Download Botany: the study of plants Botanical: of or relating to plants

Botanical Adaptations
Botany: the study of plants Botanical: of or relating to plants
Part 1
INTRODUCTION to ADAPTATIONS Introduction
1.  What is an adaptation?
Characteristic that helps organism survive
2. Why adapt? Increase reproductive fitness (# of successful offspring)
3. How adapt?
Evolution: Cumulative changes in a population as a result
of:
•  variation in a population (often caused by mutation),
•  selection for or against the survival of certain individuals
in the population •  reproduction passing on of the selected characteristic that
allowed for survival.
Example of Plant Evolution
•  Variation:
Flowers originated as modified/ adapted
leaf structures
•  Selection: Plants with flowers attracted more
pollinators
•  Reproduction: Plants with flowers produced more
offspring
Part 2
STRUCTURAL ADAPTATIONS
Adaptations
Structures - Plant Parts:
1.  Seeds and Fruits
Structure and Function:
•  seeds contains nutrients, energy and plant
parts required for early growth
•  fruits contain seeds and assist in dispersal
Monocot: one cotyledon
Dicot: two cotyledons
A epicotyl
B radicle
C cotyledon
D seed coat
Structures - Plant Parts:
2.  Flowers
Structure and Function:
•  Sexually reproductive structures
•  Allows recombination of gametes
(pollen and ovule) to create seeds/
fruits and increase variation.
Monocot: parts in multiples of threes
(usually)
Dicot: parts in multiples of fours or
fives (usually)
Structures - Plant Parts:
3.  Stems
Structure and Function:
•  contains vascular system (tissues) for water and food transport
•  xylem – takes water up through plant
(like veins)
•  phloem – takes food down through plant
(like arteries)
Monocot: xylem and phloem in separate
bundles
Dicot: xylem and phloem organized in rings
Structures - Plant Parts:
4.  Roots
Structure and Function:
•  absorb water and nutrients
•  contains vascular tissues (xylem and phloem)
Monocot: xylem and phloem arranged in rings (different
from their stems)
Dicot: xylem and phloem organized in rings (similar to
their stems)
Structures - Plant Parts:
5.  Leaves
Structure and Function:
•  external - stomata (pores)
•  middle - mesophyll
•  internal – vascular tissue
•  photosynthesis and gas exchange
Monocot: parallel leaf veins – vascular tissue
in bundles
Dicot: networked leaf veins (see diagram)
Structures - Plant Parts:
6. Modified Structures
Structure and Function:
•  modified leaves – bulbs
•  modified stems – corms, rhizomes, tubers
•  modified roots – storage
• nutrient, energy and water storage
Part 3
PHOTOSYNTHETIC ADAPTATIONS
Adaptations
Photosynthetic pathways*:
1.  What is photosynthesis?
•  Source of energy sustaining 99% of all life on earth
•  Conversion of light energy into chemical energy
(6CO2 + 6H2O + light => C6H12O6 + 6O2)
•  Occurs in two sets of reactions:
- light-dependent
- light-independent
* plants vary in how
they undergo the light-
independent reactions.
C3 1.  Who does it?
•  Most plants (dicots)
2.  Where in the leaf does it occur?
•  Mesophyll (mid-leaf cells)
3.  What enzyme is used to help the reaction occur?
•  Rubisco – requires high amounts of CO2 to be efficient
4.  When does it work well?
•  In moderate temperatures
•  Plants can keep stomata open to take in more CO2
without losing too much H2O
C4 1. Who does it?
•  Many monocots
2.  Where in the leaf does it occur?
•  Bundle sheath (surround plant veins )
3. What enzyme is used to help the reaction
occur?
•  PEP- does not require high amounts of CO2 to be
efficient
4.  When does it work well? •  In high temperatures and dry conditions
•  Plants can close stomata to avoid H2O loss and still
utilize low concentrations of CO2
Leaf Cross-sections of C3 and C4 Plants: CAM 1. Who does it?
•  Cactus and Pineapple Families
2. Where in the leaf does it occur?
•  Mesophyll (at different times night/day)
3. What enzyme is used to help the reaction
occur?
•  PEP 4. When does it work well? •  In extreme temperatures
•  Plants keep stomata closed in day to avoid H2O loss
•  Plants open stomata at night and CO2 stored for use
during the day