Biology 172 Ch. 35-38 Review Questions and Correct Answers

Plastic Plants? - Polymorpha- many different growth patterns depending on its environment - Not as much plasticity in animals as plants plants respond to challenges and opportunities in their local environment by altering their growth. (In contrast, animals typically respond by movement.) - Exhibits developmental plasticity, the ability to alter itself in response to its environment Overview of a flowering plant - The plant body is divided into a root system and a shoot system, connected by vascular tissue that is continuous throughout the plant. - Shoot system: Stems and leaves (and flowers, so three organs involved in shoot system) - Root system: the network off all the roots of a plant Root Functions - Anchor the plant into the ground - Absorb water and minerals - Food storage - Asexual reproduction Root Types - Tap root system - Fibrous root system - Lateral roots - Adventitious roots - Root hair Tap root system - One primary root - Often found in tall plants because big primary root anchors plant to the ground and helps it grow tall - Expensive in reousrces and energy because it's not absorbing nutrients, nutrients are absorbed through lateral roots but it helps it grow tall and compete for sunlight Fibrous root system - A thick mat of slender roots spreading out below the soil surface - No primary roots, many roots of equal size and equal dominance forming network (sprawling plants, harder for animals to take it out of the ground, in a place where there's periodic water, roots can absorb a lot of water when it's available, resistance to erosion Lateral roots - Attached is the extension of radical root, in tap root system - Greatly enhance the ability of the root system to anchor the plant and to acquire resources such as water and minerals from the soil by increasing surface area Adventitious roots roots that develops from unexpected place (not from a root, grow from stems, leaves, etc), in fibrous root system Root hairs - Root hairs are extensions of epidermal cells, which form a protective covering (90%) - Most water absorption occurs here Prop Roots - Adventitious roots - Modified roots in corn adventitious roots because they come from the stem - They provide support for the plant Storage roots Many plants, such as the common beet, store food and water in their roots. "Strangling" aerial roots - Adventitious roots - Aerial roots provide support - Strangler fig seeds germinate in the crevices of tall trees. Aerial roots grow to the ground, wrapping around the host tree and objects such as this Cambodian temple. Shoots grow upward and shade out the host tree, killing it. Pneumatophores - Roots grow upward so they're above the water line so they can take up oxygen Buttress roots - Provide support on soft, spongy soil - Spread out because the soil is not very deep Stem Functions 1) Provide support 2) Facilitate transport of water and food 3) Display the leaves 4) Sexual and asexual reproduction (asexually: stems can sprout roots and develop plants; sexually: support and produce flowers) Stem Structure - A stem is an organ consisting of --An alternating system of nodes, the points at which leaves are attached --Internodes, the stem segments between nodes --Spacing of leaves Axillary bud - Structure that has the potential to form a lateral shoot, or branch - Can produce leaves or branched stems - Where they are produced is called a node Apical bud - Or terminal bud, is located near the shoot tip and causes elongation of a young shoot - Mass of cells capable of mitotic cell division, which causes the stem to grow in length. - First growth is called the primary growth