Plant Structure and Function Chapter 29

Plant Growth Meristems – where plant growth originates – region where cells continuously divide. Apical meristem Intercalary Lateral meristem

Type Location Growth Function Apical meristems (primary growth) Tips of stems and roots Increase length at tips Intercalary meristems (primary growth) Between the tip and base of stems and leaves Increase length between nodes Lateral meristems (secondary growth) Sides of stems and roots Increase diameter

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Roots

Types of Roots Taproot: If the first/ primary root produced by a sprouting seed becomes the largest Many plants like carrots and certain trees have taproots.

Types of Roots Fibrous root system: The primary root does not become large, but develops into numerous small roots www.extension.umn.edu/

Types of Roots Adventitious roots: specialized roots that grow from stems or leaves www.botgard.ucla.edu

Root Structures Root cap Cover apical meristem Produces a slimy substance that acts like a lubricant Root structures are adapted for several functions.

Root Structures Root hairs Extensions of epidermal cells Increase surface area Mycorrhiza (fungus)

Apical meristem fairmanstudios.com/

Root Functions Anchoring plant Absorb water and a variety of minerals Store carbohydrates or water Some minerals are essential for plants to live. Phloem carries sugars made in leaves to the roots.

Stems Chapter 29

Stems Involved in the transport and storage of nutrients and water. Support leaves Various differences in shape and growth represent adaptations to the environment. Stems are usually adapted to support leaves and whatever their size and shape, stems also function in transporting materials and providing storage. Examples: strawberries: grow along surface and produce new plants potato: edible tuber are modified for storage cactus: store water

Stem Structures Grow only in length at their tips. Each leaf is attached at a node. Divided into segments called internodes. At the end of the internode is a bud. Stems have several features that roots lack. A bud is capable of producing a new shoot system and contains an apical meristem is enclosed in specialized leaves called bud scales.

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Stem Functions Transportation of Nutrients Storage Transport Water Stores water and nutrients Transport Water Occurs in the xylem of all plant organs Transpiration Sugars, some plant hormones and other organic compounds are transported through the phloem. Most of the time sugars move from the leaves to the roots.

Leaves Chapter 29 Section 4

Leaves Extremely variable which, like stems, represents adaptations to the environmental conditions. Tendrils- found in vines Fly traps- get additional nutrients Spines- offer protection, and reduce water loss

Leaf Shape Blade Petiole The broad flat, portion of a leaf Stalklike, where blade attaches to stem Leaves can be round, straplike, needlelike, or heart-shaped.

Leaf Shape Simple Single leaf Coumpound Divided into leaflets

Leaf Structure Cuticle Epidermis Mesophyll Vascular Bundle

Epidermis Represents the dermal tissue A single layer of cells coated with a cuticle Epidermal hairs protect against insects and intense light

Mesophyll Where photosynthesis occurs Ground tissue Made up of chloroplast-rich parenchyma cells Organized into 2 layers Palisade mesophyll: most photosynthesis Spongy mesophyll: gas exchange What is the cuticle?

Veins aka Vascular Bundles Continuous with the vascular tissue of the stem and petiole Embedded in the mesophyll Parellel vs net venation

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Leaf Functions Primary site of photosynthesis in most plants. Mesophyll cells use light energy, CO2, and water to make sugars. MAJOR LIMITATION to photosynthesis is insufficient water due to transpiration.

Capturing Light Adapt to environment to maximize light interception Leaves at top of tree are bigger and thicker. Shaded leaves are arranged to minimize shading. Hot-too much sun light, develop dense coats or live underground

Gas Exchange Controlled by the stomata The stomata is open during the day and close at night Guard cells Modified cells Regulated by the amount of water in it

Guard Cells