The crackling sound that is produced from bones rubbing against each other is termed as

Correct Answer: B

Rationale: The correct answer is B: Crepitations. Crepitations refer to the crackling sound produced by bones rubbing against each other. Rales (A) are abnormal lung sounds, Crackles (C) are fine crackling sounds heard in the lungs, and Vibration (D) is not a term related to bone sounds. Therefore, B is the correct choice as it specifically describes the bone-related sound mentioned in the question.

Correct Answer: D

Rationale: The correct answer is D: ejaculation occurs. When the penis is erect, semen is released from the male body through ejaculation. During sexual arousal, the muscles contract, pushing semen through the urethra and out of the body. Urination (choice A) is a separate process controlled by the bladder, not related to semen release. Evacuation (choice B) refers to bowel movements, not semen release. Excitement (choice C) is a psychological state and does not directly lead to semen leaving the body. Therefore, the correct answer is D as it accurately describes the physiological process of semen leaving the male body during ejaculation.

Correct Answer: C

Rationale: The correct answer is C: Iris stroma. The iris stroma contains melanocytes, which are responsible for producing the pigmented cells that determine eye color. These pigmented cells give the iris its color by absorbing and reflecting light. The ciliary epithelium (choice A) is not involved in determining eye color. The iris epithelium (choice B) is mainly responsible for controlling the size of the pupil, not for determining eye color. The corneal stroma (choice D) is a layer of the cornea that primarily provides structural support and transparency to the eye, but it does not play a role in determining eye color.

Correct Answer: D

Rationale: The correct answer is D: zygote. After fertilization, the sperm and egg unite to form a zygote, which is the initial cell of a new organism with a full set of chromosomes. A gamete (A) is a reproductive cell before fertilization, an embryo (B) is the early stage of development after the zygote, and a fetus (C) is the later stage of development in the womb. Therefore, the zygote is the correct term for the cell produced by fertilization.

Correct Answer: D

Rationale: The correct answer is D: Pulmonary vascular resistance decreases. After birth, the lungs expand and start functioning, leading to increased oxygen levels, which causes the pulmonary vascular resistance to decrease. This allows blood flow to the lungs and decreases pressure in the pulmonary artery. A: Systemic arterial pressure increasing does not directly affect the pressure in the pulmonary artery. B: Ductus arteriosus closing is part of the normal postnatal changes but does not directly cause the decrease in pulmonary artery pressure. C: Left ventricular pressure increasing is a consequence of the closure of the ductus arteriosus but does not explain the decrease in pulmonary artery pressure.