Plant Biology Quiz: Vascular Plants and Ecology

Diversity of Life

• The study of life's diversity is covered in Bio 2e, Chapters 21-29, and optionally Freeman Chapters 26-33.
• The hierarchical classification system of life includes domains, kingdoms, phyla, classes, orders, families, genera, and species.

Learning Goals

• Students will learn the major branches of the tree of life.
• Students will be able to name attributes of major animal phyla and plant divisions (e.g. invertebrates, vertebrates, plant divisions).
• Students will identify key groups of non-animal eukaryotes.
• Students will identify some major features of the groupings on the tree of life.

Relative Numbers of Named Species

• A pie chart illustrates the relative proportions of named species of various groups in the biological world, such as insects (beetles, flies, wasps, butterflies & moths with higher representation compared to vertebrates and fungi).
  • Plants/Algae account for 18% of named species.
  • Beetles represent 22% of the named species.
• Other significant groups include other invertebrates (12%), other insects (13%), fungi (4%), and other organisms (6%).
• Vertebrates account for 1% of named species.

Tree of Life/Phylogenetic Tree/Taxonomic Groups

• Three domains (Bacteria, Archaea, Eukarya) are shown on the tree, and they are derived from a common ancestor.
• Eukaryotes like animals, plants and fungi are in the domain Eukarya.
• Bacteria and Archaea are prokaryotes.
• This visual aids understanding the relationships of various organisms and their common ancestor.

LUCA

• Last Universal Common Ancestor (LUCA) was not the first form of life, but rather a survivor lineage.
• Various forms of life went extinct early on.

Prokaryotes

• Prokaryotes are the most abundant, ancient, and diverse organisms.
• They are characterized by the absence of a nucleus and membrane-bound organelles (no nucleus).
• This category includes bacteria and archaea.

Bacteria

• Proteobacteria, cyanobacteria, Gram-positive bacteria, chlamydias, and spirochetes are major groups of bacteria.

Proteobacteria

• Proteobacteria are a diverse group of bacteria.
• They include photoautotrophs, chemoautotrophs, and heterotrophs.
• There's no taxonomic distinction between "good" bacteria (essential to the biosphere) and "bad" bacteria (harmful to humans).
• Pathogenic bacteria exist within many different proteobacteria groups.
• Proteobacteria include the ancestors of mitochondria.
• Include Rhizobium species living in plant roots, and rickettsias (small pathogens living within animal cells).

Spirochetes

• Spirochetes are distinctive bacteria.
• They move via spiraling corkscrew motion.
• They can be free-living or parasitic.
• Syphilis and Lyme disease are caused by spirochetes.

Bacterial Photosynthesis

• Photosynthesis has evolved repeatedly in bacteria.
• Cyanobacteria are the best-known.
• Photosynthetic groups also include purple sulfur bacteria, green sulfur bacteria, and heliobacteria.
• Some groups use molecules other than water as electron donors.
• An example includes H2S oxidation by purple sulfur bacteria to form S granules (sulfur).

Archaea

• Archaea, although little known, are abundant and important organisms on Earth, found in habitats ranging from ordinary environments to extreme conditions.
• They are ancient organisms.
• This group includes methanogens, extreme thermophiles, and extreme halophiles.
• Unlike bacteria, archaea often have introns in their genetic sequences.
• Also similar to Eukarya, archaea have histones – proteins that compact DNA strands, unlike either Bacteria or Eukarya who frequently use different approaches to storing and using DNA..

Eukaryotes

• Eukaryotes—organisms with nuclei and nearly always with membrane-bound organelles—are a single branch on the tree of life.
• Modern studies suggest there are likely 11–20 kingdoms, including formerly classified "protists" like diplomonads and parabasalids.

Endosymbiosis

• Mitochondria and chloroplasts likely originated as symbiotic bacteria.
• The theory proposes that a prokaryotic cell engulfed another, forming a mutually beneficial relationship.
• Evidences are the double membranes, DNA, ribosomes similar to prokaryotes (in mitochondria and chloroplasts).

Viruses

• Whether or not a virus is "alive" depends on the definition of "life".
• Most viruses contain DNA or RNA.
• Viruses hijack host cells' transcription and translation mechanisms to make more viruses.
• Viruses lack metabolism and an independent energy source; they depend on a host cell for living processes.

Protists

• Protists are mostly unicellular eukaryotes.
• There are many different groups of protists, now recognized as separate "kingdoms."
• Some groups have acquired photosynthesis independently, becoming "algae," while others have evolved multicellularity.
• Some form multicellular associations, like algae.

Euglenozoa

• This is a large and significant group of flagellate protists.
• Branching off early in the eukaryote evolutionary tree, many are free-living while others are parasites.
• Some are photosynthetic mixotrophs, like Euglena.
• One important example is Trypanosoma brucei, the cause of African sleeping sickness.

Alveolates

• This eukaryotic clade has sac-like membrane structures and similar DNA sequences.
• Examples include ciliates, sporozoans, and dinoflagellates.

Ciliates

• A group of unicellular eukaryotes that move using cilia.
• Cilia are often used for feeding.
• They have both a micronucleus (for reproduction) and a macronucleus (for gene regulation).
• Many ciliates are free living, while some are parasites or commensals.

Dinoflagellates

• Dinoflagellates are important primary producers, especially in marine environments.
• They are characterized by a distinctive arrangement of two flagella, allowing them to move.
• Most dinoflagellates are mixotrophic, combining photosynthesis with prey ingestion.
• They are known for producing potent toxins.

Malaria

• Plasmodium is a genus of parasitic protists that causes malaria and infects birds, reptiles, and mammals (including humans).
• A dipteran (insect) vector (e.g. mosquito) is required for its life cycle.
• There are rounds of asexual reproduction in the vertebrate host inside red blood cells.
• Plasmodium is part of the Apicomplexa—an Alveolate group.

Malaria Life Cycle

• The malaria parasite has a complex life cycle, primarily involving mosquitoes and humans.
• Mosquitoes ingest gametocytes from human blood.
• Sporozoites develop from the zygote.
• Sporozoites migrate to the mosquito's salivary glands.
• When a mosquito bites a human, sporozoites are transferred to the bloodstream, followed by liver infection, and then red blood cells.

Plants

• There are 10 extant plants phyla.
• Some are nonvascular (e.g. mosses, liverworts, hornworts) while others are mosses.

Nonvascular Plants

• Nonvascular plants first appeared sometime in the Silurian period, around 440 million years ago.

Vascular Plants

• Plants with vascular tissue (xylem and phloem) evolved somewhat later (than nonvascular plants)
• Early vascular plants like Rhynia and Psilophyton were limited to wet areas.

Plants Adaptations to Land

• Roots absorb water and minerals from the soil.
• Leaves use photosynthesis to produce sugars.
• Vascular tissue carries substances between roots and leaves.

Plants Alternate Generations

• Plants have a life cycle that involves two alternating phases: sporophyte and gametophyte stages, with each having distinct ploidy (chromosome number)
• Sporophyte is diploid (2n), producing spores (n) through meiosis.
• Spores develop into gametophytes (n), which produce gametes (n) via mitosis.
• Fusion of gametes forms a zygote (2n), leading to sporophyte development.

Ferns

• Ferns are seedless vascular plants with diverse species (over 12,000).
• They have vascular tissue and produce spores for reproduction which are haploid.
• Dominant life cycle stage is the sporophyte.
• Mostly tropical and some temperate climates.

Seed Plants

• Seeds contain embryos and nutrients, with a protective coat.
• They are a crucial group in terrestrial ecosystems.

Gymnosperms

• Gymnosperms are a group of naked-seed plants where seeds are not enclosed in fruit.
• Conifers (pine, fir, spruce) are a diverse group.
• Gymnosperms include cone-bearing trees.

Angiosperms

• Angiosperms are flowering plants, with the most ecologically dominant group in terrestrial environments today
• Seeds are enclosed within fruits.
• Includes monocots and eudicots.

Monocots vs. Dicots (Eudicots)

• Distinguishing features based on structure of parts like roots, stems, leaves, and flowers.

Grasses

• Grasses (family Poaceae) are an important group of monocots.
• Widespread at the end of the Cretaceous period.
• Replaced ferns as the most important early-successional plants in many areas.

Animals

• Animals are multicellular organisms with homologous cell lineages descended from a single ancestor.
• Share a common ancestor with choanoflagellates, fungi, etc, forming a clade called opistokonts.
• About 35 major animal phyla have been identified.

Choanoflagellates

• Choanoflagellates are a group of single-celled protists.
• Morphology very similar to the supposed common ancestor of animals.

Sponges (Porifera)

• They are basal animals.
• Lack true tissues and organs.
• Have a body structure of a gel-like mesohyl between 2 layers of cells.
• Filter feeders with flagellated collar cells for creating water currents.
• Have regenerative capabilities. Spicules offer support but are not always present.

The Cambrian Explosion

• A period of rapid diversification of animal life around 530 million years ago.
• Most major animal phyla appeared in this period.
• Includes many extinct animal groups.

The Ediacaran Fauna

• Ediacaran fauna consisted of a diverse group of organisms that resemble animals (precursors of modern animals).
• The appearance of these forms around 600 million years ago reflects the Earth's recovery from massive glaciations.
• Characterized by unique physical structures, suggesting probable associations with microbial mats.

Ctenophores

• Ctenophores, also called comb jellies, are a group of animals.
• Morphologically similar to cnidarians in some ways.
• Thought to be an outgroup to other animals like sponges.
• They move via cilia.

Test your knowledge on the significant developments in plant evolution, reproductive strategies of ferns, and the ecological impact of vascular plants. This quiz covers a range of topics including plant structures, life cycles, and more. Perfect for biology students interested in botany and ecology!