which hormone regulates the sleep wake cycle

ATI TEAS 7

Practice Science TEAS Test

1. Which hormone regulates the sleep-wake cycle?

A. Cortisol
B. Melatonin
C. Thyroxine
D. Insulin

Correct answer: B

Rationale: The correct answer is B: Melatonin. Melatonin, produced by the pineal gland, is the hormone that regulates the sleep-wake cycle. It helps signal to the body when it's time to sleep and wake up, playing a crucial role in maintaining a healthy sleep pattern. Choice A, Cortisol, is known as the stress hormone and plays a role in the body's response to stress, not specifically in regulating the sleep-wake cycle. Choice C, Thyroxine, is a hormone produced by the thyroid gland that regulates metabolism, not the sleep-wake cycle. Choice D, Insulin, is a hormone produced by the pancreas that regulates blood sugar levels, not the sleep-wake cycle.

2. What two factors enable some intercellular chemical signals to diffuse across cell membranes and bind to intracellular receptors?

A. They are small and soluble.
B. They are large and soluble.
C. They are small and insoluble.
D. They are large and insoluble.

Correct answer: A

Rationale: The correct answer is A: 'They are small and soluble.' Small and soluble molecules can easily pass through cell membranes and bind to intracellular receptors. Being small allows them to pass through the membrane, while being soluble enables them to dissolve in the aqueous environment inside the cell. Choice B is incorrect because large molecules typically cannot pass through the cell membrane easily. Choices C and D are incorrect because insoluble molecules would not dissolve in the aqueous environment inside the cell, hindering their ability to bind to intracellular receptors.

3. What property of a wave determines its speed in a given medium?

A. Amplitude
B. Wavelength
C. Frequency
D. Medium's properties

Correct answer: D

Rationale: The speed of a wave in a given medium is determined by the properties of that medium, such as its density and elasticity. While amplitude, wavelength, and frequency are important characteristics of a wave, they do not directly impact its speed in a specific medium. Amplitude refers to the maximum displacement of particles in a wave, wavelength is the distance between two successive points in a wave that are in phase, and frequency is the number of complete oscillations a wave makes in a given time. However, these properties do not dictate the speed of a wave in a particular medium. Therefore, the correct answer is the medium's properties.

4. Which of the following statements regarding the working of the heart is not correct?

A. The atria contract, and the valves open to allow blood into the ventricles.
B. The heartbeat begins when the heart muscles relax, and blood flows into the atria.
C. The valves close to stop blood from flowing backward.
D. The ventricles contract, forcing blood to leave the heart.

Correct answer: B

Rationale: The correct answer is B because the heartbeat actually begins when the heart muscles relax, allowing the chambers to fill with blood. The contraction phase follows, which propels blood out of the heart. The other statements are accurate in describing the normal sequence of events in the heart's functioning: the atria contract to push blood into the ventricles, the valves close to prevent backflow of blood, and the ventricles contract to pump blood out of the heart.

5. What is a group of organisms of the same species living in a particular area called?

A. Community
B. Population
C. Ecosystem
D. Habitat

Correct answer: B

Rationale: A) Community refers to all the populations of different species living and interacting in a particular area. Since the question specifies organisms of the same species, community is not the correct answer. B) Population is a group of organisms of the same species living in a particular area. This term specifically refers to individuals of the same species and their interactions within a defined area. C) Ecosystem includes all the living organisms (biotic factors) and non-living components (abiotic factors) in a particular area and their interactions. While populations are part of an ecosystem, the term 'ecosystem' is broader and includes multiple populations. D) Habitat refers to the specific environment where an organism lives, including the physical and biological factors. It is the place where a population or individual organism resides, but it does not specifically refer to a group of organisms of the same species.