In human nutrition, the 'Glycemic Index' (GI) of a food measures: MCQ with Answer and Explanation

Explanation:
The stem is characterized by the presence of nodes, which are the junctions where leaves and buds arise, and internodes, the segments between two nodes. While some stems are modified to grow underground (like potatoes or onions) for storage or perennation, the primary and most common form of the stem is aerial, growing above the ground. Statements 1 and 2 are correct.

Explanation:
The pulmonary veins are the only veins in the body that carry oxygenated blood. They transport oxygen-rich blood from the lungs back to the left atrium of the heart. In contrast, the pulmonary artery carries deoxygenated blood from the right ventricle to the lungs. All other veins carry deoxygenated blood and arteries carry oxygenated blood.

Explanation:
In primary succession on a bare, lifeless rock (xerosere), the pioneer species are usually lichens (a symbiotic association of fungi and algae or cyanobacteria). Lichens can survive in harsh, dry conditions and secrete acids that slowly weather the rock, contributing to soil formation. Once a thin layer of soil is formed, mosses can colonize, followed by herbs, grasses, shrubs, and eventually a climax forest community.