Study Guide for Exam II - Biology of Plants
General Course Information
Course Title: BIO 1503 - Biology of Plants
Textbook: Bidlack, J. E., & Jansky, S. H. (2019). Stern’s Introductory Plant Biology; 14th edition; The McGraw-Hill Education.
Key Topics:
Root morphology, anatomy, and function (with emphasis on primary growth) - Chapter 5
Stem and leaf morphology, anatomy, and function (with emphasis on primary growth) - Chapter 6 (pages 85-89; pages 98-99)
Secondary growth in woody roots and stems - Chapter 6 (pages 89-96; pages 99-103)
Leaf morphology, anatomy, and function - Chapter 7
Water, nutrient, and food movement in the plant body - Chapter 9
Exam Format: In-class Exam
Preparation Guidelines
Familiarize with chapter outlines, checkpoints, bolded text, summaries, and end-of-chapter questions.
Review figures and tables from each chapter covered in the textbook.
Consult the glossary for definitions and terms covered so far.
Study lecture notes, handouts, and PowerPoint presentations from the Learning Unit #2 in Blackboard Learn.
Key Questions from Past Students
Root Morphology and Function
General Function of Roots: Roots anchor plants, absorb water and nutrients, and store food (e.g., taproots like carrots storing carbohydrates).
Thimble-shaped Mass of Parenchyma Cells: Known as the root cap; it protects the growing tip of the root as it pushes through the soil.
Geotropism (Gravitropism): Growth response of a plant to gravity, roots grow downward while shoots grow upward (e.g., a seedling root grows down into the soil).
Cell Division in Roots: Occurs in the apical meristem at the root tip.
Primary or Transitional Meristems: Three types arise:
Protoderm - gives rise to epidermis (outer protective layer).
Ground meristem - develops into cortex and pith (storage and support).
Procambium - becomes vascular tissues (xylem for water, phloem for food).
Region of Elongation: Cells here increase in size, allowing the root to extend further into the soil.
Root Hairs Development: Occurs in the region of maturation, which is involved in water and nutrient uptake.
Lateral Roots Origin: Arise from the pericycle, a layer of tissue just inside the endodermis.
Root Anatomy
Casparian Strip: A waxy barrier in the endodermis that regulates water and solute movement into the vascular system.
Different Root Systems: Examples include:
Taproot System - characterized by a single dominant root (e.g., carrots, dandelions).
Fibrous Root System - consist of many small roots (e.g., grasses, corn).
Internal Anatomy of Dicot Root: Structures include:
Epidermis
Cortex
Xylem (usually has a star-shaped arrangement)
Phloem (in between xylem arms)
Pericycle (surrounds the vascular bundle)
Endodermis (inner layer of the cortex)
Another Name for Stele: Vascular cylinder.
Monocots vs. Dicots: Monocots typically have pith in the center of roots (e.g., corn), whereas dicots do not (e.g., beans).
Pneumatophores: Specialized aerial roots that help plants obtain oxygen in waterlogged conditions (e.g., mangroves).
Fixation of Atmospheric Gases: Nitrogen is fixed by bacteria in root nodules of legumes (e.g., peanuts, clover).
Source of Minerals/Nutrients: Primarily from the soil.
Macronutrients vs. Micronutrients:
Macronutrients (needed in larger amounts) include nitrogen, phosphorus, and potassium.
Micronutrients (needed in smaller amounts) include iron, manganese, and zinc.
Soil Components: Includes minerals, organic matter, water, and air.
Stem Morphology and Function
Main Functions of Plant Stems: Support leaves and flowers, transport nutrients and water, and store food (e.g., cactus stems store water, potato tubers store starch).
External Structure of Woody Dicat’s Stem: Important to study for examination.
Differences between Monocots and Dicots:
Monocots have scattered vascular bundles (e.g., corn stem), while dicots have them in a ring (e.g., sunflower stem).
Internal Structure of Monocots and Dicots: Study the arrangement and types of tissues present.
Regrowth of Grass: Caused by the presence of intercalary meristems located at the base of leaves.
Dicot Ground Tissue Division: Divided into cortex and pith.
Increase in Diameter of Woody Dicot Stem: Caused by secondary growth from the vascular cambium and cork cambium.
Examples of Storage Structures:
Rhizome: Ginger
Bulb: Onion
Stolon: Strawberry
Tuber: Potato.
Function of Corms and Bulbs: Facilitate survival and asexual reproduction during unfavorable conditions.
Climbing Stems: Specialized stems such as tendrils (e.g., grapes, peas).
Periderm Origin: Arises from the cork cambium, which is a lateral meristem.
Gas Exchange in Stems: Facilitated by lenticels, small openings in the periderm (e.g., on the bark of many woody trees).
Dendrochronology and Dendrology:
Dendrochronology studies tree rings to understand climate history.
Dendrology focuses on the study of trees and woody plants.
Secondary Xylem: Develops into wood in the stem.
Difference between Sapwood and Heartwood:
Sapwood: Active in water conduction.
Heartwood: Forms the inner, non-conducting part of the tree and provides structural support.
Bark Composition: Includes the periderm and all tissues outward from the vascular cambium.
Leaf Morphology and Function
Parts of a Leaf: Includes:
Blade (lamina)
Margin
Vascular bundles (veins)
Petiole
Stipules
Location of Axillary Buds: Found in the leaf axils.
Types of Leaf Phyllotaxy: Study arrangements such as alternate (e.g., elm), opposite (e.g., maple), and whorled (e.g., Nerium).
Leaf Structures:
Simple Leaf: Undivided leaf blade (e.g., oak leaf).
Compound Leaf: Composed of leaflets (e.g., fern fronds, rose leaves).
Peltate Leaves: Attach to the stem at the center (e.g., nasturtium).
Perfoliate Leaves: Leaf base encircles the stem (e.g., Uvularia).
Types of Venation: Examine examples of parallel (e.g., corn, monocots), netted (e.g., oak, dicots), and dichotomous venation (e.g., ginkgo).
Stomata Functions: Tiny openings on leaves that facilitate gas exchange, allowing CO₂ in and O₂ out.
Xylem and Phloem Location: In leaves, xylem is found on the upper surface, while phloem is usually located on the lower side.
Collenchyma Function in Petiole: Provides structural support while allowing flexibility (e.g., supports celery stalks).
Characteristics of Deciduous Plants: Trees that shed leaves seasonally to conserve water and energy (e.g., maple, oak, birch).
Embryonic Leaf Name: Cotyledon (e.g., the first leaf-like structures emerging from a bean seed).
Drought-Resistant Leaf Characteristics: Thickened cuticle, reduced stomata, and leaf modifications to minimize water loss (e.g., cacti spines, succulent leaves).
Thorns from Specialized Leaves: Yes, some plants have thorns derived from modified leaves (e.g., hawthorn, barberry).
Insects in Carnivorous Plants: Used as a nutrient source for the plant (e.g., Venus flytrap captures insects, pitcher plants trap them).
Transpiration Definition: Loss of water vapor from plant leaves through stomata.
Part of Xylem for Lateral Water Movement: Function of vessels.
Guttation Definition: Active secretion of water droplets from plant leaves at night (e.g., water droplets on grass tips in the morning).
Additional Concepts
Factors Affecting Transpiration: Light intensity, humidity, temperature, and wind speed.
Cation Exchange: Involves clay particles and roots where cations (positively charged ions) are exchanged with roots for hydrogen ions (e.g., a root exchanging for soil-bound ).
Apical Dominance: Phenomenon where the main central stem of the plant is dominant over other side stems, influencing growth direction (e.g., a Christmas tree maintains a strong central leader).
English Ivy Tendrils: True, they use tendrils for climbing.
Simple Tissues of Lenticels: Generally made up of parenchyma cells.
Stomata Opening Factors: Lower concentrations of CO₂ trigger stomata to open.
Pressure-Flow Hypothesis: Explains the movement of sugars in phloem from source (where sugars are produced/stored, e.g., mature leaves) to sink (where sugars are used/stored, e.g., roots, fruits). This movement is driven by turgor pressure differences created by active loading and unloading of sucrose.
Transpiration-Cohesion Hypothesis: Describes how water moves through plant xylem from roots to leaves. Water loss (transpiration) from leaves creates a negative pressure (tension) that pulls water up the xylem. This pull is possible due to the cohesive forces between water molecules and adhesive forces between water and xylem walls.
Element Diameter Comparison: Vessel elements have a larger diameter than tracheids.
Role of Prop Roots in Corn: Provides extra support for the plant.
Function of Mucigel in Roots: Aids in establishing and protecting the root as it penetrates the soil.
Apical Meristematic Tissue Division Rate: Divides multiple times per day; exact number varies.
Mineral Soil vs. Organic Soil: Mineral soil is composed of inorganic materials, while organic soil contains decomposed living matter (e.g., loam with sand, silt, and clay vs. peat-rich soil).
Distinction Between Leaf and Leaflet: A leaf is a broader organ, while a leaflet is a smaller segment in a compound leaf (e.g., a palmately compound horse chestnut leaf has multiple leaflets originating from a single point on the petiole).
Define Apical Dominance: The inhibition of lateral shoots by the presence of a dominant apical shoot.
Secondary Growth Predominance: Found primarily in dicots (e.g., oak trees, rose bushes).
Cork Cambium Alternative Name: Phellogen.
Study of Xylem vs. Phloem: Xylem is easier to study due to its structural support properties and simpler organization.
Statoliths: Specialized cells that sense gravity in roots for geotropism.
Stipules: Small leaf-like structures that occur at the base of leaf stalks (petioles) (e.g., often found on rose stems).
Water Potential (): A measure of the potential energy of water per unit volume relative to pure water in reference conditions. Water moves from areas of higher water potential to areas of lower water potential.
Routes of Water Movement in Roots:
Apoplast Pathway: Water moves through the cell walls and extracellular spaces, without crossing any cell membranes, until it reaches the Casparian strip.
Symplast Pathway: Water moves from cell to cell via plasmodesmata, requiring passage through at least one cell membrane (at the epidermis).
Mycorrhizae Formation: A symbiotic association between plant roots and fungi (e.g., Amanita muscaria with pine trees) that enhances the plant's absorption of water and mineral nutrients, particularly phosphorus, in exchange for sugars from the plant.
Root Pressure and Guttation: When transpiration is low (e.g., at night), root cells continue to actively pump mineral ions into the xylem. This lowers the water potential in the xylem, causing water to move in by osmosis, generating root pressure, which can push water up the xylem and lead to guttation – the exudation of water droplets from leaf margins (e.g., on strawberry leaves).
*Note: Ensure to study figures, tables, and additional resources for deeper