PNB 2250 Exam 4 Questions with Complete Solutions 100% Verified| Latest
Update Graded A+
sensitivity to light 1) requires transduction of light energy into chemical signal
2) chemical signal can effect cellular processes ad behavior
e.g. phototaxis in halobacteria
non-compound eyes 1) pit
2) spherical lensed
3) multiple lenses
- focused done by changing lens shape, or moving lens towards or away from photosensitive
cells
4) refractive cornea
5) reflector
6) 2 eyes
- binocular vision, depth perception
compound eyes 1) many facets, giving single or multiple images per eye
2) each facet has its own lens
photoreceptors 1) protein plus pigment
2) rhodopsin (opsin+retinal)
3) pigment absorbs specific light wavelength, changes protein structure - signal
4) change in electrical properties of cell membrane
light energy 1) lower wavelength = more energy
,2) higher wavelength = less energy
euglena 1) eye spot
2) detect light level
3) no form vision
planaria 1) eye cup
2) light direction but not form
3) pigment cup shields photoreceptors
pinhole eye 1) increase aperture for more light - blurs image
2) decrease aperture to reduce blurring - limits sensitivity and diffraction limited
3) pinhole works for all wavelengths and does not require focusing
scallop mirror eye 1) large number of eyes
- concave, parabolic mirror of guanine crystals to focus light onto double layered retina
- poor acuity, great contrast definition, great detection of motion
functional constraints of mirror eye 1) low contrast image since light passes through retina
to reach mirror then gets reflected back to retina
2) mirror can gather lots of light
functional constraints of lensed eyes (human) 1) increased lens diameter for more light but
bigger lenses susceptible to aberrations (spherical and chromatic)
2) focusing mechanism is required
3) focus wavelength specific (chromatic aberration)
, horizontal pupil collect more light from left and right sides on same plane (better detect
presence of predators)
vertical pupil better for estimation of distance to prey by small predators
chromatic aberrations 1) refraction - light moving through different material is bent
2) wavelength specific
functional constraints of compound eyes 1) need more ommatidia to increase resolution -
diffraction limit
2) lens (facet) diameter must increase to get more light (or allow superposition of light paths) -
tradeoff with spatial resolution
terrestrial eye adaptations 1) lens important for fine adjustment
2) air-cornea interface provides most of refraction for forming image
3) focusing done by both cornea and lens
aquatic eye adaptations 1) water cornea interface causes minimal refraction so no need for
domed cornea
2) lens is spherical to provide maximum focusing ability
3) no focusing by cornea, all focusing done by lens
polarized light - bats 1) polarized light used as a directional cue
2) used in conjunction with echolocation and magnetic field to determine location and path
3) see at 90 degree angle from position of the sun at sunrise/sunset
Update Graded A+
sensitivity to light 1) requires transduction of light energy into chemical signal
2) chemical signal can effect cellular processes ad behavior
e.g. phototaxis in halobacteria
non-compound eyes 1) pit
2) spherical lensed
3) multiple lenses
- focused done by changing lens shape, or moving lens towards or away from photosensitive
cells
4) refractive cornea
5) reflector
6) 2 eyes
- binocular vision, depth perception
compound eyes 1) many facets, giving single or multiple images per eye
2) each facet has its own lens
photoreceptors 1) protein plus pigment
2) rhodopsin (opsin+retinal)
3) pigment absorbs specific light wavelength, changes protein structure - signal
4) change in electrical properties of cell membrane
light energy 1) lower wavelength = more energy
,2) higher wavelength = less energy
euglena 1) eye spot
2) detect light level
3) no form vision
planaria 1) eye cup
2) light direction but not form
3) pigment cup shields photoreceptors
pinhole eye 1) increase aperture for more light - blurs image
2) decrease aperture to reduce blurring - limits sensitivity and diffraction limited
3) pinhole works for all wavelengths and does not require focusing
scallop mirror eye 1) large number of eyes
- concave, parabolic mirror of guanine crystals to focus light onto double layered retina
- poor acuity, great contrast definition, great detection of motion
functional constraints of mirror eye 1) low contrast image since light passes through retina
to reach mirror then gets reflected back to retina
2) mirror can gather lots of light
functional constraints of lensed eyes (human) 1) increased lens diameter for more light but
bigger lenses susceptible to aberrations (spherical and chromatic)
2) focusing mechanism is required
3) focus wavelength specific (chromatic aberration)
, horizontal pupil collect more light from left and right sides on same plane (better detect
presence of predators)
vertical pupil better for estimation of distance to prey by small predators
chromatic aberrations 1) refraction - light moving through different material is bent
2) wavelength specific
functional constraints of compound eyes 1) need more ommatidia to increase resolution -
diffraction limit
2) lens (facet) diameter must increase to get more light (or allow superposition of light paths) -
tradeoff with spatial resolution
terrestrial eye adaptations 1) lens important for fine adjustment
2) air-cornea interface provides most of refraction for forming image
3) focusing done by both cornea and lens
aquatic eye adaptations 1) water cornea interface causes minimal refraction so no need for
domed cornea
2) lens is spherical to provide maximum focusing ability
3) no focusing by cornea, all focusing done by lens
polarized light - bats 1) polarized light used as a directional cue
2) used in conjunction with echolocation and magnetic field to determine location and path
3) see at 90 degree angle from position of the sun at sunrise/sunset
