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SBI3U
Plants: Anatomy, Growth
and Functions
Tissue Systems
Plant Anatomy
Description
1. Meristematic Tissue
Growth
- Undifferentiated cells that undergo mitosis
Apical Meristems – tips of the plant stem shoots and root
Cambium – increase the girth of a plant
2 types: Vascular cambium (phloem in dicots) & Cork cambium (produces cork in woody stem)
2. Dermal Tissue
Protection
- Protects the plant from disease, injury and water loss
Trichomes – hair extensions decrease water loss from evaporation
Root hairs – increase surface area which increases water absorption
3. Vascular Tissue
Transport
Xylem – transports water through specialized cells called tracheids (not living)
– water moves in only one direction: from roots to leaves
Phloem – transports food through specialized cells called sieve tube cells (living)
– food moves in both directions in these cells
4. Ground Tissue
Storage and support
- Parenchyma: many functions: photosynthesis, support, storage of food and water
- in roots, stems, leaves, fruit
- Collenchyma: thick, flexible cell walls – support
- Sclerencyma: thick, rigid walls – support
Plants consists of (1) A. root – below ground, & (2) shoot – above ground: B. stems & C. leaves
Plant Organ
A. Root
Function
-
Structure
Absorb minerals and water from soil Transport minerals and water to stem for distribution
Anchor and support the plant in soil Storage of nutrients (carbohydrates)
-
Protective end called a root cap
Epidermis layer (outer layer) is one cell
thick
Epidermis may have root hairs that help
absorb water and minerals by increasing
the surface area of the root
Cortex stores starch molecules
(carbohydrates made in leaves)
Vascular cylinder (inner layer) contains the
plant’s conducting tissues for transport
(xylem & phloem)
B. Stem
-
Transport water and minerals to
leaves
Transport sugar to and from leaves
Support the plant
Connect leaves, roots and flowers
Storage of food
-
-
Contain vascular bundles (xylem, phloem
& associated tissues) either in a ring (dicot)
or scattered (monocot)
- xylem located closer to the centre
- phloem towards the outside
- between the xylem & phloem is a thin
layer called the vascular cambium
Pith is the centre of the stem
Cortex is the outside of the stem
C. Leaves
-
Photosynthesis in green plants
(carbohydrate/food production)
6 CO2(g) + 6 H2O(l)  C6H12O6(s) + 6 O2(g)
-
-
-
-
Network of veins that conduct sugar and
water (continuation of vascular bundles
from the stem)
Cuticle – waxy covering that provides
water resistance, protection and reduces
water loss
Mesophyll cells – cells of the leaf
- Palisade layer – upper layer; very
condensed; primary role is
photosynthesis
- Spongy layer – lower layer; has many
air spaces; primary role is gas exchange
Stomata
- openings in the leaf that control the
passage of gases and allow water
vapour to escape
- transpiration – loss of water vapour
- Surrounded by guard cells (kidney
shaped cells) which control the
opening and closing of the stomata.
If water enters guard cells (high water
concentration), they swell thus
opening the stomata.
Adapted Plant Structures Specialized for their Environment
Xerophytes – Desert Plants
** try to reduce water loss **
Deep roots – to absorb water from deep underground
Rolled leaves – encloses stomata to reduce transpiration
Leaves with spines – minimize surface area
Reduced number of stomata - reduce transpiration & also
close stomata during midday (evaporation highest)
Thick waxy cuticle - reduce evaporation from leaf
Succulent tissues & thick cortex – increased water storage
Cactus
Hydrophytes – Water Plants
** lots of water, need to float for maximum light **
Thick spongy mesophyll – large air spaces to allow leaves
to float
Large number of stomata, mostly open
Stomata on upper surface of floating leaves, none on
submerged leaves
Thin cuticle - leaves do not dry out
Large flat leaves for floatation
Reduced roots – water diffuses into leaves
Water lily
Plant Plan : Root & Shoot (Stem & Leaves)
Nodes: points on the stem where leaves are attached
Internodes: intervals between the nodes
Leaf axil: angle between the leaf and stem where buds usually grow
Leaf Arrangement on Stem
Types of Plants
Woody Plants
Herbaceous Plants
- those that live for a number of years and survive winter
- contain tough, hard tissue commonly called wood
e.g. trees, shrubs (lilac)
- grow thicker over time; each year vascular cambium grows layers of new xylem & phloem
Bark: outer part of woody stem; protective tissue consisting of phloem & cork tissue
Sapwood: younger xylem, conducts water & minerals
Heartwood: older xylem that fills with resins, oils and complex compounds
- stems not woody and not very supportive
- green and usually soft
- do not survive winter and are regrown each year
e.g. buttercup
SBI3U
Plants: Anatomy, Growth
and Functions
Major Plant Groups
All plants are eukaryotic, multicellular and perform photosynthesis.
Adaptations to living on land include:
i. Protection from drying out
ii. Transport of water
iii. System of support to lift plant into the air and the sunlight
Group
Bryophyta
Filicinophyta
Coniferophyta
(Tracheophytes)
Angiospermatophyta
Other Name
Mosses
Ferns
Gymnosperms
Description
Nonvascular plants
Seedless vascular
plants
Vascular plants with
naked seeds
Transport System
No vascular system
Angiosperms
(flowering plants)
Vascular plants with
enclosed seeds within
flowers
* most abundant and
diversified group *
Extensive vascular
system
Male gametes in
pollen grain
Specialized flowers
pollinated by animals
Seeds in fruit
Reproduction
Characteristics
Size
Example
Seed
- Plant embryo
Small vascular system
(xylem & phloem)
Male gametes are free Male gametes are free
swimming sperm
swimming sperm
Extensive vascular
system
Male gametes in
pollen grain
Spores
(no seeds or flowers)
No true leaves
nor roots
Spores
(no seeds or flowers)
Leafy fonds
and small roots
Naked seeds in cones
All small in size
Moderate in size
Various sizes (large)
Mosses, liverworts,
hornworts
Ferns
Cone bearing plants
Specialized leaves
(needles) and roots
Specialized leaves and
roots
Flowers
Various sizes (large)
Flowering plants with
fruit
Consists of
i.
Seed coat
ii.
Embryo (epicotyl, hypocotyl, radicle)
iii.
Endosperm
iv.
Cotyledon (seed leaf)
Comparison of Types of Angiosperms: Based on Structure of Seeds
Monocot
Scientific Name
Dicot
Monocotyledoneae
Dicotyledoneae
~ 50 000 species
~ 200 000 species
Root
Fibrous root
Tap root
Stem
Scattered vascular bundles
Leaves
Flower Parts
Parallel venation
Narrow leaves
Petals in multiples of 3s
Vascular bundles in rings
Herbaceous vs. Woody
Netted venation
Broad leaves
Petals in multiples of 4s or 5s
Seed Leaves
1 cotyledon
2 cotyledons
Nourishment of
Embryo in seed
Example
Endosperm nourishs embryo
Cotyledons store nutrients that nourish the
embryo
Broad leaf plants, fruit trees,
most vegetable plants
Grasses, grains, rushes, bulrushes, lilies,
palms, bananas, orchids
SBI3U
Plants: Anatomy, Growth
and Functions
Plant Nutrition
History
Aristotle
Jean Baptiste van Helmont
Stephen Hales
- soil provided substance for plant growth
- plant grow mainly from water added for growth
- plants were mainly nourished by the air
Plants do extract essential nutrients from soil
- Soil nutrients only contribute a small part to the overall mass of the plant
- 80-85% of a herbaceous plant in water
o Water can be considered a plant nutrient because the hydrogen and some of the oxygen that
make up water (H2O) is incorporated into organic molecules
o 90% of water is transpired
o Primary function of water is acting as a solvent
o Functions in cell elongation, and plant form (turgid)
- Majority of plant mass is derived from CO2
- After removing the water from a plant, 95% of the mass is organic and 5% is minerals
- Many organic molecules contain nitrogen, sulphur and phosphorus which are relatively abundant in
plants
- To an extent, the minerals found in a plant reflect the composition of the soil
Essential Elements
1. If required for a plant to grow from a seed and complete the life cycle producing another generation, a
nutrient is considered essential.
2. If the plant is unable to produce the nutrient or element itself, it is considered essential.
There are 16 essential plant nutrients
Macronutrient – needed in large quantities
1. Oxygen (45.0%)
2. Carbon (45.0%)
3. Hydrogen (6.0%)
4. Nitrogen (1.5%)
5. Potassium (1.0%)
6. Calcium (0.5%)
7. Magnesium (0.2%)
8. Phosphorus (0.2%)
9. Sulphur (0.1%)
Micronutrient – needed in trace amounts
10. Chlorine (0.01%)
11. Iron (0.01%)
12. Boron (0.002%)
13. Manganese (0.005%)
14. Zinc (0.002%)
15. Copper (0.0006%)
16. Molybdenum (0.00001%)
SBI3U
Plants: Anatomy, Growth
and Functions
Plant Life Cycle
Types and Durations of Life Cycles
Life Cycle: germination to seed production
1. Annuals
- Plants whose entire life cycle occurs within one growing season
- Peas, beans, tomatoes…
2. Biennials
- Plants that do not produce seeds until the growing season after germination
- Beets, carrots, celery, cabbage…
3. Perennials
- Live from year to year and are either woody or herbaceous
- The above ground portion of the herbaceous plant dies back at the end of each growing season, but
persists underground
Alternation of Generations
The life cycles of plants consist of two generations that alternate between a haploid stage and a diploid stage.
A. Diploid Stage = Sporophyte
- produced by the fusion of two haploid gametes
- sporophyte plants produce haploid spores by meiosis (gametes produced by meiosis)
B. Haploid Stage = Gametophyte
- produce haploid gametes through mitosis
- has a male and female component
Immature body
(multicellular)
Adult diploid body
(multicellular) with
reproductive organs
Zygote 2n
(single cell)
Fertilization
Diploid = Sporophyte
---------------------------------------------------------------------------------------------Haploid = Gametophyte
Meiosis
Spore n
(single cell)
Male Gamete
(single cell)
Female Gamete
(single cell)
Adult haploid body
(multicellular) with
reproductive organs