Nokea
What is the primary function of the pyloric sphincter?
- A. to regulate the movement of food material from the stomach to the duodenum
- B. to neutralize stomach acid
- C. to prevent digested food materials and stomach acid from entering the esophagus
- D. to begin the process of chemical digestion
Correct Answer: A
Rationale: The primary function of the pyloric sphincter is to regulate the flow of partially digested food material (chyme) from the stomach into the small intestine, specifically the duodenum. This control is essential for proper digestion and absorption of nutrients in the small intestine. Choices B, C, and D are incorrect. Choice B is incorrect because neutralizing stomach acid is primarily the function of the stomach lining and antacid mechanisms. Choice C is incorrect because preventing the backflow of digested food materials and stomach acid into the esophagus is mainly the role of the lower esophageal sphincter. Choice D is incorrect because the chemical digestion process primarily starts in the stomach through the action of gastric juices, not the pyloric sphincter.
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Which of the following layers of skin acts as an energy reserve by storing adipocytes and releasing them into circulation when energy is needed?
- A. epidermis
- B. dermis
- C. hypodermis
- D. stratum basale
Correct Answer: C
Rationale: The hypodermis, also known as the subcutaneous tissue, is the deepest layer of the skin. This layer contains adipocytes (fat cells) that act as an energy reserve by storing excess energy in the form of fat. When energy is needed, these stored fats can be released into circulation to be used by the body's cells. The epidermis is the outermost layer of the skin, primarily responsible for providing a protective barrier. The dermis lies between the epidermis and hypodermis and contains blood vessels, nerves, and structures like hair follicles and sweat glands. The stratum basale is the deepest layer of the epidermis, responsible for cell renewal and regeneration.
Where is the pineal gland located in the body?
- A. Below the larynx
- B. Above the kidney
- C. At the center of the brain hemispheres
- D. At the base of the brain
Correct Answer: C
Rationale: The pineal gland is correctly located at the center of the brain, between the two hemispheres. It is a small endocrine gland often referred to as the 'third eye' due to its unique location. Choices A, B, and D are incorrect as the pineal gland is not situated below the larynx, above the kidney, or at the base of the brain.
Which of the following Mendelian laws describes how pairs of alleles within genes separate and recombine independently from other genes?
- A. law of segregation
- B. law of dominance
- C. law of independent assortment
- D. law of predictive traits
Correct Answer: C
Rationale: The law of independent assortment describes how alleles of different genes segregate independently during gamete formation. This means that different gene pairs are passed on to offspring separately from one another, allowing for various combinations of traits. Gregor Mendel discovered this law, along with the law of segregation and the law of dominance, through his experiments with pea plants. The law of segregation (choice A) refers to how alleles of a gene separate during gamete formation, while the law of dominance (choice B) states that one allele can mask the presence of another in a heterozygous individual. The 'law of predictive traits' (choice D) is not a recognized Mendelian law and does not accurately describe the principles of genetic inheritance.
Which of the following choices would contain the code for making a protein?
- A. mRNA
- B. tRNA
- C. rRNA
- D. DNA polymerase
Correct Answer: A
Rationale: The correct answer is A: mRNA (messenger RNA). mRNA contains the genetic code or instructions for making a protein. During protein synthesis, mRNA carries the genetic information from DNA in the cell nucleus to the ribosomes, where proteins are synthesized. The sequence of nucleotides in mRNA corresponds to the sequence of amino acids that will be used to build the protein. Choice B, tRNA (transfer RNA), is involved in carrying amino acids to the ribosome during protein synthesis but does not contain the code for making a protein. Choice C, rRNA (ribosomal RNA), is a component of ribosomes where protein synthesis occurs but does not contain the specific code for making a protein. Choice D, DNA polymerase, is an enzyme involved in DNA replication, not in directly coding for protein synthesis.
What term describes a series of muscle contractions that transports food down the digestive tract in a wave-like fashion?
- A. digestion
- B. deglutition
- C. defecation
- D. peristalsis
Correct Answer: D
Rationale: Peristalsis is the correct term for the series of muscle contractions that move food down the digestive tract in a wave-like manner. This process helps propel food through the esophagus, stomach, and intestines, facilitating digestion and nutrient absorption. Digestion (Choice A) refers to the breakdown of food into smaller components, deglutition (Choice B) is the act of swallowing, and defecation (Choice C) is the elimination of waste from the body. Therefore, peristalsis is the most appropriate term to describe the described muscle contractions in the digestive system.