The phase of the cardiac cycle when the ventricles relax and fill with blood is called: MCQ with Answer and Explanation

Explanation:
The fossil record shows a chronological sequence of life forms, providing direct evidence of evolutionary changes over time. Embryological similarities, such as the presence of pharyngeal slits and a notochord in early vertebrate embryos, support the idea of common ancestry. Biogeography, the study of species distribution, shows that species are not randomly distributed but are related to their geographic origins and evolutionary history. Thus, statements 1 and 2 are correct.

Explanation:
The Hardy-Weinberg principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences (like mutation, selection, gene flow, genetic drift, and non-random mating). It describes a theoretical, non-evolving population (genetic equilibrium) and provides a mathematical baseline (p2 + 2pq + q2 = 1) to measure evolutionary change.

Explanation:
Rhizobium is a symbiotic bacterium found in legume root nodules that fixes atmospheric nitrogen into ammonia. Yeast (Saccharomyces cerevisiae) undergoes anaerobic respiration, producing CO2 that leavens bread dough. The vast majority of bacteria are harmless or beneficial (e.g., gut flora, decomposers); only a small fraction are pathogenic to humans. Thus, statements 1 and 2 are correct.