ENVIRONMENTAL PHYSIOLOGY REVIEWER.pdf

ENVIRONMENTAL PHYSIOLOGY REVIEWER Environmental Physiology (Physiological Ecology)- is a Photosynthesis and Respiration branch of physiology, a biological discipline that studies the dependence and adaptation or adjustment of an...

ENVIRONMENTAL PHYSIOLOGY REVIEWER Environmental Physiology (Physiological Ecology)- is a Photosynthesis and Respiration branch of physiology, a biological discipline that studies the dependence and adaptation or adjustment of an Photosynthesis-synthesis by green plants creating sugars organism’s physiology to different environmental from carbon dioxide and water, by which the chlorophyll- conditions. containing tissues provide the basic food materials for other Plants Physiology: concerned largely with two topics: processes. mechanisms - how plants sense and respond to 2 phases: environmental change; and Light Dependent Reactions scaling or integration - how are the responses to highly variable conditions. Calvin Cycle Animals Physiology: focused on how animals (mainly Chemical Reaction vertebrates) are adapted, both physiologically and 6H20 + 6CO2+light C6H12O6 + 6O2 behaviourally, to occupy a wide range of environments and to show how these mechanisms are integrated to ensure Evolutionary Solution the survival of the animal. C4 Photosynthesis - C4 pathway evolved as a solution to Plants vs. Animals- animals likely able to escape unfavourable and changing environmental factors such as the inefficiencies of C3 photosynthesis in hot, heat, cold, drought or floods, while plants are unable to dry climates. move away and therefore must endure the adverse conditions or perish (animals go places, plants grow  have specialized leaf anatomy and biochemistry that places). minimize photorespiration. Environmental Management CAM Photosynthesis (Crassulacean Acid Metabolism)  measures to solve or prevent environmental CAM pathway is an adaptation for arid environments where problems. water conservation  involve government policies regarding the is critical. particular issue at hand. Translocation in the Phloem Systemic Approach in Environmental Photosynthate refers to products of photosynthesis. System consists of interdependent parts that make up a whole. The pathway of translocation The Systemic Approach Phloem Systemic approach- refers to an analysis method; a way to ▪ The tissue that translocates the products of photosynthesis. handle a complex system with a global point of view without focalizing on details. Transport of Water in Plants Water in Plant Life  aims for a better understanding of complexity without simplifying reality too much. ▪ Makes up most of the mass of plant cells. Systemic Thinking- considered the problem as a whole ▪ 80-95% of the mass of growing plant tissues and to perceive reality in the same way. Diffusion- random motion The Role of Critical Thinking Skills in Resolving Environmental Issue  causes the net movement of molecules from regions of high concentration to regions of low concentration. Critical thinking- involves the capacity of a person to distinguish between beliefs (what we think is true) and Bulk/Mass Flow- ▪ Pressure driven knowledge (facts supported by observation and valid ▪ Predominant mechanism for long distance transport of experimentation). water. Steps Essential for Critical Thinking Osmosis- Driven by Water Potential gradient A. Gather all Information B. Understand all Terms ▪ Water moves in response to a driving force C. Question how information/facts were derived D. Question the Source ▪ Both concentration and pressure influence the E. Questions the conclusion transport of water. F. Tolerate Uncertainty G. Examine the Big Picture Water transport through the Xylem Thermoregulation Two types of tracheary elements in Xylem: Endotherms create most of their heat via metabolic processes, and are colloquially referred to as “warm- Tracheids - long, slender cells connected to each other by pits. blooded.” Found in all vascular plants. Ectotherms use external sources of temperature to regulate Vessels - shorter, larger diameter cells with completely their body temperatures. Ectotherms are colloquially referred perforated cell wall ends. to as “cold-blooded” even though their body temperatures Cohesion-Tension Theory: (Böhm, 1893; Dixon and Joly, 1894) often stay within the same temperature ranges as warm- blooded animals.  When a water molecule evaporates from the leaf, it creates tension that “pulls” on the entire column of Chapter 3 water, down to the soil. Plant Movements Cohesion-adhesion- theory Tropisms Evaporation (the driving force) Directional growth responses and are permanent. -The lower water potential of air causes evaporation from cell Phototropism walls. The growth of a plant in response to the direction of light Cohesion (in xylem) (light stimuli). Cohesion holds water columns together in capillary-sized xylem Gravitropism elements. The growth of a plant in response Water uptake (from soil) to the influence of gravity. Transpiration Nastic Movement Three types: Nastic Movement are Non-directional plant movements Stomatal transpiration - is the process by which water that are irreversible and repeatable in response to a stimulus whose direction is determined by the anatomy of the plant. vapor is lost from a plant's leaves through tiny pores called 1. Leisurely rhythmic sleep leaf movements in nyctinastic stomata. plants; 2. Very rapid seismonastic movements triggered by Stomata mechanical stimuli, such as shaking, or vibration. ▪ Plants reduce water loss in drought by partially closing 3. Thigmonastic or thigmotropic a rapid response to touch or the stomata. mechanical stimuli. Lenticular transpiration - is the process of water vapor loss Thigmotropism through small openings in the bark of woody plants, known as The growth of a plant in response to contact with a lenticels. solid object. Lenticels are tiny pores found on the stems, branches, and Photoperiodism sometimes on fruits, primarily facilitating gas exchange Physiological response (such as flowering) of plants between the plant and the atmosphere. regulated by the photoperiod or day length with the variations in length of daylight and darkness. Cuticular transpiration - refers to the loss of water vapor from a plant through the cuticle, a waxy layer that covers the outer 1.“Short-day” plants flower rapidly only within a range of surface of leaves and stems in certain plants. photoperiods shorter than a “critical photoperiod” or when daylight is less than a critical length. Guttation is the loss or exudation of water droplets, typically 2.“Long-day” plants flower when daylight is increasing. from the tips or edges of their leaves, caused by root pressure. 3.“Day-neutral” plants do not flower in response to daylight Concept of Homeostasis changes. They flower when they reach a particular stage of The tendency of organisms to regulate and maturity or because of some other cue like temperature or water, etc. maintain relative internal stability. Claude Bernard (1872) The milieu interieur “Constancy of the internal environment is the condition of life” Walter B. Cannon (1871-1945) Sympathetic “flight or fight” response “Homeostasis”. Effects of Light on Reproductive Growth Salinity Florigen (or flowering hormone) is the hypothesized Salinity occurs due to problems like wrong usage of hormone like molecule responsible for controlling agricultural lands, lack of rain, excess evaporation, lack of drainage. and/or triggering flowering process in plants. Halophytes – plants that can grow on soils with high salt PHYTOCHROME content. A blue-green proteinaceous pigment involved in many plant responses to light, independent of photosynthesis. Flooding Temperature Flooding - used to describe the inundation by water of all or part of a plant. avoidance, which includes strategies that prevent the external stress factor from triggering responses that modify Waterlogging - flooding of the root system. plant functioning; Submergence - situation when most or all aerial tissue is tolerance, developed through the activation or even under water. modification of physiological mechanisms that allow the Plant responses to partial submergence plant to either resist stress without the onset of injuries or repair the damage. Anatomical response - generation of aerenchyma in tissues Cryoprotectants facilitates the transport of oxygen from shoots to roots. are substances that help protect plant cells and tissues from damage caused by freezing temperatures. They Morphological level - adventitious rooting and increases prevent the formation of ice crystals inside cells, which can in plant height and consequently, in the proportion of cause cell membranes to rupture. biomass above water level. Types of cryoprotectants: facilitate the oxygenation of submerged tissues through the aerenchyma tissue. Sugars (e.g., sucrose, trehalose) Physiological level - flooding modifies water relations and Amino acids and proteins plants carbon fixation. Polyols Plant water relations Heat shock proteins Flood sensitive species -a few hours after the soil Heat shock proteins are a class of molecular chaperones becomes flooded, the water uptake by roots is reduced. that help protect cells from heat stress by preventing the Photosynthesis responses denaturation (unfolding) of proteins and helping them Reduction of plant carbon fixation. refold correctly. Two Major Strategies Functions of heat shock protein: an escape strategy: LOES -low oxygen escape syndrome. Protein folding implies shoot elongation in order to restore leaf contact Preventing aggregation with the atmosphere. Stress Recovery a sit-and-wait strategy: LOQS - low oxygen quiescence Dwarfing syndrome. Most plant species in cold regions (alpine and artic based on maintaining steady energy conservation without species) evolved a dwarfed habit, either as permanent shoot elongation. feature of the genotype or as a plastic response. Resistance to Toxicity Escape: Where the incidence of toxic stress is seasonal, the active phase of the life cycle coincides with the most favourable season (i.e. phonological escape). Exclusion: the plant absorbs the toxin but acts on it to minimizes its effects within its tissues. This mechanism can involve dilution, chemical inactivation, localization in an active poll, or even excretion. Tolerance: the metabolism of the plant has evolved to function at concentrations of the toxin within the tissues which would otherwise be toxic, particular by the development of distinct isoenzymes. Chapter 4. Responses to Environmental Factors and Stress Gas exchange - in the lungs is one obvious way that the of Animals respiratory system helps maintain homeostasis that occurs in the alveoli in the lungs. Acclimation Temperature Regulation – in humans, one way the body chronic response to experimentally altered or (laboratory dissipates excess heat to maintain homeostasis is through experiment or induced) new habitat environment – exhalation. controlled environment with just a few changes. The mechanics of respiration Acclimatization Respiration is a mechanical response by a number of chronic response to a natural environment muscle complexes to chemical and nerve controls as a (winter/summer, high/low elevation) result of situations that develop in the body: Adaptation Oxygen low situation – when the body needs oxygen defined as an evolution through natural selection leading Carbon dioxide high situation – when the body needs to to an organism whose physiology, anatomy and behavior reduce the amount of carbon dioxide are matched to demands of its environment. Thermoregulation demand – when the heat energy Habituation situation requires a response either to conserve or to remove it from the body The simplest and perhaps the most common type of behavior occurring in many different animals. Vocalization – when the bird needs to communicate by voice. Homeostasis: Thermoregulation Animals use different modes of thermoregulation Terrestrial Animals processes to maintain homeostatic internal body The essential requirement for terrestrial reproduction is temperatures. to keep the eggs and embryos from desiccating. 1. Thermoregulation – the maintenance of Control of Mating Behaviour internal temperature within narrow limits; In insects - mating behavior is often triggered seasonally 2. Osmoregulation – the control of the gain by hormones, but is very much controlled by pheromones. and loss of water and solutes; and, Birds and Mammals 3. Excretion – the disposal of nitrogencontaining wastes. Female mating behaviour (termed estrus in mammals) – initiated by the effects of estrogen on the central nervous Types of Thermoregulation system; it is normally a short period of intense sexual activity. Endotherms create most of their heat via metabolic processes, and are colloquially referred to as “warm- Males - circulating testosterone brings about changes in blooded.” external genitalia and development of secondary characters such as breeding coloration or breeding plumage, and it Greek word (endon) “within” and (thermós) “hot,” may also stimulate specific territorial behaviors and Ectotherms use external sources of temperature to mateattracting behaviors, with both visual components and regulate their body temperatures. acoustic song components. “cold-blooded” Greek word (ektós) “outside” and (thermós) “hot” Homeotherms, Heterotherms, Poikilotherms Homeotherms: animals who maintain a constant internal body temperature within a narrow range of environmental conditions. Heterotherms: animals which usually keep a constant body temperature, but have specific periods where their temperature is different, such as during hibernation. Poikilotherms: animals whose temperature changes depending on the environmental temperature (fish, amphibians, and reptiles, most invertebrates) General System – Respiratory System has a number of very important functions including the provision of oxygen, the removal of carbon dioxide, the removal of excess heat(thermoregulation) as well as vocal communication.