quiz 8 Flashcards
What is a seed?
A seed is a plant embryo packaged with a food supply inside a protective coat. It develops from an ovule after fertilization and allows plants to reproduce and disperse offspring more effectively in terrestrial environments.
Compare the size and independence of the gametophyte generation of bryophytes with those of seed plants.
In bryophytes (mosses, liverworts), the gametophyte is dominant, large, and free-living, while the sporophyte is dependent on the gametophyte.
In seed plants, the sporophyte is dominant, and the gametophyte is tiny and dependent on the sporophyte, developing within the protective structures of the sporophyte (pollen and ovules).
Describe the role of the ovule and pollen grain in a seed plant.
Ovule: Contains the female gametophyte, which produces the egg. After fertilization, it develops into a seed.
Pollen grain: The male gametophyte, which carries sperm cells and allows fertilization without the need for water, enabling reproduction in dry environments.
Explain how pollination and seed formation are adaptive for terrestrial environments.
Pollination: Allows sperm to reach the egg without water by using wind or animals for dispersal.
Seed formation: Protects the embryo, provides nutrients, and enables long-distance dispersal and dormancy during unfavorable conditions.
Explain how the evolution of the flower enhanced the reproductive efficiency of angiosperms.
Flowers attract pollinators (e.g., insects, birds) using colors, nectar, and scents, leading to targeted pollen transfer.
This increases cross-pollination efficiency, reducing dependence on random wind pollination.
Define fruit and explain how fruits are modified in ways that help disperse seeds.
Fruit: A mature ovary containing seeds.
Fruits aid in seed dispersal by various mechanisms:
Wind-dispersed: Lightweight, winged structures (e.g., maple).
Animal-dispersed: Fleshy fruits eaten by animals (e.g., berries) or attach to fur (e.g., burrs).
Water-dispersed: Float and travel long distances (e.g., coconuts).
Diagram the generalized life cycle of an angiosperm.
Sporophyte Generation: Dominant, includes roots, stems, leaves, flowers.
Gametophyte Generation: Microscopic, located in pollen (male) and ovule (female).
Process:
Flower produces microspores (male) and megaspores (female).
Pollen lands on stigma → fertilization occurs in ovule.
Ovule becomes seed, ovary becomes fruit.
Seed germinates into a new sporophyte.
Explain how animals may have influenced the evolution of terrestrial plants, and vice versa.
Plants influenced animals: Provided food, shelter, and new ecological niches.
Animals influenced plants: Selected for features like bright flowers (pollination) and tasty fruits (seed dispersal), leading to coevolution.
List the distinguishing characteristics of fungi.
Eukaryotic, mostly multicellular (except yeasts).
Heterotrophic decomposers.
Cell walls made of chitin (not cellulose like plants).
Reproduce via spores.
Can form symbiotic relationships (mycorrhizae, lichens).
Explain how fungi acquire their nutrients.
Absorptive heterotrophs: Secrete digestive enzymes into surroundings and absorb nutrients.
Can be saprophytic (decomposers), parasitic (feed on living organisms), or mutualistic (benefit both organisms, e.g., mycorrhizae).
describe the basic body plan of a fungus: hyphae, mycelium.
Hyphae: Thread-like filaments that make up the body.
Mycelium: A mass of hyphae that increases surface area for nutrient absorption.
Distinguish between septate and aseptate (coenocytic) fungi.
Septate fungi: Hyphae have cross-walls (septa) with pores for nutrient flow.
Aseptate (coenocytic) fungi: No septa, forming a continuous multinucleate cell.
Describe the process of plasmogamy and karyogamy in fungi.
Plasmogamy: Fusion of cytoplasm from two different mating types.
Karyogamy: Fusion of nuclei to form a diploid zygote, later undergoing meiosis to produce haploid spores.
Distinguish among the fungal phyla and give examples.
Chytrids: Aquatic, flagellated spores (e.g., Batrachochytrium).
Zygomycetes: Fast-growing molds (e.g., Rhizopus, black bread mold).
Glomeromycetes: Form mycorrhizal associations with plants.
Ascomycetes: “Sac fungi” with asci (e.g., yeasts, truffles, Penicillium).
Basidiomycetes: “Club fungi” with basidia (e.g., mushrooms, puffballs, rusts).
List the distinguishing characteristics of animals.
Multicellular, eukaryotic, heterotrophic.
Lack cell walls (unlike fungi/plants).
Most have muscle and nervous tissue.
Reproduce sexually, with diploid stage dominating the life cycle
Distinguish between radial and bilateral symmetry.
Radial symmetry: Body parts arranged around a central axis (e.g., jellyfish).
Bilateral symmetry: Two mirror-image halves, distinct head/tail (e.g., humans, insects).
List characteristics shared by all bilaterally symmetrical animals.
Cephalization (head with sensory organs).
Triploblastic development (three germ layers).
Directional movement (usually forward).
Distinguish between diploblastic and triploblastic.
Diploblastic: Two germ layers (ectoderm & endoderm, e.g., cnidarians).
Triploblastic: Three germ layers (ectoderm, mesoderm, endoderm, e.g., most animals).
Outline the major phylogenetic branches of the animal kingdom.
Parazoa (sponges): No true tissues.
Eumetazoa: True tissues, further divided into:
Radiata: Radial symmetry (cnidarians).
Bilateria: Bilateral symmetry, includes:
Protostomes (mollusks, arthropods, annelids).
Deuterostomes (echinoderms, chordates).
