Adaptations To Terrestrial Environments Flashcards
Most terrestrial plants obtain nutrients and water from where
Soil
Saturation
Field capacity
Wilting point
Maximum water in soil after raining
Maximum amount of water retained after gravity
Lowest water potential at which plants can get water from soil
Of sand, silt and clay, which has the largest particle size? Which holds most water?
Sand is largest, then silt then clay.
Clay Holds more water because of increased surface area
Can plants extract water easily from clay?
No, too much surface tension
How does water move from roots to leaves?
Water moves into roots by osmosis, and then into xylem. Tension pulls the water upward in the xylem of the root.
Water molecules form a cohesive column in the xylem and the tension pulls the water upward through the stem.
Tension pulls the water coming up and out in the xylem of the lead veins. Water evaporates from the mesophyll cells and diffuses out of the stoma.
In soil with layered types of earth, how do roots differ?
More branched in clay to uptake all the nutrients. Long in sand to pick up water that falls quickly downward.
What wavelength colour do plants not absorb
Green, they reflect it
Extreme temperatures usually _____ the rate of photosynthesis
Reduce
Photosynthesis equation
6CO2+ 12H2O—>C6H12O6+6O2+6H2O
—->=rubisco
Carboxylation pathway
Carbon dioxide is turned into 2 PGA by ribulose biphosphate
Oxygenation pathway of photosynthesis
Oxygen is turned into 1 PGA and phosphoglycolate by ribulose biphosphate
Not as good! Less PGA and now a new byproduct to get rid of
Rubisco/ RUBP carboxylase-oxidase
Enzyme that grabs carbon dioxide and oxygen*
An enzyme involved in photosynthesis that catalyses the reaction of RUBP and CO2 to form two molecules of glyceraldehyde 3-phosphate (G3P)
2 PGA make what?
Sucrose
C3 photosynthesis
Regular photosynthesis in most plants
-carbon dioxide taken up by rubisco and enters the Calvin cycle to produce sugars
-Carbon dioxide is initially assimilated into a 3 carbon compound (G3P). Occurs in mesophyll cells in leaves.
C4 photosynthesis
A photosynthetic pathway in which CO2 is initially assimilated into a 4-carbon compounds, oxaloacetic acid (OAA).
-mesophyll cell using PEP carboxylase to bind to carbon dioxide to produce a four-carbon molecule (OAA). This occurs in the chloroplasts of the mesophyll cells of the leaf. The Calvin cycle takes place in chloroplast of the bundle sheath cells that surround the leaf veins. So plant must move the CO2 that has been assimilated in the mesophyll cells over to the bundle sheath cells.
CO2+PEP=OAA
-efficient and keeps all reactions going by using PEP (more affinity to CO2) to scavenge extra carbon dioxide when it is low.
-allows stomata to remain partially or completely closed for longer periods of time to reduce water loss.
CAM photosynthesis
-mainly in desert and epiphytes (orchid)
-uses PEP carboxylase to store CO2 in acids in tissues to be used in Calvin cycle during the day.
Therefore there is more NADPH and ATP during the day and generate more sugars in the day.
A photosynthetic pathway in which the initial assimilation of carbon into a four-carbon compound occurs at night.
-opens stomata for gas exchange during cool night when transpiration is minimal and conduct photosynthesis during hot day.
-assimilate CO2 with OAA and then conveyed to malic acid and stored at high concentration in vacuoles within the mesophyll cells of the leaf.
-during day, stomata close and stored organic acids are gradually broken down to release CO2 to the Calvin cycle:
-photosynthesis is slowed and so is growing time.
Soil
The layer of chemically and biologically altered material that overlies bedrock or other unaltered material at earths surface
Parent material
The late or bedrock that underlies soil and plays a major role in determining the type of soil that will form above it
What are the distinct layers of soil called
Horizons
Leaching
A process in which groundwater removes some substances by dissolving them and moving them down through the soil to lower layers
Matrix potential
The potential energy generated by the attractive forces between water molecules and soil particles.
How does wilting occur
If a plant cannot counteract the matrix potential with a stronger water potential in the plant, it wilts
The difference between field capacity and wilting point it the amount…..
Of water available to plants
Cation exchange capacity
The ability of a soil to retain cations
-K, Na, Mg, Ca
Older soils have more cations and therefore better fertility
What keeps high solute concentrations in plant roots
-semipermeable membranes prevent larger molecules form leaving plant roots
-cell membranes actively transport ions and small molecules against concentration gradient into the root cells
Soul salinization
The process of repeated irrigation, which causes increased soil salinity
Cohesion tension theory
The mechanism of water movement from roots to leaves due to water cohesion and water tension
Stomata
Small openings on the surface of leaves that serve as the points of entry for CO2 and exit points for water vapour
CO2+RUBP=
2 G3P
Challenges of C3 photosynthesis
Rubisco, enzyme that joints CO2 and RUBP, has a low affinity for CO2. It prefers binding to oxygen. Therefore it is inefficient at low CO2 concentrations found in leaves.
Therefore plants much pack their mesophyll leaves with large amounts of rubisco enzyme.
Photorespiration
The oxidation of carbohydrates to CO2 and H2O by rubisco, which reverses the light reactions of photosynthesis. Caused when rubisco binds to O2
2 G3P=RUBP+CO
Caused by closed stomata-to prevent water loss
Disadvantages of C4 pathway
Less leaf tissue is devoted to photosynthesis and some of the energy is produced by light reactions is used in the initial C4 assimilation steps
Crassulacean acid metabolism
CAM
Where are C3, C4 and CAM plants best suited
C3-cool, wet
C4 and CAM-warm and dry
Resins, waxy cuticles, spines and hair adaptations
Resin and waxy cuticles-help make the surfaces of plants more resistant to losing water
Spines and hairs-produce a boundary layer of still air that traps misfire and reduce evaporation
Negative feedback
The action of internal response mechanisms that restores a system of desired state, or set point, when the system deviates from that state.
Animal adaptation to extreme heat
-hunting during cooler nights
-retaining water from food
-efficient kidneys that can recover more water from urine prior to excretion (urine is higher in solute concentrations)
-sat secreting organs
Kidneys to habitat correlation
Dryer the area=the larger the kidney
Uric acid adaptation
Birds and reptiles excrete nitrogen in the form of Uric acid which requires less water and crystallizes out of solution=paste.
Uses less water but requires more energy
Exchange of heat to the environment can occur in which ways?
Radiation
Conduction
Convection
Evaporation
Radiation
The emission of electromagnetic energy by a surface
-sun is primary source on the environment
-as objects in the landscape are warmed by solar radiation, they emit lower energy infrared light.
The amount of radiation heat increased with the _____ power of absolute temperature
Absolute to degree difference
4
0°c=273°k
If a mouse has skin temperature of 310°k and a lizard has one of 290°k the difference of heat radiation between the mouse and lizard is…?
310^4/290^4=130%
Mammal radiates 30% more heat to environment
Conduction
The transfer of heat between objects that are in contact with one another
The rate at which heat moves by conduction between an organism and its surrounding depends on which factors
-surface area-greater the area, the ore exposed
-resistance to heat transfer-how much insulation you got
-temperature different between the organism and its surrounding-conduction is higher when there are larger differences
Convection
The transfer of heat by the movement of liquids and gases
Evaporation
The transformation of a liquid to a gas with the input of heat energy
-has a cooling effect by removing heat
Evaporation under dry and humid conditions
Under humid condition, evaporation occurs slowly= feels hotter
Under dry conditions, rate of evaporation doubles with each 10°c increase in temperature
Large organism have a low _____ to volume ratio
Surface area
Thermal inertia
The resistance to a change in temperature due to a large body volume
-hard to rid of heat but keeps you warm in cold
Ectothermic vs endothermic
Body temp regulation external to body (finds sun/share) -reptiles
Body temp regulation internal (uses metabolism to cool self down) -mammals and birds
-keep body temp between 35-41°c
Do ecto or endo themes require more food
Endotherms
-consume much more food to maintain the energy needed to thermoregulate
Blood shunting
An adaptation that allows specific blood vessels to shut off so that less of an animals warm blood flows to the cold extremities
Creates less of a temperature variation between extremities and cold environment so that less heat is lost
Countercurrent circulation to keep warm
Position of veins and arteries in the extremities of many animals are countercurrent. Arteries carrying warm blood away from heart are positioned alongside veins that carry choked blood from extremities back to the heart.
What 2 things are needed for the Calvin cycle to work?
Carbon dioxide and energy (ATP and ADP)
From what is energy produced to make ATP in a photosynthetic organism?
Light reactions
What 3 processes can the Calvin cycle be divided into?
Carbon fixation
Reverse of glycolysis
Reforming RuBP
Mesophyll cells contain more _____ where is where carbon dioxide is captured
Grana
Which plants take longer to saturate with radiation and carbon dioxide uptake
C4 plants
Can work in intense heat
What type of evolution has occurred with c4 plants?
Convergent
Has e rocked separately at least 45 times
Currently in 7500 species
Structural adaptations to water and heat stresses
-thin design (columnar cacti) to reduce amount of heat at hottest part of day.
-hairs (reflect light and retain humidity to reduce rate of evaporation)
-sunken stomata to reduce gradation rate of evaporation
-many split blades to leave air space to allow wind to cool.
Hypothalamus and temperature feedback control
-hypothalamus in brain senses body temperature (37°c is set point)
-if <37°c, neural or hormonal signals cause body organs to increase metabolism or increase shivering, allowing for temperature in body to rise. This sends feedback to hypothalamus that body is now warm and can stop.
-if >37°c, neural or hormonal signals tell body to sweat and pant, this reduces body temperature. Sends feedback to hypothalamus to stop.
Kangaroo rats deal with intense heat by….
Having a large loop of henle to retain water and excrete excess solutes
Low precipitation and kidney size
In low precipitation areas, kidney sizes are much larger to concentrate urine with solutes and retain water.
Penguins and heat loss
Lose heat from eyes, and under wings as these are the warmest areas. Loses less heat from foot as foot is kept at lower temperature to make sure that less heat is lost to cold environment.
Heat exchange/ warmer parts have counter current system
Almost all plants are ________ ectotherms
Poikilothermic
(Variable body temperature that fluctuates a little hotter than environment)
Except skunk cabbage
Skunk cabbage
Not ectothermic, but produce own temperature!
-large quantities of starch stored in large root
-translocates starch from root to inflorescence to be metabolized to result in heat
-this also releases volatiles that stink and attract flies as pollinators
Surviving extreme temperature methods
-inactivity (shelter)
-reduced activity to conserve energy and reduce metabolic activity
reducing metabolic rate
-hummingbirds enter state of torpor when food is scarce and night temps are extreme
-hibernation (winter)
-estivation (summer)
