MASS

Chats BIO 206 Midterm Study To-Do List

🗓 Deadline: February 24, 2025 (1:00 PM)

🔥 HIGH PRIORITY (Must Know)

✅ Photosynthesis & Endosymbiosis

• Primary vs. Secondary Endosymbiosis

• Evolution of Photosynthetic Organisms (Cyanobacteria → Green Algae → Land Plants)

• Key structures: Chloroplast membranes (2° endosymbiosis = 4 membranes), Kleptoplasty

• Role of cyanobacteria in O₂ production & nitrogen fixation (enzyme: Nitrogenase)

✅ Algae & Plant Comparative Table (Know for paper section questions)

• Differences between Cyanobacteria, Green Algae, Bryophytes, & Vascular Plants

• Traits: Cell Type, Pigments, Structure, Water Transport, Reproduction, Spore Dispersal

✅ Lab Species & Characteristics

• Cyanobacteria: Anabaena, Nostoc, Gloeocapsa, Lyngbya (Heterocysts, Mucigel)

• Green Algae: Chlamydomonas (unicell, flagella), Volvox (colonial, flagella), Chara (plant-like)

• Brown/Red Algae: Diatoms (silica), Polysiphonia (holdfast, marine)

• Bryophytes: Moss & Liverwort Life Cycles (Capsule = Meiosis, Gametophyte = Dominant)

✅ Microalgae (Thore et al. 2023)

• Evolutionary origin (Primary vs. Secondary Endosymbiosis)

• Microalgae groups: Green, Red, Brown, Diatoms, Dinoflagellates, Euglenoids

• Ecological roles: Carbon, Nitrogen, Silica Cycles, Coral Symbiosis

• Human uses: Biofuels, Omega-3s, Bioplastics, Toxins, Cultivation challenges

✅ Plant Adaptations for Land

• Cuticle (Water Retention), Stomata (Gas Exchange), Vascular Tissue (Xylem/Phloem)

• Molecular clock & master control genes in plant evolution

⚡ MEDIUM PRIORITY (Review If Time Allows)

🔲 Photosynthetic microorganisms' diversity (Lab Table 1A, 1B, 1C, 1D)
🔲 Differences in Bryophyte, Fern, and Seed Plant Reproduction
🔲 Molecular Clock & DNA-based Evolution Evidence
🔲 Experimental methods used to study photosynthesis

📝 PRACTICE QUESTIONS (Use These to Test Yourself)

✅ Endosymbiosis: How did photosynthesis evolve in eukaryotes?
✅ Chloroplast Membranes: How many membranes would a dinoflagellate chloroplast have?
✅ Algae Identification: Identify a species based on images (unicellular, colonial, thalloid, filamentous)
✅ Comparative Table: List key differences between cyanobacteria, green algae, bryophytes, and vascular plants
✅ Moss Reproduction: What happens in the capsule? (Answer: Meiosis)
✅ Microalgae Applications: Name 3 commercial uses of microalgae and their species
✅ Eutrophication: How do algal blooms impact ecosystems?

🛠 LAST MINUTE STUDY STRATEGY (Night Before Exam)

✅ Review Memory Aid (Ensure it's properly formatted & fits within 25 lines)
✅ Go through Practice Questions
✅ Review Comparative Table
✅ Skim through Lab Species & Key Structures
✅ Check Microalgae Summary

What You Need to Know for the BIO 206 Midterm?

Your midterm covers Weeks 1-5 and is divided into two parts:
✅ Part 1: Top Hat (15-20 multiple-choice, association, sorting questions)
✅ Part 2: Paper (4-6 questions including comparative tables, explanations, and applied questions)
📌 Total Marks: 35-50 (likely 40)
📌 Date: February 24 or 25, 2025
📌 Location: JOH 316 (lab coat required!)
📌 Memory Aid Allowed (must follow format)

🌱 Main Study Topics by Chapter

Chapter 1: The Origin of Photosynthesis

🔹 Definition & Process of Photosynthesis

• What is photosynthesis?

• Components & process (light-dependent & light-independent reactions)

🔹 Early Photosynthesis & Its Impact

• How cyanobacteria changed Earth's atmosphere (Great Oxygenation Event)

🔹 Origin & Evolution of Photosynthesis

• How photosynthesis evolved in prokaryotes → eukaryotes

• Scientific evidence supporting this evolution

🔹 Key Photosynthetic Microorganisms

• Cyanobacteria (Anabaena, Nostoc, Gloeocapsa)

• Be able to identify them & describe characteristics

🔹 Significance of Cyanobacteria

• Oxygen production

• Nitrogen fixation (Nitrogenase & heterocysts)

Chapter 2: Eukaryotic Plant Life

🔹 Evolution of Photosynthesis in Eukaryotes

• Primary vs. Secondary Endosymbiosis

• Evolution of red & green algae, diatoms, dinoflagellates, Euglena

🔹 Comparing Photosynthetic Traits

• Cyanobacteria vs. Algae vs. Land Plants (See Comparative Table)

🔹 Key Terms to Know
✅ Mutualism (e.g., corals & dinoflagellates)
✅ Kleptoplasty (stolen chloroplasts)
✅ Endosymbiosis (Primary = 2 membranes, Secondary = 4 membranes)
✅ Mitosis vs. Meiosis (Role in life cycles)
✅ Life Cycles of Algae (Alternation of Generations)
✅ Multicellularity (How it evolved in algae & land plants)

🔹 Scientific Evidence for Photosynthesis Evolution

• How scientists study this process (DNA, fossils, molecular clocks)

🔹 Evolution of Land Plants

• Charophytes → Bryophytes → Vascular Plants

• Importance of Algae in plant evolution

Chapter 3: Plants Invade the Land

🔹 Green Algae → Land Plant Transition

• Charophytes = Closest relatives of land plants

🔹 Evolution of Early Land Plants

• First colonizers & challenges they faced (drying out, reproduction)

🔹 Life Cycles of Nonvascular Plants (Mosses, Liverworts)

• Dominant gametophyte stage

• Capsule & spore dispersal

🔹 Key Concepts & Scientific Evidence
✅ Molecular Clock (DNA evidence of plant evolution)
✅ Evapotranspiration (Water loss through leaves)
✅ Capillary Action, Adhesion, Cohesion (Water transport in plants)
✅ Regulatory Switch (Master Control Gene) (Controls development)

🔹 Adaptations of Early Land Plants

• Cuticle, Stomata, Vascular Tissue (Xylem & Phloem)

• Reproductive Shift: Spores → Seeds → Flowers

🔹 Nonvascular vs. Vascular Plants

• Bryophytes vs. Ferns vs. Gymnosperms vs. Angiosperms

• Changes in structure, reproduction, and adaptation to land

📝 How to Prepare for the Exam

✅ Review Comparative Table (Cyanobacteria vs. Algae vs. Bryophytes vs. Vascular Plants)
✅ Understand Endosymbiosis & How Chloroplasts Evolved
✅ Know Life Cycles of Algae & Mosses (Alternation of Generations)
✅ Study Adaptations for Land Plants & Water Transport Mechanisms
✅ Identify Photosynthetic Organisms & Their Traits
✅ Practice Multiple-Choice & Applied Questions

📌 Chapter 1: The Origin of Photosynthesis

What is Photosynthesis?

🔹 Definition

Photosynthesis = The process by which organisms use light energy to convert CO₂ + H₂O into glucose (C₆H₁₂O₆) + O₂

🔹 General Equation:

🌞 Light Energy + CO₂ + H₂O → C₆H₁₂O₆ + O₂

🔹 Two Stages of Photosynthesis

✅ Light-Dependent Reactions (Occurs in Thylakoid Membrane)

• Converts light energy → ATP & NADPH

• Splits H₂O → Produces O₂

✅ Light-Independent Reactions (Calvin Cycle, Occurs in Stroma)

• Uses ATP & NADPH to fix CO₂ into glucose

importance of Photosynthesis for Life

• Produces oxygen (supports aerobic life)

• Fixes carbon (creates organic molecules for energy)

• Basis of food chains (primary producers)

• Regulates climate (removes CO₂ from atmosphere)

Early Photosynthesis & Its Impact on Earth

🔹 The Great Oxygenation Event (~2.4 BYA)

• First photosynthetic cyanobacteria produced O₂

• O₂ accumulated in oceans → reacted with iron → created iron oxide (rust) deposits

• O₂ entered atmosphere → Killed many anaerobic organisms

• Allowed the evolution of aerobic (oxygen-using) organisms

🔹 The Role of Cyanobacteria

• First oxygenic photosynthesizers

• Created Earth's oxygen-rich atmosphere

• Basis for chloroplast evolution (endosymbiosis)

Evolution of Photosynthesis (From Prokaryotes to Eukaryotes)

🔹 Step 1: Cyanobacteria - First Photosynthetic Organisms

✅ Prokaryotic (no nucleus)
✅ Used Chl a + Phycobilins
✅ No chloroplasts, just thylakoid membranes
✅ Some could fix nitrogen using heterocysts

🔹 Step 2: Endosymbiosis → Formation of Chloroplasts

✅ Primary Endosymbiosis: A eukaryotic cell engulfed a cyanobacterium → Became the first chloroplast
✅ Secondary Endosymbiosis: Another eukaryote engulfed a photosynthetic eukaryote → Spread photosynthesis further

🔹 Step 3: Evolution into Algae & Land Plants

✅ Red & Green Algae (1° Endosymbiosis)
✅ Brown Algae, Diatoms, Euglenoids (2° Endosymbiosis)
✅ Green Algae → Charophytes → First Land Plants

Scientific Evidence for the Evolution of Photosynthesis

✅ Fossil Records: Stromatolites (~3.5 BYA) contain cyanobacteria
✅ Molecular Evidence: Chloroplast DNA closely resembles cyanobacterial DNA
✅ Chloroplast Membranes: Support Endosymbiotic Theory (2 or 4 membranes)
✅ Iron Bands in Rocks: Indicate ancient oxygen production

Key Photosynthetic Microorganisms (Identification & Characteristics)

📌 Quick Recap (What to Memorize)

✅ Photosynthesis = Converts CO₂ + H₂O → O₂ + Glucose
✅ Cyanobacteria started it → Great Oxygenation Event (~2.4 BYA)
✅ Endosymbiosis → Chloroplast Formation (2° Endosymbiosis = 4 membranes)
✅ Key evidence: Stromatolites, DNA, Membranes, Iron Bands
✅ Be able to identify cyanobacteria & green algae from lab material

📝 Practice Questions

1⃣ What is the main pigment in cyanobacteria? (Answer: Chl a & Phycobilins)
2⃣ What are heterocysts, and why are they important? (Answer: Specialized cells for nitrogen fixation in cyanobacteria)
3⃣ Which event caused Earth’s atmosphere to become oxygen-rich? (Answer: Great Oxygenation Event)
4⃣ How did chloroplasts evolve in plants? (Answer: Primary Endosymbiosis of cyanobacteria)
5⃣ Which evidence supports the evolution of photosynthesis? (Answer: Fossil Stromatolites, DNA, Membranes, Iron Bands)

📌 Chapter 2: Eukaryotic Plant Life

Evolution of Photosynthesis in Eukaryotes

🔹 How Did Photosynthesis Spread to Eukaryotes?

• Prokaryotes (Cyanobacteria) → Eukaryotes (Algae & Plants)

• Primary Endosymbiosis: A eukaryotic cell engulfed a cyanobacterium → Became the first chloroplast

• Secondary Endosymbiosis: Another eukaryote engulfed a photosynthetic eukaryote → More complex chloroplasts (4 membranes)

🔹 What Came From Endosymbiosis?

✅ Primary Endosymbiosis → 2 membranes (Red & Green Algae)
✅ Secondary Endosymbiosis → 4 membranes (Diatoms, Dinoflagellates, Brown Algae, Euglenoids)

Evolutionary Relationships Among Photosynthetic Organisms

🔹 Key Photosynthetic Groups & Their Relationships

Comparing Photosynthetic Traits

Key Concepts & Definitions

✅ Mutualism → A relationship where both organisms benefit (e.g., corals + dinoflagellates)
✅ Kleptoplasty → Some protists steal chloroplasts from algae & use them temporarily
✅ Endosymbiosis → One organism lives inside another, leading to evolution of organelles
✅ Primary Endosymbiosis → Cyanobacteria → Red & Green Algae (2 membranes)
✅ Secondary Endosymbiosis → Red/Green Algae → Diatoms, Euglenoids, Brown Algae (4 membranes)
✅ Mitosis vs. Meiosis → Mitosis = Growth, Meiosis = Gametes (Haploid)
✅ Life Cycle Types:

• Haploid-Dominant (Green Algae)

• Diploid-Dominant (Some Protists, Animals)

• Alternation of Generations (Algae, Plants)

Life Cycles of Algae (Alternation of Generations)

🔹 Haploid (n) Stage = Gametophyte → Produces gametes (sperm & egg)
🔹 Diploid (2n) Stage = Sporophyte → Produces spores via meiosis
🔹 Spores → Gametophyte → Gametes → Sporophyte (Repeat)

🔹 Example: Green Algae (Ulva)

1⃣ Haploid Gametophyte (n) → Produces gametes
2⃣ Gametes fuse → Diploid Zygote (2n)
3⃣ Zygote grows into Diploid Sporophyte (2n)
4⃣ Sporophyte undergoes meiosis → haploid spores (n)
5⃣ Spores grow into a new Haploid Gametophyte (n)

🔹 Some algae have isomorphic alternation of generations (Gametophyte & Sporophyte look similar)

Evolution of Land Plants

✅ Green Algae (Charophytes) are closest relatives of land plants
✅ First land plants evolved 500 MYA
✅ Transition from aquatic → terrestrial required adaptations
✅ Importance of algae as early photosynthesizers

📌 Quick Recap (What to Memorize)

✅ Endosymbiosis (Primary = 2 membranes, Secondary = 4 membranes)
✅ Compare Photosynthetic Groups (Green, Red, Brown Algae, Diatoms, Cyanobacteria)
✅ Life Cycles: Alternation of Generations (Sporophyte → Gametophyte → Repeat)
✅ Key Terms: Mutualism, Kleptoplasty, Multicellularity
✅ Importance of Algae in Evolution of Plants

📝 Practice Questions

1⃣ What is the difference between primary and secondary endosymbiosis? (Answer: Primary = Engulfing Cyanobacteria, Secondary = Engulfing an Algae with Chloroplasts)
2⃣ Which organisms evolved from primary endosymbiosis? (Answer: Red & Green Algae)
3⃣ Which pigment is unique to red algae? (Answer: Phycobilins)
4⃣ Which group stores Floridean starch? (Answer: Red Algae)
5⃣ How is the alternation of generations different in algae vs. land plants? (Answer: Algae can have isomorphic generations; land plants show a dominant sporophyte in vascular plants)

📌 Chapter 3: Plants Invade the Land

Green Algae → Land Plants Transition

✅ Closest relatives of land plants? Charophytes (a type of green algae)
✅ Why did plants move to land?

• More sunlight for photosynthesis ☀

• More CO₂ for gas exchange 🌱

• Less competition for space and nutrients

✅ Challenges of living on land:

• Avoid drying out 🌿 (developed a cuticle)

• Support against gravity (developed vascular tissue)

• Reproducing without water (developed pollen & seeds)

Evolution of Early Land Plants

✅ First land plants? Bryophytes (Mosses, Liverworts, Hornworts)
✅ Bryophyte Traits:

• No vascular tissue (small & need moist environments)

• Dominant gametophyte stage (haploid is the main form)

• Sporophyte grows on gametophyte

• Require water for reproduction (flagellated sperm)

✅ Vascular Plants Evolution:

• Xylem & Phloem (allowed water & nutrient transport)

• Sporophyte became dominant

• Development of true roots, stems, leaves

• Pollen & Seeds (allowed reproduction without water)

Life Cycles of Nonvascular Plants (Mosses & Liverworts)

✅ Alternation of Generations Still Applies
✅ Gametophyte (haploid, n) is dominant
✅ Sporophyte (diploid, 2n) depends on gametophyte
✅ Capsule (sporangium) → Site of meiosis → Produces spores

Scientific Evidence for Early Land Plants

✅ Molecular Clock → DNA analysis shows plant evolution timeline
✅ Fossilized Spores & Plant Imprints → Oldest plant fossils ~500 MYA
✅ Comparing Algae & Land Plants → Shows gradual adaptation

Adaptations of Early Land Plants

Nonvascular vs. Vascular Plants

✅ Key takeaway: Sporophyte became dominant as plants evolved 🌱 → 🌳

Key Concepts

✅ Molecular Clock → Uses DNA to estimate evolutionary relationships
✅ Evapotranspiration → Water loss through leaves
✅ Capillary Action, Adhesion, Cohesion → How water moves in plants
✅ Regulatory Switch (Master Control Gene) → Controls plant growth & development

📌 Quick Recap (What to Memorize)

✅ Charophytes = Closest relatives to land plants
✅ Bryophytes (Mosses, Liverworts) → First Land Plants
✅ Vascular Plants Evolved Xylem, Phloem, Pollen, & Seeds
✅ Gametophyte → Sporophyte Dominance Shift in Land Plants
✅ Key Adaptations: Cuticle, Stomata, Lignin, Vascular Tissue

📝 Practice Questions

1⃣ Which group was the first to colonize land? (Answer: Bryophytes - Mosses, Liverworts, Hornworts)
2⃣ What structure prevents water loss in land plants? (Answer: Cuticle)
3⃣ What is the dominant stage in mosses? (Answer: Gametophyte (haploid, n))
4⃣ How do vascular plants transport water & nutrients? (Answer: Xylem & Phloem)
5⃣ What adaptation allowed plants to reproduce without water? (Answer: Pollen & Seeds)

Uploaded docs

📌 1. Lueth & Reski 2023 - Mosses

• Mosses are Bryophytes (second largest monophyletic land plant clade after vascular plants).

• Life Cycle:

  • Haplodiplontic (Alternation of Generations).

  • Gametophyte dominant (haploid stage is the main form).

  • Sporophyte (capsule) grows on gametophyte.

• Reproduction:

  • Sexual: Flagellated sperm, requires water.

  • Asexual: Gemmae (clonal spores).

• Adaptations:

  • Rhizoids for anchorage (not true roots).

  • Cuticle for water retention.

  • Sporopollenin-coated spores for durability.

• Important Genera:

  • Takakia: "Living fossil," resistant to extreme environments.

  • Sphagnum: Major carbon sink, prevents decomposition.

  • Physcomitrella: Model organism for genetic research.

📌 2. Thore et al. 2023 - Microalgae

• Primary Endosymbiosis:

  • Cyanobacteria → Green & Red Algae (2 membranes).

• Secondary Endosymbiosis:

  • Green & Red Algae → Diatoms, Brown Algae, Dinoflagellates (4 membranes).

• Microalgae Ecology:

  • Phytoplankton: Foundation of aquatic food webs.

  • Photosynthesis: Produces O₂ and organic matter.

  • Harmful Algal Blooms (HABs): Toxins & dead zones (e.g., cyanobacteria).

• Economic Importance:

  • Omega-3s: Alternative to fish oil (from algae like Schizochytrium).

  • Biofuels: Potential for renewable energy.

  • Bioplastics & Agriculture: Future applications.

📌 3. Tables - Photosynthetic Microorganisms

• Cyanobacteria (Prokaryotes):

  • Anabaena, Nostoc: Fix nitrogen (heterocysts).

  • Gloeocapsa: Unicellular with mucilage, lives in extreme environments.

  • Lyngbya: Filamentous, forms mats.

• Green Algae (Eukaryotes - Chlorophyta & Charophyta):

  • Chlamydomonas: Unicellular, flagellated, cup-shaped chloroplast.

  • Volvox: Colonial, hollow sphere with flagella.

  • Chara: Plant-like, branched thalli.

• Brown & Red Algae (Secondary Endosymbiosis):

  • Diatoms: Silica cell walls, brown chloroplasts.

  • Ectocarpus: Filamentous brown algae.

  • Polysiphonia: Red algae, attaches to substrates.

📌 What to Study from These Documents

1. Moss Life Cycle (Gametophyte-dominant, sporophyte capsule disperses spores).

2. Microalgae Evolution & Endosymbiosis (Primary & Secondary).

3. Algal Groups & Their Adaptations (Green, Red, Brown, Cyanobacteria).

4. Importance of Photosynthetic Microorganisms (O₂ production, nitrogen fixation).

5. Economic Applications (Biofuels, Omega-3s, Harmful Algal Blooms).

6. Comparative Traits Table (Cyanobacteria vs. Algae vs. Bryophytes vs. Vascular Plants).

Memory aid

Photosynthesis & Endosymbiosis

1. PSN = CO₂ + H₂O → C₆H₁₂O₆ + O₂ (Chl a, ATP, NADPH, Rubisco)

2. Cyanobacteria = 1° Endosymbiosis → Chloroplasts

3. Red & Green Algae = 1° PSN Euks (2 membranes)

4. 2° Endosymbiosis → Dinoflagellates, Diatoms, Euglenoids (4 membranes)

5. Kleptoplasty = Stolen chloroplasts (some protists)

Comparative Traits of Major Groups

6. Cyanobacteria (Prokaryotic, Chl a, Phycobilins, Diffusion, Binary Fission, No Spores)

7. Green Algae (Eukaryotic, Chl a, b, Flagellated Gametes, Alternation of Generations)

8. Bryophytes (Gametophyte Dominant, Capillary Action, Flagellated Sperm, Spores in Capsule)

9. Vascular Plants (Sporophyte Dominant, Xylem & Phloem, Seeds in Some, No Water Needed for Fertilization)

Key Photosynthetic Microorganisms

10. Cyanobacteria = Anabaena (Heterocysts), Nostoc (Mucigel), Gloeocapsa (Blob-like)

11. Green Algae = Chlamydomonas (Unicell, Flagella), Volvox (Colonial, Flagella), Chara (Plant-like)

12. Brown Algae = Diatoms (Silica), Ectocarpus (Filamentous, Marine)

13. Red Algae = Polysiphonia (Marine, Holdfast)

Evolution of Land Plants

14. Charophytes → First Land Plants (~500 MYA)

15. Bryophytes = Gametophyte Dominant, No Vascular Tissue, Flagellated Sperm

16. Vascular Plants = Xylem, Phloem, Sporophyte Dominant

17. Sporophyte Dominance Shift (Mosses → Ferns → Seed Plants)

Adaptations of Early Land Plants

18. Cuticle = Water Retention

19. Stomata = Gas Exchange

20. Xylem & Phloem = Water & Nutrient Transport

21. Lignin = Structural Support

22. Pollen & Seeds = Reproduction Without Water

Key Concepts & Scientific Evidence

23. Molecular Clock = DNA-based Evolution Timeline

24. Evapotranspiration = Water Loss in Plants

25. Capillary Action = Water Movement (Adhesion & Cohesion)