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Chapter

Cover The Ecology of Plants

Water Relations and Thermal Energy Balance  

This chapter starts by reviewing the evolutionary history of plants on land: the story of increasing success in obtaining water, moving it to parts of the plant far from its source, and being able to reproduce in a very dry atmosphere. It points out some of the essential structures that evolved during the course of the history of land plants. Terrestrial plants not only must obtain water, but also are faced with the problem of restricting their water losses. The chapter then examines what determines water loss, and how plants control it. The chapter also shows important factors in determining leaf and plant temperatures, and what adaptations plants possess for controlling these factors so that temperatures do not get too high or too low. The chapter examines their evolutionary solutions to these interrelated problems and takes a look at the physics of water and energy exchange between plants and their environments.

Chapter

Cover Animal Physiology

Temperature regulation in ectotherms  

This chapter explores temperature regulation in ectotherms. Almost all invertebrates, all amphibians, most fish, and most reptiles are ectotherms. Ectotherms influence their body temperatures by behavioural thermoregulation. The simplest form of behavioural thermoregulation is thermal selection according to the preferred body temperatures of aquatic animals. Meanwhile, terrestrial ectotherms adjust their rate of heat uptake and heat loss by shuttle behaviour. The chapter then looks at albedo, melanism, and thermal hysteresis. Some animals cope with cold conditions by entering a resting phase called diapause or hibernation. The chapter also considers the implications of temperature change for tissue functioning of ectotherms. According to the oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis, the capacity for oxygen uptake and transport is the major determinant of thermal tolerance of aquatic ectotherms.

Chapter

Cover Biological Science

Communication and Control 2  

Sensory Systems

This chapter explains how the sensory system provides a rich supply of information about internal and external environments. It clarifies that perception depends very much on the neural processes by which sensory stimuli are converted into patterns of action potentials and transmitted to the brain. Sensory systems respond more strongly to change or contrast compared to steady state conditions. The chapter explains how information is transmitted through taste, smell, hearing, and vision which allow for the exploration of the external world. It also considers the notion of touch, proprioception, pain, and temperature in transmitting information to the brain.

Chapter

Cover Making the Transition to University Chemistry

Kinetics  

This chapter discusses rates of reactions in kinetics. The rate of reaction is based on the rate of change of concentration per unit time. The activation energy for a reaction is the minimum energy necessary for a collision to lead to a successful reaction. The rate of reaction, then, depends on the concentration of the reactants, temperature, presence of a catalyst, and state of subdivision. The Maxwell–Boltzmann distribution pins the number of molecules in a gas with given energy against energy. On the other hand, the Arrhenius equation measures the activation energy on how the rate constant depends on the temperature.

Chapter

Cover Atkins’ Physical Chemistry

Enthalpy  

This chapter focuses on the concept of enthalpy. This property is used to track the heat output (or requirements) of physical processes and chemical reactions taking place at constant pressure. Changes in internal energy or enthalpy are measured by techniques known collectively as ‘calorimetry’. A calorimeter for studying processes at constant pressure is called an isobaric calorimeter. For a combustion reaction, an adiabatic flame calorimeter may be used. The most sophisticated way to measure enthalpy changes, however, is to use a differential scanning calorimeter (DSC). The chapter then looks at the variation of enthalpy with temperature. The enthalpy of a substance increases as its temperature is raised. The reason is the same as for the internal energy: molecules are excited to states of higher energy so their total energy increases.

Chapter

Cover Thermodynamics of Chemical Processes

Phase equilibrium and solutions  

This chapter focuses on the concept of matter existing in either the solid, liquid, or gas phase and is dependent on temperature and pressure. It explains that this phase is part of a system that is homogeneous throughout and separated from other phases by a definite boundary. It also describes the factors that determine why compounds exist in a particular phase under a particular set of conditions and what influences the transitions between phases. The chapter talks about the Gibbs energy of the phases in order to derive quantitative information on phase transitions. It considers pressure and temperature as major experimental variables that affect phase behaviour, noting that matter exists in the solid phase at sufficiently low temperatures or high pressures.

Chapter

Cover Physical Chemistry

Thermodynamics  

This chapter explains the system in which the reaction of interest being studied and the surroundings are the rest of the space around the system. It points out that the system that is supplemented by surroundings is called the universe. It also outlines different types of systems that vary according to their transfer of matter and energy and elaborates on how energy can take the form of either heat or work. The transfer of energy as heat arises when there is a difference in temperature. Work is carried out by a reaction when it opposes a force. An example is when gas is produced, and it expands against external pressure. The chapter clarifies how work is done on the system if the atmosphere pushes in on the reaction and compresses any gaseous components.

Chapter

Cover Biological Science

Communication and Control 2  

Sensory Systems

This chapter explains how the sensory system provides a rich supply of information about internal and external environments. It clarifies that perception depends very much on the neural processes by which sensory stimuli are converted into patterns of action potentials and transmitted to the brain. Sensory systems respond more strongly to change or contrast compared to steady state conditions. The chapter explains how information is transmitted through taste, smell, hearing, and vision which allow for the exploration of the external world. It also considers the notion of touch, proprioception, pain, and temperature in transmitting information to the brain.

Chapter

Cover Atkins’ Physical Chemistry

The canonical ensemble  

The chapter illustrates ensemble as the crucial concept needed in the treatment of systems of interacting particles. It notes the requirements to set up an ensemble: a closed system of specified volume, composition, and temperature. Thus, an imaginary collection of replications of the actual system with a common temperature is called the canonical ensemble. While the canonical distribution provides the most probable number of members of the ensemble with a specified total energy, the mean energy of the members of the ensemble can be calculated from the canonical partition function. The chapter notes the variation of the energy with volume.

Chapter

Cover Atkins’ Physical Chemistry

The Arrhenius equation  

This chapter discusses how rate constants of most reactions increase with increasing temperature. It introduces the ‘Arrhenius equation’, which captures this temperature dependence by using two parameters that can be determined experimentally. It also reviews the exploration of the dependence of reaction rates on temperature that leads to the formulation of theories that reveal the details of the processes that occur when reactant molecules meet and undergo reaction. The chapter looks at the temperature dependence of the rate of a reaction that depends on the activation energy and the minimum energy needed for reaction to occur in an encounter between reactants. It emphasizes how chemical reactions usually go faster as the temperature is raised, which is almost always due to the increase of the rate constant with temperature.

Chapter

Cover Cell Signalling

Stress Responses and The Changing Cell Environment  

This chapter analyses the importance of perceiving the environment and describes what happens when cells undergo a pathogen challenge, in both animals and plants. It discusses how organisms adapt to changing environments and talks about the impact of human activity and how organisms respond. It also mentions the necessity for organisms to sense their environment, noting how humans have easily evolved to be able to see the surroundings, to hear what is around, and to sense the presence of chemicals. The chapter reviews the ability of cells to survive, sense aspects of their environment, and mount the appropriate response when required. It cites climate change as one of the biggest challenges facing the world in present times and notes that the unprecedented rise in global temperature forces organisms to adapt to the changing environment to survive.

Chapter

Cover Marine Biology

The Chemical and Physical Environment  

This chapter looks into how marine organisms respond to changes in the chemical and physical aspects of their environment. Measures of organismal response include whole organism, behavioral, physiological, and biochemical factors. Marine species evolve to function at the highest efficiency in a given thermal regime. Moreover, changes to salinity present challenges to marine species because of diffusion and osmosis. The chapter explains that organisms respond to environmental change by reaching a new equilibrium through a process known as acclimation. It then considers the factors of temperature, salinity, oxygen, and light with regard to the acclimation of species in an environment.

Chapter

Cover Vertebrate Life

Ectothermy and Endothermy  

Two Ways of Regulating Body Temperature

This chapter looks at the concept of ectothermy and endothermy in relation to regulating body temperature. It highlights the importance of controlling body temperature. Vertebrates employ a variety of behavioral and physiological mechanisms to control body temperature. The evolution of endothermy was a major event in vertebrate evolution, especially within the sauropsid and synapsid lineages. Moreover, the processes of endothermy and ectothermy are not mutually exclusive since many tetrapods combine elements of both modes. The consequences of ectothermy and endothermy shaped the lifestyles of different vertebrates and this informs some important consequences of these lifestyles in the context of ecosystems.

Chapter

Cover Elements of Physical Chemistry

Entropy changes  

This chapter shows how to use the definition of entropy change to calculate the change in entropy when a system undergoes changes of volume and temperature and when a phase transition takes place. It specifically looks at Trouton's rule. The entropy of the system increases when a perfect gas expands isothermally. Entropy also increases with temperature. The chapter then demonstrates how to adapt the definition of entropy change to the calculation of the change in entropy of the surroundings. Ultimately, the change in entropy of the surroundings is calculated from the energy transferred as heat into them regardless of whether the process is reversible or not.

Chapter

Cover Statistical Thermodynamics

The electronic partition function  

This chapter focuses on the electronic partition function. Atoms and molecules can achieve electronic excitation energy levels and experience a rise in energy to states above the ground electronic state. The chapter highlights that excited electronic states showcase no regular or predictable series of increasing energies. It notes that high excitation energies mean that molecules' excited electronic states remain unpopulated unless the temperature increases to several thousands of kelvins. Additionally, the chapter includes degeneracy in the equation formula as electronic states can enter into the partition function for atoms via the degeneracy of the ground electronic state. The chapter explores the singular case of nitrogen monoxide as an isolated two-state system.

Chapter

Cover Animal Physiology

Thermal Relations  

This chapter tackles the concept of thermal relations. It enumerates the key concepts related to the thermal reactions of animals: endothermy, thermoregulation, ectotherms, endotherms, homeotherm, and heterothermy. Temperature primarily refers to a measure of the speed of incessant random motions of molecules, while heat, in comparison, is merely a form of energy that a substance poses by virtue of random motions. The chapter then looks into the influence of temperature in fish and the impact of endothermy and homeothermy on insects. It mentions how endothermy can provide organisms with distinct advantages and evolve independently in animals and some plants multiple times.

Chapter

Cover Plant Physiology and Development

The Control of Flowering and Floral Development  

This chapter addresses the fundamental questions of the phenomenon on the strong correlation between flowering and seasons, such as how plants keep track of the seasons of the year and the time of day. It looks at which environmental signals influence flowering and how those signals are perceived. It also describes how environmental signals are transduced to bring about the developmental changes associated with flowering. The chapter talks about the transitions to flowering which involve major changes in the pattern of morphogenesis and cell differentiation at the shoot apical meristem, which leads to the production of sepals, petals, stamens, and carpels. It explores temperature compensation that prevents temperature changes from affecting the period of the circadian clock.

Chapter

Cover Animal Physiology

Temperature regulation in endotherms  

This chapter studies temperature regulation in endotherms. Endotherms compensate for heat loss to their environment in order to maintain their body temperature several degrees above ambient. Animals decrease their thermal conductance to minimize their rate of heat loss. This can be achieved by erecting hairs or feathers to increase the insulating layer of air, or by the operation of countercurrent heat exchangers in the extremities. The thermoneutral zone is the ambient temperature range within which an animal does not need to change its rate of heat production to regulate its temperature. The chapter then looks at how endotherms regulate their body temperature in hot conditions, cold conditions, through the seasons, and in water. Some species of endotherms exhibit regional endothermy: they generate heat and retain it in specific regions of the body. The chapter considers endothermic fishes, reptiles, and insects.

Chapter

Cover Inorganic Materials Chemistry

The synthesis of inorganic materials  

This chapter examines the synthesis of inorganic materials. The synthesis methods used in the preparation of inorganic materials, many of which have extended lattices rather than discrete molecules, are quite different from those used by organic, organometallic, and coordination chemists. Rather than altering a single functional group or ligand attached to a molecule, the materials chemist works with complete lattices, either building or modifying them. The chapter begins by looking at high temperature reactions. The most widely used method for the synthesis of inorganic materials follows an almost universal route that involves heating the components together at high temperature over an extended period. The chapter then details the process of the reaction between solids, before studying the precursor, solution, and gel methods. It also assesses hydrothermal methods, phase diagrams, and low temperature methods.

Chapter

Cover Genetic Analysis

Mutant phenotypes and gene activity  

This chapter discusses what mutant phenotypes and DNA sequences can tell us about molecular function. It looks specifically at pleiotropy—a mutation in a gene that influences more than a single phenotype. Conditional mutations and temperature-shift experiments have been used to analyse mutant phenotypes and associated gene activity. The chapter notes biological noise as the stochastic variation in the level of gene expression occurring under natural conditions. It also looks at mosaic organisms, which have wild-type and mutant cells; such organisms can be used to focus on gene activity at a cellular level. While small changes in the level of gene expression can be easily determined, the same cannot be said of their impact on changes to phenotype.