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Plant Root & Leaf Lab

Although we do not normally see the roots of most plants, they perform vital functions for vascular plants (absorption of water and nutrients, anchorage, support, storage). There are two basic types of root systems, fibrous and tap roots.

The roots of land plants absorb the water and dissolved minerals used by the plants for food-making and for growth of the plant body. Most roots grow downward, then branch outward from the center of the plant. In this way they anchor the plant firmly in the soil and support the plant body that grows above ground level.

Roots are plant organs the function by means of specialized tissues. Some tissues conduct water and minerals upward to the stem; other tissues conduct food upward or downward. Still other tissues store food for the plant. All of the specialized tissues of a root arise from the apical meristem, the growth region of a root tip where new cells are produced.

Objective: Identify modification of roots, stems and leaves for different functions: bulbs, stem tubers, storage roots and tendrils

Objective: Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues

Directions

Many of the structures you are tasked with drawing will be visible from multiple slides.  Using all of the suggested images, create a single drawing.

PART A: Structure of Root Tip

PART B: Root Hair

Part D: Vascular Bundle

Part C: Leaf Structure

Plants are able to harness the energy of the sun to turn CO2 from the air into the carbon-based molecules of life: carbohydrates, proteins, lipids, and nucleic acids.  Plants capture the sun’s light within their green leaves. Inside a leaf’s cells are green organelles, chloroplasts, which do all this hard work of producing the food that feeds the plant… and, in fact, the whole rest of the world, too!

To do this job best, leaves have evolved a specific structure, 3 types of tissue arranged in

layers: epidermis, mesophyll, and vascular tissue.  The epidermis is the outer layer of cells that acts like a protective “skin” for the leaf. Covering the epidermis is a waxy coating, called the cuticle, which stops evaporation of water from the leaves thereby helping plants conserve water. In the lower epidermis are openings called stomata surrounded by two cells called guard cells. The stomates act like the lungs of the plant in that they allow gas exchange, letting CO2 into the inner plant tissues for photosynthesis and then allowing O2 out as a waste product of photosynthesis.  The mesophyll is the main inner leaf tissue making up the blade of the leaf. Most of the photosynthesis of the plant takes place in the mesophyll. The mesophyll in the upper part of the leaf is made up of tightly packed cells, full of chloroplasts, and is called the palisades layer.  The mesophyll in the lower part of the leaves is made up of loosely packed cells and is called the spongy layer.  The vascular tissue functions like the circulatory system of the plant. The xylem carries water from the roots to the leaves and to the other upper parts of the plant. The phloem carries the sugars produced during photosynthesis in the chloroplasts of the leaves to any place else in the plant that needs the food. Xylem and phloem are found in vascular bundles in the veins of the leaf.

Below is a diagram of a cross section through a leaf.  Label the following structures using the descriptions above.