sensory mechanisms

The _____ is the region of the eye where photoreceptors are most highly concentrated. A lens B fovea C optic nerve D pupil E sclera

B

What name is given to the opening that allows light into the interior of the eye? A sclera B pupil C ligament D optic nerve E retina

B

Which of the following statements about photoreception is true? A Rod cells are responsible for color vision. B The retinal molecule changes shape when it absorbs light. C Cone cells are sensitive to dim light. D Rhodopsin is found in cone cells.

B

Which part of the eye bends light to focus it on the retina? A Sclera. B Lens. C Fovea. D Optic nerve.

B

Which part of the eye contains the densest concentration of cone cells? A Lens. B Fovea. C Opsin. D Cornea.

B

Which part of the eye is the opening through which light initially passes? A Sclera. B Fovea. C Pupil. D Retina.

C

The _____ changes shape to focus light on the retina. A vitreous humor B blind spot C cornea D lens E optic nerve

D

What name is given to the tough layer that forms the "white" of the eye? A blind spot B choroid C fovea D sclera E aqueous humor

D

Which of the following statements does not describe a vertebrate eye? A It acquires images by focusing light on receptor cells. B It contains photoreceptors that are either rod- or cone-shaped. C It contains cells that are sensitive to either dim light or color. D It contains many light-sensing columns called ommatidia.

D

True or false? Cone cells are color photoreceptors that use different retinal molecules to absorb different wavelengths of light. True False

False

True or false? The "blind spot" in vertebrate eyes is a region of the retina that contains no photoreceptors. True False

True

photoreceptor

a molecule, cell, or organ that is specialized for the detection of light

cones

a photoreceptor cell in the retina with a cone-shaped outer portion; partially sensitive to bright light of a certain color (blue, red, or green)

rods

a photoreceptor cell in the retina with a rod shaped outer portion; partially sensitive to dim light but its not used to distinguish color

fovea

a small region of the retina in which the photoreceptors are very tightly packed, producing the most acute vision

Retina

a think layer of light-sensitive cells (rods or cones) and neurons at the back of a camera-like eye, such as the eyes of vertebrates and cephalopods

lens

highly transparent lens-shaped or nearly spherical body in the eye that focuses light rays onto the retina

cornea

the transparent sheet of connective tissue at the very front of the eye in vertebrates and some other animals. the cornea protects the eye and focuses light onto the retina