The pacemaker of the heart is the: MCQ with Answer and Explanation

Explanation:
The cell membrane has a phospholipid bilayer with embedded proteins and is selectively permeable, not fully permeable. So 2 is incorrect.

Explanation:
R.H. Whittaker's five kingdom classification places all prokaryotic organisms in Kingdom Monera and unicellular eukaryotes in Kingdom Protista. Fungi are a distinct kingdom characterized by heterotrophic nutrition, primarily saprophytic or parasitic, and possess chitinous cell walls. They are not photosynthetic autotrophs. Therefore, statements 1 and 2 are correct, while 3 is incorrect.

Explanation:
Bacteria exhibit diverse roles; many are beneficial (e.g., gut flora, nitrogen fixers, decomposers), while some are pathogenic and cause diseases. Fungi are extensively used in food production, such as yeast (Saccharomyces) in baking and brewing, and molds (Penicillium) in cheese making (e.g., Roquefort, Camembert). Viruses are considered non-living outside a host cell because they lack metabolic machinery and cannot replicate independently; they only exhibit living characteristics when inside a host. Thus, statements 1 and 2 are correct.