CH. 25 Leaves

Question 1

Describe the functions of leaves.
define transpiration

Answer 1

Main photosynthetic organ of the plants
transpiration- movement of water through the plant/evaporation via the leaves

Question 2

Identify the basic structure and terminology of a simple leaf
including blade, stipule, petiole, sessile, sheath.

Answer 2

Blade: The flat, expanded portion of the leaf where photosynthesis primarily occurs.

Stipule: Small, leaf-like structures found at the base of the petiole in some plants.

Petiole: The stalk that connects the blade to the stem.

Sessile: When a leaf lacks a petiole and is directly attached to the stem.

Sheath: A structure that wraps around the stem in some plants, such as grasses.

Question 3

define vascular bundle

Answer 3

A bundle of xylem and phloem tissues responsible for transporting water, nutrients, and sugars throughout the leaf. also known as leaf veins

Question 4

define guard cells

Answer 4

Specialized cells that surround stomata and regulate their opening and closing.

Question 5

define stomata

Answer 5

Small openings on the leaf surface that allow for gas exchange and transpiration.

Question 6

define palisade mesophyll

Answer 6

A layer of closely packed, elongated cells in the leaf that contains many chloroplasts and is the primary site of photosynthesis.

Question 7

define spongy mesophyll

Answer 7

A layer of loosely packed, irregularly shaped cells beneath the palisade mesophyll that also participates in photosynthesis and aids in gas exchange.

Question 8

define bulliform cells

Answer 8

Large, water-storing cells found in some grasses that help the leaf curl in response to water loss.

Question 9

define simple leaf

Answer 9

A leaf that consists of a single blade, either with or without a petiole.

Question 10

define compound leaf

Answer 10

A leaf that is divided into multiple leaflets, each attached to a common petiole.

Question 11

define rachis

Answer 11

The central axis of a compound leaf to which leaflets are attached.

Question 12

define prickles

Answer 12

Small, sharp outgrowths on the leaf surface, often found in plants like roses for defense.

Question 13

define stomatal crypt

Answer 13

Small chambers or pits surrounding stomata that can help reduce water loss.

Question 14

Recognize the various arrangements and composition
patterns found in stems and leaves (alternate, opposite,
whorled, distichous, decussate).

Answer 14

alternate (one leaf per node), opposite (two leaves per node, opposite each other),
whorled (three or more leaves per node),
distichous (leaves arranged in two vertical rows),
decussate (leaves arranged in pairs at right angles to the pairs above and below).

Question 15

Leaf Patterns:

Answer 15

Simple Leaf: A leaf with a single undivided blade.
Palmately Compound Leaf like a hand : A compound leaf with leaflets radiating from a common point
Pinnately Compound Leaf: A compound leaf with leaflets arranged along a central axis, like the barbs on a feather.

Question 16

Compare and contrast a sun and shade leaf, and explain the
structural differences between these types of leaves.

Answer 16

Sun leaves are adapted for high light conditions and are usually thicker, with more palisade mesophyll.
Shade leaves are adapted for low light conditions and are thinner with a larger spongy mesophyll layer.

Question 17

Compare and contrast a mesophytic, hydrophytic, and
xerophytic leaf, and explain the survival strategies of these
characteristics.

Answer 17

Mesophytic leaves are adapted to moderate environmental conditions and have a typical structure.

Hydrophytic leaves are adapted to aquatic environments and often have reduced or absent cuticles and stomata.

Xerophytic leaves are adapted to arid conditions and may have specialized features like reduced leaf size and thick cuticles to reduce water loss.

Question 18

Identify the parts in a cross-section of a mesophytic leaf.

Answer 18

A typical cross-section of a mesophytic leaf includes the upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, stomata, and vascular bundles.

Question 19

• Describe the method of leaf abscission.

Answer 19

Leaf abscission is the process by which a plant sheds its leaves. It is usually triggered by environmental factors such as seasonal changes, drought, or reduced light. The plant forms an abscission layer at the base of the petiole, eventually causing the leaf to detach.

Question 20

Identify several leaf modifications and species they are
associated with…

Answer 20

tendrils (stent or leaf) ex grapes
spines ex cactus
bracts
bulb (underground leaves) -onion
insectivorous leaves - Venus fly trap

Question 21

Explain in what aspects leaves can be more variable than
stems and roots.

Answer 21

Leaves can exhibit more variability than stems and roots because leaves are exposed to the external environment, and their form and structure often adapt to specific ecological niches and functions. Stems and roots tend to have more consistent roles in structural support and nutrient uptake, respectively, which leads to less diversity in their forms.