Study Guide - Anatomy of Flowering Plants

Anatomy of Flowering Plants Study Guide

Study Guide: Anatomy of Flowering Plants

Short-Answer Quiz

Instructions: Answer the following ten questions in two to three complete sentences based on the source material.

1. What is plant anatomy, and what are the three basic tissue systems found in flowering plants?

Plant anatomy is the study of the internal structure of plants. The three basic tissue systems, categorized by their structure and location, are the epidermal tissue system (outer covering), the ground tissue system (main bulk of the plant), and the vascular or conducting tissue system (xylem and phloem).

2. Describe the structure and primary functions of the stomatal apparatus.

The stomatal apparatus consists of the stomatal aperture (pore), two guard cells, and the surrounding subsidiary cells. Stomata, present in the epidermis of leaves, regulate transpiration and gaseous exchange. The guard cells, which are bean-shaped or dumb-bell shaped and contain chloroplasts, control the opening and closing of the pore.

3. How do open and closed vascular bundles differ, and in which types of plants are they typically found?

Open vascular bundles contain a layer of cambium between the xylem and phloem, which allows them to form secondary tissues and undergo secondary growth; they are characteristic of dicotyledonous stems. Closed vascular bundles lack cambium, do not form secondary tissues, and are typically found in monocotyledons.

4. Explain the composition and role of the ground tissue system in a plant.

The ground tissue system constitutes all tissues in a plant except for the epidermis and vascular bundles. It is composed of simple tissues like parenchyma, collenchyma, and sclerenchyma. This system forms the cortex, pericycle, pith, and medullary rays in stems and roots, and the mesophyll in leaves.

5. What are Casparian strips, and in which specific tissue and organ are they located?

Casparian strips are depositions of a water-impermeable, waxy material called suberin. They are found on the tangential and radial walls of the barrel-shaped cells that form the endodermis, which is the innermost layer of the cortex in plant roots.

6. Describe two key anatomical differences between a monocot root and a dicot root.

One key difference is the number of xylem bundles; dicot roots typically have two to four (diarch to tetrarch), while monocot roots usually have more than six (polyarch). Secondly, the pith in a dicot root is small or inconspicuous, whereas in a monocot root, the pith is large and well-developed.

7. How is the arrangement of vascular bundles in a dicot stem different from that in a monocot stem?

In a dicot stem, a large number of vascular bundles are arranged in a distinct ring. In contrast, a monocot stem features numerous vascular bundles that are scattered throughout the parenchymatous ground tissue.

8. What is mesophyll, and how is it structurally different in a dorsiventral (dicot) leaf compared to an isobilateral (monocot) leaf?

Mesophyll is the chloroplast-containing ground tissue between the upper and lower epidermis of a leaf, responsible for photosynthesis. In a dorsiventral (dicot) leaf, it is differentiated into an upper, elongated palisade parenchyma and a lower, loosely arranged spongy parenchyma. In an isobilateral (monocot) leaf, the mesophyll is not differentiated.

9. Identify and describe the epidermal appendages found on plant roots and stems.

The epidermal appendages on roots are root hairs, which are unicellular elongations of epidermal cells that absorb water and minerals. On the stem, the appendages are called trichomes; they are usually multicellular, can be branched or unbranched, and help prevent water loss from transpiration.

10. What are bulliform cells, and what is their function in grasses?

Bulliform cells are large, empty, and colorless cells that are modifications of certain adaxial epidermal cells along the veins in grasses. When turgid with water, they keep the leaf surface exposed, but when they become flaccid due to water stress, they cause the leaves to curl inwards to minimize water loss.

Essay Questions

1. Stem Anatomy Comparison

Compare and contrast the complete anatomical structure of a dicotyledonous stem and a monocotyledonous stem. Discuss differences in the epidermis, hypodermis, ground tissue, and the type, arrangement, and characteristics of their vascular bundles.

2. Root Water Transport

Describe the journey of water and minerals absorbed by a dicot root until they reach the xylem. Detail the tissues the water must pass through, including the epiblema, cortex, and endodermis, paying special attention to the role of the Casparian strip.

3. Leaf Adaptations

Explain how the internal anatomy of a leaf is adapted for its primary functions of photosynthesis and regulation of water loss. Refer to the specific roles of the cuticle, epidermis, stomata, mesophyll tissue (both types), and vascular bundles.

4. Tissue Systems Overview

Detail the three tissue systems (epidermal, ground, and vascular) in a flowering plant. For each system, describe its location, component tissues/cells, and primary functions.

5. Microscopic Identification Guide

Using anatomical features alone, provide a step-by-step guide on how to distinguish between a monocot root, a dicot root, a monocot stem, and a dicot stem when viewing their transverse sections.

Glossary of Key Terms

Anatomy

The study of the internal structure of plants.

Bulliform Cells

Large, empty, colorless adaxial epidermal cells in grasses that help regulate water loss by causing leaves to curl inward when flaccid.

Cambium

A layer of tissue present between the phloem and xylem in dicot stems that has the ability to form secondary xylem and phloem tissues.

Casparian Strips

A deposition of water-impermeable, waxy suberin on the tangential and radial walls of endodermal cells in the root.

Conjunctive Tissue

The parenchymatous cells which lie between the xylem and the phloem in a dicot root.

Cortex

The region of tissue composed of multiple layers of cells, located between the epidermis and the pericycle in stems and roots.

Cuticle

A waxy, thick layer that often covers the outside of the epidermis, preventing the loss of water. It is absent in roots.

Endodermis

The innermost layer of the cortex, comprising a single layer of barrel-shaped cells. In dicot stems, it is referred to as the starch sheath.

Epidermal Tissue System

The outermost covering of the whole plant body, which comprises epidermal cells, stomata, and epidermal appendages (trichomes and hairs).

Ground Tissue System

All tissues except the epidermis and vascular bundles. It consists of simple tissues like parenchyma, collenchyma, and sclerenchyma.

Guard Cells

Two bean-shaped (or dumb-bell shaped in grasses) cells that enclose a stomatal pore and regulate its opening and closing.

Medullary Rays

A few layers of radially placed parenchymatous cells located between the vascular bundles in a dicot stem.

Mesophyll

The ground tissue in leaves, located between the upper and lower epidermis. It possesses chloroplasts, carries out photosynthesis, and is made of parenchyma cells.

Pericycle

A few layers of thick-walled parenchymatous cells located next to the endodermis. It is the site of initiation for lateral roots and vascular cambium.

Phloem

A complex tissue within the vascular system responsible for translocating food material.

Pith

The central portion of the stem or root, constituted by a large number of rounded, parenchymatous cells with large intercellular spaces.

Root Hairs

Unicellular elongations of the epidermal cells in roots that help absorb water and minerals from the soil.

Starch Sheath

Another name for the endodermis in a dicot stem, so-called because its cells are rich in starch grains.

Stele

All tissues on the inner side of the endodermis, including the pericycle, vascular bundles, and pith.

Stomata

Structures present in the epidermis of leaves that regulate the process of transpiration and gaseous exchange.

Stomatal Apparatus

The collective term for the stomatal aperture, the guard cells, and the surrounding subsidiary cells.

Subsidiary Cells

A few specialized epidermal cells in the vicinity of the guard cells, distinct in their shape and size.

Trichomes

Epidermal hairs on the shoot system, which are usually multicellular and help in preventing water loss due to transpiration.

Vascular Bundles

A component of the vascular tissue system where the xylem and phloem are located together.

Vascular Tissue System

The conducting tissue system consisting of the complex tissues phloem and xylem.

Xylem

A complex tissue within the vascular system responsible for translocating water and minerals.