The first heart sound 'lub' is produced by the closure of: MCQ with Answer and Explanation

Explanation:
In C4 plants, the initial fixation of CO2 occurs in the mesophyll cells. The primary CO2 acceptor is a 3-carbon compound, phosphoenolpyruvate (PEP). The enzyme PEP carboxylase catalyzes the reaction, forming a 4-carbon compound, oxaloacetate (OAA). In C3 plants, the primary acceptor is RuBP, a 5-carbon compound, and the enzyme is RuBisCO.

Explanation:
Dermal tissue (epidermis in primary growth, periderm in secondary growth) forms the outermost protective layer of leaves, stems, and roots. It includes specialized cells like guard cells and root hairs. Vascular tissue (xylem, phloem) conducts, ground tissue fills and stores, meristematic is for growth.

Explanation:
Panthera leo is the binomial name for the lion. Panthera tigris is the tiger, Felis catus is the domestic cat, and Canis lupus is the grey wolf. The genus Panthera includes roaring cats: lion, tiger, jaguar, and leopard. Binomial nomenclature uses a capitalized genus and lowercase species epithet, both italicized.