For a Pair of Stars to Be Classified as a Visual

question 113

Multiple Choice

For a pair of stars to be classified as a visual binary,which condition must be TRUE?

• A) The stars must be orbiting around each other, and both stars must be visible through telescopes from Earth.
• B) The stars must be orbiting around each other, and absorption or emission lines from both stars must be visible in the spectrum.
• C) The stars must be orbiting around each other, and one must periodically cross in front of the other (i.e., it must eclipse the other) as seen from Earth.
• D) The stars must lie in almost the same direction from Earth but must not be orbiting around each other.

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Definitions:

Waxy Cell Wall

A waxy cell wall is characteristic of plant cells and some microorganisms, providing a protective, waterproof layer.

Mycoplasma

A genus of bacteria that lack a cell wall, making them resistant to many common antibiotics and causing various diseases in humans and animals.

Peptidoglycan

A polymer that makes up the cell walls of most bacteria, consisting of sugars and amino acids, and provides structural strength to the bacterial cell wall.

Cell Walls

Rigid or semi-rigid structures surrounding the cell membrane of plants, fungi, and some bacteria, providing shape, support, and protection.