Biology - Fungi - Quick Guides | Biology

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Study GuideBiology–Fungi1. Fungi DefinedFungi, along with bacteria, play a huge role in nature asdecomposers. They help break downorganic material and recycle nutrients back into the environment. Without them, dead plants andanimalswould pile up everywhere.Most fungi aresaprobes, which means they feed on nonliving organic matter such as fallen leaves,rotting wood, and dead animals. Some fungi, however, areparasites. These fungi live on or insideother living organisms and can cause diseases. In fact, fungi are responsible for many plant diseasesthat affect crops, as well as several diseases in humans.1.1 How Fungi Get Their FoodFungi are different from plants and animals because of both their structure and how they obtainnutrients. Instead of eating or photosynthesizing, fungi use a process calledextracellular digestion.Here’s how it works:•Fungi release special enzymes into their surroundings.•These enzymes break down large organic materials into smallermolecules.•The fungi then absorb these small nutrient particles through their cell membranes.This method allows fungi to feed efficiently on a wide range of materials in their environment.1.2 Structure of FungiMost fungi aremulticellular, except for yeast, which is unicellular. The body of a multicellular fungusis made up of tiny, thread-like structures calledhyphae(singular:hypha).•Each hypha is a microscopic filament.•Many hyphae weave together to form a dense network called amycelium(plural:mycelia).

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Study Guide•The mycelium is usually the visible part of the fungus, such as mold on bread or theunderground network of a mushroom.Fungal cells are also unique because their cell walls containchitin, a strong polysaccharide. In somefungi, the cell walls may also includecellulose. Fungi usually live inacidic environmentsand tendto prefercarbohydrate-rich foods.1.3 Reproduction in FungiFungi can reproduce in bothasexualandsexualways, giving them flexibility to survive in differentconditions.Asexual Reproduction•Parts of the mycelium can break off and grow into new fungi.•Fungi can also producesporesasexually.•These spores spread through air, water, or other means.•When conditions are favorable, spores germinate and grow into new fungi that are geneticallyidentical to the parent.Most fungalhyphae and spores are haploid, meaning they contain only one set of chromosomes.The haploid stage is the main stage in a fungus’s life cycle. Fungal spores are tough and can surviveextreme dryness and cold until conditions improve.1.4 Sexual ReproductionFungi can also reproduce sexually. In this process:•Two haploid cells join to form a short-liveddiploidcell (with two sets of chromosomes).•This diploid cell quickly undergoesmeiosis, producing new haploid cells.•These cells develop into spores.•The spores divide bymitosis, forming new hyphae and eventually a new mycelium.

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Study Guide1.5 Classification of FungiScientists classify fungi into four major divisions based on their reproductive structures and life cycles:•Zygomycetes•Ascomycetes•Basidiomycetes•DeuteromycetesThis classification helps biologists understand how different fungi are related and how they reproduce.2. Quiz Fungi1. QuestionFill in the blank:Most fungi are ________.Answer Choices•autotrophs•parasites•saprobesCorrect AnswersaprobesWhy This Is CorrectMost fungi obtain their food by breaking down dead and decaying organic matter, such as fallenleaves, wood, and dead organisms. Organisms that feed this way are calledsaprobes.

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Study GuideFungi release enzymes into their surroundings to digest the materialexternally and then absorb thenutrients. This makes saprobes thecorrect answer.2.QuestionFill in the blank:How do fungi obtain their nutrients?Answer Choices•extracellular digestion•photosynthesis•predationCorrect Answerextracellular digestionWhy This Is CorrectFungi obtain nutrients by releasing enzymes into their surroundings to break down organic matteroutside their bodies. This process is calledextracellular digestion.After the food is broken down into smaller molecules, fungi absorb the nutrients through their cellmembranes. They do not make food by photosynthesis, and they do not hunt or capture prey likepredators.3.QuestionFill in the blank:What component of fungal cells is unique?Answer Choices•cellulose•chitin•peptidoglycan

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Study GuideCorrect AnswerchitinWhy This Is CorrectFungal cell walls are made ofchitin, a tough and flexible substance that is not found in plant orbacterial cell walls.Plants have cell walls made ofcellulose, and bacteria have cell walls made of peptidoglycan.Because chitin is unique to fungi (and also found in some animals like insects), it is thecorrectanswer.4.QuestionFill in the blank:Fungal reproduction is usually via whatprocess?Answer Choices•alien intervention•asexual reproduction•sexual reproductionCorrect Answerasexual reproductionWhy This Is CorrectMost fungi reproduceasexually, often by producing spores that can grow into new fungi without theneed for another organism.While some fungi are capable of sexual reproduction, asexual reproduction is more common andallows fungi to reproduce quickly and efficiently.

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Study Guide5.QuestionFill in the blank:Why are spores helpful to fungalreproduction?Answer Choices•They allow parasitism.•They increase variation.•They withstand extreme dryness and cold.Correct AnswerThey withstand extreme dryness and cold.Why This Is CorrectFungal spores are specially adapted to surviveharsh environmental conditions, such as extremedryness and cold.This ability allows spores to remain dormant for long periods and spread to new locations. Whenconditions become favorable, the spores can grow into new fungi, making reproduction moresuccessful.3. AscomycetesAscomycetesare a very large and diverse group of fungi. Members of this division come in manyshapes and sizes, which makes them especially interesting to study.Some ascomycetes areunicellular, such as yeasts. Others are much more complex, including:•Powdery mildewsthat grow on plants•Cottony molds•Large, visiblecup-shaped fungi

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