Four rigorous NGSS informational science passages with parallel scaffolding tracks, morphological Greek/Latin root breakdowns, interactive vector models, and authentic WIDA ACCESS reading comprehension items.
During a chemical reaction, constituent atoms within reactant molecules are rearranged through the cleavage and formation of chemical bonds. According to the Law of Conservation of Mass, matter is neither created nor destroyed within an isolated thermodynamic system. Consequently, the aggregate mass of the initial reactants precisely equals the total mass of the resulting products. In an exothermic reaction, excess chemical potential energy is released into the ambient environment as thermal radiation, whereas endothermic processes continuously absorb ambient thermal energy to drive molecular synthesis.
During a chemical reaction, the small parts (atoms) in the starting materials (reactants) break apart and rearrange to make new substances (products). The universal Law of Conservation of Mass states that no matter can be created or destroyed. Consequently, the total weight of the starting materials always equals the total weight of the ending products. When heat is released to the outside, we call it exothermic; when heat is absorbed from the outside, we call it endothermic.
Genetic mutations are permanent alterations in the nucleotide sequence of an organism's genome. While many mutations remain neutral or deleterious, beneficial mutations confer adaptive phenotypic traits that elevate an individual's survivability. In a dynamic environment undergoing ecological shifts, individuals possessing advantageous structural or behavioral adaptations exhibit heightened reproductive fitness. Consequently, through the mechanism of natural selection, these favorable alleles proliferate across successive generations, driving population-level evolutionary divergence.
A genetic mutation is a change in the DNA instructions of a living organism. While many changes are harmless or harmful (deleterious), helpful mutations give organisms special physical features (phenotypes) that help them survive. When the environment changes, animals with these helpful traits survive longer and have more offspring (reproductive fitness). Consequently, these helpful gene versions (alleles) spread to more animals in future generations.