ATI TEAS 7
ATI TEAS 7 Version 1 Science Questions
Extract:
Question 1 of 5
What is the approximate threshold value for mammalian neurons?
Correct Answer: B
Rationale: The approximate threshold value for mammalian neurons is around -55 mV. At this membrane potential, the neuron becomes more excitable and is more likely to generate an action potential. If the membrane potential reaches this level or depolarizes beyond it, it triggers the opening of voltage-gated ion channels, leading to the initiation of an action potential. Values below this threshold are considered subthreshold and do not usually result in action potential generation. Understanding the threshold potential is crucial in assessing the excitability and firing properties of neurons, as it represents the critical point at which the neuron transitions from a resting state to an active state, enabling the transmission of electrical signals.
Question 2 of 5
Which of the following are the major parts of the nervous system?
Correct Answer: C
Rationale: The nervous system comprises two major parts: the peripheral nervous system (PNS) and the central nervous system (CNS). The PNS includes nerves outside the brain and spinal cord, while the CNS consists of the brain and spinal cord. Choice C (PNS and CNS) correctly identifies the primary divisions of the nervous system, encompassing both the peripheral and central components. Therefore, the correct answer is C.
Question 3 of 5
Which of the following substances is responsible for donating H+ ions to act as a buffer when blood pH rises?
Correct Answer: D
Rationale: Carbonic acid is a pivotal buffer in blood that plays a key role in maintaining pH balance. When blood pH rises, indicating increased alkalinity, carbonic acid releases hydrogen ions (H+) to counterbalance the excess base, thereby preventing significant changes in pH levels. This mechanism highlights the essential function of carbonic acid in regulating the acid-base equilibrium in the blood.
Question 4 of 5
Which substance protects the body from ultraviolet rays?
Correct Answer: D
Rationale: Melanin is the pigment responsible for skin color and serves as a natural defense against ultraviolet (UV) rays. When the skin is exposed to UV rays, melanin production increases to absorb and dissipate the radiation, acting as a protective mechanism. This helps prevent DNA damage, reducing the risk of skin cancer and other UV-induced skin issues. Therefore, melanin is the substance that effectively shields the body from the harmful effects of UV radiation.
Question 5 of 5
Which of the following substances is excreted by the sweat glands in response to the breakdown of proteins and the formation of ammonia?
Correct Answer: C
Rationale: The correct answer is Urea. Sweat glands excrete urea in response to the breakdown of proteins and the formation of ammonia. Urea is a waste product formed in the liver by the breakdown of amino acids. It is then excreted by the kidneys in urine and by sweat glands through perspiration. Urea plays a vital role in the excretory process by helping eliminate nitrogenous wastes from the body and maintaining proper physiological balance.