Nokea
What are the components of the male external genitalia and their functions?
- A. Prostate gland: produces seminal fluid
- B. Scrotum: protects and maintains the temperature of the testes
- C. Penis: delivers sperm to female reproductive tract
- D. Urethra: conducts urine out of the body
Correct Answer: C
Rationale: The correct answer is C. The penis is responsible for delivering sperm to the female reproductive tract during sexual intercourse. The scrotum is not involved in producing sperm but rather protects and regulates the temperature of the testes, which is essential for sperm production. The prostate gland is involved in producing seminal fluid, not sperm. The urethra serves the purpose of conducting urine out of the body and also acts as a passage for semen during ejaculation.
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A pediatrician notes that an infant's cartilage is disappearing and being replaced by bone. What process has the doctor observed?
- A. Mineralization
- B. Ossification
- C. Osteoporosis
- D. Calcification
Correct Answer: B
Rationale: The doctor has observed the process of ossification. Ossification is the natural process where cartilage in the body is replaced by bone. This process takes place during fetal development, growth, and bone fracture healing. Ossification involves the formation of bone tissue by depositing minerals like calcium and phosphorus within the cartilage matrix, leading to the development of a bone structure. Choice A, mineralization, refers to the process of forming mineral deposits in tissues, but it does not involve the replacement of cartilage by bone. Choice C, osteoporosis, is a condition characterized by bone density loss and increased fragility, not the natural process of cartilage replacement by bone. Choice D, calcification, is the process of deposition of calcium salts in various tissues, but it does not specifically involve the replacement of cartilage by bone as in ossification.
What do large intestines absorb?
- A. Water, sodium, and potassium ions
- B. Proteins and carbohydrates
- C. Water, vitamin K, and bile salts
- D. Vitamins A, D, E, K
Correct Answer: C
Rationale: The correct answer is C. The large intestine absorbs water, vitamin K, bile salts, sodium, and chloride ions. It helps in maintaining the body's water and electrolyte balance, and also plays a role in absorbing certain vitamins and nutrients such as vitamin K. Choices A, B, and D are incorrect because proteins, carbohydrates, vitamins A, D, E, and K are primarily absorbed in the small intestine, not the large intestine.
Which of the following structures is unique to eukaryotic cells?
- A. Cell walls
- B. Nuclei
- C. Cell membranes
- D. Vacuoles
Correct Answer: B
Rationale: Nuclei are structures that are unique to eukaryotic cells. Prokaryotic cells lack a defined nucleus, and their genetic material floats freely in the cytoplasm. Eukaryotic cells have nuclei that house the genetic material in the form of chromosomes, separated from the cytoplasm by a nuclear membrane. This distinct organelle is a key feature that sets eukaryotic cells apart from prokaryotic cells. Cell walls (Choice A) are found in plant cells, fungi, and some prokaryotes but are not unique to eukaryotic cells. Cell membranes (Choice C) are present in both prokaryotic and eukaryotic cells, serving as a barrier that encloses the cell contents. Vacuoles (Choice D) are membrane-bound organelles found in both plant and animal cells, making them not unique to eukaryotic cells.
What defines the systole phase in the cardiac cycle?
- A. Relaxation of the heart
- B. Contraction of the heart
- C. Diastole of the heart
- D. Pulse rate of the heart
Correct Answer: B
Rationale: The correct answer is B: Contraction of the heart. Systole is the phase of the cardiac cycle during which the heart muscle contracts, pumping blood out of the chambers. It is essential for maintaining circulation and delivering oxygen and nutrients to the body's tissues. Diastole (choice C) is the relaxation phase of the heart when the chambers fill with blood. Pulse rate (choice D) is the number of heartbeats per minute, not specifically related to the systole phase. Choice A, 'Relaxation of the heart,' is incorrect because systole refers to the contraction phase of the cardiac cycle, not relaxation.
What is the purpose of a catalyst?
- A. To increase a reaction rate by increasing the activation energy
- B. To increase a reaction rate by increasing the temperature
- C. To increase a reaction rate by decreasing the activation energy
- D. To increase a reaction rate by decreasing the temperature
Correct Answer: C
Rationale: The purpose of a catalyst is to increase a reaction's rate by decreasing the activation energy required for the reaction to occur. This allows the reaction to proceed more quickly without being consumed in the process. The catalyst provides an alternate mechanism with a lower activation energy, making it easier for the reactants to convert into products. Choice A is incorrect because a catalyst lowers, not increases, the activation energy. Choice B is incorrect because a catalyst does not affect the temperature directly but provides an alternative pathway for the reaction to occur more easily. Choice D is incorrect because a catalyst does not lower the temperature but facilitates the reaction by lowering the activation energy barrier. Therefore, the correct answer is C, 'To increase a reaction rate by decreasing the activation energy.'