Question

1.Which one of the following is INCORRECT about kidney function?
Select one:
a. Angiotensin II can directly constrict blood vessels
b. Aldosterone has a major role in water reabsorption
c. Antidiuretic hormone acts in the collecting ducts to increase water reabsorption
d. A small quantity of filtrate is reabsorbed in the renal pelvis
e. There is major reabsorption of sodium ions in the proximal tubule

2.Which one of the following is correct?
Select one:
a. Angiotensin II is a potent vasodilator of the Bowman’s capsule
b. Vasopressin plays a major role in water reabsorption in the pituitary
c. Renin would be expected to be secreted from the kidneys in response to low extracellular fluid volume or low blood pressure
d. Renin is primarily released from the lungs
e. Aldosterone acts predominantly in the ureters to increase sodium reabsorption

3.Which one of the following occurs during phototransduction in the human eye?
Select one:
a. Hyperpolarisation of mainly cone photoreceptor cell membrane and glutamate release leads to excitation of bipolar cells
b. Hyperpolarisation of mainly rod photoreceptor cell membrane and inhibition of glutamate release leads to generation of action potentials in retinal ganglion cells
c. Hyperpolarisation of photoreceptor cell membrane and glutamate release leads to generation of action potentials in retinal ganglion cells
d. Hyperpolarisation of photoreceptor cell membrane and inhibition of glutamate release leads to generation of action potentials in retinal ganglion cells
e. Depolarisation of mainly rod photoreceptor cell membrane and inhibition of glutamate release leads to generation of action potentials in retinal ganglion cells

4.Which one of the following statements about the eye is CORRECT?
Select one:
a. The aqueous humor and vitreous humor nourish the lens
b. The conjunctiva and tears nourish the cornea and lens
c. The aqueous humor and tears nourish the cornea and lens
d. Both the conjunctiva and tears nourish the cornea and lens AND the aqueous humor nourishes the cornea and lens
e. The aqueous humor nourishes the cornea and lens

5.Which one of the following statements about near vision is INCORRECT?
Select one:
a. The pupils constrict to facilitate focusing of light entering the eye on the macula
b. The eyeballs converge depending upon the distance of the object seen
c. As the lens loses its elasticity with age, the near point of vision recedes
d. The lens flattens to focus light on the macula
e. The ciliary muscles contract to facilitate accommodation of the lens

6.Which one of the following statements regarding human vision is INCORRECT?
Select one:
a. Peripheral vision provides perception about form, depth and movement of objects
b. Central vision provides visual perception in bright light
c. Peripheral vision has lower resolution than central vision
d. Temporal visual field is monocular whereas nasal visual field is binocular
e. Peripheral vision is largely used for recognition of objects in dim light

Answer 1

Ans 1: Renal pelvis, enlarged upper end of the ureter, the tube through which urine flows from the kidney to the urinary bladder. The pelvis, which is shaped somewhat like a funnel that is curved to one side, is almost completely enclosed in the deep indentation on the concave side of the kidney, the sinus.

Hence option D is incorrect about kidney function.

2:  Vasopressin regulates the tonicity of body fluids. It is released from the posterior pituitary in response to hypertonicity and causes the kidneys to reabsorb solute-free water and return it to the circulation from the tubules of the nephron, thus returning the tonicity of the body fluids toward normal.

Hence option B is correct.

3: Bipolar cells do not generate action potentials. However they do release transmitter onto ganglion cells, which are the first site of action potential generation in the visual system. Unlike most sensory receptor cells, photoreceptors actually become hyperpolarized when stimulated; and conversely are depolarized when not stimulated. This means that glutamate is released continuously when the cell is unstimulated, and stimulus causes release to stop. When light hits a photoreceptive pigment within the photoreceptor cell, the pigment changes shape. The pigment, called iodopsin or rhodopsin, consists of large proteins called opsin (situated in the plasma membrane), attached to a covalently bound prosthetic group: an organic molecule called retinal (a derivative of vitamin A). The retinal exists in the 11-cis-retinal form when in the dark, and stimulation by light causes its structure to change to all-trans-retinal. This structural change causes opsin (a G protein-coupled receptor) to activate its G protein transducin, which leads to the activation of cGMP phosphodiesterase, which breaks cGMP down into 5'-GMP. Reduction in cGMP allows the ion channels to close, preventing the influx of positive ions, hyperpolarizing the cell, and stopping the release of neurotransmitters.

So in phototransduction of human eye hyperpolarisation of mainly rod photoreceptor cell membrane and inhibition of glutamate release leads to generation of action potentials in retinal ganglion cells
Hence option B is correct.

4: The aqueous humour is a thin, transparent fluid similar to plasma. It's made up of 99.9% water – the other 0.1% consists of sugars, vitamins, proteins and other nutrients. This fluid nourishes the cornea and the lens, and gives the eye its shape.

Hence option E is correct.

5: The pupils constrict to direct illumination (direct response) and to illumination of the opposite eye (consensual response). The pupil dilates in the dark. Both pupils constrict when the eye is focused on a near object. The cornea is the clear, dome-shaped “front window” of the eye. The cornea is a lens that bends (refracts) light rays as they pass through. This accounts for about 70 percent of the eye's total focusing power.

Hence option A is incorrect.

6: The normal (monocular) human visual field extends to approximately 60 degrees nasally (toward the nose, or inward) from the vertical meridian in each eye, to 107 degrees temporally (away from the nose, or outwards) from the vertical meridian, and approximately 70 degrees above and 80 below the horizontal meridian.

The binocular visual field is the superimposition of the two monocular fields. In the binocular field, the area left of the vertical meridian is referred to as the left visual field (which is temporally for the left, and nasally for the right eye); a corresponding definition holds for the right visual field.

Hence option D is incorrect.