Topic 7 -Plant Adaptations Flashcards
Plants have evolved a variety of adaptations to successfully grow reproduce and survive across the entire range of environmental conditions on earth which are
Light
temperature
water availability
Photosynthesis takes place in specialize cells called
Mesophyll cells in the leaf
Net photosynthesis equals
Photosynthesis minus respiration
Carbon uptake minus carbon loss
CO2 diffuses into the leaf through openings in the surface of the leaf called
Stomata
As CO2 diffuses into the leaf water diffuses
Out of the leaf (transpiration)
Tree top (direct sunlight)
_________, ________ leaves
________ water loss in direct sunlight
Smaller, thicker
Reduces
Tree bottom (shade)
________, ________ leaves
_______ photosynthetic rate in shade
Larger, thinner
Increase
In many environments different leaf ____ Can be beneficial
Leaves in arid environments minimize ________ by angling leaves away from the sun
Angles
Evaporation
Shade tolerant plants have
Lower production of Rubisco in leaf tissue so they do not expend energy producing high amounts of Rubisco
Less photosynthesis
How do shade tolerant plants compensate
Higher production of chlorophyll
Higher leaf surface area
Higher growth of leaves than roots
Shade intolerant plants have a ______ growth rates under sunlight but ______ growth rates in shade
High, low
Shade tolerant plants grow ______ under sunlight and shade due to limited rubisco numbers
Similarly
Mountain Avens are flowers that track the
Movement of the sun
Parabolic formation of pedals concentrate light to maintain a constant temperature of 25°C
A maximum rate of photosynthesis and respiration occur at
Different points as temperature rises above zero
To maintain optimal levels of photosynthesis a leaf must exchange excess heat with the surrounding environment by
Convection
conduction (radiation)
evaporation (transpiration)
Heat loss by convection
Transfer of heat to a moving fluid body example wind
Heat loss by conduction
Keep moving from a warmer to a cooler body
Heat loss by evaporation
Evaporation causes a loss of heat energy and temperatures drop due to evaporated cooling
What is pubescence
Small light coloured hairs that line a leafs surface and reflect
Less Heat obtained from solar radiation
Creates an insulated boundary later
What accumulation of compounds prevent ice formation
Sugars and amino acids (proline) and other solutes
Super cooling
Special antifreeze proteins preventing ice crystal growth allowing plants to survive up to -35°C
Present in floral and shoot buds
Frost hardening
Changes composition of membranes allowing cells to export water and ice to form between cells instead of within
Survives up to -50°C
How do deciduous trees survive in winter
Adaptive loss of leaves as the temperature drops in the fall months
What do plants do when the atmosphere humidity and soil moisture levels are low
Close stomata
How do plants prevent water loss for short time scales
Close stomata during the hottest part of the day and also curl or wilt leaves to reduce surface area
How do plants manage water loss or uptake during moderate time scales
For wet conditions increase leave tissue and decrease root and shoot
For dry conditions increase root tissue decrease leave and shoot
Long time scale leaf morphology adaptations to dry conditions
Smaller and thicker leaves
smaller stomata
cover leaves in wax resin or a little hairs
Alter Net photosynthesis pathways such as C4 photosynthesis and CAM photosynthesis
Why is the alternate photosynthesis pathways beneficial
Reduce O2 binding by RuBisCO
concentrate CO2 to RuBisCO
high much higher maximum rate of photosynthesis
Plant loses less water per unit of photosynthetic product, Greater water use efficiency
