what is the principle behind optical fibers used in communication

ATI TEAS 7

TEAS 7 science practice

1. What is the principle behind optical fibers used in communication?

A. Reflection of light within the fiber
B. Refraction of light due to different densities within the fiber
C. Total internal reflection guiding light through the fiber core
D. Diffraction of light around bends in the fiber

Correct answer: C

Rationale: Optical fibers used in communication rely on the principle of total internal reflection guiding light through the fiber core. Total internal reflection occurs when light traveling through the core of the fiber is reflected back into the core due to the higher refractive index of the core compared to the cladding. This reflection ensures that the light remains confined within the core and propagates along the fiber without significant loss, allowing for efficient transmission of signals over long distances in optical communication systems. Choice A is incorrect because optical fibers do not primarily rely on simple reflection; instead, they utilize total internal reflection to guide light. Choice B is incorrect as the primary principle is not the refraction of light due to different densities within the fiber, but rather total internal reflection. Choice D is incorrect as diffraction is not the main principle behind optical fibers, which mainly rely on total internal reflection to guide light through the fiber core.

2. Which of the following is not a biological macromolecule?

A. Glycoproteins
B. DNA
C. Phospholipid
D. Glucose

Correct answer: D

Rationale: Glucose is a monosaccharide, which is a simple sugar and not a macromolecule. Glycoproteins, DNA, and phospholipids are all examples of biological macromolecules. Glycoproteins are proteins covalently bonded to carbohydrates, DNA is a nucleic acid, and phospholipids are lipids that contain a phosphate group.

3. Which of the following are examples of positive correlation?

A. As rainfall increases, plant stem length decreases.
B. As rainfall increases, roots show longer length.
C. When plotting a comparison of rainfall to plant length, the line trends to the lower right.
D. When plotting a comparison of rainfall to plant length, the line trends to the upper right.

Correct answer: D

Rationale: The correct answer is D. Positive correlation indicates that as one variable increases, the other variable also increases. In this case, when plotting a comparison of rainfall to plant length, if the line trends to the upper right, it shows a positive correlation where as rainfall increases, plant length also increases. Choices A, B, and C show either no correlation or negative correlation, as they describe scenarios where the variables move in different or opposite directions.

4. Which type of muscle is characterized by involuntary contractions, is striated, and is primarily found in the heart?

A. Skeletal muscle
B. Smooth muscle
C. Cardiac muscle
D. Elastic muscle

Correct answer: C

Rationale: The correct answer is C, Cardiac muscle. Cardiac muscle fits the description provided in the question as it exhibits involuntary contractions, striations, and is predominantly located in the heart. Skeletal muscle, while also striated, is voluntary and not involuntary like cardiac muscle. Smooth muscle lacks striations and is typically found in the walls of internal organs. Elastic muscle is not a recognized type of muscle tissue in human anatomy, making it an incorrect choice.

5. Which hormone is responsible for regulating blood sugar levels and is produced by the pancreas?

A. Insulin
B. Glucagon
C. Testosterone
D. Estrogen

Correct answer: A

Rationale: Insulin is the correct answer. It is the hormone produced by the pancreas that regulates blood sugar levels by facilitating the uptake of glucose from the blood into cells for energy production or storage. Glucagon, also produced by the pancreas, has the opposite effect of increasing blood sugar levels by promoting the release of stored glucose from the liver. Testosterone and estrogen are sex hormones produced by the testes and ovaries, respectively, and are not directly involved in regulating blood sugar levels.