct role in stimulating adaptive immunity.