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Life 121 unit 3
| Question | Answer |
|---|---|
| homeostasis | process by which living organisms maintain a stable internal environment |
| regulator | organism that actively controls its internal conditions so they stay relatively constant |
| conformer | organism whose internal conditions change with the external environment |
| distinguish between negative and positive feedback | negative feedback- stabilizes a system positive feedback- intensifies a process |
| set point | normal or target value that the body tries to maintain for a particular condition |
| stimulus | any change in the internal or external environment that triggers a response in an organism |
| sensor | structure that detects a change in the internal or external environment |
| response | reaction of an organism or body system to a change in the environment |
| how do changes externally and internally affect the response of a homeostasis system | external- occurs outside the body and detected by the sensor; body responses like sweating or shivering internal- occurs inside the body; responses like hormone release |
| Compare and contrast the ways that plants and animals are able to respond to external and internal stimuli | plants- stationary, grows toward or away from stimulus, grows toward light animals- mobile, immediate physical or behavioral responses like fleeing and seeking shelter |
| What are the two laws of thermodynamics? | 1st- energy cannot be created or destroyed, only transferred or transformed 2nd- in any energy or transformation, the total entropy (disorder) of an isolated system always increases |
| simple diffusion | movement of particle from an area of high to low concentration without using energy |
| facilitated diffusion | movement of molecules from an area of high to low concentration with the help of proteins without using energy |
| negative feedback | mechanism that reverses a change in a system to maintain stability (homeostasis) |
| positive ffedback | mechanism that amplifies a change in a system, moving it further from its set point |
| stimulatory feedback | signal that starts a reponse |
| inhibitory feedback | signal that stops a response |
| hormones signaling | molecules that can circulate long distances and change cell behavior, secreted from endocrine system, occurs slower, long-term, widespread |
| neural signaling | short distance signals from cell to cell that transmits electrical impulses, occurs rapidly, stops once stimulus is removed, localized |
| peptide hormones and ability to cross membranes | large, polar, hydrophilic that cannot cross a cell membrane, so they bind to cell membrane receptors |
| sterile hormones and ability to cross membranes | small, nonpolar, lipid-soluble that can cross cell membranes, so then they bind to receptors in the cytosol |
| endocrine pathway | stimulus is detected by endocrine system which then releases one hormone that causes a response |
| neuroendocrine pathway | stimulus is detected by neurons that then release a hormone into the blood from the brain, triggering a response |
| hormone cascade | stimulus is detected by hypothalamus which secretes a hormone that stimulates the pituitary gland to release a hormone that affects the body |
| endotherm | maintains constant internal temp |
| ectotherm | internal temp changes with surrounding |
| What are the benefits of being an ectotherm? | do not have to spend as much energy, so metabolic rate is lower |
| What are the benefits of being an endotherm? | can survive in wider range of environments, metabolic rate is higher |
| How does the 1st Law of Thermodynamics relate to metabolism? | all chemical energy in glucose is converted to other forms: ATP (chemical energy) & heat (thermal energy transfer) |
| How does the 2nd Law of Thermodynamics relate to metabolism? | metabolic reactions release heat, affecting body temp in both endotherms & ectotherms (heat increases entropy) |
| What are the resources that plants and animals need to survive? | plants- sunlight, shelter from weather, water, CO2 animals- food, mineral nutrients, shelter, oxygen, water |
| How do plants and animals maintain homeostasis when resources are limited? | plants- close stomata, increase root growth, reduce or increase leaf area, recycle nutrients internally animals- lower metabolic rate, metabolize glycogen stores, reduce sweating, slow metabolism shift to anaerobic pathways, insulation changes |
| Where does photosynthesis, cellular respiration, and transpiration occur? | photosynthesis- chloroplasts cellular respiration- cytoplasm and mitochondria transpiration- leaves, primarily stomata |
| What effect does photosynthesis have on the plant? Cellular respiration? Transpiration? | photosynthesis- builds energy rich molecules and supports growth cellular respiration- releases useable energy for the plant's daily function transpiration- loss of water from leaves, mostly thru stomata creating a force that pulls water up the plant |
| What is the flow of substances through the plant for photosynthesis? Cellular respiration? Transpiration? | Photosynthesis- water (ylem) + CO2 Stomata) = glucose (phloem) + O2 (stomata) CR- glucose (phloem) + O2 = ATP + CO2 (stomata) + water Transpiration- roots to xylem to leaves to stomata to atmosphere |
| What role do xylem and phloem play in plants? | xylem transports water upward and phloem transports sugars throughout the plant |
| difference b/w long and short distance transport in plants | short- cell to cell, membrane level movement, includes all types of membrane transport long- movement driven by pressure gradient, no crossing membrane |
| ion channel | protein embedded in the cell membrane that allows specific ions to move passively accross the membrane |
| proton pump | membrane protein that uses ATP to actively transport H+ ions across a membrane, creating an electrochemical gradient |
| cotransport | active transport where one substance moves down its electrochemical gradient and pulls another substance with it against its gradient |
| osmosis | passive movement of water across a selectively permeable membrane from an area of high-water potential to lower water potential |
| What is moving and in what direction relative to the concentration gradient for each? | osmosis- water moves toward higher solute concentration ion channel- specific ions move from high to low concentration proton pump- H+ ions move against the gradient from low to high cotransport- ion moves down its gradient |
| water potential | how likely water is to move from one place to another; high to low pressure; water potential equals solute potential + pressure potential |
| How does solute potential and pressure potential impact water potential? | solute potential always lowers water potential while pressure potential always raises water potential |
| wilted | when a cell loses turgor pressure because they don't have enough water |
| turgid | when cells are full of water and turgor pressure is high |
| Contrast the ways that plants are able to respond to temperature stress with the responses available to animals | plants- slow biochemical and structural adjustments like heat-shock proteins, membrane changes, and solute acclimation animals- rapid behavioral and physiological mechanisms controlled by the hypothalamus. |
| countercurrent heat exchange | heat-saving mechanism where warm arterial blood flowing outward from the body core runs next to cool venous blood flowing inward from the extremities |
| vasodilation/vasocontraction | dilation- directs warm blood to flow near skin increasing heat loss constriction- vessels divert blood flow deeper into tissue reducing heat loss |
| What is the purpose of shivering/sweating/panting? | shivering generate heat through increased muscle activity, sweating cools the body as sweat evaporates, panting releases heat without losing too much water from the skin |
| What role does the hypothalamus have in regulating body temperature? | detects temp change and activates cooling and warming mechanisms |
| short-term response | rapid, temporary physiological adjustment that helps maintain homeostasis in changing conditions |
| acclimatization | reversible, medium-term physiological adjustment that occurs when on organism is exposed to a new environmental condition |
| adaptation | changes that occur over multiple generations in a population of organisms |
| solute potential | part of water potential that depends on how many solutes are present in the solution |
| pressure potential | physical pressure exerted on water inside a cell |
| Do more solutes mean more higher or lower solute potential? | lower soloute potential |
| What happens if a flaccid cell is placed in a solution with a solute concentration higher than that of the inside of the cell? | net water movement will be out of cell |
| What happens if a flaccid cell is placed in a solution with a solute concentration lower than that of the inside of the cell? | net water movement will be into the cell |
| xylem cells | made of dead, hollow cells that form long tubes running from the roots all the way to the leaves |
| How do xylem cells allow water to move against the force of gravity? | adhesion, cohesion, tension, and the water potential gradient |
| Is transpiration a passive or active (energy-requiring) process? | passive process because of the negative pressure from evaporation at stomata |
| How and why do stomata open and close? | Stomata opens when guard cells are turgid and close when guard cells are flaccid to regulate gas exchange |
| Describe the organismal (internal) and environmental (external) cues that cause plants to open and close their stomata | differences in water potential inside vs outside the cell causing more or less water transported in the cell |
| What minerals are primarily taken in by roots? | hydrogen, nitrogen, phosphorus, calcium |
| How do roots they get oxygen? | through the stomata, roots, and breaking down water |
| To open stomata | transport K+ into cell, decreasing the water potential in cell. This will cause water to flow into the cell, becoming more turgid |
| To close stomata | transport K+ out of cell, increasing water potential in cell. This will cause water to flow out of cell, become more flaccid |
| How do guard cells regulate K+ ion channels? | through changes in membrane potential, creating membrane potential different, which triggers K+ ion channels to open |
| Is K+ ion channel active or passive? | passive |
| Is proton pump channels active or passive? | active |
| Cues that cause stomata to open | circadian rhythm, light at dawn, CO2 depletion |
| Cues that cause stomata to close | circadian rhythm, drought or lack of water |
| What responsibilities does the circulatory system have? | distribute nutrients, deliver gases, remove cellular waste, circulate hormones |
| How do oxygen and carbon dioxide move through the circulatory system? | O2 and CO2 move by simple diffusion across membranes while circulatory system transports them via hemoglobin for O2 and bicarbonate/hemoglobin for CO2 |
| open circulatory system | - hemolymph is circulated to flow around cells, it isn't directed - less energy required - slower and less efficient |
| closed circulatory system | - blood moves through a series of closed tubes which are routed to deliver water, nutrients, and oxygen - higher pressure system - requires more energy |
| What is the pathway that blood follows? | blood is oxygenated at lungs, returns to heart to increase pressure, blood delivers O2 to cells, blood picks up CO2, blood travels back to heart to be re-pressurized, blood travels to lungs to expel CO2 |
| osmoregulation vs osmoconformer | osmoregulation- maintains stable internal solute concentration regardless of external environment osmoconformer- internal solute concentration matches the external environment |
| nitrogenous waste excretion | animals convert or eliminate toxic ammonia as ammonia, urea, or uric acid depending on environment, water availability, and adaptations |
| digestion | breaking down food into absorbable molecules the body can use for energy, growth, and maintenance |
| glucose homeostasis | insulin lowers blood glucose by promoting storage and uptake, while glucagon raises blood glucose by releasing stored fuel — together they maintain a stable internal environment |
| What is the flow of glucose, water, proteins, and urea? | glucose: SI-blood-liver-blood-all cells-used for ATP water: SI + LI-blood + tissues-cells + kidneys-excreted proteins: SI-blood-liver-blood-all cells-build proteins urea: liver-blood-kidneys-excreted in urine |
| countercurrent | blood always has less O2 than water, so there is more consistent diffusion of O2 from water to blood |
| concurrent | stronger gradient at first, but then by midway through the capillary, the O2 concentration is similar b/w water and blood |
| single vs double circulatory systems in vertebrates | single- simple, low pressure, used by fish double- more complex, supports higher metabolism, used by land vertebrates |
| challenges in conducting gas exchange in water vs air | water-oxygen is dissolved in water, low efficiency, high energy cost, conducted in gills, skin, and lungs air- atmospheric oxygen, higher efficiency, lower energy cost, conducted in lungs and tracheae |
| How and why adaptations in mammals and birds relate to increased circulatory efficiency? | mammals and birds evolved a fully separated, high-pressure, double circulatory system because endothermy requires extremely efficient oxygen delivery to support high metabolic rates |
| Why did natural selection favor these adaptations in endotherms? | because they allowed endotherms to sustain high metabolic rates, stay active in diverse environments, and outcompete organisms with less efficient oxygen delivery systems |
| Explain how regulation of breathing is related to homeostasis of blood pH | breathing regulates blood pH by controlling CO₂ levels; faster breathing removes CO₂ to raise pH, while slower breathing retains CO₂ to lower pH, keeping the body in homeostasis |
| filtration | contents of blood pushed from blood vessel to kidney tubule |
| reabsorption | valuable substances removed from the filtrate to go back into the body |
| secretion | toxins and excess ions extracted from body fluids and go into tubule |
| excretion | the filtrate will leave the body as urine |
| Explain how counter-current exchange in the kidney and the production of anti-diuretic hormone by the brain impacts kidney functions and blood osmolarity | counter‑current exchange creates a strong osmotic gradient that allows water to be reabsorbed, and ADH adjusts how much water is reclaimed |
| membrane transport and effect on blood and urine osmolarity | membrane transport in the nephron creates osmotic gradients, and ADH controls water permeability in the collecting duct; together they determine how much water is returned to the blood |
| kidney nephron structure/function and effect on blood and urine osmolarity | nephron uses selective membrane transport to create an osmotic gradient, and ADH determines how much water is reabsorbed in the collecting duct |
| osmoregulation homeostasis and effect on blood and urine osmolarity | by adjusting water reabsorption in the nephron—ADH increases water retention when blood osmolarity is high, producing concentrated urine, while low ADH leads to dilute urine and restores normal blood osmolarity |
| nitrogenous waste and effect on homeostasis | removed ammonia, kidneys regulate concentration, urea recycling created a medullary gradient, and urea and ADH determine how much water is absorbed |
| What is transported by phloem and what is the movement of sap within the phloem? | phloem transports sugars and other organic molecules, and sap moves by pressure‑driven bulk flow from sources (where sugars are loaded) to sinks (where sugars are used or stored) |
| How is this directionality related to photosynthesis? | photosynthesis loads sugars into the phloem in leaves, creating high pressure that drives sap toward low‑pressure sinks like roots, fruits, and growing tissues |
| sugar sources vs sinks | sources (high sugar con.)- fully mature leaves, roots/storage structures at start of growing season, seeds sinks (low sugar con.)- roots and storage structures when leaves are sources, new devoloping leaves/buds, flowers/fruits |
| Why does directionality of flow of phloem sap change seasonally for certain plant structures? | direction of phloem sap flow reverses b/w roots and leaves based on the storage of sources or sinks which changes during different seasons |
| describe movement in which phloem operates | phloem operates by pressure‑driven bulk flow, moving sap from high‑pressure sources to low‑pressure sinks |
| How is the movement of sugars from sources to sinks reliant on various transport mechanisms? | sugars move from sources to sinks because active transport loads sucrose into phloem, osmosis raises pressure, bulk flow pushes sap through sieve tubes, and unloading at sinks lowers pressure |
| ingestion | how food gets into the body |
| mechanical digestion | physically breaking up food through chewing |
| chemical digestion | enzymes break down molecules |
| intracellular vs extracellular digestion | intracellular- food particles are engulfed by phagocytosis then digested in food vacuoles extracellular- enzymes are secreted into a gastrovascular cavity then nutrients are absorbed by cells |
| absorption | small molecules resulting from digestion are absorbed into the bloodstream |
| elimination | undigested material passes out via feces |
| How do the microvilli facilitate adaptive digestive function? | by maximizing surface area and optimizing nutrient capture |
| How does the proximity to the circulatory system facilitate adaptive digestive function? | rapid transport of absorbed nutrients, maintenance of steep diffusion gradient, support of high metabolic activity of intestinal cells, fast integration into whole-body homeostasis, enables more complex digestive systems |
| How do nutrients in food get processed then transported to different parts of the body? | broken down, nutrients are absorbed, processed, then distributed for energy or storage |
| examples of source and sink pairs | mature leaves (source) and roots (sink), roots (sources) and leaf buds (sink), and bulbs (source) and flowers (sink) |
| explain connections among digestion, cell respiration, metabolic rate, and thermoregulation | digestion supplies nutrients for respiration, respiration generates ATP and heat which defines metabolic rate, and the heat is used for thermoregulation |
| explain why glucose homeostasis is important, how it is maintained via hormone regulation, apply homeostasis terms and feedback terms to this system | it is important because cells, especially in the brain, depend on stable glucose levels; pancreases maintain this stability through a negative feedback loop in which insulin lowers high glucose and glucagon raises low glucose |
| explain how diabetes disrupts the glucose homeostasis system | the insulin-based negative feedback loop fails, and the body can either not produce insulin (type 1) or the cells do not respond to it (type 2) |
| xylem | long distance bulk flow via negative pressure, movement is driven by transpiration, passive flow through connective b/w cells within the xylem, movement in and out of xylem is passive |
| phloem | long distance bulk flow via positive pressure, movement can be up or down but always source to sink, passive flow through connection b/w cells within the phloem, loading is active or passive, water flows down gradient |
| complete vs incomplete gut | complete- digestive system with a mouth and anus incomplete- digestive system with one opening that serves as both the mouth and anus |
| How does diabetes disrupt homeostasis? | decreased sensitivity to insulin |
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