General Biology: Protists, Plants, Fungi, and Related Groups – Study Guide

Protists and Their Diversity

Definition and Classification

Protists are a diverse group of eukaryotic microorganisms, including both unicellular and multicellular forms, that are neither plants, animals, nor fungi.

• Monophyletic Group: Protists are not a monophyletic group; they include organisms from multiple evolutionary lineages.

• Examples: Algae, protozoa, slime molds, and water molds.

Key Protist Groups and Features

• Foraminifera: Have organic material shells hardened with calcium carbonate.

• Diatoms: Unicellular, with silica-based shells (frustules).

• Phaeophyta (Brown Algae): Multicellular, photosynthetic, contain fucoxanthin pigment.

• Red Algae (Rhodophyta): Multicellular, photosynthetic, contain phycoerythrin pigment.

Plant Structure and Function

Vascular System

The vascular system in plants consists of xylem and phloem:

• Xylem: Transports water and minerals from roots to shoots.

• Phloem: Transports sugars produced by photosynthesis to other parts of the plant.

Functions of Roots

• Anchorage: Hold plants firmly in the soil.

• Absorption: Take up water and minerals from the soil.

• Storage: Store carbohydrates and water.

• Specialized Functions: Pneumatophores in mangroves help with oxygen intake in waterlogged environments.

Stomata Regulation

• Gas Exchange: Allow CO2 in for photosynthesis and release O2.

• Water Regulation: Control water loss through transpiration.

• Environmental Response: Open/close in response to light, CO2, and drought via abscisic acid.

Accessory Pigments in Plants

• Chlorophyll b and carotenoids are accessory pigments that aid in photosynthesis.

Major Plant Groups and Evolution

Classification of Plants

• Vascular Plants: Have xylem and phloem; include ferns, gymnosperms, and angiosperms.

• Nonvascular Plants: Lack vascular tissue; include mosses, liverworts, and hornworts.

Alternation of Generations

Plants alternate between producing gametes and spores. This cycle ensures genetic diversity and adaptation.

• Gametophyte Stage (n): Produces haploid gametes (eggs and sperm) via mitosis.

• Fertilization: Two gametes unite to form a diploid zygote.

• Sporophyte Stage (2n): Zygote develops into a multicellular diploid sporophyte that produces spores by meiosis.

Adaptations for Terrestrial Life

• Vascular Tissues: Allow transport of water and nutrients, structural support, and greater height.

• Cuticle: Waxy layer that prevents water loss.

• Seeds: Protect and nourish the embryo, aiding in dispersal and survival.

Fungi: Structure and Function

Characteristics of Fungi

• Hyphae: Filamentous structures that form a mycelium; can be septate or coenocytic.

• Cell Walls: Made of chitin.

• Nutrition: Absorptive heterotrophs; secrete enzymes to digest food externally.

Fungal Reproduction

• Sexual and Asexual Spores: Fungi can produce spores by both methods.

Fungi and Symbiosis

• Lichens: Mutualistic relationship between a fungus and a photosynthetic partner (alga or cyanobacterium).

• Mycorrhizae: Symbiotic association between fungi and plant roots, aiding in nutrient and water absorption.

Comparisons and Classifications

Vascular vs. Nonvascular Plants

Feature	Vascular Plants	Nonvascular Plants
Vascular Tissue	Present (xylem & phloem)	Absent
Size	Can grow tall	Usually small
Dominant Generation	Sporophyte	Gametophyte
Examples	Ferns, conifers, flowering plants	Mosses, liverworts

Fungi vs. Animals

• Similarities: Both are heterotrophic and digest food using enzymes.

• Differences: Fungi absorb nutrients externally after secreting enzymes; animals ingest food and digest it internally.

Bacteria vs. Fungi

• Similarity: Both decompose organic matter.

• Difference: Bacteria are prokaryotic; fungi are eukaryotic and multicellular (in most cases).

Major Plant and Protist Groups

Key Plant Phyla

• Anthophyta (Angiosperms): Flowering plants, produce seeds within fruits.

• Coniferophyta: Conifers, gymnosperms with needle-like leaves and cones (e.g., pine, fir, redwood).

• Bryophyta: Mosses, nonvascular, dominant gametophyte stage.

• Hepatophyta: Liverworts, nonvascular, flattened thalloid body.

• Charophyta: Green algae closely related to land plants.

Protist Supergroups

• Excavata: e.g., Euglenids (some photosynthetic, have flagella).

• SAR: Stramenopiles (diatoms, brown algae), Alveolates (dinoflagellates), Rhizarians (foraminiferans).

• Archaeplastida: Red algae, green algae, land plants.

• Unikonta: Amoebozoa (slime molds, amoeba), Fungi, Animals.

Endosymbiotic Theory

Evidence for the Origin of Chloroplasts and Mitochondria

• Both organelles have their own mitochondrial DNA.

• They are similar in size and structure to certain prokaryotes.

• They replicate independently of the cell cycle.

Adaptations and Ecological Roles

Plant Adaptations

• Epiphytes: Grow on other plants, absorb water and minerals from the air.

• Carnivorous Plants: Trap and digest insects to supplement nutrient intake.

• Parasitic Plants: Obtain nutrients from host plants.

Fungal Adaptations

• Production of Toxins: Some fungi produce toxic compounds (e.g., mycotoxins) as a defense mechanism.

Tables and Diagrams

Comparison of the Three Domains of Life

Characteristic	Bacteria	Archaea	Eukarya
Cell Type	Prokaryotic	Prokaryotic	Eukaryotic
Cell Wall	Peptidoglycan	Varied, no peptidoglycan	Cellulose (plants), chitin (fungi), none (animals)
Membrane Lipids	Ester-linked	Ether-linked	Ester-linked
RNA Polymerase	One kind	Several kinds	Several kinds
Examples	Escherichia coli	Halobacterium	Plants, fungi, animals

Additional info:

• Some explanations and examples have been expanded for clarity and completeness.

• Tables have been recreated and summarized for study purposes.