Comprehensive Biology Study Guide: Ecosystems, Forest Ecology, Plant Anatomy, Fungi, and Animal Classification

Course Exam Preparation Guidelines

  • Primary study materials for the exam consist of class notebook notes and the course handout (pruju), specifically pages 1–20, which cover the fundamental core topics.
  • Secondary study materials include the online Google Classroom topic modules, along with attached web links and instructional videos designed to clarify and deepen conceptual understanding.

Ecosystem Function

  • Ecosystem Definition: An ecosystem is a functional ecological unit formed by the interaction of a community of living organisms (biotic factors) with their non-living physical and chemical environment (abiotic factors) within a specific defined area.
  • Two Main Components of Nature and Ecosystems:
    • Biotic Component (Elollinen luonto): All living organisms inhabiting the ecosystem, including plants, animals, fungi, protists, and bacteria.
    • Abiotic Component (Eloton luonto): Non-living environmental physical and chemical elements, including sunlight, ambient temperature, water/precipitation, atmospheric gases, soil type, pH levels, and inorganic nutrients.
  • Significance of Environmental / Habitat Factors (Kasvupaikkatekijät): Abiotic habitat factors determine which species are able to survive, grow, and reproduce in a given region. They set physiological limits, drive natural selection, and influence community structure.
  • Three Primary Roles of the Biotic Community:
    1. Producers (Tuottajat): Autotrophic organisms (primarily green plants, algae, and cyanobacteria) that convert solar energy into chemical energy via photosynthesis, producing biomass from inorganic carbon dioxide and water.
    2. Consumers (Kuluttajat): Heterotrophic organisms that obtain energy and organic nutrients by consuming other living or recently killed organisms. Divided into primary consumers (herbivores), secondary consumers (carnivores/omnivores), and tertiary consumers (top predators).
    3. Decomposers (Hajottajat): Heterotrophic organisms (fungi, bacteria, detritivores) that break down organic waste, leaf litter, and dead organismal matter, releasing simple inorganic minerals and nutrients back into the soil and water for producer reuse.
  • Food Chain (Ravintoketju): A linear sequence of organisms showing the unidirectional transfer of energy and nutrients as one organism consumes another, beginning with a primary producer and ending with a top predator or decomposer.
  • Food Pyramid / Trophic Pyramid (Ravintopyramidi): A graphical representation of the biomass, energy, or number of organisms at successive trophic levels in an ecosystem.
    • Ecological Efficiency: Only approximately 10%10\% of the chemical energy at one trophic level is converted into new biomass at the next higher level; the remaining 90%90\% is lost to metabolic heat, cellular respiration, movement, and unconsumed structural tissue.
  • Flow of Energy vs. Cycling of Matter:
    • Energy Flow: One-way, open-system flow. Solar energy enters the ecosystem, passes through trophic levels, and ultimately dissipates as heat into outer space. Energy does not cycle.
    • Nutrient/Matter Cycling: Closed-system flow. Biogeochemical elements (carbon, nitrogen, phosphorus, water) continuously cycle indefinitely between biotic organisms and abiotic reservoirs.

Plant Structure and Physiology

  • Main Structural Parts of a Plant and Their Functions:
    • Roots (Juuret): Anchor the plant firmly in the soil, absorb water and dissolved mineral nutrients from the ground, store energy reserves (carbohydrates), and sometimes enable vegetative reproduction.
    • Stem / Trunk (Varsi / Runkosuoja): Supports leaves, flowers, and fruits in space; houses vascular transport tissues (xylem for water/minerals upward, phloem for photoassimilates downward).
    • Leaves (Lehdet): Primary photosynthetic organs engineered for gas exchange (taking up CO2CO_2, releasing O2O_2) via stomata, and driving transpiration to transport water upward through root pressure and transpirational pull.
  • Influence of Habitat Factors on Plant Morphology:
    • Sunlight availability determines leaf surface area and thickness (e.g., shade leaves are broad and thin; sun leaves are small and thick).
    • Moisture availability alters root depth and leaf cuticles (xerophytes in dry soils develop deep taproots, thick waxy cuticles, or needles; hydrophytes in aquatic environments develop buoyant air tissue).
    • Soil nutrient levels dictate root-to-shoot ratios and mycorrhizal reliance.

Tree Growth and Trunk Architecture

  • Factors Affecting Tree Growth:
    • Sunlight duration and intensity (photosynthetic energy input).
    • Ambient air and soil temperatures (enzymatic rates and length of growing season).
    • Soil moisture and ambient precipitation levels.
    • Availability of essential soil minerals (nitrogen, phosphorus, potassium, magnesium).
    • Atmospheric carbon dioxide concentration (CO2CO_2).
  • Trunk Cross-Sectional Layers and Their Functions:
    • Outer Bark (Kaarna / Ulkokuori): Outer dead protective layer shielding inner living tissues from mechanical injury, extreme heat, cold, desiccation, insect attack, and fungal infections.
    • Inner Bark / Phloem (Nila): Living inner bark layer responsible for transporting organic sugars and metabolic products synthesized in the leaves downward to roots and growing tissues.
    • Vascular Cambium (Jälsi): A thin lateral meristematic tissue layer located between phloem and xylem that undergoes cell division to produce new secondary phloem outward and secondary xylem inward, causing annual diameter growth.
    • Sapwood / Xylem (Manto / Puu-osa): Light-colored active outer wood tissue that conducts water and dissolved mineral ions upward from the roots to the crown.
    • Heartwood (Sydänpuu): Dense, inactive inner core of dead wood impregnated with extractives and resins, providing structural stability and decay resistance.

Plant Reproduction

  • Asexual vs. Sexual Reproduction:
    • Asexual Reproduction (Suvuton lisääntyminen): Offspring arise from a single parent without gamete fusion, producing genetically identical clones. Highly efficient, rapid, requires less energy, but lacks genetic diversity.
    • Sexual Reproduction (Suvullinen lisääntyminen): Offspring arise from the fusion of male and female gametes, producing genetically unique individuals. Introduces genetic variation necessary for adaptation to changing environments.
  • Structure of an Angiosperm Flower:
    • Petals (Terälehdet): Attract animal pollinators using bright colors, patterns, and scents.
    • Sepals (Verholehdet): Enclose and protect the developing flower bud before opening.
    • Stamen (Hede - Male Reproductive Unit): Composed of the Filament (Palho) which supports the Anther (Pölyhuone / Pons) where pollen grains are produced.
    • Pistil / Carpel (Emi - Female Reproductive Unit): Composed of the sticky Stigma (Luotti) to catch pollen, the neck-like Style (Vartalo), and the basal Ovary (Sikiö) containing one or more Ovules (Siemenaihe).
  • Plant Sexes and Inflorescences:
    • Monoecious species possess separate male and female flowers/cones on the same individual plant (e.g., Pine, Spruce, Birch).
    • Dioecious species possess male flowers on one individual plant and female flowers on another individual plant (e.g., Willow, Aspen).
  • Pollination Methods:
    • Wind Pollination (Tuulipölytys): Plants produce enormous quantities of light, dry, smooth pollen carried passively by air currents. Flowers lack bright colors, scent, or nectar (e.g., grasses, coniferous trees, birch).
    • Insect / Animal Pollination (Hyönteispölytys): Plants produce large, sticky, textured pollen grains, sticky stigmas, nectar rewards, and showy colorful petals to attract specific insects or animals.
  • Pros and Cons of Pollination Strategies:
    • Wind Pollination Advantages: Does not depend on the presence or survival of animal vectors; effective in open or dense monospecific stands.
    • Wind Pollination Disadvantages: Extremely inefficient, requiring massive energy expenditure to produce immense pollen volume; mostly wasted pollen.
    • Insect Pollination Advantages: Highly targeted and efficient transfer of pollen; smaller pollen volumes required.
    • Insect Pollination Disadvantages: Vulnerable to weather conditions inhibiting insect flight, insect population declines, or vector absence.
  • Sequential Events from Pollination to Seed Formation:
    1. Pollination: A viable pollen grain lands on the compatible stigma of a flower.
    2. Pollen Tube Growth: The pollen grain germinates, extending a long pollen tube down through the style into the ovary.
    3. Fertilization: Sperm cells travel down the pollen tube into the ovule, fusing with the egg cell to form a diploid zygote.
    4. Embryo and Seed Development: The fertilized egg develops into a plant embryo, the ovule matures into a protective seed containing nutrient reserves, and the surrounding ovary matures into a fruit.
  • Seed Dispersal Mechanisms:
    • Wind (Anemochory): Seeds feature wings, plumes, or hairs to float through air (e.g., dandelion, pine, birch).
    • Water (Hydrochory): Seeds feature buoyant, air-trapping tissue to float along rivers or coastlines.
    • Animals (Zoochory): Seeds possess hooks/barbs to stick to fur (epizoochory) or are encased in fleshy edible fruits ingested and later defecated elsewhere (endozoochory).
    • Mechanical / Explosive (Autochory): Seed pods build up turgor pressure and burst open violently to fling seeds away.
  • Methods of Asexual Reproduction in Plants:
    • Runners / Stolons: Horizontal above-ground stems forming roots at nodes (e.g., wild strawberry).
    • Rhizomes: Underground horizontal stems generating new vertical shoots (e.g., lily of the valley).
    • Tubers: Swollen underground nutrient storage stem structures capable of sprouting (e.g., potato).
    • Root Suckers: Shoots arising from lateral parent roots (e.g., aspen).
    • Fragmentation: Detached stem, leaf, or root fragments forming complete new plants.

Forest Layers and Species Characteristics

  • Vertical Forest Layers (Metsän kerrokset):
    1. Tree Layer (Puu-kerros): Upper canopy dominated by mature trees (> 2–5 meters tall); controls light availability to lower levels.
    2. Shrub Layer (Pensas-kerros): Composed of woody shrubs, saplings, and young trees (0.5 to 2–5 meters tall).
    3. Field / Herb Layer (Kenttä-kerros): Composed of dwarf shrubs (varvut), herbaceous flowering plants (ruohot), ferns, and grasses (< 0.5 meters tall).
    4. Bottom / Ground Layer (Pohja-kerros): Ground surface layer composed of non-vascular cryptogams including mosses (sammalet) and lichens (jäkälät).
  • Differences Between Coniferous and Deciduous Trees:
    • Coniferous Trees (Havupuut): Evergreen (except larch), tough needle-like leaves coated with a thick cuticle, produce seeds inside wooden cones, suited to cold and dry conditions.
    • Deciduous Trees (Lehtipuut): Broad-leaved plants, shed leaves annually in autumn to limit winter water loss, produce flowers and enclosed seeds/fruits.
  • Comparison of Spruce and Pine:
    • Norway Spruce (Kuusi - Picea abies):
    • Shade-tolerant (menestyy varjossa).
    • Shallow, widespread root system (pinta-juuristo), vulnerable to storm windthrows.
    • Pyramidal/conical tree crown shape.
    • Single, short, four-angled needles attached individually around branches.
    • Prefers moist, fertile, clay or nutrient-rich moraine soils.
    • Scots Pine (Mänty - Pinus sylvestris):
    • Light-demanding / intolerant of shade (valopuu).
    • Deep taproot system (paalujuuri) providing strong anchoring against winds.
    • Umbrella-like or flattened crown top in mature/old trees.
    • Long, paired needles held in bundles of two.
    • Tolerates dry, nutrient-poor, sandy, or rocky soils.
  • Comparison of Dwarf Shrubs and Herbaceous Plants:
    • Dwarf Shrubs (Varvut): Low-growing perennial woody plants whose stems persist above ground year-round (e.g., bilberry/blueberry, lingonberry, heather).
    • Herbaceous Plants / Herbs (Ruohot): Non-woody soft green stems that die back to soil level at the end of the growing season (e.g., wood sorrel, starflower).
  • Characteristics of Mosses and Lichens:
    • Mosses (Sammalet): Non-vascular primitive land plants, lack true roots/xylem/phloem, absorb water and dissolved nutrients directly across their thin leafy bodies, require humid conditions for survival and reproduction via spores.
    • Lichens (Jäkälät): Symbiotic dual organisms composed of a fungal partner (mycobiont) providing physical structure/protection and an algal/cyanobacterial partner (photobiont) providing photosynthetic carbohydrates. Highly resistant to extreme desiccation and low nutrients, but sensitive to sulfur air pollution.

Finnish Forest Types

  • Three Main Boreal Forest Types in Finland:

    1. Dry Heath Forest (Kuiva kangasmetsä):
    • Soil: Dry, sandy, coarse moraine, or gravel soil with very low nutrient availability and fast drainage.
    • Dominant Tree: Scots Pine (Pinus sylvestris).
    • Understory Vegetation: Heather (Calluna vulgaris), lingonberry (Vaccinium vitis-idaea), reindeer lichens (Cladonia species), and drought-resistant mosses.
    • Light: Open canopy, high light levels reaching the ground.
    1. Moist Heath Forest (Tuore kangasmetsä):
    • Soil: Fine moraine or silt soil retaining moderate moisture and balanced organic humus; moderate to high nutrient levels.
    • Dominant Tree: Norway Spruce (Picea abies), often mixed with birch or pine.
    • Understory Vegetation: Bilberry / Blueberry (Vaccinium myrtillus), wood horsetail, feather mosses (e.g., Hylocomium splendens, Ptilium crista-castrensis).
    • Light: Dense closed canopy, shady forest floor.
    1. Herb-Rich Forest / Grove (Lehto):
    • Soil: Extremely fertile, nutrient-rich mull soil; optimal soil moisture and rapid mineral decomposition.
    • Dominant Tree: Deciduous species (birch, aspen, alder, oak, linden) mixed with shade-tolerant spruce.
    • Understory Vegetation: Rich, diverse carpet of broad-leaved herbaceous flowering plants (e.g., wood sorrel, lily of the valley, hepaticas) and delicate ferns; minimal lichen presence.
    • Light: Dynamic light conditions; abundant light early in spring before canopy leaf-out.

  • Comparative Analysis of Finnish Forest Types:

    • Soil Moisture: Dry Heath (Low) < Moist Heath (Moderate/High) < Herb-Rich Forest (Optimal/Moist).
    • Nutrient Status: Dry Heath (Poor) < Moist Heath (Medium) < Herb-Rich Forest (Rich).
    • Ground Layer Dominance: Dry Heath (Lichens & dwarf shrubs) →\rightarrow Moist Heath (Mosses & dwarf shrubs) →\rightarrow Herb-Rich Forest (Herbs & rich humus micro-flora).

Fungi

  • Structure of Fungi:
    • Hyphae (Sienirihmasto): Microscopic, thread-like filaments forming the primary vegetative growing structure.
    • Mycelium: Massive, interconnected subterranean or intra-substrate network of hyphae responsible for nutrient absorption.
    • Fruiting Body (Itiöemä): Aerial reproductive structure formed above ground to produce and disperse spores, consisting of a stem (jalka), cap (lakki), and spore-bearing surfaces underneath (gills/heltta, pores/pilli, or spines/piikki).
  • Main Fungal Functional Groups:
    • Gill Fungi (Helttasienet): Produce spores on blade-like gills under the cap (e.g., Amanita, chanterelles).
    • Pore Fungi / Boletes (Pillisienet / Tatti): Produce spores inside tight vertical tubes opening as pores under the cap (e.g., Boletus edulis).
    • Bracket / Shelf Fungi (Käävät): Hard, woody, shelf-like fruiting bodies growing on tree trunks.
    • Molds, Cup Fungi, and Yeasts: Microscopic single-celled or cup-shaped spore-producing fungi.
  • Modes of Fungal Nutrition and Lifestyles:
    • Decomposers / Saprotrophs (Hajottajasienet): Secrete digestive enzymes into dead plant matter, wood, or animal carcasses to absorb simple compounds, recycling carbon and nutrients.
    • Symbionts / Mycorrhizal Fungi (Sienijuuri): Form mutualistic symbiotic relationships with plant/tree roots. The fungus provides the tree with expanded water absorption capacity and mineral nutrients (especially phosphorus and nitrogen); in return, the tree supplies photosynthetic sugars (C6H12O6C_6H_{12}O_6) to the fungus.
    • Parasites (Loisienet): Infect living host plants or animals, absorbing nutrients directly from host tissues while harming or eventually killing the host.

Animal Classification

  • Primary Division of Animal Kingdom:

    • Vertebrates (Selkärankaiset): Animals possessing an internal cartilaginous or bony backbone/vertebral column surrounding the spinal cord.
    • Invertebrates (Selkärangattomat): Animals lacking a backbone; supported by fluid pressure (hydroskeleton), external hard coverings (exoskeleton), or soft tissues.

  • Comparison of Vertebrates and Invertebrates:

    • Internal Skeleton: Present in all vertebrates (endoskeleton); absent in invertebrates.
    • Size Limits: Vertebrates can grow significantly larger due to sturdy internal support; invertebrates are limited in size by structural constraints or weight of exoskeletons.
    • Abundance: Invertebrates comprise over 95%95\% of all known animal species on Earth, while vertebrates represent under 5%5\%.

  • Five Major Classes of Vertebrates:

    1. Fish (Kalat): Ectothermic (cold-blooded), aquatic organisms with scales, fins, and gills for oxygen exchange; lay gelatinous non-amniotic eggs in water.
    2. Amphibians (Sammakkoeläimet): Ectothermic; dual life cycle starting with aquatic gilled larvae (tadpoles) metamorphosing into air-breathing terrestrial adults with moist, permeable skin; lay soft eggs in moist environment.
    3. Reptiles (Matelijat): Ectothermic; dry, scaly skin protecting against water loss; breathe via lungs; lay amniotic, leathery-shelled eggs on land.
    4. Birds (Linnut): Endothermic (warm-blooded); bodies covered in insulating feathers; forelimbs modified into wings; toothless beak; lay hard-shelled calcium carbonate eggs.
    5. Mammals (Nisäkkäät): Endothermic; body covered in hair/fur; females possess mammary glands to produce milk for offspring; feed and protect young; mostly give live birth.

  • Major Groups and Examples of Invertebrates:

    • Insects (Hyönteiset): Exoskeleton made of chitin; body divided into 3 segments (head, thorax, abdomen); 6 jointed legs; often wings (e.g., beetles, butterflies, ants).
    • Arachnids (Hämähäkkieläimet): 2 body segments (cephalothorax, abdomen); 8 jointed legs; no antennae (e.g., spiders, ticks, scorpions).
    • Crustaceans (Äyriäiset): Mostly aquatic; hard calcified exoskeleton; 2 pairs of antennae; multiple pairs of jointed legs (e.g., crayfish, crabs, woodlice).
    • Mollusks (Nilviäiset): Soft-bodied unsegmented organisms, often protected by a hard calcium carbonate shell (e.g., snails, slugs, clams, squids).
    • Annelids / Segmented Worms (Nivelmadot): Cylindrical bodies divided into repeating linear segments (e.g., earthworms, leeches).