Nokea
What type of molecule forms the cell membrane and controls what enters and exits the cell?
- A. Proteins
- B. Carbohydrates
- C. Lipids
- D. Nucleic acids
Correct Answer: C
Rationale: The cell membrane is primarily composed of lipids, specifically phospholipids, which form a lipid bilayer. This lipid bilayer controls what enters and exits the cell, providing a barrier that is selectively permeable. While proteins are also important components of the cell membrane and play various roles, lipids are the main structural component responsible for the membrane's permeability and function. Carbohydrates and nucleic acids are not the primary components of the cell membrane and do not have the same structural role as lipids.
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The control center of the cell, containing genetic information (DNA), is the:
- A. Golgi apparatus
- B. Ribosome
- C. Nucleus
- D. Endoplasmic reticulum
Correct Answer: C
Rationale: The correct answer is C, the nucleus. The nucleus is the control center of the cell and houses the genetic information in the form of DNA. The Golgi apparatus (choice A) is responsible for packaging and processing proteins, the ribosome (choice B) is involved in protein synthesis, and the endoplasmic reticulum (choice D) is involved in protein and lipid synthesis. Therefore, choices A, B, and D are not the correct answers as they do not house the genetic information or serve as the control center of the cell.
Which of these organisms belongs to the kingdom Protista?
- A. Coral
- B. Yeast
- C. Euglena
- D. Mushroom
Correct Answer: C
Rationale: A) Coral belongs to the kingdom Animalia, specifically in the phylum Cnidaria. B) Yeast belongs to the kingdom Fungi. C) Euglena is a unicellular organism that belongs to the kingdom Protista. It is a type of protist that has characteristics of both plants and animals. D) Mushroom belongs to the kingdom Fungi. Therefore, among the options provided, only Euglena belongs to the kingdom Protista.
What term describes the functional unit of a skeletal muscle responsible for muscle contraction?
- A. Myofibril
- B. Sarcomere
- C. Tendon
- D. Myoglobin
Correct Answer: B
Rationale: The correct answer is B, 'Sarcomere.' The sarcomere is indeed the functional unit of a skeletal muscle responsible for muscle contraction. It is composed of actin and myosin filaments that interact to generate muscle contraction. Choice A, 'Myofibril,' is incorrect as myofibrils are composed of sarcomeres, not the functional units themselves. Choice C, 'Tendon,' is incorrect as tendons connect muscles to bones and do not directly participate in muscle contraction. Choice D, 'Myoglobin,' is incorrect as myoglobin is a protein that stores oxygen in muscle cells and is not directly involved in muscle contraction.
Which hormone stimulates the release of pancreatic enzymes and bile?
- A. Gastrin
- B. Insulin
- C. Cholecystokinin (CCK)
- D. Glucagon
Correct Answer: C
Rationale: Cholecystokinin (CCK) is the correct answer. It is the hormone that stimulates the release of pancreatic enzymes and bile. CCK is released by the small intestine in response to the presence of fats and proteins in the duodenum, triggering the release of digestive enzymes and bile to aid in the digestion of fats and proteins. Gastrin (Choice A) primarily stimulates gastric acid secretion, not the release of pancreatic enzymes and bile. Insulin (Choice B) regulates blood sugar levels by promoting glucose uptake. Glucagon (Choice D) raises blood glucose levels by stimulating the breakdown of glycogen in the liver.
What is the relationship between work and the displacement of an object?
- A. Work depends only on the force applied, not displacement
- B. Work is directly proportional to displacement
- C. Work is inversely proportional to displacement
- D. Work is unrelated to displacement
Correct Answer: B
Rationale: Work is directly proportional to displacement. In physics, work is defined as the product of the force applied to an object and the displacement of the object in the direction of the force. Therefore, work is directly proportional to displacement. Choice A is incorrect because work is dependent on both force and displacement. Choice C is incorrect because work is not inversely proportional to displacement; it is directly proportional. Choice D is incorrect because work is indeed related to displacement, as described in the definition of work in physics.