Microscope and Leaf Structure Quiz

Parts and Components of a Microscope

• A microscope magnifies small objects, enabling observation at the cellular level.
• Allows visualization of cell structures like nuclei, mitochondria, and organelles.

External Structure of the Leaf

• Leaves are flattened green outgrowths from the stem of vascular plants.
• Composed of:
  • Blade: the broad part of the leaf.
  • Leaf-stalk (Petiole): connects blade to stem in dicots; called leaf-sheath in monocots.
  • Sessile Leaves: lack a petiole; include various classifications based on leaf-base attachment.

Types of Sessile Leaves

• Amplexicaul: leaf base clasps the stem.
• Perfoliate: lobes meet around the stem, appearing pierced.
• Decurrent: lower edges extend down the stem.
• Sheathing: blade base encircles the stem.

Compound Leaves

• Comprised of leaflets attached to petiolules, with a central rachis.
• Types:
  • Pinnate: leaflets arranged along a main stalk.
    • Simple: unbranched with a double row of leaflets.
    • Twice Pinnate: leaflets arranged on branches off the rachis.
  • Simple Palmate: leaflets attach at the tip of the petiole; ternate has three leaflets.

Leaf Arrangement (Phyllotaxy)

• Alternate: one leaf per node; alternate sides.
• Opposite: two leaves per node, one on each side.
• Fasciculate: multiple leaves arise from a single node on the same side.
• Whorled: three or more leaves arranged around the stem at one node.
• Decussate: pairs of opposite leaves oriented at right angles.
• Secund: all leaves inclined to one side.

Venation

• Adaxial Surface: upper surface of the leaf.
• Abaxial Surface: lower surface of the leaf.
• Veinlets: ultimate divisions of leaf veins.

Floral Structure

• Staminate Flowers: contain only male parts.
• Pistillate Flowers: contain only female parts.
• Corolla: petals fused together in flowers.
• Sepals: protective outer parts before flowering, fused forms a calyx.
• Perianth: combined sepals and petals; indistinct forms are tepals.
• Bract: green leaves beneath the sepals.
• Pedicels: flower stems; the receptacle is where flowers attach.

Classification of Flowers

• Complete Flower: possesses all four organs (stamen, pistil, petals, sepals).
• Perfect Flower: includes both stamens and pistils.
• Imperfect Flower: contains only one essential organ (either staminate or pistillate).
• Incomplete Flower: lacks one or more organs.

Flower Symmetry

• Regular Flower: symmetric upon dissection.
• Irregular Flower: asymmetrical petals and sepals.

Plant Sexuality

• Monoecious: same plant bears both staminate and pistillate flowers (e.g., corn).
• Dioecious: staminate and pistillate flowers found on separate plants (e.g., papaya).
• Polygamous: contains both perfect and unisexual flowers on the same plant.

Coalescence of Parts

• Cohesion: union of similar parts (e.g., synandry for stamens).
• Adhesion: union of dissimilar parts, such as epipetaly where stamens attach to corolla.

Types of Inflorescence

• Peduncle: main stem of the inflorescence.
• Pedicels: branch from the peduncle to support individual flowers.
• Types:
  • Spike: unbranched with stemless florets.
  • Raceme: unbranched with florets on short pedicels.
  • Panicle: loosely branched, pyramidal structure.
  • Corymb: flat-topped, blooms from outside edges.
  • Cyme: center flower opens first in a flat-topped arrangement.
  • Umbel: shaped like an inverted umbrella with pedicels from one point.
  • Spadix: fleshy spike surrounded by a colorful bract (spathe).

Test your knowledge about the parts and components of a microscope, as well as the external structure of a leaf. Learn about the magnification process and the anatomy of leaves.