Assertion (A): Water is essential for photosynthesis. Reason (R): Water is split to release oxygen, and its hydrogen is used to reduce CO₂. MCQ with Answer and Explanation

Explanation:
The 5' cap is a specially altered nucleotide (7-methylguanosine) attached via a 5'-5' triphosphate linkage to the 5' end of a eukaryotic mRNA molecule shortly after transcription begins. Its primary functions are to protect the nascent mRNA from degradation by 5' exonucleases, to facilitate the export of the mature mRNA from the nucleus to the cytoplasm, and, crucially, to be recognized by the eukaryotic initiation factor 4E (eIF4E), which is essential for recruiting the ribosome to the mRNA to initiate translation.

Explanation:
The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and the spinal cord, which process and coordinate information. The PNS consists of all the neural structures outside the CNS, including cranial nerves, spinal nerves, and ganglia, which connect the CNS to the rest of the body. Thus, statements 1 and 3 are correct.

Explanation:
The juxtaglomerular apparatus (JGA) is formed by the macula densa cells of the distal tubule and granular cells of the afferent arteriole. It detects NaCl concentration in the filtrate and releases renin, which regulates GFR and systemic blood pressure via the renin-angiotensin-aldosterone system. Bowman's capsule collects filtrate, PCT reabsorbs, collecting duct concentrates urine.