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Biology 102 > Ch 50 B > Flashcards

Ch 50 B Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Who has the most simple light-detecting organs? What is it?

A

Planarians
Pair of ocelli called eyespots

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2
Q

What is negative phototaxis?

A

when animals move away from light

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3
Q

What are compound eyes composed of? What are its benefits?

A

Ommatidia
Effective at detecting movement
Have excellent color vision

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4
Q

What changes the diameter of the pupil?

A

iris

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5
Q

What controls how much light enters?

A

Pupil

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6
Q

How many lens do vertebrates have?

A

single lens

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7
Q

What is the choroid?
What is its function?

A

Thin, pigmented layer
Provides nutrients and blood

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8
Q

Where is the choroid located?

A

outside the retina

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9
Q

What is the Retina?

A

a layer of photoreceptors cells and glial cells within the eye

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10
Q

What is the lens?

A

a transparent disk of protein

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11
Q

What is in front of the lens and is clear and watery

A

aqueous humor

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12
Q

What is behind the lens and is jellylike?

A

Vitreous humor

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13
Q

When light enters and strikes the retina it reaches?

A

Rods and cones
(Photoreceptors)

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14
Q

Where does the neurons of the retina then relay visual information to?

A

Optic nerve and brain

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15
Q

What lacks photoreceptors and doesn’t detect light

A

Optic disk

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16
Q

Human two main types of photoreceptor cells

A

Rods: sensitive light but no color
Cones: provide color vision

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17
Q

light absorbing pigment bound to a membrane protein opsin

A

Retinal

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18
Q

Rhodopsin

A

visual pigment
contains retinal and opsin

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19
Q

What does absorption of light cause?

A

shape change in retinal

20
Q

What does the transduction of visual information to the nervous system begin with?

A

conversion of cis-retinal to trans-retinal (from light)

21
Q

What is the process of converting trans-retinal to cis-retinal called?

A

bleaching

22
Q

What activates rhodospin?

A

Trans-retinal

23
Q

What does rhodopsin activate?

A

G protein (transducin) which activates phosphodiesterase which leads to hydrolysis of cyclic GMP

24
Q

What is the function of Cyclic GMP in the eye?

A

In the dark binds sodium ion channels and keeps them open

25
Q

What happens with cyclic GMP breaks down? (3)

A

1) Na channels close
2) Causes hyper polarizes the cell
3) Signal Transduction pathway usually shuts off again as enzymes convert retinal back to the cis form

26
Q

Processing of visual information begins

A

Retina

27
Q

Rods and cones continually release the neurotransmitter? into what?

A

Glutamate into synapses with neurons called bipolar cells

28
Q

What happens when light strikes the rods and cones? (very general)

A

They hyperpolarize shutting off their release of glutamate

29
Q

What does the decrease in glutamate cause?

A

Change membrane potential of bipolar cells

30
Q

What is lateral inhibition

A

When a rod or cone stimulates a horizontal cell and the horizontal cell then inhibits more distant photoreceptors and bipolar cells

31
Q

What does lateral inhibition help?

A

Helps enhances contrast

32
Q

What is a receptive field?

A

the cones and rods defined by a single ganglion

33
Q

What causes sharper images?

A

A smaller receptive field

34
Q

Where do the optic nerves meet at?

A

At the optic chiasm near the center of the base of the cerebral cortex

35
Q

Where do sensations of visual fields from each side of the brain go to?

A

The opposite side of the brain

36
Q

What do mammals that are nocturnal have high proportion of

A

They have high proportions of rods and don’t see vivd colors during the day

37
Q

What are the three types of cones

A

Red
Green
Blue

38
Q

What are RGB pigments are called

A

photopsins

39
Q

How are photopsins formed?

A

formed when retinal binds to three distinct opsin proteins

40
Q

Where do abnormal color vision results from?

A

Mutations in the genes for one or more photospin proteins

41
Q

what is focusing?

A

changing shape of the lens

42
Q

What is the fovea?

A

Center of the visual field and contains no rods but a high density of cones

43
Q

What are the 2 types of accommodation?

A

1) near vision
2) distance vision

44
Q

explain near vision accommodation (3)

A

1) ciliary muscles contract
2) suspensory ligaments relax
3) lens becomes rounder

45
Q

explain distance vision accommodation (3)

A

1) ciliary muscle relax
2) suspensory ligaments
3) lens becomes flatter

Biology 102 (38 decks)

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