Lakshya Education MCQs

Question: The characteristic that is shared by urea, uric acid, and ammonia is/are,



(I) They are nitrogenous wastes                               

(II) They all need a very large amount of water for excretion

(III) They are equally toxic                           

(IV) They are excretory products
Options:
A.I and III
B.I and IV
C.I, III and IV          
D.I only
Answer: Option B
: B

Urea, uric acid and ammonia are all nitrogenous wastes and excretory products. Ammonia is highly toxic and highly soluble in water, therefore, requires a large amount of water for excretion. Urea is less toxic and less soluble in water than ammonia. Uric acid crystals are non-toxic and almost insoluble in water. So their level of toxicity and the amount of water needed for their elimination differs for each of them.

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Question 1. The micturition reflex ______.
  1.    Can be stimulated or inhibited by higher centers in the brain.
  2.    Is stimulated by increased pressure in the bladder.
  3.    Can be stimulated by irritation of the bladder or urethra.
  4.    All of these
Answer: Option D
: D

Micturition is the process of urination, or flow of urine from the bladder through the urethra. When enough urine is accumulated in the bladder, it causes a stretch in the bladder walls. A threshold amount of this stretch causes a signal to be sent to the CNS. The CNS correlates the stretch information to volume of urine present and initiates what is called the micturition reflex. Conversely, an increased pressure in the bladder also stimulates it. It can also be stimulated by irritation of the bladder or urethra.
Question 2. Tubular secretion helps maintain a proper acid-base balance in the body, by removing which of the following, from blood?
  1.    H+ ions and urea
  2.    Uric acid
  3.    H+ ions and ammonia
  4.    Ammonia and creatinine
Answer: Option C
: C

Tubular secretion helps maintain a proper acid-base balance by removing H+ ions and ammonia from the blood.
Question 3. The outline of principal events of urination is given in random manner.

(1) Stretch receptors on the wall of urinary bladder send signals to the CNS.   

(2) The bladder fills with urine.             

(3) Micturition               

(4) CNS passes on motor messages to initiate the contraction  of smooth muscles of bladder and simultaneous  

relaxation of sphincter. The correct sequence of the event is:
  1.    1, 2, 3, 4
  2.    4, 3, 2, 1
  3.    2, 1, 4, 3
  4.    3, 2, 1, 4
Answer: Option C
: C

The bladder fills with urine. Stretch receptors on the wall of urinary bladder send signals to the CNS. CNS passes on motor messages to initiate the contraction of smooth muscles of bladder and simultaneous relaxation of sphincter. Micturition
Question 4. A person suffering from kidney stones is advised to avoid excess intake of spinach and beet roots in his diet. What could be the possible reason?
  1.    Spinach and beet root have more calcium oxalate.
  2.    Spinach and beet root have more water content.
  3.    Spinach and beet root's unwanted digested products cannot be filtered.
  4.    Spinach and beetroot pigments have adverse affects on health.
Answer: Option A
: A

Calcium oxalate is an excretory product of plants stored in vacuoles of plant cells and they are the main components of kidney stones. This compound is abundant in spinach and beet roots. So they are notincluded in diet to avoid further complications in a person suffering fromkidney stones.
Question 5. The elastic and flexible organ in the human excretory system is __________.
  1.    Kidney
  2.    Urinary bladder
  3.    Ureter
  4.    Nephron
Answer: Option B
: B

The elastic and flexible organ in the human excretory system is urinary bladder. Itstores urine temporarily before it is expelled out through the process of urination. The urinary bladder is a pear-shaped muscular sac which iscapable of expanding as urine gets collected in it.

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