Botany Chapter 8: Leaves Structure and Types

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Questions and Answers

What is the function of guard cells in leaves?

  • Store excess sugar molecules
  • Help in capturing light energy
  • Control water loss by opening or closing stomata pores (correct)
  • Aid in disposing of waste products

Which type of leaves have all leaflets attached at the same point at the end of the petiole?

  • Pinnately compound leaves
  • Bipinnately compound leaves
  • Simple leaves
  • Palmately compound leaves (correct)

What is the main purpose of photosynthesis in leaves?

  • Creating water vapor
  • Regulating water loss
  • Trapping and storing light energy in sugar molecules (correct)
  • Disposing of waste products

In which type of leaves are leaflets arranged in pairs along the rachis (petiole)?

<p>Bipinnately compound leaves (A)</p> Signup and view all the answers

What is the primary function of stomata on the lower surfaces of leaves?

<p>Allow carbon dioxide to enter and oxygen to exit (B)</p> Signup and view all the answers

What differentiates simple and compound leaves?

<p>Blade structure - single blade versus divided into leaflets (D)</p> Signup and view all the answers

What is the primary function of transpiration in plants?

<p>To move water absorbed by the roots (B)</p> Signup and view all the answers

What is the name of the secretory tissue at the tips of leaf veins where guttation occurs?

<p>Hydathodes (C)</p> Signup and view all the answers

Which leaf arrangement has three or more leaves attached at each node?

<p>Whorled (C)</p> Signup and view all the answers

What is the name of the venation pattern where the primary veins fan out from the base of the leaf blade?

<p>Palmate (D)</p> Signup and view all the answers

Which leaf venation pattern is characteristic of monocot plants?

<p>Parallel (A)</p> Signup and view all the answers

What is the term used to describe the arrangement of leaves on a stem?

<p>Phyllotaxy (B)</p> Signup and view all the answers

Which type of venation is characteristic of monocots?

<p>Parallel venation (D)</p> Signup and view all the answers

Which layer of the leaf is responsible for the majority of photosynthesis?

<p>Mesophyll (D)</p> Signup and view all the answers

What is the primary function of the stomata on the leaf surface?

<p>To regulate gas exchange and water evaporation (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of the epidermal cells in leaves?

<p>Contain chloroplasts (B)</p> Signup and view all the answers

What is the relationship between the guard cells and the stomata?

<p>The guard cells originate from the same parent cell and contain chloroplasts, which allow them to control the stomatal aperture. (C)</p> Signup and view all the answers

Which type of venation pattern is characteristic of gymnosperms?

<p>Dichotomous venation (A)</p> Signup and view all the answers

What pigments are present in the chloroplasts of mature leaves?

<p>Carotenoids and Anthocyanins (B)</p> Signup and view all the answers

What process results in the shedding of leaves in deciduous plants?

<p>Abscission (C)</p> Signup and view all the answers

Which group of pigments may be present in the vacuole and contribute to red or blue coloration in leaves?

<p>Anthocyanins (A)</p> Signup and view all the answers

What protective layer is present in the abscission zone near the base of the leaf petiole?

<p>Suberin-coated cells (A)</p> Signup and view all the answers

Which of the following is NOT a human or ecological relevance of leaves as mentioned in the text?

<p>Metal production (B)</p> Signup and view all the answers

What is the term for the collective aging and decline process in plants?

<p>Senescence (C)</p> Signup and view all the answers

What is the primary function of the palisade mesophyll in a leaf?

<p>To contain most of the leaf's chloroplasts (B)</p> Signup and view all the answers

What is the role of bulliform cells in monocot leaves?

<p>To regulate leaf rolling or folding under dry conditions (B)</p> Signup and view all the answers

Which of the following is a characteristic of shade leaves compared to sun leaves?

<p>Fewer chloroplasts (C)</p> Signup and view all the answers

What is the primary function of the spongy mesophyll in a leaf?

<p>To facilitate gas exchange (B)</p> Signup and view all the answers

What is the primary function of veins (vascular bundles) in leaves?

<p>To transport water and nutrients (D)</p> Signup and view all the answers

Which of the following is a characteristic of leaves adapted to arid regions?

<p>Specialized structures to reduce water loss (D)</p> Signup and view all the answers

Match the specialized leaf type with its description:

<p>Tendrils = Modified leaves that curl around more rigid objects, helping the plant to climb or to support weak stems Spines = Modified leaves that reduce leaf surface and water loss, and protect from herbivory Storage leaves = Succulent leaves are modified for water storage, have parenchyma cells with large vacuoles Flower-Pot Leaves = Leaves develop into urn-like pouches that become home of ant colonies</p> Signup and view all the answers

Match the specialized stem type with its description:

<p>Thorns = Modified stems arising in the axils of leaves of woody plants Prickles = Outgrowths from epidermis or cortex</p> Signup and view all the answers

Match the leaf adaptation with its characteristic:

<p>Aquatic Areas = Less xylem and phloem, mesophyll not differentiated into palisade and spongy layers, large air spaces Succulent desert plants of Africa = Leaves buried in ground, except for exposed end</p> Signup and view all the answers

Match the leaf structure with its function:

<p>Thick, leathery leaves = Reduce loss of water by providing a sturdy protective layer Dense, hairy coverings = Aid in reducing water loss by creating a barrier against transpiration</p> Signup and view all the answers

Match the plant species with its specialized leaf type:

<p>Garden peas = Tendrils Cacti = Spines</p> Signup and view all the answers

Match the specialized leaf feature with the plant it is found in:

<p>Fleshy leaves store carbohydrates = Onions, lily Window leaves = In succulent desert plants of Africa</p> Signup and view all the answers

Match the following leaf structures with their descriptions:

<p>Petiole = Stalk of a leaf Lamina = Flattened blade of a leaf Veins = Network of vascular bundles in a leaf Stipules = Small structures at the base of the petiole</p> Signup and view all the answers

Match the following leaf types with their characteristics:

<p>Simple leaves = Leaves with a single blade Compound leaves = Leaves with a blade divided into leaflets Pinnately compound leaves = Leaflets in pairs along the rachis (petiole) Palmately compound leaves = All leaflets attached at the same point at the end of the petiole</p> Signup and view all the answers

Match the following leaf functions with their descriptions:

<p>Photosynthesis = Trapping light energy to produce sugar molecules Stomata = Tiny pores allowing gas exchange and water vapor release Guard Cells = Regulate opening and closing of stomatal pores Waste disposal = Accumulation and shedding of metabolic wastes in leaves</p> Signup and view all the answers

Match the following leaf shapes with their function:

<p>Biological Solar Panels = Leaves capturing light energy for photosynthesis Green Leaves = Capture light energy by means of photosynthesis Palmately Compound Leaf = Leaf shape where all leaflets are attached at the same point Bipinnately Compound Leaf = Leaf shape with subdivided leaflets</p> Signup and view all the answers

Match the following leaf terms with their roles:

<p>Transpiration = Water loss control and gas exchange in leaves Vascular Bundles (Veins) = Transport nutrients and water throughout the leaf Spongy Mesophyll = Support gas exchange and photosynthesis in leaves Palisade Mesophyll = Primary site for photosynthesis in leaves</p> Signup and view all the answers

Match the following leaf adaptations with their characteristics:

<p>Arid Region Leaves = Leaves adapted to dry environments Shade Leaves = Leaves adapted to low light conditions Guard Cells Function = Regulate water loss through stomatal pores Abscission Zone Layer = Protective layer near the base of the leaf petiole</p> Signup and view all the answers

Match the following leaf layers with their descriptions:

<p>Palisade Mesophyll = Compactly stacked, barrel-shaped parenchyma cells with most of leaf's chloroplasts Spongy Mesophyll = Loosely arranged parenchyma cells with abundant air spaces Veins = Consist of xylem and phloem tissues surrounded by bundle sheath of thicker-walled parenchyma Bulliform Cells = Cells that partly collapse under dry conditions causing leaf to fold or roll</p> Signup and view all the answers

Match the following leaf types with their characteristics:

<p>Sun Leaves = Tend to be larger and thicker with well-defined mesophyll layers and more chloroplasts Shade Leaves = Receive less total light, tend to be thinner, have fewer well-defined mesophyll layers and fewer chloroplasts Arid Region Leaves = Adapted to limited water availability, wide temperature ranges, and high light intensities Monocot Leaves = Often lack differentiated palisade and spongy layers, may have bulliform cells and rolled blades</p> Signup and view all the answers

Match the following leaf adaptations with their functions:

<p>Collapsing Bulliform Cells = Causes leaf folding or rolling under dry conditions Turgid Bulliform Cells = Help maintain an open blade structure Guard Cells = Regulate the opening and closing of stomata for gas exchange Vascular Bundles in Veins = Transport water (xylem) and nutrients (phloem) throughout the leaf</p> Signup and view all the answers

Match the following leaf structures with their functions:

<p>Epidermal Cells = Outer protective layer of the leaf Chloroplasts in Mesophyll = Site of photosynthesis within the leaf cells Stomata on Leaf Surface = Regulate gas exchange and transpiration Bundle Sheath Parenchyma = Surround vascular bundles in veins providing support and protection</p> Signup and view all the answers

Match the following leaf characteristics with their descriptions:

<p>Simple Leaves = Consist of a single blade attached to the petiole Compound Leaves = Have multiple leaflets attached at the end of a common petiole (rachis) Fan Out Venation Pattern = Primary veins radiate outward from base of leaf blade Monocot Venation Pattern = Veins are parallel or reticulated without distinct palisade and spongy layers</p> Signup and view all the answers

Match the following specialized leaf features with their corresponding types:

<p>Fewer Hairs = Characteristic of shade leaves compared to sun leaves Rolled Blade Structure = Resulting from collapsing bulliform cells in monocot leaves Open Blade Structure = Maintained by turgid bulliform cells in monocot leaves Well-Defined Mesophyll Layers = Characteristics of sun leaves compared to shade leaves</p> Signup and view all the answers

Match the leaf arrangement with the number of leaves attached at each node:

<p>Alternate = One leaf per node Opposite = One leaf per node Whorled = Three or more leaves per node</p> Signup and view all the answers

Match the venation type with its description:

<p>Pinnately veined leaves = Main midvein included within enlarged midrib Palmately veined leaves = Several primary veins fan out from base of blade Pinnate venation (Tulip poplar) = Main midvein included within enlarged midrib Palmate venation (Maple) = Several primary veins fan out from base of blade</p> Signup and view all the answers

Match the plant type with its primary venation pattern:

<p>Monocots = Netted or reticulate venation Dicots = Parallel venation</p> Signup and view all the answers

Match the term with its description:

<p>Guttation = Root pressure forces water out hydathodes at tips of leaf veins Phyllotaxy = Arrangement of leaves on stem Venation = Arrangement of veins in a leaf or leaflet blade Dichotomous venation = Veins fork evenly and progressively from base of blade</p> Signup and view all the answers

Match the leaf type with its description:

<p>Monocots = Primary veins divergent in various ways = netted or reticulate venation Dicots = Primary veins parallel = Parallel venation</p> Signup and view all the answers

Match the leaf structure with its function:

<p>Guard cells = Regulate opening and closing of stomata Palisade mesophyll = Majority of photosynthesis in leaves Spongy mesophyll = Vascular bundles (veins) =</p> Signup and view all the answers

Match the specialized leaf structure with its description:

<p>Pitcher Plants = Insects trapped and digested inside cone-shaped leaves Sundews = Round to oval leaves covered with sticky glandular hairs Venus's Flytraps = Blade halves trap insects in North Carolina and South Carolina Bladderworts = Tiny bladders on leaves with trap doors trap insects inside</p> Signup and view all the answers

Match the plant species with its description of specialized floral leaves (bracts):

<p>Poinsettia = Flowers surrounded by brightly colored bracts instead of petals Clary's sage = Colorful bracts located at top of flowering stalks above flowers Bougainvillea sp. = Brightly colored bracts surrounding flowers Fenestria aurantica = Specialized floral leaves at bases of flowers or flower stalks</p> Signup and view all the answers

Match the leaf structure with its primary function in trapping insects:

<p>Pitcher Plants = Trapping and digesting insects inside cone-shaped leaves Sundews = Having glandular hairs and sticky fluid to digest trapped insects Venus's Flytraps = Trapping insects with blade halves in specific regions Bladderworts = Using tiny bladders with trap doors to capture insects</p> Signup and view all the answers

Match the leaf adaptation with its corresponding plant species:

<p>Mother of Thousands = Tiny plantlets along leaf margins for reproduction Walking Fern = New plants growing at leaf tips for propagation Haworthia emelyae var. comptoniana = Transparent water storage cells under thick epidermis Frithia pulchra = Possessing specialized leaves for reproductive purposes</p> Signup and view all the answers

Match the leaf description with its corresponding plant species:

<p>Haworthia emelyae var. comptoniana = Longitudinal section end with transparent, thick epidermis Fenestria aurantica = Specialized leaves allowing light into leaf while preventing drying out Walking Fern = Producing new plants at leaf tips for propagation Mother of Thousands = Having tiny plantlets along leaf margins</p> Signup and view all the answers

Match the floral leave (bract) characteristic with its corresponding plant species:

<p>Poinsettia = Flowers surrounded by brightly colored bracts instead of petals Clary's sage = Colorful bracts located at top of flowering stalks above flowers Bougainvillea sp. = Brightly colored bracts surrounding flowers Fenestria aurantica = Specialized floral leaves at bases of flowers or flower stalks</p> Signup and view all the answers

What is the main function of leaves in plants?

<p>The main function of leaves in plants is to capture light energy through photosynthesis, which converts water and carbon dioxide into sugar molecules that store energy.</p> Signup and view all the answers

How do stomata on the leaf surface function?

<p>Stomata are tiny pores on the lower surface of leaves that allow carbon dioxide to enter and oxygen to diffuse out. They are controlled by guard cells, which can open or close the pore to regulate water loss through transpiration.</p> Signup and view all the answers

What is the difference between simple and compound leaves?

<p>Simple leaves have a single, undivided blade, while compound leaves have a blade that is divided into distinct leaflets.</p> Signup and view all the answers

What is the primary function of veins (vascular bundles) in leaves?

<p>The primary function of veins (vascular bundles) in leaves is to transport water, nutrients, and photosynthetic products throughout the leaf.</p> Signup and view all the answers

What is the relationship between guard cells and stomata in leaves?

<p>Guard cells are responsible for controlling the opening and closing of the stomatal pore. They can expand or contract to regulate the size of the stomatal aperture, which in turn controls the rate of gas exchange and water loss through transpiration.</p> Signup and view all the answers

What is the primary function of the palisade mesophyll layer in a leaf?

<p>The primary function of the palisade mesophyll layer in a leaf is to perform the majority of photosynthesis.</p> Signup and view all the answers

What are the three ways leaves reduce water loss?

<p>Thick, leathery leaves, fewer stomata or sunken stomata, succulent/water-retaining leaves</p> Signup and view all the answers

What is the primary function of tendrils in plants?

<p>To help the plant climb or support weak stems</p> Signup and view all the answers

How do spines on plants help reduce water loss?

<p>Spines reduce leaf surface and protect from herbivory</p> Signup and view all the answers

What is the main purpose of storage leaves in plants?

<p>To store water or carbohydrates</p> Signup and view all the answers

How do flower-pot leaves benefit plants in their environment?

<p>They provide a home for ant colonies and improve soil quality with nitrogenous wastes</p> Signup and view all the answers

What is the unique characteristic of window leaves in succulent desert plants?

<p>Leaves are buried in the ground except for the exposed end</p> Signup and view all the answers

What are the main differences between the palisade mesophyll and spongy mesophyll layers in a leaf?

<p>The palisade mesophyll is compactly stacked with barrel-shaped parenchyma cells, commonly in two rows, and contains most of the leaf's chloroplasts. The spongy mesophyll has loosely arranged parenchyma cells with abundant air spaces.</p> Signup and view all the answers

How do bulliform cells in monocot leaves function to help the plant adapt to dry conditions?

<p>Bulliform cells on either side of the main central vein in monocot leaves can partly collapse under dry conditions, causing the leaf blade to fold or roll. This reduces the surface area exposed to transpiration, helping the plant conserve water.</p> Signup and view all the answers

What are the key differences between sun leaves and shade leaves in terms of their structure and function?

<p>Compared to sun leaves, shade leaves tend to be larger and thinner, have fewer well-defined mesophyll layers and chloroplasts, and have fewer hairs. These adaptations allow shade leaves to maximize light capture and photosynthesis under low-light conditions.</p> Signup and view all the answers

Describe the structure and function of the veins (vascular bundles) in a leaf.

<p>The veins, or vascular bundles, are scattered throughout the mesophyll of the leaf. They consist of xylem and phloem tissues surrounded by a bundle sheath of thicker-walled parenchyma cells. The veins transport water, nutrients, and photosynthates throughout the leaf.</p> Signup and view all the answers

How do the mesophyll layers in monocot leaves differ from those in dicot leaves?

<p>Monocot leaves often do not have the mesophyll differentiated into distinct palisade and spongy layers. Instead, the mesophyll cells are more uniformly arranged throughout the leaf.</p> Signup and view all the answers

What is the primary function of the palisade mesophyll layer in a leaf?

<p>The palisade mesophyll layer contains most of the leaf's chloroplasts and is the primary site of photosynthesis in the leaf.</p> Signup and view all the answers

What pigments are revealed in mature leaves when chlorophylls break down in the fall?

<p>Carotenoids</p> Signup and view all the answers

What is the process by which leaves are shed in deciduous plants?

<p>Abscission</p> Signup and view all the answers

What is the protective layer in the abscission zone near the base of the leaf petiole?

<p>Suberin</p> Signup and view all the answers

Name a water-soluble pigment that may be present in the vacuole of leaves, which can be red or blue.

<p>Anthocyanins</p> Signup and view all the answers

What is the collective aging and decline process in plants known as?

<p>Senescence</p> Signup and view all the answers

What is the main function of the vascular bundles (veins) in leaves?

<p>Transport water and nutrients</p> Signup and view all the answers

Describe the function of the transparent, thick epidermis and water storage cells in the leaves of Haworthia emelyae var. comptoniana.

<p>The transparent, thick epidermis and water storage cells in the leaves of Haworthia emelyae var. comptoniana allow light to enter the leaf while keeping the plant from drying out when the leaves are buried.</p> Signup and view all the answers

What is the primary function of the brightly colored bracts in Poinsettia and Clary's sage?

<p>The brightly colored bracts in Poinsettia and Clary's sage surround the flowers and serve as floral leaves.</p> Signup and view all the answers

Explain the purpose of the insect-trapping leaves in pitcher plants, sundews, and bladderworts.

<p>Insect-trapping leaves in pitcher plants, sundews, and bladderworts allow these plants to trap and digest insects to obtain nitrogen and other deficient elements from the soil in swampy areas and bogs.</p> Signup and view all the answers

How do the new plants at the leaf tips of walking ferns and the tiny plantlets along the leaf margins of mother of thousands demonstrate specialized leaves?

<p>The new plants that form at the leaf tips of walking ferns and the tiny plantlets that develop along the leaf margins of mother of thousands are examples of specialized leaves that can produce offspring.</p> Signup and view all the answers

Describe how the blade halves of Venus's flytraps trap insects.

<p>The blade halves of the leaves in Venus's flytraps trap insects when they close around them.</p> Signup and view all the answers

Explain the function of the tiny bladders on the leaves of bladderworts that trap insects.

<p>The tiny bladders on the leaves of bladderworts have trap doors that allow them to trap insects inside the bladders.</p> Signup and view all the answers

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Study Notes

Introduction to Leaves

  • Leaves originate as primordia in buds
  • Most leaves have a stalk (petiole), a flattened blade (lamina), a network of veins (vascular bundles), and stipules at the base of the petiole
  • Flowering plants have leaves associated with leaf gaps and axillary buds at the base

Types of Leaves

  • Simple leaves: have a single blade
  • Compound leaves: blade is divided into leaflets
    • Pinnately compound leaves: leaflets are in pairs along the rachis (petiole)
    • Bipinnately compound leaves: leaflets are subdivided
    • Palmately compound leaves: all leaflets are attached at the same point at the end of the petiole

Leaf Arrangements and Types

  • Leaves are attached to stems at nodes, with stem regions between known as internodes
  • Phyllotaxy: the arrangement of leaves on a stem
    • Alternate: one leaf per node
    • Opposite: two leaves per node
    • Whorled: three or more leaves at a node
  • Venation: the arrangement of veins in a leaf or leaflet blade
    • Pinnately veined leaves: main midvein included within the enlarged midrib
    • Palmately veined leaves: several primary veins fan out from the base of the blade
    • Monocots: primary veins are parallel (parallel venation)
    • Dicots: primary veins are divergent in various ways (netted or reticulate venation)

Internal Structure of Leaves

  • Three regions: epidermis, mesophyll, and veins (vascular bundles)
  • Epidermis: a single layer of cells covering the entire surface of the leaf
    • Devoid of chloroplasts
    • Coated with cuticle (with cutin)
    • Functions to protect tissues inside the leaf
  • Mesophyll: the internal tissue of the leaf
    • Palisade mesophyll: compactly stacked, barrel-shaped parenchyma cells
    • Spongy mesophyll: loosely arranged parenchyma cells with abundant air spaces

Stomata

  • Tiny pores on the lower surface of leaves
  • Allow carbon dioxide to enter and oxygen to diffuse out
  • Water vapor also escapes via stomata
  • Guard cells control water loss by opening or closing the pore of the stomatal apparatus

Specialized Leaves

  • Leaves of arid regions:
    • Thick, leathery leaves
    • Fewer stomata or sunken stomata
    • Succulent, water-retaining leaves, or no leaves
    • Dense, hairy coverings
  • Leaves of aquatic areas:
    • Less xylem and phloem
    • Mesophyll not differentiated into palisade and spongy layers
    • Large air spaces
  • Tendrils: modified leaves that curl around more rigid objects
  • Spines: modified leaves that reduce leaf surface and water loss, and protect from herbivory
  • Storage leaves: modified for water storage
  • Flower-pot leaves: leaves that develop into urn-like pouches that become homes of ant colonies

Autumnal Changes in Leaf Color

  • Chloroplasts of mature leaves contain several groups of pigments
  • Chlorophylls: green
  • Carotenoids: yellows
  • In fall, chlorophylls break down, and other colors are revealed
  • Water-soluble anthocyanins (red or blue) and betacyanins (red) may also be present in the vacuole

Abscission

  • Deciduous plants drop leaves seasonally
  • Senescence: the collective aging and decline process
  • Abscission: the process by which leaves are shed
  • Occurs as a result of changes in the abscission zone near the base of the petiole

Human and Ecological Relevance of Leaves

  • Landscaping: shade trees
  • Food: cabbage, lettuce, celery petioles, spices
  • Dyes
  • Perfumes: oils of orange tree, lavender
  • Ropes and twine: agave, hemp fibers
  • Drugs: narcotics, tobacco, marijuana
  • Beverages: tea, tequila (agave leaves)
  • Insecticides: rotenone
  • Waxes: carnauba and caussu waxes
  • Aesthetics: floral arrangements, gardens

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