The Plant Body
1. Describe and compare the three basic organs of vascular plants. Explain how these basic organs are interdependent.
The three basic organs of a vascular plant are the stems, leaves, and roots. The stems consist of nodes, where leaves attach, and internodes between the nodes. The stem is responsible for elongation of the plant and acts as a central axis for other organs to attach to. The roots help to anchor the plant as well as absorb water and nutrients from the soil. In addition, roots often form mycorrhizae with fungi, providing further advantage. Some roots are specially designed to store nutrients for later use of the plant. Leaves are wide flat regions that grow off of the stem. Their primary purpose is to add surface area for photosynthesis.
2. List the basic functions of roots. Describe and compare the structures and functions of fibrous roots, taproots, root hairs, and adventitious roots.
The roots help to anchor the plant as well as absorb water and nutrients from the soil. Roots often form mycorrhizae with fungi, providing further advantage. Some roots are specially designed to store nutrients for later use of the plant. Roots come in two types: fibrous roots and roots that stem from a taproot. Fibrous roots are net-like and generally thin, spreading out underground, but not off of a main root. Taproots are primary roots that lateral roots branch off of. Taproots are much thicker and can go deeper underground, providing better anchorage. Root hairs grow from root tips and, while not technically roots on their own, provide additional surface area for absorption of water and nutrients. Adventitious roots grow off of the stem. They usually help plants that are tall and stalky not fall over.
3. Describe the basic structure of plant stems.
The stem is responsible for most primary growth. It is also the organ that the leaves and reproductive structures are attached too. Some stems are modified, providing additional services. Examples of these are bulbs, stolons, tubers, and rhizomes.
4. Explain the phenomenon of apical dominance.
Apical dominance is a phenomenon in which axillary buds in close nearness to terminal buds do not grow out.
5. Describe the structures and functions of four types of modified shoots.
Stolons: act as “runners” that spread out from a parent plant horizontally above the ground. They then form completely new plants in other locations. This allows plants to reproduce asexually without the use of seeds.
Bulbs: modified stems that store food in special leaves. An onion is an example of this.
Tubers: Tubers are large ends of rhizomes that, like bulbs, store food (however, not in special leaves).
Rhizomes: horizontal stems that grow either just under or above the surface. They provide a more solid base for a plant and allow it to grow over a wider area.
6. Describe and distinguish between the leaves of monocots and those of eudicots.
Monocots have leaves with parallel veins, while eudicots have leaves with highly branched, netlike veins.
7. Describe the three tissue systems that make up plant organs.
Dermal tissue system: acts as an outer protective covering. Vascular tissue system: consists of xylem and phloem.
Ground tissue system: tissue that is neither dermal nor vascular. 8. Describe and distinguish between the three basic cell types of plant tissues. For each tissue, describe one characteristic structural feature and explain its functional significance.
Dermal tissue system: In non-woody plants, usually consists of a layer of tightly packed cells called the epidermis. In woody plants, consists of the periderm (part of bark). The dermal tissue system also includes the root tip, which protects the root apical meristems from abrasion.
Vascular tissue system: Serves as a transport system for water, nutrients, and organic materials like sugar.
Ground tissue system: = includes...