Core Biology 2 Study Guide for Lecture Exam 3

Chapter 32: An Overview of Animal Diversity1. List the characteristics that distinguish all animals.

Animals are heterotrophs that ingest their food. Animals are multicellular eukaryotes. Their cells are supported and connected to one another by collagen and other structural proteins located outside the cell membrane. Nervous tissue and muscle tissue are key animal features. In most animals, gastrulation follows the formation of the blastula and leads to the formation of embryonic tissue layers. All animals have Hox genes that regulate the development of body form. Although Hox genes have been highly conserved over the course of evolution, they can produce a wide diversity of animal morphology.

2. Distinguish between radial and bilateral symmetry.Radial symmetry. A radial animal, such as a sea anemone (phylum Cnidaria), does

not have a left side and a right side. Any imaginary slice through the central axis divides the animal into mirror images.

Bilateral symmetry. A bilateral animal, such as a lobster (phylum Arthropoda), has a left side and a right side. Only one imaginary cut divides the animal into mirror-image halves.3. Distinguish among acoelomate, pseudocoelomate and coelomate.

4. Distinguish between spiral and radial cleavage, determinant and indeterminate cleavage, schizocoelous and enterocoelous, parazoa and eumatozoa.Parazoa: specialized cells without true tissue, such as poriferans, for instance.

Eumatozoa: true tissue – all other animals. Protostome: spiral (divides diagonally) determinate (differentiate after 1 cell stage) cleavage, and mesoderm splits on both sides of the blastopore - schizocoelomate. Deuterostome: radial (parallel and perpendicular) indeterminate (after the 8 cell stage they differentiate) coelom, and mesoderm invaginates – enterocoelomate.

Chapter 33: An Introduction to Invertebrates5. List the four classes of Cnidaria and distinguish them by their life cycle &

morphological characteristics. Hydrozoans: most hydrozoans alternate between an asexually reproducing polyp and sexually reproducing medusa form. The common freshwater hydras exist only in polyp form. Scyphozoans: the medusa stage is more prevalent in the scyphozoans. The sessile polyp stage often does not occur in the jellies of the open ocean. Cubozoans: have a box-shaped medusa stage and complex eyes in the fringe of their medusae. Many species, such as the sea wasp, have highly toxic cnidocytes. Anthozoans: sea anemones and corals occur only as polyps. Corals secrete calcified external skeletons, and the accumulation of such skeletons produces coral.

6. List distinguishing characteristics descriptive of the phylum nemertea.Also called proboscis worms or ribbon worms, nemerteans swim through water or

burrow in sand, extending a unique proboscis to capture prey. Like flatworms, they lack a true coelom. However, unlike flatworms, nemerteans have an alimentary canaland a closed circulatory sys- tem in which the blood is contained in vessels and hence is distinct from fluidin the body cavity.7. Describe the advantages and disadvantages of exoskeleton.

Also called proboscis worms or ribbon worms, nemerteans swim through water or burrow in sand, extending a unique proboscis to capture prey. Like flatworms, they lack a true coelom. However, unlike flatworms, nemerteans have an alimentary canaland a closed circulatory sys- tem in which the blood is contained in vessels and hence is distinct from fluidin the body cavity.8. Define lophophore and list three lophophorate phyla

Crown of cilia for feeding Phylum Platyhelminthes Phylum Nemertea Phylum Ectoprocta Phylum Brachiopoda Phylum Phoronida Phylum Rotifera Phylum Cycliophora Phylum Mollusca Phylum Annelida

Invertebrates

Chapter 34: The Origin and Evolution of Vertebrates

9. Define the following terms: craniate, agnathans, osteiechthyes, and chondrichytes. Craniate: After the evolution of the basic chordate body plan, that seen in lancelets and tunicate larvae, the next major transition in chordate evolution was the appearance of a head. Chordates with a head are known as craniates (from the word cranium, skull). The origin of a head—consisting of a brain at the ante- rior end of the dorsal nerve cord, eyes and other sensory organs, and a skull—enabled chordates to coordinate more complex movement and feeding behaviors. Agnathans: any member of the group of primitive jawless fishes that includes the lampreys (order Petromyzoniformes), hagfishes (order Myxiniformes), and several extinct groups. Osteiechthyes: also called bony fish, they are a taxonomic group of fish that have bone, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of 45 orders, and over 435 families and 28,000 species.[1] It is the largest class of vertebrates in existence today. Osteichthyes are divided into the ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii). The oldest known fossils of bony fish are about 420 million years ago, which are also transitional fossils, showing a tooth pattern that is in between the tooth rows of sharks and bony fishes. Chondrichytes: are the only cells found in healthy cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and proteoglycans. Although the word chondroblast is commonly used to describe an immature chondrocyte, the term is imprecise, since the progenitor of chondrocytes (which are mesenchymal stem cells) can differentiate into various cell types, including osteoblasts. How chondrocytes are organized within cartilage depends on the type of cartilage and where they are found in the tissue.

10. Describe how reptiles are adapted to their environment.Most reptiles are ectothermic – they absorb external heat rather that generating

their own – but they may regulate their body temperature through behavioral adaptations. Birds are endothermic, warming their body with metabolic heat11. List the distinguishing characteristics of birds and explain any special adaptation

for flight. Archosaurus Reduced weight Light feathers Airfol-shaiped wings Endothermic Excellent vision Large brain Theropods, group of bipedal saurischian dinosaurs

Chapter 31: Fungi12. List the characteristics that distinguish fungi from organisms in other kingdoms

Most multicellular, some unicellular Terrestrial and aquatic fungi Fruiting bodies, above ground part that produce haploid spores Mycelium, bellow ground part compounded by network of filaments (hyphae) Hyphae. Could be septated (divided), with crosswalls, coenocytic, with no crosswalls, or haustoria, with penetrating hyphae – lichen. Reproduction: asexually, release haploid spores and grow by mitosis, or sexually – plasmogamy, cytoplasm fuse (dikaryotic/heterokaryotic), or karyogamy, when the nucleus fuses (zygote).

13. Explain how fungi acquire nutrients.All fungi (including decomposers and symbionts) are heterotrophs that acquire

nutrients by absorption. Many fungi secrete enzymes that break down complex molecules to smaller molecules that can be absorbed.

Most fungi grow as thin, multicellular filaments called hyphae; relatively few species grow only as single-celled yeasts. In their multicellular form, fungi consist of mycelia, networks of branched hyphae adapted for absorption. Mycorrhizal fungi have specialized hyphae that enable them to form a mutually beneficial relationship with plants. 14. Explain how non-motile fungi seek new food sources and how they disperse.

Fungal hyphae form an interwoven mass called a mycelium (plural, mycelia) that infiltrates the material on which the fungus feeds. A mycelium’s structure maximizes its surface-to-volume ratio, making feeding very efficient. Just 1 cm3 of rich soil may

contain as much as 1 km of hyphae with a total surface area of 300 cm2 in contact with the soil. A fungal mycelium grows rapidly, as proteins and other materials synthesized by the fungus are channeled through cytoplasmic streaming to the tips of the extending hyphae. The fungus concentrates its energy and resources on adding hyphal length and thus overall absorptive surface area, rather than on increasing hyphal girth. Fungi are not motile in the typical sense—they cannot run, swim, or fly in search of food or mates. However, as they grow, fungi can move into new territory, swiftly extending the tips of their hyphae.15. Describe the body structure of fungi

Most fungi are composed of multicellular filaments. Some are single-celled yeasts, which may inhabit liquid or moist habitats. Some species can grow as both filaments and yeasts.

A typical multicellular fungal body consists of a network of filamentous hyphae, which form a mass called a mycelium. This body form provides an extensive surface area for absorption of nutrients. The tubular cell walls are composed of chitin. Although fungi are nonmotile, the rapid growth of their hyphae enables them to enter new food territory.

The hyphae of most fungi are divided into cells by cross-walls called septa, which usually have pores thought which nutrients and cell organelles can pass. Coenocytic fungi lack septa and consist of a continuous cytoplasmatic mass containing many nuclei.

16. Describe some advantages of the dikaryotic stage. Some fungi have a dikaryotic (two nuclei in one cell) stage, more commonly

known as a heterokaryotic stage, because the fungus can wait for an opportune time to fuse the nuclei together and grow. The fungus would not want to grow rapidly in the diploid stage unless it had adequate food sources. This waiting will allow for maximum efficiency during its growth.17. Sexual and asexual reproduction and structures of Zygomycota, Ascomycota and

Basidiomycota

18. What are conidia?Ascomycetes reproduce asexually by producing enormous numbers of asexual

spores called conidia (singular, conidium). Conidia are not formed inside sporangia, as are the asexual spores of most zygomycetes. Rather, they are produced externally at the tips of specialized hyphae called conidiophores, often in clusters or long chains, from which they may be dispersed by the wind.19. Explain why deuteromycota are called imperfect fungi.

Because they have no known sexual stage20. Parasitic, saprotrophic, and mutualistic fungi

Fungi are decomposers of organic matter, facilitating the essential recycling of chemical elements for plant growth.

Mycorryzae are very common and important in natural ecosystems and agriculture. The leaves or other parts of all plant species studied thus far have symbiotic endophytes, which benefit plants by either producing toxins that deter herbivores.

Fungal parasites of plants are common, killing chestnut and pine trees and spoiling grain and fruit crops