Transcript Structure and Trasport in Flowering Plants

Chapter 24: Kingdom
Plantae
Leaving Certificate Biology
Higher Level
Structure of Flowering Plant
• The flowering plant (also called angiosperm) is
an example of a living organism that has
organisational complexity
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Root
Stem
Leaf
Flower
Seed
Vascular (transport) structures
Structure of
Flowering
Plant
Structure of Flowering Plant
• Function of root and shoot system:
– Roots:
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Anchorage
Absorb water and minerals
Transport water and minerals up plant
Some root store food
– Shoot:
• Transport water, minerals, food
• Sexual reproduction
• Photosynthesis
Roots
• Types:
– Tap roots: main root that originates from the
radicle at germination
• Lateral: emerge from the primary root
– Fibrous roots: equal size roots that emerge
from the stem – common in
monocotyledonous plants, e.g. grass
Root Zonation
• Protection: root cap protects growing tip
• Meristematic tissue: region of high cell
production (mitosis) and growth
• Elongation: new cells formed within the
meristem then elongate under the
influence of growth regulators
• Differentiation: elongated cells
differentiate into specialised cells (dermal,
ground, vascular)
Meristem
• The meristem is the region of the shoot tip
or root tip where there is rapid mitosis
occurring and is responsible for the growth
of the plant
– The meristematic regions are present in the
root and shoot tips and in peripheral regions
such as in the axillary buds, leaves and fruits
Stems
• The stem supports the plant and carries the
leaves, flowers and fruits of the flowering plant
• Depending on the plant species the stem is
either herbaceous (soft, green stem) or woody
(hard, usually brown stem)
• The leaves and branches emerge from points on
the stem called nodes – whereas the section in
between the nodes is called the internode
• Woody stems also have lenticels present on
their surface – which are responsible for gas
exchange
Functions of the Stem
• Support
• Transport of water, minerals and food
• Herbaceous stems carry out
photosynthesis
• Some store food
Leaf
• The leaf is an organ of food production – the site
of photosynthesis
• The leaf of a plant is attached to the stem or
branch by the petiole located at the node
• The leaf is a flattened structure (blade/lamina)
designed to capture sunlight
• The leaf has a midrib and veins which are
continuations of the petiole and which contain
vascular tissues
Leaf Venation
• Leaf venation depends son the plant
species and can be either parallel or
net/reticulate
– Parallel: veins run parallel to each other and
are most common in monocotyledonous
plants such as grasses
– Reticulate: veins form a network of veins by
branching out filling the leaf structure and are
most common in dicotyledonous plants such
as horse chestnut (see leaf structure on
previous slide)
Function of the Leaf
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Photosynthesis and food production
Gas exchange
Transpiration – process of losing water
Food storage
Flower Structure
Function of the Flower
• The flower function in sexual reproduction
by attracting insects (presence of nectar)
and animals (seed and fruit formation after
fertilisation)
Types of Plant Tissue
• Dermal:
– Functions in protection by having a thick cuticle
– Also has stomata and controls gas exchange
– Also has root hairs and controls absorption of water
and minerals
• Ground tissue:
– Is responsible for photosynthesis, food storage and
gives strength and support to the plant
• Vascular tissue:
– Xylem: transports water and minerals
– Phloem: transports food
Xylem
• Xylem is a vascular tissue made up of two
different types of cell:
– Xylem tracheids
– Xylem vessels
• Tracheids: long, tapered, hollow and dead cells
whose walls contain pits that allow water
movement
• Vessels: they are strong (supported by lignin),
long, hollow, dead, tubular cells with their end
walls broken down to form a continuous tube
throughout the tissue
Tracheid
Vessels
Phloem
• Phloem is a transport system running
alongside xylem that allows products of
photosynthesis to be redistributed by the
plant
• Phloem consists of sieve tubes that
transport the sugars and companion cells
that help in transferring the sugars to the
sieve tubes
Structure of
Phloem
Xylem versus Phloem
Transverse Section of the Root
Structure
of Leaf
Monocots versus Dicots
• Monocotyledonous plants:
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1 cotyledon (storage leaf) in seed
Mostly herbaceous plants – soft, green stem
Long, narrow leaf with parallel venation
Vascular bundles arranged randomly in stem
Petals, leaves arranged in 3s or multiples of 3
• Dicotyledonous plants:
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2 cotyledons (storage leaves) in seed
Herbaceous or woody
Broad leaves with network or reticulate venation
Vascular bundles arranged in ring in stem
Petals, leaves arranged in 4s or 5s or multiples of 4s
or 5s