Bio- Chapter 29 Section 4

mesophyll

-a ground tissue composed of chloroplast-rich parenchyma cells -uses light energy, carbon dioxide, and water to make sugars (photosynthesis) -organized into two layers

tendril

-a modified leaf found in many vines -it wraps around objects and supports the climbing vine examples: peas and pumpkins

spongy mesophyll

-beneath the palisade layer -consists of irregularly shaped cells surrounded by large air spaces -air spaces allow oxygen, carbon dioxide, and water to diffuse into and out of the leaf

What are some different modifications for capturing light?

-leaves that develop in full sun are thicker, have a smaller area per leaf, and have more chloroplasts per unit area -shade leaf chloroplasts are arranged so that chloroplasts don't shade each other -in dry environments where they receive too much light, they have evolved dense coatings of hairs and some grow underground

palisade mesophyll

-occurs directly beneath the upper epidermis -site of most photosynthesis -packed tightly together in one or two layers with air spaces between the long side walls

parallel venation

-several main veins are roughly parallel to each other -monocots

blade

-the broad, flat portion of a leaf -the site of photosynthesis

net venation

-the main vein or veins repeatedly branch to form a conspicuous network of smaller veins -dicots

guard cells

-two kidney-shaped cells that guard the stomata -modified cells on the leaf epidermis that regulate gas and water exchange

tubular leaves

-unusual leaf modification occurs in carnivorous plants -function as food traps example: pitcher plant

veins

-vascular bundles that make up the vascular tissue system of leaves -they lie embedded in the mesophyll

What are advantages and disadvantages of stomata closing?

advantage- reduces further water loss and may help plant survive until the next rain disadvantage- virtually sits down photosynthesis by cutting of carbon dioxide supply

What are some advantages and disadvantage of transpiration?

advantages- cooling the plant and speeding the transport of mineral nutrients through the xylem disadvantages- major limitation to plant photosynthesis due to insufficient water

How are all three tissue systems represented in leaves?

dermal- epidermis ground- the mesophyll vascular- vascular bundles (veins)

doubly compound leaf

each leaflet is subdivided into smaller leaflets example: honeylocust

How are sugars made in the leaf used?

either used in the leaf or transported as an energy source or as building blocks for cells

What are the different shapes of leaves?

round, straplike, needlelike, or heart-shaped

petiole

stalklike structure that attaches the blade to the stem

venation

the arrangement of veins in a leaf

compound leaves

the blade is divided into leaflets example: the white clover

How do guard cells function in regulating opening and closing of stomata?

Daytime- 1. epidermal cells pump potassium ions into guard cells so water moves into guard cells by osmosis 2. influx of water makes guard cells swell, causing them to bow apart and form a pore Darkness- 1. Potassium ions are pumped out of guard cells and water leaves by osmosis 2. guard cells shrink slightly and the pore closes

simple leaf

has a single blade example: maple leaf

spines

leaves, or parts of leaves, that are modified to protect the plant from being eaten by animals Example: the barberry