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Biological Systems Pt. 2

Biological Systems Pt. 2. Responses to Environmental Stimuli Note: This section will utilize lots of prior knowledge and questioning. Feedback Loops and Homeostasis. Responses to Stimuli Recommended Reading: OpenStax Chapter 24.3 (Homeostasis). Positive and Negative Feedback Loops.

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Biological Systems Pt. 2

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  1. Biological Systems Pt. 2 Responses to Environmental StimuliNote: This section will utilize lots of prior knowledge and questioning.

  2. Feedback Loops and Homeostasis Responses to Stimuli Recommended Reading: OpenStax Chapter 24.3 (Homeostasis)

  3. Positive and Negative Feedback Loops • Environmental Science 20 connection: Do you remember discussing this? • What did it involve? Bozeman Science – Positive and Negative Feedback Loops

  4. Negative feedback loops • Temperature regulation (how do we cool or warm up?) • Feedback can be a good or bad thing – negative feedback loops negate more feedback. • Negative feedback loops can help us maintain homeostasis. • An example of a negative feedback loop is:

  5. Negative feedback loopsA leads to B which cancels out A. • Temperature regulation (how do we cool or warm up?) • Feedback can be a good or bad thing – negative feedback loops negate more feedback. • Negative feedback loops can help us maintain homeostasis. • An example of a negative feedback loop is: We sweat to cool ourselves off back to an optimal functioning temperature.

  6. Positive feedback loop • Amplification of a signal or response bya response. • Ripening of fruit – how does this happen? • Lactation in mammals is a positive feedback loop – how does this happen?

  7. Positive feedback loopA leads to Bwhich leads to more of A. • Amplification of a signal or response bya response. • Ripening of fruit – how does this happen?Ethlyene is released by ripening fruit which triggers the ripening process (causing yellowing-browning of bananas or “redding” of apples), this triggers the release of even more ethylene • Lactation in mammals is a positive feedback loop – how does this happen?When mammals breastfeed, it triggers the release of prolactin which stimulates the production of milk, which is further stimulated as their offspring breastfeed

  8. Consequences of feedback alteration If we alter some of these feedback loops in our body, complications can arise. • Diabetes mellitus in response to decreased insulin. (how does this relate to feedback loops getting altered?) • Graves’ disease (hyperthyroidism) - (how does this relate to feedback loops getting altered?) • Blood clotting (why is it good, why is it bad)?

  9. Environment Influences Homeostasis - Cell • Certain cell activities are affected by the interaction between biotic and abiotic factors. • Anyone remember/know what biofilm is? (Look it up, how might it relate – what factors trigger its growth?) • How might sunlight trigger cell activity?

  10. Environment Influences Homeostasis - Cell • Certain cell activities are affected by the interaction between biotic and abiotic factors. Photosynthesis – what abiotic factor(s) might influence cell activity? Sunlight! • Anyone remember/know what biofilm is? (Look it up, how might it relate – what factors trigger its growth?) • How might sunlight trigger cell activity?

  11. Environment Influences Homeostasis - Organism • Organismal activities are affected by the interaction between biotic and abiotic factors. • Symbiotic relationships are relationships between organisms in which there is some form of benefit/deficit or effects borne of their interactions • Come up with an example of these symbiotic relationships: Mutualistic,Commensalistic; andParasitic Bozeman Science – Biotic and Abiotic Factors

  12. Environment Influences Homeostasis - Community • The community of organisms in an ecosystem are affected by the interaction between biotic and abiotic factors. • Much like we observed in our labs – there is an ebb and flow based on increased/decreased abiotic/biotic factors in a population.

  13. Homeostasis -Varying Mechanisms for Nutrient Uptake and Waste Elimination Choose one of the ideas and compare two organisms (Fish Example) • What is the difference in gas exchange/respiratory systems between aquatic and terrestrial plants/animals? • Waste production and removal in aquatic vs terrestrial animals? • What is the difference between two animals gastrovascular cavities for nutrient absorption (are there any that ingest the same way they eliminate)? Most organ systems (health science 20) support homeostasis in some capacity,but a diversity exists in how this looks organism-organism.

  14. HomeostasisOsmoregulation (OpenStax AP Biology - Chapter 32.1) in Microbes/Fish • To maintain homeostasis, some organisms use osmoregulation to maintain their osmotic pressure inside their cells. Osmoregulation is the adjustment of the concentration of solute within cells. • This can be done by adjusting their ________________ in their cells! • Why are some fish only freshwater fish (or saltwater fish)? How can some fish be freshwater and saltwater?

  15. HomeostasisOsmoregulation (OpenStax AP Biology - Chapter 32.1) in Microbes/Fish • To maintain homeostasis, some organisms use osmoregulation to maintain their osmotic pressure inside their cells. • This can be done by adjusting their salt concentrations in their cells! • Why are some fish only freshwater fish (or saltwater fish)? How can some fish be freshwater and saltwater? Fish need to maintain certain concentrations of solute to maintain homeostasis with their environment so that their cells do not shrink or inflate

  16. AP Free Response Question Sample

  17. Zebra Mussels in SK • What are zebra mussels? • https://www.saskatchewan.ca/residents/environment-public-health-and-safety/wildlife-issues/invasive-species/clean-drain-and-dry-your-boat • Any fishers? Do you ever read the guide? • http://bcinvasives.ca/news-events/recent-highlights/zebra-mussels-pose-threat-to-saskatchewan-waters/ • Invasive species can disrupt homeostasis in ecosystems – how so (consider our lab)?

  18. Zebra Mussels in SK • What are zebra mussels? • https://www.saskatchewan.ca/residents/environment-public-health-and-safety/wildlife-issues/invasive-species/clean-drain-and-dry-your-boat • Any fishers? Do you ever read the guide? • http://bcinvasives.ca/news-events/recent-highlights/zebra-mussels-pose-threat-to-saskatchewan-waters/ • Invasive species can disrupt homeostasis in ecosystems – how so (consider our lab)? • They may outcompete organisms currently living in that environment, which affects the distribution of energy through the ecosystem. We typically want to maintain ecosystem homeostasis (stability).

  19. Immune System An example of responses to stimuli. Recommended Reading: Chapter 33 of OpenStax AP Biology Text

  20. Disruptions to homeostasis affects health • What does our body do when we get sick? • Why? • Are there certain things our bodies do that are “non-specific” immune responses or our first line of defence (not long term immunity)?

  21. Disruptions to homeostasis affects health • What does our body do when we get sick? Fatigue, fever, mucous generation/congestion, coughing, diarrhea, vomiting • Why?Fever – raises internal body temperature providing a less ideal environment for pathogen. • Are there certain things our bodies do that are “non-specific” immune responses or our first line of defence (not long term immunity)?Yes – many things occur that are simply responses to mostforeign invaders (mucous generation, fever, etc).

  22. Mammalian Immune Response • Cell mediated - is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. (1) • Humoral - is the aspect of immunity that is mediated by macromolecules found in extracellular fluids such as secreted antibodies, complement proteins, and certain antimicrobial peptides. (2)

  23. Comparing Immunity • Cell-mediated - Cytotoxic T-Cells, a lymphocytic white blood cell, “target” intracellular pathogens when antigens are displayed on the outside of cells. • Humoral response – B Cells – a type of lymphocytic white blood cell. • Antigens are recognized by antibodies specific to the antigen. Antibodies are proteins created by B cells. Second exposure to a similar antigen promotes a quicker immune response.

  24. Crash Courses: Immune SystemTake notes from each!

  25. Crash Courses: Immune SystemTake notes from each! • Skin, mucous membranes, and fever are innate defences • Many specialized cells exist to eliminate faulty cells or pathogens and this occurs through the release and use of enzymes and proteins. • Adaptive immune system has the ability to remember specific pathogens through the creation of antibodies.

  26. Comparison of Adaptive Immunity

  27. Flu Shots and Vaccinations • How do they work? Neutralized virus introduced – adaptive immune system develops resistance. • Do they work?Overall success is subject to the virus targeted due to multiple strains and mutations – however it can work very well for many viruses. • Herd Immunity https://www.youtube.com/watch?v=IMC9auZGnZk

  28. Flu Shots and Vaccinations • How do they work? • Do they work? • Herd Immunity https://www.youtube.com/watch?v=IMC9auZGnZk

  29. Herd Immunity and Bill Nye • Scope out – we can see these immunities on an organismal scale – but how does this affect the population? • Netflix: Bill Nye Saves the World – Anti-Vaxxers

  30. Specialization and Responses Occurs at the level of the cellular, organismal, and communities of organisms.

  31. Response at the Cellular LevelCell Differentiation/Specialization • For Immunity – how do our cells become different from one another (ex. neutrophils and phagocytes)? • Why/how do we have muscle cells, brain cells, skin cells? • Do all our cells have the same DNA?

  32. Response at the Cellular LevelCell Differentiation/Specialization • For Immunity – how do our cells become different from one another (ex. neutrophils and phagocytes)?Different parts of our DNA are read and used to make different cells. • Why/how do we have muscle cells, brain cells, skin cells?Different function. • Do all our cells have the same DNA?In general, yes (except for gametes).

  33. Response at the Cellular LevelSpecialization • Our cells differentiate/specialize over time due to different molecular triggers or signalling during our growth (this “activates” certain parts of our DNA – connected to genetic expression). • This includes the process of our development from embryo to fetus.

  34. Response at the Cellular LevelGenetic Expression(More of this next Unit) • Different triggers exist that cause these developments to occur in sequences. • Many of these triggers cause transcription (creation of specific proteins)to occur, causing different anatomical structures to form. (This is similar in plants when seeds germinate in certain temps and moisture). • Specific genes that regulate this are called homeotic. • For proper embryonic development, specific homeotic genes need to activate in a certain order. • If mutated, we may see drastic changes in the phenotype of the organism. • Part of what helps this is microRNAs. • Some of these triggers even cause our own cells to die. More on the italicized terms in our genetics unit.

  35. Response at the Cellular LevelApoptosisProgrammed Cell Death (OpenStax AP Biology pg 385) • Programmed cell death also helps in our development! • Additional, “unnecessary” growth gets stopped or countered. • Fingers don’t extend out when connected early on, the cells between the digits die. • It might seem wasteful to kill cells our body made, but the macromolecules are recycled.

  36. Response at the Organismal LevelInnate behaviour vs learned behaviour Organisms respond to changes in their environment on a cellular, system-based, and organism-organism level. This normally takes the form of behaviours. • Innate – • Learned – • Sometimes this is hard to differentiate: Is migration learned or innate?

  37. Response at the Organismal LevelInnate behaviour vs learned behaviour Organisms respond to changes in their environment on a cellular, system-based, and organism-organism ways. This normally takes the form of behaviours.Behaviour is the change in activity of an organism in response to a stimulus. • Innate – born with • Learned – observed NATURE VS NURTURE • Sometimes this is hard to differentiate: Is migration learned or innate?

  38. Organismal Response (why and how?) Many different organismal responses exist, how do they work?Try the Ctrl+F (find) function with the OpenStax text to look up one of these terms • Photoperiodism (why do flowers open at certain times?) • Phototropism (how do plants grow towards light?) • Hibernation and migration (how do organisms “know” where to migrate?) • Taxis and kinesis - Chemotaxis in bacteria • Nocturnal and diurnal activity: circadian rhythms (internal clocks) • Shivering/sweating (why, and how?)

  39. Organismal Response (why and how?) Many different organismal responses exist, how do they work?Try the Ctrl+F (find) function with the OpenStax text to look up one of these terms • Photoperiodism (why do flowers open at certain times?) – photoreceptor proteins – if they are triggered, it causes blooming (think of phototsynthesis). • Phototropism (how do plants grow towards light?) – growth hormones are triggered and the shady side of plants grow to bend the plant towards the light source • Hibernation and migration (how do organisms “know” where to migrate?) – based on temperature changing, it triggers different “thoughts”/behaviours in organism • Taxis and kinesis - Chemotaxis in bacteria – chemical “sensing” triggers movement • Nocturnal and diurnal activity: circadian rhythms (internal clocks) – proteins responsible for sensing light/time of day trigger behaviour such as a desire to sleep/wake up. • Shivering/sweating (why, and how?) – nerves responsible for cold-sensing trigger the brain to make muscles move “shiver” to generate heat.

  40. Organismal ResponseEnvironmental Responses • The environment triggers molecular signals in plants- Phototropism - - Photoperiodism - • Internal and external signals regulate and cause certain physiological responses (ie. Affect homeostasis). • Is working night shifts good for our health? • Is jet lag a thing? How does it work?

  41. Health effects of shift work and extended hours of workhttp://oem.bmj.com/content/58/1/68 Give this article a read – highlight or write out at least five points that stood out from the post to share in small group discussion. This is what most peer-reviewed scientific articles look like (ish). WHAT IS THE EVIDENCE TO SUPPORT/GO AGAINST SHIFT WORK?

  42. Organismal Response - Environmental triggers • Just like sunlight and time of day, different environmental triggers exist for bacteria, fungi, and protists (different types of organisms – mostly unicellular)! • Some bacteria practice quorum sensing. • Quorum sensing involves this environmental triggering that we’ve talked about, except they release molecules that also trigger responses in nearby bacteria potentially leading to vast increases in population density, like biofilm!

  43. Organismal-Community ResponseCoordination amongst organisms and mechanisms • Organismal communication allows organism’s to respond and act on different environment triggers (which can be biotic or abiotic) molecularly and behaviourally. • Innateresponses are ones we inherit genetically, learning occurs through the interactions organisms have with the environment and organisms - do you think biofilm would be innate or learned? • What are some examples of innate responses/behaviours vs learned responses/behaviours? (5 each)

  44. Organismal-Community ResponseInnate vs Learned Behaviour(both still involve a molecular response) Innate Learned

  45. Organismal-Community ResponseInnate vs Learned Behaviour(both still involve a molecular response) Innate Learned Prairie dogs sounding the alarm (yelling) – habituation Birds following fish Dog rings a bell to go outside Waking up at the same time every morning. Sharing (learned social skill) • Spider spinning a web • Bird building a nest • Smiling • Breathing • Regurgitation

  46. Connecting Responses to Natural Selection • Which of the previous traits we listed may see a variety of outcomes that may be vital in terms of natural selection? • Phototropism = the plants ability to respond to light maximizes its exposure to leaves. • Photoperiodism = amount of light helps regulate flowering and preparation for winter (less light, lower temp = prep for winter). Bozeman Science – Behaviour and Natural Selection

  47. Connecting Responses to Natural Selection- Organism • An organism’s ability to respond to environmental cues are vital to their reproduction, survival, and natural selection. • What happens if… Frogs don’t hibernate? Turtles don’t estivate? Canadian Geese don’t migrate? Humans don’t “court” one another?

  48. Connecting Responses to Natural Selection- Community • An organism’s ability to cooperate with other organisms can be vital to their reproduction, survival, and natural selection. • What happens if… Bees don’t pollinate? Probiotics don’t help us digest?

  49. Access AP Biology Curriculum (Course and Exam Description) Let’s go over Big Idea 2 to confirm we’ve covered everything we need to cover!

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