Ch. 23 Plant Structure and Function
23.1. Plant Cells and Tissues
A. Types of Plant Cells – See differences in kingdoms from ch. 17
1. Parenchyma – spherical cell with thin cell walls and large central vacuole. Most abundant cell found
in plant tissue. Function as: __________________ (vacuole) and contain chloroplasts for food production
2. Collenchyma – long, flexible cells with unevenly thick cell walls; most common in actively
growing tissues.
3. Sclerenchyma – thick cell with rigid cell wall; include fiber and stone cells. Provide support
for plant and major component of vascular tissue.
B. Plant Tissues – tissues are a group of cells that function together to perform an activity
1. Dermal tissues
a. ____________________ b. _________________ c. __________________ d. __________________
flattened parenchyma cells openings in the cuticle of - control the opening and hairlike projections that
that cover all parts of the
the leaf that control gas
closing of guard cells
extend form the
plant (ex: cuticle)
exchange
epidermis (ex: root hairs)
2. Vascular tissue
a. __________________ – tubular cells that transport water and
minerals from the roots to the rest of the plant (most are dead at
maturity)
b. __________________ – tubular cells tapered at each end that
transport water throughout a plant (common in conifers)
c. __________________ elements – tubular cells that transport
water (common in anthophytes)
d. __________________ – a series of living tube cells that
transport sugars from leaves to plant parts
e. ______ tube members – long, cylindrical cells w/out a nucleus
that transport sugars
f. _______________ cells – nucleated cells that manage the
transport of sugars through sieve cells
3. Ground tissue – includes all tissues other than dermal tissues and vascular tissue. The functions
include photosynthesis, storage and support.
4. Meristematic tissue - a growing plant needs to produce new cells
a. __________________________ – regions of actively dividing cells
b. _____________ meristems
c. _________
_________
produce cells that allow the roots
produces new xylem and
and stems to increase in length
phloem cells in stems and roots
d. _________
_________
(lateral meristem) – produces a
tough covering for the surface
of stems and roots (ex: bark)
23.2. Roots, Stems, and Leaves
A. Roots – the underground structure that anchors, absorbs water and minerals, and transports nutrients
1. The structure of roots – an epidermal covering with projecting root hairs to increase surface area
a. __________________ – involved in transporting water
and ions into the vascular core at the root center and can act as a
storage center for food and water
b. __________________ – a single layer of cells that forms
a waterproof seal that surrounds the root’s vascular tissue
c. Pericycle – tissue that gives rise to the lateral roots
2. Root growth – roots are constantly growing
a. ________________-protective layer at the tip of each root
B. Stems – provide support, contain vascular tissue for transporting
and storing water and sugar
1. Internal structure – monocots have scattered vascular
bundles while dicots have xylem and phloem that form a ring in the
cortex
2. Woody stems – the inner part of trunk is composed of __________________ cells that form growth
rings, phloem and cork cells compose bark
3. Stems store and transport materials like water sugar and nutrients
a. ____________ – any part of the plant that stores sugars (ex: cortex)
b. ____________________- the movement of sugars from the leaves through the phloem
C. Leaves – trap light for photosynthesis
1. Leaf variation – leaves can vary in shape and size. Some leafs are joined directly to the stem (ex:
grass). Some can be needle-like (ex: pine )
a. _______________ – stalk that joins the leaf blade to the stem
2. Leaf Structure – vascular tissue is located in the veins
a. ___________________ – the photosynthetic tissue of a leaf
c. ______________________-the evaporation of water through
the stomata in leaves
3. Venation patterns – veins are parallel in _________________ and
branching in __________________________
4. Leaf Modifications 23.3. Plant Responses
A. Plant Hormones
a. ________________ – a chemical that causes a physiological change
1. ____________________ -cause cell elongation
2. _____________________ –hormone that cause plants to grow taller
3. _____________________ – stimulate cell division or cytokinesis
4. _____________________ – gas promotes ripening
B. Plant Responses – though plants lack a nervous system, they can respond to
stimuli
1. ____________________ - a plant’s response to an external
stimulus that comes from a certain direction
(ex: phototropism = plants bend toward light, ex: gravitropism = plants defy gravity
and grow toward light, ex: thigmotropism = response to touching objects like a
climbing vine)
2. _____________ movement – a responsive movement of a plant
that is not dependent on the direction of the stimuli (ex: Venus flytrap)