All organisms are composed of cells, but what is the definition of a cell? Can size, shape or function be used to distinguish cells from non-living biological systems such as a virus? Whatever the definition of a cell is, it can probably be contradicted by cells with unusual characteristics. For example, there are cells as long as a giraffe’s neck while others are smaller than a mitochondrion. Sometimes it is hard to know the difference between an animal and a plant cell. Despite their diversity of shapes and sizes, cells are small—most of the time. Why has natural selection favored small cells? Would it be possible for big organisms to have big cells? It would seem safe to say viruses are small, except some are quite large. In the end, this book will provide evidence that cells are difficult to characterize and define even though they are the foundation of all living things.
Several genetic and pathogenic diseases are described to illustrate how diseases can and do disrupt normal molecular and cellular functions, and how those disruptions affect entire organisms. In the case of genetic diseases, how they arise and are maintained in populations is discussed. In the case of pathogenic and parasitic organisms, understanding their complex life cycles and their modes of transmission is critical to understanding their effects on individuals and how disease outbreaks occur in ecological systems. Communication between the pathogen and the host organism occurs in the course of infection and involves the disruption of normal cell function. Finally, epidemiology is briefly discussed, using the case of severe acute respiratory syndrome (SARS). Data are used to describe how the disease may have originated and evolved to infect humans, and how it spread relatively quickly and almost caused a global pandemic. Understanding how disease outbreaks occur in ecological systems is critical to controlling the spread of disease.
It is easy to understand how cells are produced from preexisting cells. And it is possible to imagine how space dust condensed to form inanimate planets. But what stumps most people is how inanimate matter suddenly formed the first living cell. This problem has vexed scientists and philosophers over the millennia, but recent research has cracked open this black box that is the origin of life. After formally defining evolution, this book presents the modern classic experiments that show how abiotic molecules can be formed from inorganic starting materials. Once biologically important molecules such as lipids and RNA were formed, they could self-assemble into complex shapes that exhibit life-like traits such as growth, reproduction, competition and energy storage. Biologists have produced all these behaviors in non-living vesicles to the point it becomes difficult to distinguish when to know if an object is living or not. In addition, this book addresses the important question of how religion and science can coexist without one threatening the other.
Why do some children look more like one parent than another? How can two parents with dark hair have a child with red hair? How can two dark-skinned parents have a baby that has light skin? Everyone has wondered these questions, but in order to understand such unexpected outcomes, an understanding of what Gregor Mendel discovered—the rules of genetics—is necessary. This book reproduces Mendel’s original data that Mendel used to discover how traits are passed from one generation to the next. In addition to the rules governing DNA inheritance, this book also examines how cells reproduce—all cells. Do bacterial cells reproduce the same way animal cells do? And when a person has a cut that needs to heal, do those cells reproduce the same way that sperm and egg cells are produced? How do all these cells keep track of how much DNA is needed in order to function properly? Data will be examined that explains how reproduction works for every cell on the planet.
One of the overarching themes in nature is that form meets function, meaning that the shape of an object determines how well the object can perform its function. This book begins with some basics about specificity of shapes and the four increasing levels of protein structure. Most of this book examines how epinephrine (adrenaline) can cause the liver to release glucose when a person experiences a fight or flight response. Whenever someone gets scared, all of their cells are bathed in epinephrine. A subset of those cells will respond directly to this hormone, and the liver cells prepare other cells for the extra energy they might need to survive. This book presents some of the data that revealed how the information of fear is carried inside liver cells. This book will also consider how and why some cell membranes are wavy. In short, this book looks at the structure/function relationship at the molecular level.
William King (1650–1729) was perhaps the dominant Irish intellect of the period from 1688 until his death in 1729. An Anglican (Church of Ireland) by conversion, King was a strident critic of John Toland and the clerical superior of Jonathan Swift.
Two systems illustrate how individual cells of an organ system function, communicate, and coordinate activities. The digestive system breaks down and absorbs nutrients, and some specialized cells break down and absorb nutrients. The case of parietal cells in the stomach and epithelial cells in the small intestine are used to describe how cells function as a unit within organ systems, coordinating activities and communicating with one another. The endocrine system of insects affects molting and metamorphosis, and specialized cells are also important in each of these processes within that organ system. The experiments that were devised to determine the role of hormones in insect molting and metamorphosis are described. Finally, stem cells are healthy components of several different systems in animal bodies and are described in relation to a disruption in function. In this breakdown of function, cancer cells, in contrast to stem cells, can abnormally affect cell cycle regulation.
Population growth, dynamics, and blooms of bacterial, unicellular eukaryotes, and toxic algae are described in this book. Microbes are used to illustrate both exponential and logistic population growth. Microbes are also used to illustrate dynamics in other aspects of ecological systems, including nutrient cycling. The movement of nitrogen in ecological systems is largely affected by microbes, some of which have symbiotic relationships with legumes. The effects of the environment on the growth of microbes and the effects of the microbes on ecological systems are described in reference to nutrient cycles and harmful algal blooms. Populations of harmful algal can quickly grow and exceed carrying capacity, with resulting negative effects on other species, including humans.
Three of the four major mechanisms of evolution, natural selection, genetic drift, and gene flow are examined. There are 5 tenets of natural selection that influence individual organisms: Individuals within populations are variable, that variation is heritable, organisms differ in their ability to survive and reproduce, more individuals are produced in a generation than can survive, and survival & reproduction of those variable individuals are non-random. Organisms respond evolutionarily to changes in their environment and other selection pressures, including global climate change. The importance of spatial structure of a population in relation to how it affects the strength of gene flow and/or genetic drift, as well as the genetic variation and evolution of populations, is shown. Gene flow tends to reduce variation between populations and increase it within populations, whereas genetic drift tends to reduce genetic variation, especially in small, isolated populations. The mechanisms of evolution can lead to speciation, which requires both time and genetic isolation of populations, in addition to natural selection or genetic drift.
Food webs, energy flow, indirect effects, and nutrient cycling are described as properties that emerge in ecological systems. Several of these properties are shown in this book to result from indirect effects and interactions between species and abiotic components of ecological systems. For instance, top predators affect organisms with which they do not directly interact, including plants and non-prey animals. In some other interactions, including competition, the nonliving components of ecological systems (the abiota) can alter the outcome of a biotic interaction. A limiting resource often results in competition, but varying environmental conditions allow for species coexistence. Finally, this book illustrates how energy flows in ecological systems, why it is rather inefficient, and how species interactions relate to homeostasis and emergent properties. In the course of that discussion, primary production, secondary production, and trophic levels are defined. Energy flow in ecological systems is tied to the carbon cycle.
Organisms maintain homeostasis in a variety of ways. In the first part of this book, mammals are shown to regulate their body temperatures through homeostatic mechanisms. The data from thermoregulation experiments that demonstrated the role of neurons in body temperature homeostasis are examined. The second part of this book discusses how organisms allocate the limited energy that is available to them for survival, growth, or reproduction. Excess energy in individuals can translate to growth of populations: if enough remains after survival and growth, it can be allocated to reproduction. However, even closely related organisms may have different strategies for allocating resources that are dependent upon the environmental conditions in which they exist.
This book describes and analyzes genetic and environmental factors that cause variation in individuals and populations. Data will be used to evaluate the processes by which variation is generated in organisms and how variation affects natural selection. Genetic factors include mutation, independent assortment, crossing over, and recombination. Environmental factors include gradients and differences in abiotic conditions. Genotype frequencies can be used to determine allele frequencies and this information can be used to determine whether a population is evolving at a genetic locus. The Hardy-Weinberg equilibrium will be applied as a null model to make this determination. Non-Mendelian genetics can affect the evolution of viruses and reassortment in viruses will be used to illustrate another mechanism that generates variation in organisms and how this mechanism relates to rapid evolution of viruses and the need for annual flu vaccines.
This book describes how evolutionary history is studied using several well-known examples and also using evolutionary trees. Evolutionary trees are analyzed and used to explain adaptive radiations of orchids and the diversification of bats over geologic time. Evolutionary trees and genetic evidence is used to infer when and from what ancestors terrestrial plants evolved and invaded land. Specific adaptations of early land plants led to the evolution of terrestrial plants and their success on land. Evidence about the ancestors and habitats of humans is used to infer and analyze the evolution of the human family tree, whose populations were subject to the same forces of evolution to which other species are subject. Human evolution was not linear, involved offshoot species that did not survive, and took many thousands of years. In contrast, evolution can be seen in just a few years or less in other examples, and analysis of the evolution of mechanisms of pesticide resistance in insects will be used to illustrate this rapid evolution.
Properties of populations include age and spatial distribution, both of which emerge from actions and properties of individuals and can affect population dynamics, the changes in populations and metapopulations over time and space. The age structure of a population is described and analyzed to determine how it affects the growth of a population. The various aspects of spatial structure of populations, which also arise from characteristics and behaviors of individuals, are examined and used to develop the concept of a metapopulation. Finally, this book discusses how individuals perform behaviors that can lead to other properties observed at the population level, such as birds flocking. The advantages and disadvantages to flying in flocks are evaluated, as are the mechanisms by which flocks of birds are maintained and how they respond to an attack by a predator.
This book will synthesize the concepts of selection against individuals in response to environmental change to illustrate how selection against individuals results in homeostasis at the population level. For instance, selection against the light phenotype of the peppered moth during the early part of the industrial revolution led to an increase of the dark phenotype, which was better camouflaged against the soot that accumulated on tree bark as a result of burning coal. Populations are shown to be regulated by feedback mechanisms, several of which are discussed here. Populations are regulated by extrinsic factors, such as competition and predation, and that lead to changes in intrinsic factors, such as reproduction. Changes in population density often lead to initiation of feedback mechanisms, such as changes in birth or death rates. In a final example, pollutants are shown to be a factor that can disrupt homeostasis of populations. In particular, populations of top predators, such as raptors, have suffered due to biomagnification of toxins.
This book begins by describing what an individual organism is, comparing preconceptions of the individual to non-standard ways of thinking about individuals. Variation in what individuals are is described, using giant fungi, clonal trees and honey bee hives as examples. Individuals are thus shown to be emergent properties. Other emergent properties of individuals are also described. Classic experiments that elucidated the source of emotions in humans and other mammals are described. Emotions arise from the actions of the nervous and endocrine system and often include a variety of signals given to other individuals of the same or different species. In particular, this book focuses on fear and anger, two emotions that are closely related and often confused, but that have been well studied. In one final example of emergent properties of individuals, cooperative behavior is analyzed. The behaviors displayed by individuals that facilitate cooperation among individuals and why those individuals may actually cooperate instead of compete when acquiring resources or defending against predators are discussed.
Animal behavior includes the exchange of non-heritable information between individuals of the same species. Animals exchange information for a variety of reasons, including mating, defense, and cooperation, and all of these situations will be discussed. This book will describe the functions of communication and information transfer between organisms and explain how animals communicate and find each other through use of different signals. The costs and benefits of using various signals will be evaluated, as will the costs and benefits of living in groups. Playback experiments and the comparative method are approaches used for understanding and interpreting signals used by organisms to communicate information to other members of the same species. Plants also communicate information between individuals, often for purposes of species identification during mating. Female reproductive structures in plants recognize pollen from members of the same species. Finally, the commonalities and differences between animal and plant communication will be identified
This book examines three ways plants respond to their changing environment. The first example can be found in all plants. Despite the extreme changes in weather, plants have to stay where they are and respond to whatever nature produces. Plants have the capacity to respond quickly and yet they can evolve in a single generation. The second example addresses how an individual leaf has to respond rapidly and repeatedly to maintain the proper balance of carbon dioxide (CO2) and water so that it can photosynthesize but not dry out. This delicate balance is governed by a pair of cells that regulate the size of openings on leaves. The final chapter examines a unique example of a leaf that can move fast enough to trap insects and digest them. This book presents data that led to our understanding of how plants function on different time scales.
What happens to a meal after it is eaten? Food consists primarily of lipids, proteins and carbohydrates (sugars). How do cells in the body process food once it is eaten and turned it into a form of energy that other cells can use? This book examines some of the classic experimental data that revealed how cells break down food to extract the energy. Metabolism of food is regulated so that energy extraction increases when needed and slows down when not needed. This type of self-regulation is all part of the complex web of enzymes that convert food into energy. Adding to this complexity is that all food eventually winds up as two carbon bits that are all processed the same way. This book will also reveal why animals breathe oxygen and how that relates to the end of the energy extraction process and oxygen’s only role in the body. Rather than look at all the details, this book takes a wider view and shows how cellular respiration is self-regulating.
Whenever a dancer or an athlete performs amazing feats, it is the consequence of two very interesting cell types: neurons and muscles. When the two of these cell types work together, animals can move in complex ways with surprising control. Not only do they work together to produce movement, they have many traits in common. They both convert chemical signals into electrical information, and then back into chemical information again. This book will examine how neurons process information and communicate to adjacent cells. This book presents how muscle cells know when to contract and how contraction leads to bigger muscles. Finally, the last chapter presents how long-term memories are formed. In all three chapters, some of the original data that have contributed to our understanding of these two fascinating cell types are reproduced to provide supporting evidence for the function of these two cell types.
Once the first cell arose on Earth, how did genetic diversity arise if DNA replication and cell division generate exact copies? The answer is that neither process is perfect and that changes do occur at each step. Some changes are small and subtle while others are large and dramatic. As DNA mutates, evolution of a population takes place. But when can someone determine if a single species has changed enough to be considered two separate species? How is a species defined and is this definition useful in the real world? Real biological data will be examined to confront and answer these questions. Finally, the book examines an example of evolution that takes place in humans on a regular basis—the mammalian immune system. White blood cells evolve rapidly to confront any substance that enters a body and is perceived as a threat. With each exposure, these cells get better and better at neutralizing the threat.
This book examines four examples of animal physiology that illustrate emergent properties in whole organisms. The first example shows how mammals coordinate the activity of all their cells using a daily rhythm. The second case explains an apparent contradiction that happens every time a woman gets pregnant and delivers a healthy baby—how the immune system tolerates a foreign tissue such as the fetus. The next case study in this book shows how bodies regulate the amount of fat using a complex interaction of proteins that function as a lipostat, a self-regulating fat maintenance system. Finally, the book provides an understanding of why some species live long lives while others die after very short lives, and under what conditions each situation is favored. What is evolutionarily adaptive about death? These four case studies provide sufficient evidence to understand how animals regulate many of their own metabolic functions.
It is common for most people to mistakenly think that humans are the only species that can coordinate their behavior and build structures that protect them from the environment. Students of nature will think of birds building nests, but very few people know that bacteria are able to communicate and restructure their environment in complex ways that improve their ability to survive. This book presents experimental evidence of quorum sensing, biofilm formation, self-assembly of microbes into visible and mobile creatures. This book also examines the experimental evidence showing how bacteria can keep track of time and coordinate the behavior of an entire population. Individual cells, it turns out, are capable of functioning in ways that blur the distinction between unicellular and multicellular organisms.
Many people were taught that DNA is the “blueprint of the cell,” but what does that really mean? If taken literally, it would reveal a static image of what the cell looks like, but that would be incorrect. DNA codes the necessary information to produce a living being but the DNA itself is insufficient to bring a cell to life. DNA must be transcribed into segments of RNA and the RNA must generate proteins from unassembled amino acids. The conversion of DNA information into functional proteins is often referred to as central dogma, which reflects its critical role in life. However, every cell in a body contains the same genes but only a subset of genes is needed to be activated in any given cell for a cell to function properly. This book will explore many of the classic experiments that led to our current understanding central dogma. Furthermore, real data are used to discover that central dogma information is not linear and that cells must cut and paste together segments of RNA in order to build the functional proteins of cells.
This book introduces the concept of emergent properties, which are unexpected traits found only when two or more biological components interact. Experimental evidence of several emergent properties explains how hemoglobin can act like a high affinity oxygen carrier some times and then switch to a low affinity carrier exactly when and where it should. The second example presents how one particular virus determines whether it should stay latent within its host or whether it should kill its host and spread its progeny into the environment. The final example looks at the surprising properties that emerge as a consequence of random behaviors at the molecular level. It is unlikely that many people are aware of these unexpected behaviors that come from non-living molecules based on their structures.
Perhaps the most important chemical reactions on the planet take place inside a plant’s chloroplasts. In this tiny green organelle, plants have the capacity to capture the energy in light and use that energy to convert CO2 gas into building blocks used to produce all four categories of biological molecules—lipids, carbohydrates, proteins and nucleic acids. Animals could not survive if plants did not exist. Not only do they provide us with oxygen to breathe, they also generate the starting materials for everything we eat. Rather than focusing on names and trivial details, this book shows how plants harvest energy in a way that self-regulates. Plants shift how they process light energy to maximize their productivity and minimize their exposure to dehydration. All of this regulation is carried out inside every plant on earth. In addition to plants, there are microbial primary producers that can harvest energy from a range of environmental sources so that no place on earth is devoid of life.
Everyone who has taken any biology class knows that DNA is the heritable material. However, very few people know the evidence that led to this conclusion. Science is a discipline based on evidence not acceptance based on faith in a teacher or other authority. This book presents the historical and scientific context to understand how we know DNA is the heritable material. Furthermore, how the structure of DNA reveals its function will be discussed. The famous double helix shape foretold how it would be replicated. Two biochemists conducted the research to confirm that each of the two strands serve as template for new DNA synthesis. Despite its central role in cell function, the order of bases in DNA is not the full story. This book also introduces the topic of epigenetics by presenting the first animal experiments that showed epigenetic changes can lead to a change in phenotype even though the DNA is not mutated.
Many people have a vague sense that the hypothesized origin of life, in the form of bacteria, sounds plausible. However, few people can fathom how the first eukaryotic cell, complete with nucleus, mitochondria and maybe chloroplast, came into being. This book presents the evidence that reveals the origins of all three DNA-containing organelles. In addition, this book will illustrate how DNA, a molecule that is 2 meters (6 feet) long, can fit into all cells’ nuclei that are only about 2 microns (0.000002 meters) in diameter. Once eukaryotes evolved, the next obvious question is how multicellular organism could have evolved from simpler unicellular species. This book looks at multicellular algae as a case study on the origins of multicellularity.
This book identifies the commonalities between communication within a species and communication between species. Behavior and exchange of non-heritable information occurs between individuals of different species, in animals and plants, in order to exploit other species and compete for resources. Several examples of adaptations of one species to exploit the information passed between individuals of another species are given. This book describes how animals make decisions while gathering information and resources, selecting habitat, and interacting with potential competitors. Plants grow in response to nutrients in soil, which may require gene regulation in response to information in the environment. Information is also exhibited in biodiversity, in the number and types of species present, and this information is used by other organisms as they assess their surroundings. The information content of ecological systems changes when species are added or lost.
Pairwise and diffuse coevolution are defined, with examples that include mutualisms and predator-prey interactions. In any example of coevolution, the costs and benefits to both species involved in the interaction must be assessed in order to understand evolution of the interaction. Models to explain coral bleaching are examined in the context of a coevolutionary mutualism, as are the implications for the possible extinction of coral reefs. Data are examined in order to determine which model is best supported. Other examples of how evolution affects interactions and communities of organisms include adaptation to living in particular habitats and evolution to frequent and somewhat predictable disturbances. For the former, physiological adaptations possessed by some plants to live in low light conditions are described and assessed. Ecological disturbances are defined, and the role of disturbance on evolution of ecological systems is assessed through the use of data. Finally, how time and spatial scales affect disturbances and the evolutionary responses of organisms to disturbances are also examined.
This go-to study guide provides the concepts, study strategies, and practice you need to dramatically raise your ACT score McGraw-Hill Education: ACT focuses on the fundamental concepts tested on the exam as well as the reasoning and analytical skills necessary to overcome common traps. The book covers the foundations of each essential concept, introduces strategies developed by the authors, and includes review exercises in each chapter so you can increase your test-taking confidence. 6 full-length practice exams--4 in the book, 2 online 40 problem-solving videos by renowned ACT coaches online Test Planner app helps you organize your time and set your own study schedules Answer keys provide full explanations that identify common errors
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