Plant Biology: Hormones and Symbiotic Relationships

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Questions and Answers

What is the primary function of gibberellins in plants?

Promote leaf senescence

Stimulate root growth and development

Inhibit seed germination

Stimulate shoot elongation and fruit maturation (correct)

Which of the following accurately describes mycorrhizae?

Fungi that solely parasitize living plant roots

A symbiotic association between fungi and plant roots (correct)

Fungi that thrive in aquatic environments

Plants that grow on other plants for nutrition

Which characteristic distinguishes saprophytes from other types of organisms?

Engage in symbiotic relationships with plants

Obtain food from living plants directly

Obtain food from decomposing organic matter (correct)

Contain chlorophyll for photosynthesis

Which feature is NOT typically associated with animals?

Photosynthesis for energy Signup and view all the answers

What defines the body plan of animals, particularly in relation to embryonic tissue layers?

Number of embryonic tissue layers present Signup and view all the answers

What term describes animals that have three tissue types in their embryo?

Triploblasts Signup and view all the answers

Which body plan allows for equal environmental interaction from all directions?

Radial symmetry Signup and view all the answers

What is the main characteristic of a coelom?

An enclosed fluid-filled body cavity Signup and view all the answers

Which developmental process produces three primary germ layers?

Gastrulation Signup and view all the answers

Which group of animals develops the mouth second during embryonic development?

Deuterostomes Signup and view all the answers

Which type of epithelial tissue is characterized by its flat, overlapping cells?

Squamous epithelium Signup and view all the answers

In which structure do muscle cells attach in vertebrates?

Endoskeleton Signup and view all the answers

What type of skeleton allows limbless animals to move through coordinated contractions?

Hydrostatic skeletons Signup and view all the answers

What is the primary substance that gives connective tissue its density?

Ground substance Signup and view all the answers

Which of the following is a defining feature of cells in the blood?

Have a liquid matrix Signup and view all the answers

What characterizes cartilaginous fish such as sharks and rays?

Lateral line system for detecting vibrations Signup and view all the answers

Which of the following is a trait unique to amphibians compared to other vertebrates?

Dual life stages in water and on land Signup and view all the answers

What is the primary function of the swim bladder in bony fish?

Buoyancy control Signup and view all the answers

How do reptiles generally reproduce?

Both internal and external fertilization methods Signup and view all the answers

What adaptation do amniotes have that provides a protective environment for embryos?

Amniotic membranes Signup and view all the answers

What characterizes the reproductive strategy of ovoviviparous sharks?

Eggs remain fertilized inside the oviduct until hatching Signup and view all the answers

Which of the following terms refers to organisms with jaws, including fishes and tetrapods?

Gnathostomes Signup and view all the answers

What unique feature characterizes salamanders among amphibians?

They do not undergo metamorphosis Signup and view all the answers

Which feature is found in all reptiles but not in amphibians?

Scaly skin Signup and view all the answers

Which of the following traits is NOT characteristic of bony fish?

Skeletal structure made of cartilage Signup and view all the answers

What process is responsible for the formation of coelom in protostomes?

Schizocoely Signup and view all the answers

Which characteristic is NOT true about sponges?

They have true tissues. Signup and view all the answers

What defines the unique body plan of mollusks?

A muscular foot and a visceral mass. Signup and view all the answers

What is the primary function of nematocysts in cnidarians?

Prey capture and defense Signup and view all the answers

Which class of cnidarians is known for having a life cycle that includes both polyp and medusa forms?

Hydrozoa Signup and view all the answers

Which structure is associated with the lophotrochozoan phyla?

Radula Signup and view all the answers

What structure do arthropods primarily use for protection from predators?

Hard exoskeleton Signup and view all the answers

In which group can you find organisms that undergo ecdysis?

Ecdysozoa Signup and view all the answers

What type of body symmetry is exhibited by cnidarians?

Radial symmetry Signup and view all the answers

What is the main feature that distinguishes echinoderms from other animal phyla?

Water vascular system Signup and view all the answers

Which of the following is a characteristic of annelids?

Body divided into segments Signup and view all the answers

What is the function of the clitellum in some annelids?

Transfer of sperm and egg storage Signup and view all the answers

Which group of mollusks is known for having a shell composed of multiple plates?

Polyplacophora Signup and view all the answers

What role do chaetae play in annelids?

Locomotion Signup and view all the answers

Study Notes

Plant Hormones

Gibberellins (GAs) stimulate shoot elongation, seed germination, and fruit/flower maturation
Auxins control meristem differentiation and are responsible for cell elongation in phototropism and gravitropism

Mycorrhizae

Symbiotic fungi associated with plant roots
Fungi are integrated into the root's physical structure
Plants obtain essential elements from the soil
Fungus obtains nutrients from plants

Epiphytes

Plants that grow on other plants
Not dependent on a host plant for nutrition
Two types of roots: clinging aerial and aerial
Clinging aerial roots absorb nutrients from humus accumulated in trees
Aerial roots absorb moisture from the atmosphere

Saprophytes

Lack chlorophyll
Obtain food from dead organic matter
Enzymes break down organic food materials into simpler forms
Many parasitize fungi that digest dead matter or are mycorrhizal

Choanoflagellates

Sessile protists, some colonial

Sponges

Multicellular, sessile animals
Major animal characteristics: multicellular, heterotrophs, and move at some point in their lives

Body Plans

Asymmetry: Sponges
Radial symmetry: Body parts arranged around a central axis, allowing organisms to experience the environment equally in all directions (e.g., Cnidarians)
Bilateral symmetry: Body parts arranged along a single plane (e.g., most animals)

Body Cavities

Coelom: A fluid-filled body cavity surrounded by mesoderm; found in some animals
Diploblasts lack a coelom; coelom is enclosed, fluid filled body cavity in some animals

Blastula & Gastrula

Blastula: Rapidly dividing cells that transition to gastrula, which develops specialized cells.
Gastrula comprises of three primary germ layers: ectoderm, endoderm, and mesoderm.

Hydrostatic Skeletons

Allow limbless animals to move via coordinated muscle contractions

Tube-within-a-tube body plan

Protostomes or deuterostomes
Outer tube forms body wall and inner tube forms digestive tract
Digestive system formed from endoderm
Body wall formed from ectoderm
Muscles and organs formed by mesoderm

Protostomes and Deuterostomes

Protostomes: Mouth develops first
Deuterostomes: Anus develops first

Epithelial Tissues (Summary)

Squamous: Flattened, overlapping cells (e.g., skin, mouth)
Columnar: Long and wide cells (e.g., nose, trachea)
Transitional: Elongated, compacted cells (e.g., urinary bladder)

Animal Body Plan Features

Number of embryonic tissue layers
- Diploblasts: 2 tissue layers (endoderm and ectoderm).
- Triploblasts: 3 tissue layers (endoderm, ectoderm, mesoderm).
Presence/absence of fluid-filled body cavity (coelom)
Nervous system, body symmetry, and cephalization (development of a head region)
Earliest events of embryonic development

Triploblasts

Animals with three tissue layers

Animal Development Gastrulation

Process that develops blastopore (hollow) from zygote (fertilized egg).
Germ layers form during this process (ectoderm, endoderm, and mesoderm)
These layers develop into organ systems (tissues, organs, etc).

Mouth Development (Summary)

Two major groups
Protostomes
- Mesoderm separates to form body cavity in schizocoely process
Deuterostomes
- Mesoderm pinches off (enterocoely process) body cavity

Animal Phylogeny

Specialized tissue
Symmetry
Coelom
Protostome vs. deuterostome

Animal Phylogeny: Defining Features of Groups

Porifera: Sponges, mostly marine, no true tissues. Suspension feeders, filtering water through their porous bodies. Reproduction: (asexual budding, sexual – eggs + sperm).
Cnidaria: Jellyfish, corals, anemones. Primarily marine. Diploblastic. Radial symmetry. 2 body forms (polyp and medusa). Stinging cells (nematocysts) for predation
Lophotrochozoa: Bilateral symmetry. Coelom present in some. Not all undergo a larval stage. Flatworms, annelids, and mollusks.
Platyhelminthes: (Flatworms) – dorsoventrally flattened bodies. Most are free-living, some are parasitic. No coelom, but have a simple digestive system.
Annelida: (Segmented worms) – Bodies subdivided into repeating segments. True coelom, complex digestive and circulatory systems.
Mollusca: Snails, clams, octopuses. Soft-bodied animals, often with a hard shell (calcium carbonate). Well-developed muscular foot, visceral mass, mantle.
Ecdysozoa: Grow by shedding their external covering. Bilateral symmetry. Segmented bodies and jointed legs. Protostomes. Nematodes (roundworms), and arthropods.
Nematoda: (Roundworms) – Unsegmented, tubular bodies with a pseudocoelom. Most are free-living, some are parasitic.
Arthropoda: Insects, crustaceans, arachnids. Segmented bodies, exoskeleton made of chitin, jointed appendages, well-developed sensory organs. Bilateral symmetry. Complex digestive, respiratory, and circulatory systems.
Echinodermata: Starfish, sea urchins, sea cucumbers. Primarily marine. Bilateral symmetry as larvae, radial symmetry as adults. Water vascular system for movement and feeding. Endoskeleton. Unique deuterostome lineage.

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Description

This quiz explores key concepts in plant biology, including the roles of hormones like gibberellins and auxins, as well as various symbiotic relationships found in nature, such as mycorrhizae, epiphytes, and saprophytes. Test your knowledge on how these interactions help plants thrive in their environments.