Nokea
Why is the lining of the stomach covered with rugae?
- A. Rugae increase the output of gastric juices.
- B. Rugae increase the surface area of the stomach.
- C. Rugae increase the permeability of the stomach walls.
- D. Rugae increase the types of nutrients that can diffuse.
Correct Answer: B
Rationale: Rugae are folds in the stomach lining that increase its surface area. This increased surface area allows for more efficient digestion and absorption of nutrients in the stomach. Choice A is incorrect because rugae do not directly affect the output of gastric juices. Choice C is incorrect because rugae do not impact the permeability of the stomach walls. Choice D is incorrect because rugae do not influence the types of nutrients that can diffuse.
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Which statement confirms that the cell membrane is selectively permeable?
- A. Receptors are found on a cell's surface.
- B. Cells communicate with each other using cell signals.
- C. Environmental changes can cause a cell to expand or shrink.
- D. Sodium ions must travel through ion channels to enter the cell.
Correct Answer: D
Rationale: The correct answer is D because selective permeability is demonstrated by the fact that specific ions, such as sodium, require ion channels to cross the cell membrane. This process allows the cell to control what substances can enter or exit, highlighting the selective nature of the cell membrane. Choices A, B, and C do not directly relate to the concept of selective permeability of the cell membrane. Receptors on a cell's surface (Choice A) are involved in cell signaling rather than selective permeability. Cell communication through signals (Choice B) and environmental changes affecting cell size (Choice C) are not directly related to the selective permeability of the cell membrane, which specifically refers to the regulation of substances passing through the membrane.
After a person eats birthday cake, which of the following enzymes is needed to break down the sucrose in the cake?
- A. Lactase
- B. Maltase
- C. Peptidase
- D. Sucrase
Correct Answer: D
Rationale: Sucrase is the correct enzyme needed to break down sucrose into its component sugars, glucose, and fructose. Lactase is responsible for breaking down lactose, maltase for maltose, and peptidase for proteins; therefore, they are not the enzymes required to digest sucrose specifically. In the context of digesting birthday cake, which contains sucrose, sucrase is the enzyme needed for this particular sugar.
A person wakes up with a fever. The body begins its response to locate the origin of the problem and fix it. What type of feedback mechanism is this?
- A. Equal
- B. Negative
- C. Neutral
- D. Positive
Correct Answer: B
Rationale: This scenario describes a negative feedback mechanism. When the body detects a fever, it initiates responses to lower the temperature back to normal levels. Negative feedback mechanisms work to counteract changes and maintain homeostasis in the body. Choice A ('Equal') is incorrect as feedback mechanisms aim to restore balance, not maintain an equal state. Choice C ('Neutral') is incorrect as it does not describe the corrective nature of negative feedback. Choice D ('Positive') is incorrect as it would amplify the fever rather than regulate it.
Which element's neutral atom has 2 electrons in the first shell and 6 electrons in the second shell of the electron cloud?
- A. Beryllium
- B. Carbon
- C. Helium
- D. Oxygen
Correct Answer: D
Rationale: The correct answer is Oxygen. Oxygen has a total of 8 electrons, with 2 in the first shell and 6 in the second shell. This configuration matches the description provided in the question. Choice A, Beryllium, has 2 electrons in total, so it cannot have 2 in the first shell and 6 in the second. Choice B, Carbon, has 6 electrons in total, so it also does not match the given electron distribution. Choice C, Helium, has only 2 electrons in total and therefore does not fit the electron configuration described in the question.
Which deadly disease was eliminated through an intensive vaccination program?
- A. AIDS
- B. Smallpox
- C. Diabetes type 1
- D. Rheumatoid arthritis
Correct Answer: B
Rationale: Smallpox was eradicated globally through an intensive vaccination program. The World Health Organization (WHO) led a successful global campaign to vaccinate people against smallpox, ultimately leading to its eradication in 1980. AIDS, diabetes type 1, and rheumatoid arthritis are serious conditions, but they were not eliminated through vaccination programs like smallpox. Therefore, the correct answer is B, Smallpox. AIDS is caused by the human immunodeficiency virus (HIV) and remains a significant global health issue. Diabetes type 1 is an autoimmune condition where the body attacks insulin-producing cells, leading to high blood sugar levels. Rheumatoid arthritis is an autoimmune condition that primarily affects the joints, causing inflammation and pain.