Biological Concepts in Ecology and Botany

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Questions and Answers

What does the Biological Species Concept (BSC) define a species as?

Any organisms that share the same habitat

Populations of organisms that can reproduce with one another and are reproductively isolated from others (correct)

A group of organisms that can migrate freely between populations

A collection of organisms with similar physical traits only

Why is it challenging to apply the Biological Species Concept to prokaryotes?

Prokaryotes grow in environments that are hard to study.

Prokaryotes do not reproduce sexually. (correct)

Prokaryotes rarely exchange DNA with other species.

Prokaryotes have very few distinct morphological features.

Which type of algae is characterized as being mostly multicellular and includes several edible varieties?

Cyanophyta

Ochrophyta

Chlorophytes

Rhodophyta (correct)

How are different bacterial species defined according to genetic similarity?

By overall similarity of their DNA, classified at 97% similarity Signup and view all the answers

What is the estimated range of total living species on Earth?

2-20 million Signup and view all the answers

What is a significant role that plants play in Earth's ecosystems?

They produce most of Earth's oxygen. Signup and view all the answers

Which of the following statements about land plants (Embryophyta) is true?

They reproduce with alternating haploid and diploid stages. Signup and view all the answers

Which of the following is NOT a problem with the Biological Species Concept?

It provides a clear definition for all species. Signup and view all the answers

What aspect of brown algae is an adaptation to prevent dehydration?

Gel-like cell walls Signup and view all the answers

What distinguishes the closest living relatives of land plants?

They are chlorophytes. Signup and view all the answers

Which of the following plant types are commonly found in tundra environments?

Mosses Signup and view all the answers

What is a key characteristic of organisms classified as opisthokonts?

Presence of a single, posterior flagellum Signup and view all the answers

How do fungi obtain nutrients?

Secreting digestive enzymes and absorbing dissolved molecules Signup and view all the answers

What distinguishes filamentous fungi from yeast?

Filamentous fungi grow as multicellular structures called hyphae Signup and view all the answers

Which role is NOT typically associated with fungi?

Producers of oxygen Signup and view all the answers

Which structure in molluscs is responsible for secreting the shell?

Mantle Signup and view all the answers

What is the primary component of the mollusc shell?

Calcium carbonate Signup and view all the answers

What is a unique feature of the radula in cephalopods?

It forms a beak along with the cutting plates. Signup and view all the answers

Which of the following is true regarding the fossil record of molluscs?

Their fossils can help correlate the ages of rocks. Signup and view all the answers

Which part of the mollusc body is primarily used for movement?

Foot Signup and view all the answers

What role do cilia play in the digestive system of molluscs?

They move mucus into the stomach. Signup and view all the answers

How does the nervous system in snails differ from that in other molluscs?

The oesophagus runs through the middle of the brain. Signup and view all the answers

Which characteristic of mollusc fossils is correct?

Mollusc fossils are primarily useful for dating rock layers. Signup and view all the answers

What characteristic is unique to Platyhelminthes compared to other Lophotrochozoa members?

Flat body with no circulatory system Signup and view all the answers

What type of larva is associated with members of the Lophotrochozoa?

Trochophore Signup and view all the answers

Which of the following organisms exhibits a lophophore?

Bryozoans Signup and view all the answers

What type of reproduction is seen in some species of Rotifera?

Parthenogenesis Signup and view all the answers

Which group of annelids is typically characterized by a reduced head and limited appendages?

Earthworms Signup and view all the answers

What is a significant feature of the digestive system in Platyhelminthes?

Single opening for ingestion and excretion Signup and view all the answers

How does segmentation benefit annelid worms?

Increased mobility and flexibility Signup and view all the answers

Which of the following statements is true regarding brachiopods?

They are primarily marine filter feeders. Signup and view all the answers

What makes the fossil record of molluscs significant?

Many possess hard calcareous shells. Signup and view all the answers

What distinguishes schistosomiasis as a disease?

It is associated with flatworm parasites. Signup and view all the answers

What is the primary function of haemocyanin in mollusc blood?

Oxygen transport Signup and view all the answers

Which reproductive strategy do some molluscs exhibit?

Hermaphroditism Signup and view all the answers

How do cephalopods differ in their circulatory system compared to most molluscs?

They possess a closed circulatory system Signup and view all the answers

What is the role of nephridia in molluscs?

Waste product excretion Signup and view all the answers

What unique feature do gastropods undergo during larval development?

Torsion Signup and view all the answers

Which mollusc class is known for having a dorsal shell made of eight plates?

Polyplacophora Signup and view all the answers

What is the primitive larval stage of molluscs called?

Trochophore Signup and view all the answers

How do land snails adapt their mantle cavity for respiration?

They modify it into a primitive lung Signup and view all the answers

Which class of molluscs includes the majority of species?

Gastropoda Signup and view all the answers

Which function does the heart of molluscs serve beyond pumping blood?

Filtration of waste products Signup and view all the answers

Study Notes

Origins of Life

Phylogeny is the evolutionary tree
Biodiversity is the diversity of life, including genetic, taxonomic, and ecosystem diversity
Morphology refers to the shape of a species

What is a Species? And How Many?

It is difficult to precisely define a species
Biological Species Concept: a group of populations that can interbreed and are reproductively isolated from other such populations
Problems with BSC:
- It's often hard to observe reproductive isolation in species
- Some clearly distinct species can interbreed (e.g., a liger)
- It does not apply to fossil species
- Defining species in prokaryotes (Archaea and Bacteria) is difficult because of DNA exchange
- Species are classified based on DNA similarity; 97% similarity indicates the same species
Eukaryotes: organisms with complex cells (plants, animals, and fungi)
- Estimates of eukaryotic species:
  - 8.7 million
  - 5-3 million

How Can We Assess Diversity?

Taxonomy is the identification, description, naming, and classification of organisms
Systematics/classification: the organization of organisms into groups according to some system
Phylogenetics: a branch of biology studying evolutionary relationships
Carl Linnaeus (1707-1778): Father of modern taxonomy
- First to classify organisms
- Introduced binomial nomenclature (genus and species names) for classifying organisms
- Proposed classification ranks (kingdom, phylum, class, etc.)

An additional Rank

An additional rank above Kingdom is Domain

Phylogenetics

The study of evolutionary relationships between organisms
Evolution outcomes:
- Better adaptation to the environment
- Speciation (formation of new species)
- Extinction
The tree of life is fundamental to Linnaean classification

Eukaryotes

Earliest eukaryotes: 1.65 billion years ago
Earliest multicellular eukaryotes: 1.635 billion years ago
Eukaryotes are diverse and have complex cells and life cycles
Eukaryotes have evolved multicellularity
- Many have distinctive features like a nucleus within their cells
- Larger genomes than prokaryotes
Eukaryotes sometimes reproduce sexually to promote genetic variation
- Processes include meiosis (haploid cells from diploid cells) and fertilization (diploid cells formed from two haploid cells)
- All cells are either haploid or diploid

Cells

Nuclei separate processes like DNA replication and transcription from translation which provides additional gene expression regulation
- DNA is structured into linear chromosomes within the nucleus
Mitochondria: Present in most eukaryotes (sometimes lost). Essential for cellular respiration
- Some eukaryotes lose mitochondria due to parasitic nature
- Mitochondria are considered to have arisen from free-living bacteria that evolved into eukaryotes
Chloroplasts: Photosynthetic organelles in plants and algae
- Originate from free-living bacteria
Cells compartmentalized into specialized components.

Diversity of Eukaryotes

Most eukaryotes are single-celled organisms called protists
Protists can be related to animals, plants, or fungi
Some protists known as excavates are important parasites (Giardia and Trichomonas)
- Lack/reduced mitochondria

Alveolates

A type of protist that includes dinoflagellates, important marine plankton that are photosynthetic and can produce red tides that harm wildlife and produce bioluminescence
- Also includes important parasites (e.g. Trichomonas)

Slime Moulds

Usually single-celled organisms, but they can form a multicellular body when food is scarce.

Algae

Most algae are photosynthetic
Algae have varying levels of complexity from unicellular to multicellular forms.
- Green algae are related to land plants
- Red algae include some edible seaweed
- Brown algae include seaweeds like kelp which are large multicellular organisms that can form forests in the ocean

Plants (Embryophyta)

Plants are multicellular
Majority are terrestrial and obtain energy from photosynthesis
Plants have complex reproductive cycles, alternating between haploid and diploid stages
Sporophytes are the diploid stage (producing spores)
- Gametophytes are the haploid stage (producing gametes)
Land plants evolved from a group of green algae
The oldest known land plants evolved about 430 million years ago and were mostly small

Adaptation

Plants on land had challenges like maintaining moisture
Plants' developed cuticles and stomata (pores) to address this

Non-vascular Plants

Lack vascular tissue, which are critical for transporting water and nutrients

Vascular Plants

Have xylem (water transport) and phloem (nutrient transport)

Seeds and Flowers

Seeds and flowers are a characteristic of many plants
The ability to reproduce through seeds is a key adaptation leading to diverse plant groups
Different plant groups:
- Ferns
- Gymnosperms (conifers, cycads)
- Angiosperms (flowering plants)
Angiosperms are critical to human activities

Earth's Biomes

Earth's biomes are largely determined by plant communities
Examples include tundra, grasslands, forests

Opisthokonts

Animals and Fungi are closely related; both are eukaryotes and include a number of important parasites
They are all Opisthokonts
Have single posterior flagella

Fungi

Fungi are heterotrophs, obtaining nutrients by secreting digestive enzymes and absorbing dissolved molecules
Fungi are a critical part of many ecosystems; they decompose organic matter
Many fungi are important to humans (food, antibiotics)

Animalia (Metazoa)

Animals are motile (capable of active movement at some point in their life cycle)
Animals are closely related to choanoflagellates (eukaryotes)
Several phylum exist including:
- Porifera (sponges): Simplest animals
- Radiata (jellyfish, corals, sea anemones): Radial symmetry
- Bilateria (most animals): Bilateral symmetry

Sponges

Simplest animals (no true tissues)
Feed by filtering water into their bodies
Have specialized cells to move water and capture food particles

Cnidarians (jellyfish, corals)

Contain specialized stinging cells called nematocysts
Can exist as polyps (sessile) or medusae (free-swimming)
Corals are colonial organisms that build up coral reefs

Bilateria

Majority of animals
Some are bilaterally symmetrical
Triploblastic (3 germ cell layers)
Often have a body cavity (coelom)

Protostomes

A major lineage of bilaterian animals
Two major groupings:
- Lophotrochozoa
- Ecdysozoa

Lophotrochozoa

Includes organisms with feeding structures called lophophores and larvae called trochophores
- Examples include molluscs (snails, clams), annelids (worms)

Ecdysozoa

Includes animals that shed their external covering (cuticle) during growth
Many groups within like arthropods and nematodes

Arthropods

Have external skeletons, segmented bodies, and jointed appendages
Includes insects, crustaceans, spiders.

Mollusk

Diverse group of animals (snails, clams, squid)
Often have a shell and a muscular foot
Many have a mantle that secretes the shell

Cephalopods (squid, octopus)

Some of the most intelligent invertebrates
Use complex behaviors and sophisticated sensory systems.

Annelids

Segmented worms (earthworms, leeches)
Have repetitive segments

Nematodes

Roundworms, parasitic in a wide range of organisms
Important decomposers and in some ecosystems

Tardigrades

Water bears, can survive extreme conditions

Onychophora

Velvet worms

Crustaceans

Aquatic arthropods (crabs, shrimp)
Often have a hard exoskeleton

Hexapods

Insects
Usually have three pairs of legs

Malacostraca

Diverse group of crustaceans.

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Description

Test your knowledge on species definitions and ecological roles within the Biological Species Concept, as well as the characteristics and classifications of plants and fungi. This quiz covers the challenges of applying the BSC to prokaryotes, types of algae, and the ecological significance of various organisms. Dive into questions regarding multicellular algae, nutrient acquisition in fungi, and plant adaptations.