BIO 220 biome, ecosystem and symbiosis post: a guide
The prompt lists predator-prey among its examples of symbiosis, and it is the one example that is not symbiosis. Choosing a different relationship is the easiest mark here.
Editorial process
Last reviewed · August 10, 2026
What does this biome and symbiosis discussion require?
Three things are being asked and the first one is a nesting relationship rather than two separate choices. Select a global biome, then select an ecosystem found inside it, which means your two answers have to fit together. The prompt's own parenthesis gives you the biome options: grassland, forest, desert. An ecosystem is a particular place within one of those, defined by its living and non-living components, so the tallgrass prairie of the North American interior is an ecosystem within the grassland biome, and the Sonoran Desert is an ecosystem within the desert biome. Naming a biome twice, or naming a continent, is the commonest way to lose the first half of this. Be specific enough that the plants and animals you list next actually live in one place together, because the second half of the prompt will expose a choice that was too broad. If you cannot picture standing in it, the unit you have named is probably still a biome.
The species question is asking you to demonstrate that your ecosystem is real rather than generic. What kind of animals and plants would you expect to make up that ecosystem is an invitation to name organisms, and a post that says grasses, small mammals and birds of prey could be describing any grassland on earth. Give actual names, and give them at more than one level: the dominant plants, a few herbivores, a predator or two, and if you can, a decomposer, since decomposers are almost always omitted and their absence is noticeable to anyone marking ecology. Four or five named species with a sentence on what each does in the system is worth far more than a longer list of categories, and it also gives you material for the symbiosis question that follows.
The third part contains a mistake in the prompt itself, and spotting it is the single easiest way to lift this post. It asks for one symbiotic relationship and offers mutualism, commensalism and predator-prey as examples. The first two are symbiotic relationships. Predator-prey is not: symbiosis describes organisms living in close, persistent association, and the recognised categories are mutualism, where both partners benefit, commensalism, where one benefits and the other is unaffected, and parasitism, where one benefits at the other's expense. A predator does not live in association with its prey; it eats it. Choose mutualism or commensalism, and if you want to be diplomatic about it, note in passing that predation is an ecological interaction rather than a symbiosis, since the two are often taught together and the distinction is worth stating rather than assuming. Getting this right costs you one sentence and it is the clearest signal in the post that you understood the terms rather than matched them.
Good examples are easy to find once you know what you are looking for, and the strongest ones are specific to your ecosystem rather than borrowed from a textbook. In arid systems, the relationship between yucca plants and yucca moths is obligate mutualism: the moth is the plant's only pollinator and the plant is the moth larvae's only food. In grasslands, the mycorrhizal association between fungi and grass roots is mutualism at the scale of the whole system, with the fungus extending the root's reach for water and phosphorus in exchange for sugars. In forests, epiphytes growing on branches are the standard commensalism, gaining height and light while the tree is unaffected. Describe what each partner gets, because a relationship named without its costs and benefits has not been classified, only labelled. The classification is the whole point of the question: mutualism and commensalism differ only in whether the second partner is affected, so you cannot tell them apart without saying what happens to that partner.
One further point will make the post read as more than an exercise, and it is genuinely current ecology rather than embellishment. These categories are not as sharp as the definitions suggest. The literature increasingly treats mutualism, commensalism and parasitism as a continuum along which a relationship can move, depending on conditions and on the stage of the organisms' life histories. A fungus that is mutualistic with a plant in nutrient-poor soil can behave parasitically when nutrients are abundant and the plant no longer needs it. Adding one sentence to that effect, with a source, distinguishes a post that has read about symbiosis from one that has memorised three definitions. It also gives your peers something to reply to, which matters if participation is graded separately from the initial post, as it usually is in this course.
On format, this is a discussion post rather than a paper, so aim for the substance and length your course specifies for an initial response and keep it structured. Three short paragraphs will do: the biome and ecosystem, the species, and the symbiotic relationship with its costs and benefits. Cite at least one source, and prefer one specific to your ecosystem over a general ecology reference, because the specific one supports the part of the post a marker cannot check from memory. If your course expects replies to peers, the easiest substantive reply is to classify somebody else's chosen relationship, or to point out gently where the predator-prey example belongs. Both are substantive contributions in the sense the participation rules mean, because both add something the original post did not contain rather than agreeing with it.
Likely learning objectives
Inferred from the brief — check these against your own rubric.
- 01Nest the chosen ecosystem correctly inside the chosen biome.
- 02Name real species rather than categories of organism.
- 03Include a decomposer, which is almost always omitted.
- 04Classify a relationship as symbiosis correctly, excluding predation.
- 05Describe what each partner gains or loses rather than only naming the relationship.
- 06Note that these categories sit on a continuum rather than in fixed boxes.
Read the full question
Review every instruction before using the planning guidance that follows.
Course-wide instructions that accompany this question
Important information for writing discussion questions and participation Hi Class, Please read through the following information on writing a Discussion question response and participation posts. Contact me if you have any questions. Important information on Writing a Discussion Question Your response needs to be a minimum of 150 words (not including your list of references) There needs to be at least TWO references with ONE being a peer reviewed professional journal article. Include in-text citations in your response Do not include quotes—instead summarize and paraphrase the information Follow APA-7th edition Points will be deducted if the above is not followed Participation –replies to your classmates or instructor A minimum of 6 responses per week, on at least 3 days of the week. Each response needs at least ONE reference with citations—best if it is a peer reviewed journal article Each response needs to be at least 75 words in length (does not include your list of references) Responses need to be substantive by bringing information to the discussion or further enhance the discussion. Responses of “I agree” or “great post” does not count for the word count. Follow APA 7th edition Points will be deducted if the above is not followed Remember to use and follow APA-7th edition for all weekly assignments, discussion questions, and participation points. Here are some helpful links Student paper example Citing Sources The Writing Center is a great resource Welcome to class Hello class and welcome to the class and I will be your instructor for this course. This is a -week course and requires a lot of time commitment, organization, and a high level of dedication. Please use the class syllabus to guide you through all the assignments required for the course. I have also attached the classroom policies to this announcement to know your expectations for this course. Please review this document carefully and ask me any questions if you do. You could email me at any time or send me a message via the “message” icon in halo if you need to contact me. I check my email regularly, so you should get a response within 24 hours. If you have not heard from me within 24 hours and need to contact me urgently, please send a follow up text to. I strongly encourage that you do not wait until the very last minute to complete your assignments. Your assignments in weeks 4 and 5 require early planning as you would need to present a teaching plan and interview a community health provider. I advise you look at the requirements for these assignments at the beginning of the course and plan accordingly. I have posted the YouTube link that explains all the class assignments in detail. It is required that you watch this 32-minute video as the assignments from week 3 through 5 require that you follow the instructions to the letter to succeed. Failure to complete these assignments according to instructions might lead to a zero. After watching the video, please schedule a one-on-one with me to discuss your topic for your project by the second week of class. Use this link to schedule a 15-minute session. Please, call me at the time of your appointment on my number. Please note that I will NOT call you. Please, be advised I do NOT accept any assignments by email. If you are having technical issues with uploading an assignment, contact the technical department and inform me of the issue. If you have any issues that would prevent you from getting your assignments to me by the deadline, please inform me to request a possible extension. Note that working fulltime or overtime is no excuse for late assignments. There is a 5%-point deduction for every day your assignment is late. This only applies to approved extensions. Late assignments will not be accepted. If you think you would be needing accommodations due to any reasons, please contact the appropriate department to request accommodations. Plagiarism is highly prohibited. Please ensure you are citing your sources correctly using APA 7th edition. All assignments including discussion posts should be formatted in APA with the appropriate spacing, font, margin, and indents. Any papers not well formatted would be returned back to you, hence, I advise you review APA formatting style. I have attached a sample paper in APA format and will also post sample discussion responses in subsequent announcements. Your initial discussion post should be a minimum of 200 words and response posts should be a minimum of 150 words. Be advised that I grade based on quality and not necessarily the number of words you post. A minimum of TWO references should be used for your initial post. For your response post, you do not need references as personal experiences would count as response posts. If you however cite anything from the literature for your response post, it is required that you cite your reference. You should include a minimum of THREE references for papers in this course. Please note that references should be no more than 5 years old except recommended as a resource for the class. Furthermore, for each discussion board question, you need ONE initial substantive response and TWO substantive responses to either your classmates or your instructor for a total of THREE responses. There are TWO discussion questions each week, hence, you need a total minimum of SIX discussion posts for each week. I usually post a discussion question each week. You could also respond to these as it would count towards your required SIX discussion posts for the week. I understand this is a lot of information to cover in 5 weeks, however, the Bible says in Philippians 4:13 that we can do all things through Christ that strengthens us. Even in times like this, we are encouraged by God’s word that we have that ability in us to succeed with His strength. I pray that each and every one of you receives strength for this course and life generally as we navigate through this pandemic that is shaking our world today. Relax and enjoy the course! BIO 220 Week 2 Discussion 1 What kind of animals and plants would you expect to make up that ecosystem Grid View List View Excellent Point range: 90–100 Good Point range: 80–89 Fair Point range: 70–79 Poor Point range: 0–69 In 4 or 5 sentences, describe the anatomy of the basic unit of the nervous sytem, the neuron. Include each part of the neuron and a general overview of electrical impulse conduction, the pathway it travels, and the net result at the termination of the impulse. Be specific and provide examples. 12 (16%) – 13 (17.33%) The response accurately and clearly describes in detail the anatomy of the neuron. The response accurately and clearly describes in detail each part of the neuron, and it includes a detailed explanation of the general overview of electrical impulse conduction, the pathway it travels, and the net result at the termination of the impulse. Examples fully support the response provided. 11 (14.67%) – 11 (14.67%) The response accurately describes the anatomy of the neuron. The response accurately describes each part of the neuron, and it includes a general overview of electrical impulse conduction, the pathway it travels, and the net result at the termination of the impulse. Examples support the response provided. 10 (13.33%) – 10 (13.33%) The response provides an inaccurate or vague description of the anatomy of the neuron. The response inaccurately or vaguely describes each part of the neuron, and it includes an inaccurate or vague overview of electrical impulse conduction, the pathway it travels, and the net result at the termination of the impulse. Examples vaguely support the response provided. 0 (0%) – 9 (12%) The response provides an inaccurate or incomplete description of the anatomy of the neuron, or is missing. The response inaccurately or incompletely describes each part of the neuron, and it includes an inaccurate or vague overview of electrical impulse conduction, the pathway it travels, and the net result at the termination of the impulse, or is missing. Examples do not support the response provided, or is missing. Answer the following (listing is acceptable for these questions): a. What are the major components that make up the subcortical structures? b. Which component plays a role in learning, memory, and addiction? c. What are the two key neurotransmitters located in the nigra striatal region of the brain that play a major role in motor control? 12 (16%) – 13 (17.33%) The response accurately and clearly details the major components that make up the subcortical structures. The response accurately and clearly details which component plays a role in learning, memory, and addiction. The response accurately and clearly identifies the two neurotransmitters located in the nigra striatal region of the brain that play a major role in motor control. 11 (14.67%) – 11 (14.67%) The response accurately identifies the major components that make up the subcortical structures. The response accurately identifies which component plays a role in learning, memory, and addiction. The response accurately identifies the two neurotransmitters located in the nigra striatal region of the brain that play a major role in motor control. 10 (13.33%) – 10 (13.33%) The response inaccurately identifies the major components that make up the subcortical structures. The response inaccurately identifies which component plays a role in learning, memory, and addiction. The response inaccurately identifies two neurotransmitters located in the nigra striatal region of the brain that play a major role in motor control. 0 (0%) – 9 (12%) The response inaccurately and incompletely identifies the major components that make up the subcortical structures, or is missing. The response inaccurately and incompletely identifies which component plays a role in learning, memory, and addiction, or is missing. The response inaccurately and incompletely identifies two neurotransmitters in the nigra striatal region of the brain that play a major role in motor control, or is missing. In 3 or 4 sentences, explain how glia cells function in the central nervous system. Be specific and provide examples. 12 (16%) – 13 (17.33%) The response accurately and clearly explains in detail how glia cells function in the central nervous system. Examples fully support the response provided. 11 (14.67%) – 11 (14.67%) The response accurately explains how glia cells function in the central nervous system. Examples support the response provided. 10 (13.33%) – 10 (13.33%) The response inaccurately or vaguely explains how glia cells function in the central nervous system. Examples inaccurately or vaguely support the response provided. 0 (0%) – 9 (12%) The response inaccurately and vaguely explains how glia cells function in the central nervous system, or is missing. Examples do not support the response provided, or is missing. The synapse is an area between two neurons that allows for chemical communication. In 3 or 4 sentences, explain what part of the neurons are communicating with each other and in which direction does this communication occur? Be specific. 12 (16%) – 13 (17.33%) The response accurately and clearly explains in detail the part of the neurons that communicate with each other and the direction in which this communication occurs. 11 (14.67%) – 11 (14.67%) The response accurately explains the part of the neurons that communicate with each other and the direction in which this communication occurs. 10 (13.33%) – 10 (13.33%) The response inaccurately or vaguely explains the part of the neurons that communicate with each other and the direction in which this communication occurs. 0 (0%) – 9 (12%) The response inaccurately and vaguely explains the part of the neurons that communicate with each other and the direction in which this communication occurs, or is missing. In 3–5 sentences, explain the concept of “neuroplasticity.” Be specific and provide examples. 12 (16%) – 13 (17.33%) The response accurately and clearly explains in detail the concept of neuroplasticity. Examples provided fully support the response provided. 11 (14.67%) – 11 (14.67%) The response accurately explains the concept of neuroplasticity. Examples provided support the response provided. 10 (13.33%) – 10 (13.33%) The response inaccurately or vaguely explains the concept of neuroplasticity. Examples inaccurately or vaguely support the response provided. 0 (0%) – 9 (12%) The response inaccurately and vaguely explains the concept of neuroplasticity, or is missing. Examples do not support the response provided, or is missing. Written Expression and Formatting – English writing standards: Correct grammar, mechanics, and proper punctuation 5 (6.67%) – 5 (6.67%) Uses correct grammar, spelling, and punctuation with no errors. 4 (5.33%) – 4 (5.33%) Contains a few (1 or 2) grammar, spelling, and punctuation errors. 3.5 (4.67%) – 3.5 (4.67%) Contains several (3 or 4) grammar, spelling, and punctuation errors. 0 (0%) – 2 (2.67%) Contains many (≥ 5) grammar, spelling, and punctuation errors that interfere with the reader’s understanding. Written Expression and Formatting – The paper follows correct APA format for title page, headings, font, spacing, margins, indentations, page numbers, 5 (6.67%) – 5 (6.67%) Uses correct APA format with no errors. 4 (5.33%) – 4 (5.33%) Contains a few (1 or 2) APA format errors. 3.5 (4.67%) – 3.5 (4.67%) Contains several (3 or 4) APA format errors. 0 (0%) – 2 (2.67%) Contains many (≥ 5) APA format errors. parenthetical/in-text citations, and reference list. Total Points: 75
Three parts and how they fit together
- 01A named global biome.
- 02A named ecosystem found within that biome.
- 03The plants and animals you would expect to find in that ecosystem.
- 04One example of a symbiotic relationship within that ecosystem.
- 05At least one source supporting the post.
Biome, ecosystem, species, relationship
Biome and ecosystem
Name the biome, then the specific ecosystem inside it, and say what distinguishes the ecosystem from the biome as a whole.
The species
Name dominant plants, herbivores, predators and a decomposer, with what each contributes.
The symbiotic relationship
Identify one mutualism or commensalism from that ecosystem and state what each partner gains or loses.
The continuum
Note in one sentence that these categories can shift with conditions, with a source.
Where to find species and symbioses for your ecosystem
Recommended databases
- The Biome Explorer supplied with the course
- National park, reserve and wildlife agency pages for species lists by place
- PubMed Central for research on symbiotic relationships and their classification
- Your course textbook, for the biome and ecosystem definitions the prompt assumes
Search sequence
- 1.Choose the biome first, then find a named ecosystem within it that has published species information.
- 2.Build a short species list covering producers, consumers at two levels, and a decomposer.
- 3.Search for a documented symbiosis involving one of the species you have already named.
- 4.Check the classification of that relationship rather than assuming it.
- 5.Find one source on the mutualism to parasitism continuum for the closing sentence.
Reference shortlist
These are authoritative starting points, not a ready-made bibliography. A qualified reviewer must confirm that each source fits the assignment and supports the claim beside which it is cited.
Nothing here is cleared for citation until you have read it.
- 01
Unity Makes Strength: A Review on Mutualistic Symbiosis in Representative Insect Clades
Life · 2019
Worked examples of mutualism with the costs and benefits to each partner spelled out, which is what the symbiosis half of this prompt needs.
- 02
Molecular causes of an evolutionary shift along the parasitism-mutualism continuum in a bacterial symbiont
PubMed Central · 2020
Direct evidence that a relationship can move between categories. The source for the continuum sentence that lifts the post.
- 03
Common themes in nutrient acquisition by plant symbiotic microbes, described by the Gene Ontology
BMC Microbiology · 2009
Covers mycorrhizal and root-associated mutualism, which is the most widely applicable example if your ecosystem is grassland or forest.
- 04
Genesis of ectosymbiotic features based on commensalistic syntrophy
PubMed Central · 2024
Useful if you choose commensalism, since it treats the category seriously rather than as the leftover between mutualism and parasitism.
Review before submission
Common mistakes
- Naming two biomes, or naming a continent instead of an ecosystem.
- Listing categories of organism rather than named species.
- Omitting decomposers entirely.
- Choosing predator-prey, which the prompt offers but which is not symbiosis.
- Naming a relationship without saying what each partner gets from it.
- Borrowing a textbook example that does not occur in the chosen ecosystem.
- Writing a post short enough to miss the course's substantive response threshold.
Submission checklist
- The ecosystem is genuinely located within the named biome.
- At least four organisms are named specifically.
- The organisms named plausibly co-occur.
- The symbiotic relationship is mutualism, commensalism or parasitism.
- Costs and benefits to both partners are stated.
- The example occurs in the chosen ecosystem.
- At least one source is cited, ideally specific to the ecosystem.
Use this guide to plan and review your own work. Follow your institution's rules and read our academic-integrity policy.
Written by
Aaron Bishop
MA, Education
assignment interpretation and research-methods coaching across disciplines
Aaron leads the EssayCrackers editorial desk. He works on how assignment briefs are read — what a rubric is actually asking for, and where students most often answer a different question than the one set.
Reviewed by
Dr. Nathan Cole
PhD, Rhetoric & Composition
Argumentation and thesis development
Nathan teaches first-year composition and directs a university writing center. He reviews EssayCrackers guides for argumentative soundness and citation accuracy.