The structure that controls the entry of light into the eye by adjusting pupil size is the: MCQ with Answer and Explanation

Explanation:
Gymnosperms are seed-producing plants where the ovules are not enclosed in an ovary; hence, the seeds are naked. They are predominantly perennial, evergreen, woody trees like pines and cedars. Double fertilization and the formation of triploid endosperm are unique characteristics of angiosperms, not gymnosperms. Thus, statements 1 and 2 are correct.

Explanation:
Active vitamin D (calcitriol) induces synthesis of calcium-binding proteins in the intestinal mucosa, enhancing calcium absorption. Calcium is vital for bones, teeth, blood clotting, and nerve-muscle function.

Explanation:
The midbrain (mesencephalon) is the uppermost part of the brainstem. Its dorsal surface features four rounded elevations called the corpora quadrigemina (meaning 'four bodies'). These consist of two upper, larger swellings called the superior colliculi, which are reflex centers for visual movements (like tracking moving objects), and two lower, smaller swellings called the inferior colliculi, which are part of the auditory pathway and relay sound information to the thalamus.