quiz 7 Flashcards
Photoautotrophs
Use light as an energy source and CO₂ as a carbon source.
Example: Cyanobacteria (e.g., Anabaena)
Chemoautotrophs
Use inorganic chemicals (like H₂S, NH₃) for energy and CO₂ as a carbon source.
Photoheterotrophs
Use light for energy but obtain carbon from organic compounds.
Example: Purple non-sulfur bacteria (e.g., Rhodobacter)
Chemoheterotroph
Obtain both energy and carbon from organic compounds.
Example: Escherichia coli, most pathogenic bacteria
Obligate aerobes
Require O₂ for survival (e.g., Mycobacterium tuberculosis).
Facultative anaerobes
Can use O₂ when available but can also grow without it (e.g., E. coli).
Obligate anaerobes
Cannot survive in the presence of O₂ (e.g., Clostridium botulinum).
. Structural and Functional Diversity of protists
- Unicellular, colonial, or multicellular forms
- Locomotion via flagella, cilia, or pseudopodia
- Diverse reproductive strategies (asexual, sexual, or both)
. Nutrition Types in Protists
- Photoautotrophs – Perform photosynthesis (e.g., algae).
- Heterotrophs – Consume organic material (e.g., amoebas).
- Mixotrophs – Combine photosynthesis and heterotrophy (e.g., Euglena).
Endosymbiosis in Evolution
- Primary endosymbiosis: A prokaryotic cell engulfed another (e.g., mitochondria evolved from an aerobic bacterium).
- Secondary endosymbiosis: A eukaryote engulfed a photosynthetic eukaryote (e.g., chloroplasts in some protists).
Supergroups & Example Organisms
- Excavata – Characterized by a feeding groove, some have modified mitochondria.
o Example: Euglena - SAR Clade – Diverse group including diatoms, brown algae, and dinoflagellates.
o Example: Plasmodium (causes malaria) - Archaeplastida – Includes red and green algae and land plants.
o Example: Chlamydomonas (green alga) - Unikonta – Includes amoebas, fungi, and animals.
o Example: Amoeba proteus
Life Cycle, Ecology, and Impact of Specific Protists
- Diatoms – Photosynthetic, silica cell walls, major oceanic oxygen producers.
- Kelp (Brown Algae) – Forms underwater forests, supports marine life.
- Red Algae – Found in deep waters, important for food (e.g., nori).
. Evolutionary Ancestors of Land Plants, Fungi, and Animals
- Land plants – Evolved from green algae (charophytes).
- Fungi – Evolved from unicellular protists related to nucleariids.
- Animals – Evolved from a protist similar to choanoflagellates
Four Key Traits of Land Plants (vs. Charophytes)
- Alternation of generations (sporophyte & gametophyte phases).
- Multicellular dependent embryos (protected by maternal tissue).
- Walled spores in sporangia (prevents desiccation).
- Apical meristems (growth regions for roots & shoots).
Generalized Plant Life Cycle
- Sporophyte (2n) → Spores (n) via meiosis → Gametophyte (n) → Gametes (n) via mitosis → Fertilization → Zygote (2n) → Sporophyte
Characteristics of Non-Vascular Plants (Bryophytes)
- Phylum Hepatophyta (Liverworts) – Leafy or thalloid, reproduce via gemmae.
- Phylum Bryophyta (Mosses) – Simple rhizoids, dominant gametophyte.
- Phylum Anthocerophyta (Hornworts) – Single large chloroplast per cell.
Moss Life Cycle (Diagram Needed)
- Dominant gametophyte phase
- Antheridia (male) and archegonia (female) produce gametes
- Water-dependent fertilization
- Zygote grows into sporophyte, which produces spores
Why Bryophytes Grow Close to the Ground
- Lack vascular tissue → No support for vertical growth.
- Depend on water for reproduction.
. Traits of Vascular Plants & Their Advantages
- Xylem and phloem (transport of water/nutrients).
- Roots (absorb water and provide anchorage).
- Leaves (increase photosynthesis).
- Sporophyte-dominant life cycle (more efficient reproduction).
Differences Between Moss and Fern Life Cycles
- Mosses – Gametophyte dominant, requires water for fertilization.
- Ferns – Sporophyte dominant, still water-dependent for sperm mobility but better adapted to land.
