The respiratory pigment in human blood that transports oxygen is: MCQ with Answer and Explanation

Explanation:
Crossing over, the exchange of genetic material between non-sister chromatids of homologous chromosomes, occurs during the pachytene stage of prophase I. The synaptonemal complex facilitates this. Chiasmata become visible in diplotene when the synaptonemal complex dissolves. Leptotene is chromosome condensation, zygotene is synapsis. This process is crucial for genetic variation.

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.

Explanation:
The Krebs cycle, also known as the citric acid cycle or TCA cycle, is the central metabolic pathway for the oxidation of acetyl-CoA to produce energy (ATP, NADH, FADH2). It was discovered by the British-German biochemist Sir Hans Adolf Krebs in 1937. He was awarded the Nobel Prize in Physiology or Medicine in 1953 for this discovery. Melvin Calvin elucidated the carbon pathway in photosynthesis.