NEET 2017 Biology question

Out of 'X' pairs of ribs in humans only 'Y' pairs are true ribs. Select the option that correctly represents values of X and Y and provides their explanation :

(1)X = 12, Y = 7 : True ribs are attached dorsally to vertebral column and ventrally to the sternumCorrect
(2)X = 12, Y = 5 : True ribs are attached dorsally to vertebral column and sternum on the two ends
(3)X = 24, Y = 7 : True ribs are dorsally attached to vertebral column but are free on ventral side
(4)X = 24, Y = 12 : True ribs are dorsally attached to vertebral column but are free on ventral side

Answer: (1)

Solution

Humans have 12 pairs of ribs. The first seven pairs are true ribs: they are attached dorsally to the thoracic vertebrae and ventrally to the sternum through hyaline cartilage. The 8th, 9th and 10th pairs are vertebrochondral (false)

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Question ID VK-092158