EVERYDAY SCIENCE

Detailed explanation-1: -The earliest animals evolved from coloni al protists more than 600 million years ago. Many important animal adaptations evolved in invertebrates, including tissues and a brain. The first animals to live on land were invertebrates. Amphibians were the first vertebrates to live on land.

Detailed explanation-2: -The protists are thought to have arisen from bacteria, with symbiotic associations being involved in some way. Some researchers have hypothesized that the first protists were of a nonpigmented heterotrophic form. From within the vast array of protists, there must have arisen the early eukaryotes.

Detailed explanation-3: -Animals and plants evolved from different ancestral unicellular eukaryotes (37), and their characteristic developmental symmetries, transport systems, and complex forms have evolved independently from each other (Fig.

Detailed explanation-4: -These protists are thought to have originated when a eukaryote engulfed a green alga, the latter of which had already established an endosymbiotic relationship with a photosynthetic cyanobacterium (Figure).

Detailed explanation-5: -The protists have evolved from prokaryotes during which the nucleus divided via mitosis, histones were associated with the DNA, an endomembrane system and a cytoskeleton were formed, and they developed the ability to make flagella or cilia for movement from one place to another.