In the resting state of neurons, diffusion due to concentration gradients, if allowed, would drive:
1. K+ into the cell
2. K+ and Na+ out of the cell
3. Na+ out of the cell
4. Na+ into the cell
(4) The concentration of sodium in ECF is about 10 times higher.
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When we move from dark to light, we fail to see for some time but soon visibility becomes normal. It is:
1. Accommodation
2. Photoperiodism
3. Adaptation
4. Mutation
(3) The rod cells of eye contain a purplish pigment called visual purple, or rhodopsin. They function in dim light and at night. Bright light splits rhodopsin into a lipoprotein scotopsin and a carotenoid pigment retinene. The splitting of rhodopsin depolarizes the rod cell. In the dark, rhodopsin is resynthesized from scotopsin and retinene. This process is called “dark adaptation.” It makes the rods functional. It takes some time for rhodopsin to be reformed.
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The myelin sheath in the CNS is synthesized by:
(1) Oligodendrocytes
(2) Astrocytess
(3) Schwann cells
(4) Microglia
(1) Schwann cells are found in the PNS.
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Answer 4
Read page 321, Xl NCERT
Brain stem does have structure from the hind brain but does not include cerebellum
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Which of the following is a major coordinating center for sensory and motor signaling for the cerebrum?
1. Hypothalamus
2. Thalamus
3. Corpora quadrigemina
4. Amygdala
(2) Read page 321, XI NCERT
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The sensory neuron enters the spinal cord through:
1. The dorsal root of the spinal nerve
2. The ventral root of the spinal nerve
3. Either dorsal or ventral root depending on the point of origin
4. Both dorsal and ventral roots of the spinal nerves
Anser: 1
Read page 322, Xl NCERT
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From inside to outside the correct order of the following cells in the retina would be:
1. Ganglion cells - Photoreceptor cells - Bipolar cells
2. Ganglion cells - Bipolar cells - Photoreceptor cells
3. Bipolar cells - Photoreceptor cells - Ganglion cells
4. Photoreceptor cells - Ganglion cells - Bipolar cells
(2) Read page 323, XI NCERT
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In the human eye, the visual acuity is highest at:
(1) Macula lutea
(2) Optic disc
(3) Fovea centralis
(4) Optic chiasma
(3) The area of greatest visual acuity is fovea centralis which is situated inside the macula lutea. It has the maximum number of rods responsible for vision.
Read page 324, XI NCERT
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Reissner's membrane separates
1. Scala vestibuli and Scala media
2. Tympanic cavity and Pharynx
3. Fenestra rotundus and Fenestra ovalis
4. Scala media and Scala tympani
(4) Read page 326, Figure 21.8, XI NCERT
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The resting membrane potential is established primarily due to:
1. Sodium-potassium pump
2. Efflux of potassium
3. Influx of sodium
4. Influx of chloride
Audio Explanation:
(2) The resting membrane potential is near the Nernst potential of potassium. Sodium potassium pump is a minor contributor to the value of the resting membrane potential.
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