first photox bacteria evolved 3.6 bya billion years ago

#FIRST PHOTOX BACTERIA EVOLVED 3.6 BYA BILLION YEARS AGO SKIN#

Organisms grow and develop according to specific instructions coded for by their genes. As an environment changes, natural selection causes the characteristics of the individuals in a population to track those changes. All adaptations enhance the reproductive potential of the individual exhibiting them, including their ability to survive to reproduce. Examples of adaptations are diverse and unique, from heat-resistant Archaea that live in boiling hot springs to the tongue length of a nectar-feeding moth that matches the size of the flower from which it feeds. Biologists refer to this fit as adaptation and it is a consequence of evolution by natural selection, which operates in every lineage of reproducing organisms.

AdaptationĪll living organisms exhibit a “fit” to their environment. These genes are the reason that the offspring will belong to the same species and will have characteristics similar to the parent, such as fur color and blood type. When reproduction occurs, DNA containing genes is passed along to an organism’s offspring. Many multicellular organisms (those made up of more than one cell) produce specialized reproductive cells that will form new individuals. Single-celled organisms reproduce by first duplicating their DNA, which is the genetic material, and then dividing it equally as the cell prepares to divide to form two new cells. Watch this video to see how the sensitive plant responds to a touch stimulus. After a few minutes, the plant returns to its normal state. Figure 1.3 The leaves of this sensitive plant (Mimosa pudica) will instantly droop and fold when touched. Movement toward a stimulus is considered a positive response, while movement away from a stimulus is considered a negative response. Even tiny bacteria can move toward or away from chemicals (a process called chemotaxis) or light (phototaxis). For example, plants can bend toward a source of light or respond to touch. Figure 1.2 A toad represents a highly organized structure consisting of cells, tissues, organs, and organ systems.

#FIRST PHOTOX BACTERIA EVOLVED 3.6 BYA BILLION YEARS AGO SKIN#

How these specialized cells come together to form organs such as the heart, lung, or skin in organisms like the toad shown in Figure 1. Multicellular organisms, which may consist of millions of individual cells, have an advantage over single-celled organisms in that their cells can be specialized to perform specific functions, and even sacrificed in certain situations for the good of the organism as a whole. These in turn make up cell components or organelles. Inside each cell, atoms make up molecules.

Even very simple, single-celled organisms are remarkably complex.

Organisms are highly organized structures that consist of one or more cells. When viewed together, these eight characteristics serve to define life. Properties of LifeĪll groups of living organisms share multiple key characteristics or functions: order, sensitivity or response to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing. It turns out that although viruses can attack living organisms, cause diseases, and even reproduce, they do not meet the criteria that biologists use to define life.įrom its earliest beginnings, biology has wrestled with four questions: What are the shared properties that make something “alive”? How do those various living things function? When faced with the remarkable diversity of life, how do we organize the different kinds of organisms so that we can better understand them? And, finally-what biologists ultimately seek to understand-how did this diversity arise and how is it continuing? As new organisms are discovered every day, biologists continue to seek answers to these and other questions. For example, a branch of biology called virology studies viruses, which exhibit some of the characteristics of living entities but lack others. What exactly is life? This may sound like a silly question with an obvious answer, but it is not easy to define life. Biology is the science that studies life.

First photox bacteria evolved 3.6 bya billion years ago