Iris (anatomy): Quiz

Question 1: The iris consists of two layers: the front ________ fibrovascular tissue known as a stroma and, beneath the stroma, pigmented epithelial cells.

Question 2: The muscle cells of the iris are ________ in mammals and amphibians, but are striated muscle in birds and reptiles.
Smooth muscleIntrafusal muscle fiberCardiac muscleSkeletal muscle

Question 3: Simple selective absorption and reflection by biological molecules (hemoglobin in the blood vessels, ________ in the vessel walls and stroma) is the most important element.
CollagenCollagen, type I, alpha 1Lysyl hydroxylaseKeratin

Question 4: Interference is recognised by characteristic dependence of color on the angle of view, as seen in eyespots of some ________ wings, although the chemical components remain the same.

Question 5: ________ and Anastasios the First were dubbed dikoro*s (dikoros, "with two pupils") for their patent heterochromias.
Macedonia (ancient kingdom)Alexander the GreatPtolemaic KingdomSeleucid Empire

Question 6: Occasionally its color is due to lack of pigmentation, as in the pinkish-white of oculo-cutaneous ________, or to obscuration of its pigment by blood vessels, as in the red of an abnormally vascularised iris.
PhotophobiaMyopiaAlbinismAlbinism in popular culture

Question 7: The iris is usually strongly pigmented, with ________ ranging from brown to green, blue, grey, and hazel (which is how it earned its name, iris being Greek for "rainbow"1).
PurplePrimary colorColorYellow

Question 8: ________ and Tyndall scattering, (which also happen in the sky) and diffraction also occur.
Optical fiberRayleigh scatteringLightDiffuse sky radiation

Question 9: A person's "eye color" is actually the color of one's iris, the ________ being transparent and the white sclera entirely outside the area of interest.
CorneaRetinaIris (anatomy)Bowman's membrane

Question 10: Abnormal clumping of melanosomes does occur in disease and may lead to irreversible changes in iris color (see ________, below).
Photoreceptor cellHeterochromiaTapetum lucidumIris (anatomy)

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