The primary product of photosynthesis is: MCQ with Answer and Explanation

Explanation:
Phloem transports organic solutes (mainly sucrose) from source (leaves) to sink (roots, fruits) in a process called translocation, using sieve tubes and companion cells. Xylem transports water and minerals from roots upwards. Collenchyma and sclerenchyma are mechanical tissues providing support. Phloem is alive at maturity, while xylem vessels are dead. Companion cells regulate sieve tube activity.

Explanation:
Natural killer (NK) cells were discovered in the 1970s by Rolf Kiessling and others. They are part of innate immunity, killing virus-infected and tumor cells.

Explanation:
Dengue is a viral disease caused by the Dengue virus, not a protozoan (malaria is caused by a protozoan). Filariasis (elephantiasis) is caused by parasitic nematode worms like Wuchereria bancrofti, which block lymphatic vessels. Pneumonia is an infection that inflames the air sacs in one or both lungs, affecting the respiratory system. Thus, statements 2 and 3 are correct.