BIOL 106 Module 1 Review PDF

Exam 1 Chapter 13: Diversity of Microbes, Fungi, and Protist Chapter 14: Diversity of Plants Test Format: 40-50 Multiple Choice Questions NO SCANTRON REQUIRED Chapter 13.1-13.2 Introduction Bacteria and Archaea—are prokaryotic, meaning that they lack both a nucleus and true membrane-bound organelles...

Exam 1 Chapter 13: Diversity of Microbes, Fungi, and Protist Chapter 14: Diversity of Plants Test Format: 40-50 Multiple Choice Questions NO SCANTRON REQUIRED Chapter 13.1-13.2 Introduction Bacteria and Archaea—are prokaryotic, meaning that they lack both a nucleus and true membrane-bound organelles. ○ Prokaryotes were the first inhabitants on Earth, perhaps appearing approximately 3.9 billion years ago. The Eukarya include the familiar kingdoms of animals, plants, and fungi. ○ They also include a diverse group of kingdoms formerly grouped together as protists. Prokaryotic Characteristics Prokaryotic organisms generally fall into three categories, based on shape: ○ cocci (spherical), bacilli (rod-shaped), and spirilla (spiral-shaped) Bacteria are often divided into two groups, Gram positive and Gram negative, based on the reaction of their cell wall to Gram staining Recall that most prokaryotic reproduction is asexual and occurs by binary fission. ○ This does not allow for a change in genetic diversity, so prokaryotes gain genetic diversity by transformations, transductions, or conjugations. Prokaryotes display many different methods for obtaining energy, such as phototrophy and chemotrophy. A generalized prokaryotic cell All prokaryotes are unicellular organisms that lack a nucleus and membrane bound organelles. Prokaryotes are united by the presence of circular DNA in a nucleoid region, cell wall, cytoplasm, and ribosomes 4 Image: Concepts of Biology. OpenStax. Fig. 13.5 Prokaryote Reproduction Binary Division: results in exact copies of parent cell Binary division can be quite rapid, resulting in doubling every ~20 minutes Genetic Diversity & Exchange in Prokaryotes Transformation: Prokaryotes take up DNA found in the environment Transduction: Bacteriophages (viruses that infect bacteria) move DNA from one bacteria to another in the process of infecting multiple cells Conjugation: DNA, usually as a plasmid, is transferred from one prokaryote to another through a pilus Chapter 13.3 The term “protist” still is used informally to describe this tremendously diverse group of eukaryotes. ○ Junk Drawer As a collective group, protists display an astounding diversity of morphologies, physiologies, and ecologies. Protist Characteristics Protist is the catchall term used for eukaryotic organisms that are not animals, fungi, or plants. ○ Most protists are microscopic and unicellular but some multicellular forms ○ ○ ○ do exist, like the large seaweed Caulerpa. Protists may be aerobic or anaerobic and exhibit a wide range of nutrition (autotrophs and heterotrophs). Most protists are capable of asexual reproduction, and some can facultatively switch to sexual reproduction, depending on environmental conditions. Considered the simplest eukaryotes Protist Structure Cells can be small (< 1 micron) to large (~ 0.3 meters) Outer covering can be ○ Cell membranes (like animal cells) ○ Cell walls (like plants) ○ Pellicle: Layer of elastic proteins that gives shape to many unwalled, single-celled protists Most protists are motile; varied mechanisms Which Protist are most closely related to animals? Choanoflagellates ○ Closest know protist relatives of animals ○ Aquatic, heterotrophic protists ○ Has flagellum surrounded by a “collar” of threadlike projections ○ Similar to sponge cells ○ Most live as single cells ○ Some are colonial collar flagellum Which Protist is most closely related to plants? Red algae, green algae, and land plants all have a cell wall made of cellulose, store sugars as starch, and have chloroplasts that evolved from a cyanobacterial ancestor Charophyte algae (Chara) are the closest relatives of land plants: Unlike most other green algae, Chara cells divide by cell plate formation, and have cytoplasmic connections between neighbouring cells Malaria Malaria is a leading cause of human death Mosquitoes carry Plasmodium from one human host to another (vector) Malaria has been a potent selective force on humans in Africa because the allele that produces sickle-cell anemia also provides protection against malaria Natural selection also acts on Plasmodium, which has become resistant to several antimalarial drugs Cannot survive at low temperatures African Sleeping Sickness Trypanosoma, a parasitic flagellate with a single mitochondrion and a membrane-encased flagellum All trypanosomes are parasites Biting insects (vectors) transmit trypanosomes such as Trypanosoma brucei, which causes African sleeping sickness (Tsetse flies) base of flagellum red blood cell flagellum attached to cell by membrane Naegleria fowleri Brain eating amoeba Primary Amebic Meningoencephalitis Infection occurs when water containing the amoeba enters the body through the nose Typically occurs with swimming/diving warm freshwater Infection does not occur through drinking contaminated water https://www.cdc.gov/parasites/naegleria/index.html Dinoflagellates & Diatoms Dinoflagellates are aquatic heterotrophs and autotrophs with cellulose plates ○ Most are marine plankton with two flagella ○ Photosynthetic dinoflagellates supply reef-building corals with sugars and oxygen, receive shelter and carbon dioxide, coral die without them ○ Some cause for red tides Harmful Algal Blooms Mote Marine Laboratory Diatoms are photosynthetic Characterized by a two-part silica shell Some cells live individually and others form chains ○ found in lakes, seas, and damp soils Single-celled photosynthetic protist with brown accessory pigments in its chloroplasts Can produce toxins Chapter 13.4 Fungi: eukaryote that secretes digestive enzymes onto its food then absorbs the resulting breakdown products (extracellular digestion) ○ Fungi are strictly heterotrophic and most often obtain nutrients by decomposition (i.e., feed on organic wastes and remains; saprophytic) ○ Fungal digestive enzymes can break down sturdy structural proteins that animals digestive enzymes cannot, such as cellulose, lignin, and keratin ○ Some live on or in other living organisms Example: parasitic fungi Fungi Characteristics A substance called chitin contained in fungal cell walls gives them structural strength. Thallus - vegetative body of a fungi Yeast - fungus that lives as a single cell Multicellular fungi live as a mesh of threadlike filaments collectively called a mycelium ○ Each filament in the mycelium is a hypha Hypha: consists of haploid, walled cells attached end to end Asexual Reproduction in Fungi Budding of the parent’s body Multicellular fungi form spores by mitosis at the tips of specialized hyphae Most fungi produce a large number of microscopic spores that are disseminated by the wind. ○ A fungal spore is typically one or more haploid (n) cells enclosed within a thick coat ○ When the spore germinates (becomes active), it grows into a new haploid mycelium Sexual Reproduction in Fungi 2 3 4 1 2 Two haploid hyphae meet and cells at their tips fuse ○ This cytoplasmic fusion produces a dikaryotic cell cell that has two genetically distinct nuclei (n+n) The fungal zygote forms when the two nuclei inside the dikaryotic cell fuse The zygote then undergoes meiosis, producing a structure that produces haploid spores These spores germinate, releasing cells that divide by mitosis to form a new haploid mycelium Sexual Reproduction in Fungi dikaryotic stage (n+n) Fusion of cytoplasm 2 Fusion of nuclei spore-producing structure (n) 3 mycelium (n) Asexual Cycle spores (n) zygote (2n) 1 Meiosis 4 Sexual Cycle Beneficial Fungal Partnerships Many fungi take part in mutualism ○ Interspecific interaction that benefits both participants Mycorrhiza: partnership between a soil fungus and the root of a vascular plant ○ Hyphae branch inside plant cell walls and deliver nutrients and water to the plant ○ Plant provides sugars to the fungi Lichen Composite organism that consists of a sac fungus and either cyanobacteria or green algae ○ Hyphae surround the photosynthetic cells, which provide the fungus with sugars or fixed nitrogen ○ Lichens play an important ecological role by colonizing places too hostile for most organisms Lichens are often among the first organisms to colonize bare rock Chapter 14 Plants influence climates, shape topography, and form the foundation of most food chains. ○ Without plants, life on Earth as we currently know it would not exist. Facilitated oxygenation of ancient Earth’s atmosphere Fix atmospheric carbon into carbohydrates for heterotrophs All ~300,000 described species of plants are thought to share a common ancestor. Human civilizations have relied on plant products since the beginning of time, from the wood used to build houses to the compounds derived from plants that are used in medicines. Plant Characteristics: Adaptations to Land A major challenge that land plants face is desiccation. To account for this, plants developed a ○ waxy cuticle (retention of water) ○ xylem (transports water and nutrients upward) ○ phloem (transports carbohydrates from photosynthesis) As a means of defense to herbivory, plants developed various defenses and deterrents secondary compounds such as alkaloids. tissue modifications such as thorns and spines ○ To facilitate reproductive success plants also developed alternation of generations colorful flowers and nectar appetizing fruits to aid in seed dispersal. Major Division of Land Plants Seedless Plants Seedless plants dominated the Carboniferous period, some 300 million years ago. ○ Now they represent only a fraction of global plant diversity. Bryophytes are seedless nonvascular plants that include the liverworts, hornworts, and mosses. Seedless vascular plants include the horsetails, club mosses, whisk ferns, and ferns. Seed Plants Two major groups ○ Gymnosperms Seeds are “naked”, or not within a fruit Lack both flowers and fruits Examples are conifers , cycads, and Gingko trees ○ Angiosperms Possess flowers and fruits Dependent on animals for flower pollination and seed dispersion Gymnosperms There are currently around 1000 species of known gymnosperm that belong to four distinct divisions: Coniferophyta, Cycadophyta, Ginkgophyta, and Gnetophyta. ○ Conifers, such as pine trees, are the most numerous and familiar group of gymnosperm. ○ Cycads superficially resemble palms and were dominant during the time of the dinosaurs. ○ There is only one surviving species of the group Ginkgophyta. ○ Gnetophytes are the most closely related group to angiosperms. Angiosperms Jurassic period (202–145.5 MYA) flowering plants have successfully evolved to dominate most terrestrial ecosystems. ○ Angiosperms include a staggering number of genera and species; with more than 260,000 species Angiosperm survivability is a result of two novel structures that ensure reproductive success ○ Flowers allowed plants to form cooperative evolutionary relationships with animals, in particular insects, to disperse their pollen to female gametophytes in a highly targeted way. ○ Fruit protect the developing embryo and serve as an agent of dispersal. Different structures on fruit reflect the dispersal strategies that help with the spreading of seeds. Flowers Flowers are just modified leaves. ○ Flowers display an amazing diversity of forms but are all composed of sepals, petals, pistils, and stamen. The primary purpose of flowers is to attract pollinators and aid in the transfer of the pollen. Fruits A fruit is usually just a fertilized and fully developed ovary ○ Apples, grapes, and tomatoes ○ However, some fruit is formed by clusters of flowers (such as pineapple) or from separate ovaries in the same flower (such as blackberries) The overall goal of fruit is to aid in dispersal, usually by an animal consuming the fruit and passing on the seeds to a different location, by wind, or by attachment to an animal. Angiosperm Double Fertilization Angiosperms undergo a unique process called double fertilization ○ One sperm fertilizes the egg to produce the zygote ○ The other fuses with the nucleus in the embryo sac to form an endosperm, which acts as an energy reserve for the seed and developing plant.