Bio of Plants Lab 7 Quiz - (Leaves & Flowering Plants)

Leaves are the main plant ____ responsible for collecting______

organs; CO2 and energy from sunlight for photosynthesis

What is the formula for photosynthesis?

6CO2 + 6H2O + sunlight energy ---> 6O2 + sugar (C6H12O6)

Stipule (what is it and what is its function)

located at the base of the leaf petiole, attached to the stem; helps protect

bud/young leaf, usually in pairs

Mesophyll (what is it and what is its function)

specialized, photosynthetic ground tissue; found between upper & lower epidermis; main site of photosynthesis; consists of parenchyma

Simple leaves

whole, undivided leaves; each leaf has one blade

Compound leaves

leaves divided into leaflets; each leaf is made up of more than one blade (leaflets)

Axillary bud

embryonic shoot located in the axil of leaf; develop lateral branches, leaves, flower; always in the axils of the LEAF, never in the axils of the LEAFLETS

2 types of compound leaves & characteristics of each

palmately compound- leaflets arise from a common point

pinnately compound- leaflets arise at several locations along an elongate axis (the “rachis”)

opposite leaves

whorled leaves

alternate leaves

rosette

Alternate leaf arrangement

emerge one at a time, alternating sides along the stem

Opposite leaf arrangement

emerge in pairs directly across from one another at the same node

Dicot and Monocot leaf differences

Dicot- guard cells are kidney shaped, two types of mesophyll (palisade & spongy parenchyma), only have stomata on the lower epidermis

Monocot- guard cells are dumb-bell shaped, vascular bundles (veins) are more parallel, have stomata on upper and lower epidermis

Aquatic plants

(hydrophytes)- submerged, adapted for water:

• leaves may lack the external protective tissues (cuticle)

required by land plants which prevents water loss

• may lack stomata or only have them on upper surface

• specialized leaf shapes (dissected or divided) allow for large SA for absorption & photosynthesis

• leaves and stems tend to lack mechanical strengthening tissue allows plant to be flexible for changing water levels

• roots adapted for anchorage and less water absorption

Arid plants

(xerophytes)-plants living in very hot or dry climates; adapted for storing water and limiting water loss:

• leaves may be completely lacking, reducing water loss

• leaves may be fleshy leaves for water storage/supply

• leaves may have thick cuticle to prevent water loss and damage

• sunken stomata

Thorns

modified stems: connected to vascular system, positioned over leaf scar

Prickles

modified hairs: part of epidermis, not connected/easy to remove, random positioning

Spines

modified leaves: connected to vascular system, positioned under leaf scar

Monocot vs. Dicot leaves (characteristics)

• monocots have single cotyledons, dicots have 2

• monocots leaves are long and narrow with parallel veins, dicots are broad with a network of veins

• monocots vascular bundles are scattered, dicots have vascular bundles arranged in ring

• monocots floral parts are in multiples of 3, dicots floral parts are in multiple 4 or 5

Bracts

modified leaves: look like petals (ex.poinsettas)

other parts of modified leaves (parts of flowers)

petals (corolla), stamens (androecium), and carpels or pistils (gynoecium) are also highly modified flowers

Bulb

modified leaf: onion bulb contains modified leaves – fleshy food storage leaves and scaly leaves that cover the bulb

Modified Leaves for Asexual Reproduction

succulent that produces numerous small plantlets on the ends of its leaves, which can easily

detach and grow into new plants

Tendrils

modified leaves of the common pea plant produce tendrils from their leaves and wrap around other objects to help the plant to grow vertically in their environment.