Biology Homework Chapter 17: Eukaryotes: Fungi

Homework

• Reading Preparation
• WebLecture
• Study Activity
• Preparation work for chat
• Online Quiz
• Lab Instructions

Reading Preparation

Textbook assignment:Chapter 17: The Evolution of Plant and Fungal Diversity, sections 12-19.

Study Notes

• 17.12 Fungi digest food like animals, but do it outside their own bodies by excreting enzymes to break down complex nutrients which they can then absorb. Although they resemble plants, they are composed of filaments of hyphae that branch to form rootball-like mycelium and (usually above-ground) fruiting bodies. Fungi that pull their nutrients from decomposing organic matter are decomposers. Fungi that pull their nutrients from living organisms are parasites, like those bacteria, archaea, and protists we discussed in the previous chapter.
• 17.13 Fungi produce asexually by cloning cells (mitosis), and sexually by fusing hyphae with different nuclei (heterokaryotic stage) or mating types into a zygote which undergoes meiosis to release haploid spores. Molds (imperfect fungi) reproduce asexually by creating diploid spores, and yeasts produce asexually by budding or mitosis.
• 17.14 There are five phyla of fungi, listed in order of their appearance in a phylogenetic tree:
  • chytrids - have flagella, decomposers found in lakes, soil
  • zygote fungi (zygomycetes) - molds
  • arbuscular mycorrhizal fungi (glomeromycetes) - essential mycorrhizae
  • sac fungi (ascomycetes) - sac structures, pathogens and symbionts (lichen)
  • club fungi (basidiomycetes) - mushrooms

  Details of cycles of different fungi phyla differ but usually fungi will reproduce asexually when possible and sexually when conditions are less favorable and diversity is an advantage.

• 17.15 Fungi acting as decomposers are essential to the ecosystem; they may be able to clean up toxic pollutants.
• 17.16 Single-celled fungi, such as yeasts, allow us to make wine, cheese, beer, and bread; they provide medication against certain bacterial infections.
• 17.17 Lichens are mutualistic relationships in which both the algae or cyanobacteria and the fungal hyphae involved receive benefits. The functions each performs allows both to live in habitats otherwise not accessible to either; usually the relationship is so complete that neither can live without the other, so the joint community is classified as a single organism and species.
• 17.18 The symbiotic relationship between mycorrhizae and plants has implications for evolution theory and for practical agriculture.
• 17.19 Parasitic fungi are more likely to attack plants than animals and some types pose serious threats to food crops. Molds that develop in damp conditions in human dwellings can lead to mycosis or serious lung infections.

Web Lecture

Read the following weblecture before chat: Fungi

Take notes on any questions you have, and be prepared to discuss the lecture in chat.

Perform the study activity below:

Chat Preparation Activities

• Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
• Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.

Chapter Quiz

• Required: Complete the Mastery Exercise with a score of 85% or better.
• Optional: Test yourself with the textbook multiple choice questions and note any that you miss that still don't make sense. Bring questions to chat!
• Go to the Moodle and take the quiz for this chapter.

Lab Work

Read through the lab for this week; bring questions to chat on any aspect of the lab, whether you intend not perform it or not. If you decide to perform the lab, be sure to submit your report by the posted due date.

• Lab Instructions: Complete the lab for Scholars Online Biology Investigation #1: Artificial Selection

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