Ecology of Fungi and Unicellular Algae

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Questions and Answers

What is the primary ecological role of fungi in ecosystems?

They are principal decomposers and contribute to nutrient cycling. (correct)

They act as producers by synthesizing organic compounds.

They create symbiotic relationships exclusively with plants.

They serve as the main source of energy for herbivores.

How do fungi contribute to environmental nutrient exchange?

Through the absorption of carbon dioxide and release of oxygen.

Through symbiotic partnerships that eliminate other organisms.

By breaking down organic matter and redistributing nutrients. (correct)

By producing organic waste materials that enrich the soil.

What distinguishes fungi's role in the decomposition of organic matter?

They occupy the highest trophic level in food webs.

They rely on sunlight for energy during decomposition.

They can decompose materials that many other organisms cannot. (correct)

They are strictly aerobic, requiring oxygen for all decomposition processes.

Which factor is least likely to be influenced by fungi in an ecological system?

The physical structure of the soil. Signup and view all the answers

In what way do fungi differ from plants in their ecological functions?

Fungi are heterotrophic and rely on decomposition for nutrition. Signup and view all the answers

What characterizes unicellular algae?

They are formed from a single cell. Signup and view all the answers

Which of the following is an example of a unicellular alga?

Chlorella Signup and view all the answers

Which of the following statements about unicellular algae is false?

They exist only in marine environments. Signup and view all the answers

What role do fossils play in relation to oil production?

They help in locating specific rock layers where oil accumulates. Signup and view all the answers

Which organisms are classified as unicellular algae?

Chlorella and diatoms Signup and view all the answers

Which of the following is a key feature of diatoms?

They are all unicellular. Signup and view all the answers

In what industries is the oil derived from fossil-rich rock layers primarily utilized?

Energy and plastics industries. Signup and view all the answers

Which statement most accurately reflects the relationship between fossils and rock layers?

Fossils indicate the presence of ancient life, which can correlate with oil deposits. Signup and view all the answers

What is a common misconception about the role of fossils in oil refinement?

Fossils help identify the best locations for extracting oil but do not play a role in refinement. Signup and view all the answers

Which characteristic of rock layers is important for oil accumulation?

The presence of specific types of rock and fossils. Signup and view all the answers

What type of environment do these plants thrive in?

Shady damp places with moisture Signup and view all the answers

Which feature is NOT characteristic of the gametophytic plant body?

Having differentiated true roots, stem, and leaves Signup and view all the answers

What replaces true roots in the gametophytic plant body?

Rhizoids, either unicellular or multicellular Signup and view all the answers

What is the primary requirement for the lifecycle completion of these terrestrial plants?

Water availability Signup and view all the answers

Which statement accurately describes the gametophytic structure?

It has the ability to perform photosynthesis. Signup and view all the answers

What characteristic is highlighted about certain organisms in terms of water loss?

They have evolved anatomical devices to manage water loss. Signup and view all the answers

Which statement best describes the evolutionary adaptations of some organisms related to drought resistance?

They have anatomical structures to conserve water. Signup and view all the answers

In the context of physiological drought resistance, what does the term 'anatomical devices' refer to?

Physical changes in body structure that prevent water loss. Signup and view all the answers

Which of the following is NOT a benefit of having anatomical devices for drought resistance?

Greater reliance on frequent watering. Signup and view all the answers

What implications do the adaptations for physiological drought resistance have on the survival of certain species?

They enable species to endure prolonged periods without water. Signup and view all the answers

What is the primary function of the air chambers mentioned?

To facilitate gaseous exchange Signup and view all the answers

Where do the air chambers open in relation to the thallus?

On the dorsal surface Signup and view all the answers

Which part of the thallus does the Lower Storage Zone represent?

The ventral tissue Signup and view all the answers

What is the placement of the Lower Storage Zone in relation to the photosynthetic zone?

Below the photosynthetic zone Signup and view all the answers

What is NOT a function of the air chambers in the thallus?

Storage of liquid nutrients Signup and view all the answers

Study Notes

Plant Paleontology

Paleontology is the area of geology that studies fossils.
Fossils are crucial for identifying and dating past environments and are helpful in geological mapping.
The Latin word "fossilis" means "dug up".
In the 19th century, "fossil" referred to virtually anything unearthed, including artifacts and mummies.

Fossils

Fossils are the naturally preserved remains or traces of organisms that lived in the geological past.
Egyptian mummies, preserved by humans, are not considered fossils.
Fossilization is a natural process where organisms turn into stone.

Fossilization

Fossilization is a natural process.
Durability of the organism's body (hard parts: teeth, claws, shells, bones) is crucial.
Environment with high deposition (like marine environments) favors fossilization (burial within hours to days).

Types of Fossils

Fossils are categorized into:
- Body fossils: Remains of organisms (e.g., whole body of Pleistocene mammoths, teeth, bones, shells, and leaves)
- Trace fossils: Evidence of an organism's presence or activity (e.g., footprints, tracks, trails, burrows)
- Chemical fossils: Organic compounds produced by organisms (e.g., oil, gas, coal).

Fossil Formation (Footprint Fossils)

Organisms step into soft mud (silty sediment).
The impression is covered with loose sand.
The sand hardens into sandstone.
The rock splits, revealing the footprint and cast.

Modes of Preservation

Preservation without alteration: In rare cases, original parts (including soft tissues) are preserved intact. This occurs in cold or arid climates, where organisms freeze in ice or dry out in the desert air. Desiccation is the removal of water from an organism. Examples are frozen mammoths and dried Egyptian remains.
Preservation with alteration: Most fossils undergo some alteration. Common alterations include permineralization, replacement, carbonization, recrystallization, and the formation of molds and casts.

Fossilization Processes

Permineralization: Empty spaces within an organism get filled with mineral-rich groundwater. Minerals precipitate, filling the spaces.
Carbonization: Original plant or animal remains change to a thin layer of carbon, outlining the original form.
Recrystallization: Less stable mineral forms convert to more stable forms. This is often seen in clam and snail shells, where aragonite (a less stable form of calcium carbonate) gradually transforms into calcite.
Freezing: Preserves organisms intact. Rare and rarely very old. Examples include mummified mammoths.
Drying (Desiccation): Preserves remains, particularly in arid environments. Examples are dried camels, ground sloths, and marsupial wolves.
Petrification/ mineral replacement: Organic materials are converted into stone or a similar mineral substance. Petrified wood is a well-known example.
Molds and Casts:
- Mold: Hard body parts dissolve, leaving an impression of the organism's shape.
- Cast: The mold is filled with sediment or mineral deposits, replicating the original shape of the organism.

Importance of Fossils

Understanding the past: Fossils reveal insights into how prehistoric plants and animals obtained food, reproduced, and behaved. They can also provide clues into the cause of their death.
Dating Earth's layers: Fossils help determine the ages of rock layers, allowing researchers to match layers in different locations by determining how similar the fossils are. These insights help us understand the formation of various rock layers even when the locations are separated by great distances.
Documenting change: The types of fossils found in a location reveal the environments that existed when the fossils were formed. For example, discovering marine fossils in a current terrestrial location indicates a past ocean.
Commercial Applications (e.g., Fossils & Oil): Oil, Coal, and Gases are considered 'Fossil Fuels' and are formed from the organic remains of prehistoric organisms. Studying fossils near oil wells is used for improved geological exploration and oil reserves.

Evolution

Fossils are vital to understanding evolution.
Fossil evidence allows scientists to reconstruct organisms and create "Trees of Life", which display the evolutionary relationships between organisms.

Studying Climate Changes

Fossils help determine how the Earth's climate and landscape changed over time.
The presence of a particular plant fossil in a specific location and time period suggests the suitable climate for that organism at that period.

Plant Fossils

Plants are crucial to life on Earth. Fossilized plant remains are responsible for many coal deposits and potentially large oil reserves.
Remains are often seen as individual parts (leaves, fern fronds, cones, bark sections, spores, flowers, and petrified wood).

The Six Kingdoms of Life (Diagram)

All living things.
Prokaryote (Archaebacteria and Eubacteria, Monera).
Eukaryote (Protista, Fungi, Plantae, Animalia).
Virus (Unknown, or undetermined)

Domain: Prokaryote, Kingdom: Bacteria

Bacteria are single-celled microorganisms that survive in diverse environments.
They are prokaryotes.
Bacteria consist of a single cell with a simple internal structure and free-floating, twisted DNA strands (bacterial chromosome).

Morphology of Bacterial Cells (Diagram)

Bacterial cells take diverse shapes (cocci, bacilli, vibrio, spirillum).

Bacterial Endospores

Microorganisms adapt to environmental changes.
When nutrients are scarce, some bacteria form tough, dormant endospores to preserve their DNA.
Endospores are highly resistant to extreme conditions such as heat, radiation, drying, and chemical damage.

Endospore Structure

Endospores have a proteinaceous coat, a cortex of peptidoglycan, a germ cell wall, an inner membrane, and a core containing the cell's DNA and ribosomes, along with high amounts of dipicolinic acid.
Spore-specific proteins (SASPs) also contribute to their resilience.

Endospore Development (Diagram)

Endospore formation is a multifaceted process.
The bacterial cell divides asymmetrically, and one cell becomes the spore.
The mother cell degrades, releasing the endospore into the environment following cell maturation and dehydration.
The endospore remains dormant until favorable conditions arise.

Location of Endospores (Diagram)

Endospore location varies among bacterial species.
Placement is a useful identifier.

Spore Germination

A released endospore, when exposed to favorable conditions, germinates into a new bacterium.

Domain: Eukaryote, Kingdom: Fungi (Mycota) (Diagram)

Fungi are eukaryotic organisms that acquire food by absorbing dissolved molecules via secreted digestive enzymes.
Most fungi grow as long thin strands called "Hyphae" which can form larger masses called "Mycelia".
Some fungi are unicellular (e.g. Yeast).

Hyphae or Mycelium (Diagram)

Hyphae/Mycelium are long thin threadlike structures ranging in size.
Septate hyphae are divided into cells by internal walls.
Coenocytic hyphae lack these walls and have a continuous cytoplasm.

Importance of Fungi

Decomposition: Fungi break down organic matter, recycling nutrients.
Food: Mushrooms are a food source.
Food Production: Fungi are used in bread, wine, beer, soy sauce fermentation.
Medicine: Antibiotic production and enzymes for industrial use.
Biological Pesticides: Fungi produce compounds to control weeds, diseases, and pests.
Risk of Fungi: Fungi can be pathogenic to humans and animals and cause crop losses and food spoilage.
Fossil Fungi: Fossil fungi are rare and mostly microscopic.

Fossil Fungi

Fossil fungi are not common and their fossils have not received much attention compared to other fossils.
Most fungal fossils are microscopic.
Some fungal fossils found in amber (Cretaceous Period in Northern France) provide information about extinct fungi and their possible relationships to living fungi.
Fossil evidence of particular fungal characteristics (e.g. reproductive structures) provide insights into the evolutionary history of the fungi.

Fossil Algae

Algae are a diverse group of eukaryotic photosynthetic organisms.
They are essential producers in aquatic ecosystems.
Algae convert carbon dioxide and nutrients into carbohydrates and proteins.
Algae come in a variety of morphologies, including unicellular, colonial, filamentous, and membranous forms (e.g. Chlorelia, diatoms, giant kelp).

Algal Pigments

Algae contain pigments (chlorophyll, carotenoids, phycobiliproteins).
These pigments contribute to algae's color.
Pigments protect the cells and help with photosynthesis.

Importance of Algal Fossils

Fossils reveal past environments of deposition and ecosystems.
Algal types indicate water depth.
Certain algae photosynthesize at specific wavelengths, reflecting water depth.

Calcareous Algae

Calcareous algae deposit calcium carbonate within or around their tissues.
Remains of these algae are abundant in Cenozoic limestones on Guam, and they are significant components in limestone formation.

Coralline Algae

Coralline algae are red algae within the order Corallinales.
Their thallus is hard due to calcareous deposits.
They can be pink, red, purple, yellow, blue, white, or gray-green.
Coralline algae are important to coral reef ecosystems.

Divisions/Classes/Orders of Archegoniatae

There are different types of archegoniate plants.
Archegoniatae encompasses Bryophytes (Mosses, liverworts, hornworts).

Division: Bryophyta

Bryophytes are small, non-vascular plants that require moist environments to reproduce.
They typically reproduce sexually using sperm that swim to the egg of another plant.

General Characteristics of Bryophytes

Lack of vascular tissue (xylem and phloem).
Absence of true roots and leaves (leafy or thalloid).
Sporophyte is dependent on the gametophyte.
Reproduction is oogamous (motile sperm, non-motile egg).
Dominant gametophyte in the life cycle
Reproduction typically involves the separation of a sporophyte from the parent plant.

General Characters of Liverworts

Limited to moist environments due to lack of vascular tissue.
Sperm cells must swim to reach the egg (reproduction is oogamous).
They use chlorophyll, chlorophyll-b, and carotenoids as photosynthetic pigments.
Food reserves stored as starch.
The thallus is dorsiventral (has distinct front and rear sides).
The plant is small and green, lacking true roots, stems, leaves. The thallus has a leaf-like structure and rhizoids for anchoring.
Capsules are usually ovoid or spherical and have no lid, splitting into 4 valves when mature.
The seta is weak and colorless.

Order: Marchantiales

The largest order of thalloid liverwort.
Physiological drought resistance.
Dominate exposed sites with intense light.
Dorsiventrally flattened thallus.
Some have ventral scales.

Family: Ricciaceae, Genus: Riccia

Includes about 200 species worldwide.
Predominantly terrestrial.
Some species are aquatic.

Gametophytic Phase of Riccia

The plant body of Riccia is gametophytic and the gametophytes are fleshy, prostrate, and dichotomously branched.

Anatomy of Gametophyte

The thallus is differentiated into upper photosynthetic zone and lower storage zone.

Upper Photosynthetic Zone

The upper part of the thallus is green.
It consists of vertical rows of un-branched photosynthetic filaments.

Lower Storage Zone

Located beneath the photosynthetic zone.
Contains parenchyma cells with starch reserves.
Forms the lower epidermis.

Reproduction in Riccia

Riccia reproduces vegetatively and sexually.

Vegetative Reproduction in Riccia (Detailed)

Death and decay of older thallus: portions of an aging/drought-stressed thallus rot.
Adventitious branches: Branches arising from the ventral thallus surface.
Persistent apices: Thickened growing points become new thalli.
Tubers: Apices of the lobes become swollen, acting as perennating tubers.
Rhizoids: Gemmae form on young rhizoids, which then grow into new thalli.

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Explore the vital roles of fungi and unicellular algae in ecosystems through this quiz. Learn about their contributions to nutrient exchange, decomposition, and fossil relationships in oil production. Test your knowledge on their unique characteristics and ecological functions.