MCQ
The only human system that is derived from all the three germ layers is:
- ADigestive system
- BExcretory system
- CRespiratory system
- DNervous system
Explanation:
The digestive system is derived from three germinal layers: mesoderm, endoderm, ectoderm.
Mesoderm gives rise to the connective tissue, including the wall of the gut tube and the smooth muscle.
Endoderm is the source of the epithelial lining of the gastrointestinal tract, liver, gallbladder, pancreas.
The ectoderm is the source of the epidermis, the lens of eyes, nails, hair, brain, spinal cord, neurons of the GI tract.
The excretory system is derived from the mesoderm.
The respiratory system is derived from the endoderm.
The nervous system is derived from the ectoderm.
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$(I)$ Vertebrate hearts.
$(II)$ Vertebrate brains
$(III)$ Thorn and tendrils of Bougainvillea andcucurbita respectively
$(IV)$ Vertebrate limbs.
The correct combination is
Reason : Progesterone level decreases.