7 What structure directly alters the shape of the lens for far and near vision?
ID: 3518666 • Letter: 7
Question
7 What structure directly alters the shape of the lens for far and near vision? A) aqueous humor B) cliary muscle D) optic nerve E) orbicularis oculi 18 a. One of the folowing statements about the retina is inaccurate. Which one is ? A) There are three layers of retinal neurons B) Each retina has about 6 million rods and 120 million cones. C) C) Rods help the human see black-and-white vision in dim light, and allow shapes and be seen D) Cones provide color vision in bright light E) Cones are most densely concentrated in the central fovea. 19. Normally, aqueous humor is completely replaced about every A) one and one-half hours B) s?x to seven hours. C) ten to twelve hours D) two days E) two weeks. 20. What percent of our focusing occurs at the cornea? A) 15 percent B) 25 percent C) 50 percent D) 75 percent E) 90 percent 21. For vision to occur, which of the following is in the correct sequence? A) bipolar-…> photoreceptors-... > ganglion cells-.. > thalamus--> optic nerve B) ganglion cells>thalamus>photoreceptorsoccipital lobe thalamus C) photoreceptorsganglion cells>optic nerve>bipolar cells..> occipital lobe D) photoreceptors E) ganglion cels bipolar cels.> ganglion cells optic nervethalamus photoreceptorsbipolar cells> thalamus>occipital lobe 22 In reference to photopigments Al) allvisual photopigments contain two parts: a gycoprotein and a derivative of vitamin A B) night blindness is an inability to see well at low lights C) retinal is the light-absorbing protein of all photopigments D) rhodopsin absorbs blue to green light most effectively E) all of the above statements are true.Explanation / Answer
17] Option [ b] ciliary muscles
The ciliary muscles hold the lense in place. The lense can become narrow or broad as per the object distance, to alter the focal length of the eye lense. When the ciliary muscles contract, the lense becomes long and thin and when the ciliary muscles expand, the lense becomes short and thick , thus altering the focal length of the lense.
18] Option [b] Each retina has 6 million rods and 120 million cones
It is the other way around i.e. each retina has about 6 to 7 million cones and 75 to 150 million rods.
20] Option [d] 75%
The cornea is a dome shaped lense that starts the process of focussing light
21] Option [ d] photoreceptors-- bipolar cells-- ganglion cells -- optic nerve -- thalamus
The photoreceptors are the cells which are activated and induce the bipolar cells to activate the ganglion .
22] Option [a] All visual photopigments contain two parts- a glycoprotein and a derivative of vitamin A
Photopigments change shape when they detect light and this triggers a series of reactions ,sending signals to the visual cortex which helps to create a picture of the outside.
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