3: Adaptations to Terrestrial Environments Flashcards
what is special about Camels adaptations?
they cool their brains w/ increased blood flow and maintain relatively constant temp in high heat
- 30-40% of body mass is stored water
soil nutrients that plant needs:
nitrogen, phosphorous, calcium, potassium,
- oxygen, hydrogen (H + O from water in soil)
water potential
measure of water’s potential energy (mvmt of water in soil)
water potential depends on..
gravity, pressure, osmotic potential, and matric potential (soil particles)
matric potential
potential energy generated by attraction b/w water and soil molecules
- units of pressure (mPa)
Field capacity
max amnt of water held by soil particles against gravity; -0.01 mP
Wilting point
water potential when plants can’t retrieve water from soil
- ~1.5 MPa
Xylem
long tubes transport water and minerals
- ~95% of water comes from transpiration on the leaves
Phloem
transport glucose/food/fluid move in any direction ; sieve tube and companion cells
Apoplastic pathway
water move cell-to-cell through cell walls
Simplistic pathway
water move across cytoplasm–>xylem
Salinization
repeated irrigation (w/ salty water) causing increased soil salinity; challenge for crops
Cohesion of water
mutual attraction of water molecules
- Attraction of h. bonds causes water to move up xylem
- Helps column of water move up vessels of tall plants
Root pressure
osmotic potential in roots draw water into and up xylem
- Counteracted by gravity in o. potential inside root cells
Transpiration
water loss bc of evaporation
- stomata open, water levels inside of plant = higher than outside
Cohesion-tension theory:
water pulled up roots–>leaves bc of water cohesion and tension generated by transpiration
- limits plant heights to ~130 m
ways plants reduce transpiration (to keep more water)
- waxy cuticle, stomata guard cells open/close
- keeping needles / shedding leaves
- orient to minimize/maximize solar gain
Electromagnetic radiation
energy from the sun in photons
Highest energy photon =
highest frequency, shortest wavelength (nm)
Visible light
wavelengths in b/w infrared and ultraviolet radiation visible to human eye
Chloroplasts
eukaryotic photosynthetic organisms specialized organelles
Photosynthetically active region of light spectrum
visible portion of spectrum; wavelengths suitable for photsyn.
- 400 nm (violet) –> 700 nm (red)
- Plants, algae, bacteria absorb for photosynthesis
Thylakoids
stacks of membranes; where light reaction occurs
Stroma
fluid filled space our thylakoids; where calvin cycle occurs
Carotenoids function
pigments in thylakoid that absorb solar radiation
- reflect orange and red light
Chlorophylls function
pigments in thylakoid that capture light energy (solar radiation) for photosynthesis
- absorb red and violet light
Chlorophylls reflect…
green and blue light
- gives leaves their color
Chlorophyll a
all organisms have
Chlorophyll b, c, d, f
accessory pigments; capture light and give to “a”
Photosynthesis
energy from photons (sunlight) –> chem energy in high-energy bonds
- occurs in the chloroplast
Photosynthesis equation
6 CO2 (from air) + 6 H2O (from roots) + photons (from sun) —-> C6H12O6 (glucose) + 6 O2
Light reactions (step 1):
energy from the sun + (H+) + (ADP) –> ATP
energy from the sun + (H+) + (NADP+) –> NADPH
- occurs in thylakoid
Calvin Cycle (step 2):
cell uses energy to convert CO2 –> glucose; in stroma of chloroplast
- occurs in stroma
- carbon fixation
- occurs during day, “dark reactions”
C3 photosynthesis
- occurs in chloroplast
- in cool climates
- 6-carbon sugar catalyzed by Rubisco
photorespiration
oxidation of carbohydrates to CO2 and H2O by Rubisco
- reverses light reaction of photosynthesis
C4 photosynthesis:
—> adds initial assimilation of CO2 when low:
—> catalyzed by PEP (higher affinity for CO2 than Rubisco)
- occurs in mesophyll
- in hot climates
- mostly grains
CAM (crassulacean acid metabolism) Photosynthesis:
–> Open stomata for gas exchange at night, close during day
- between mesophyll and bundle sheath cells
- Water-stressed environments
- ex: Cacti, pineapple, etc.
Structural adaptations for water loss/gain:
- Shallow/deep roots, rapid uptake of water/storage
- cuticles (lead resins), spines, hairs
- Reduce water loss
- Traps moisture from air
Homeostasis
ability to maintain constant internal conditions in varying environments
Negative feedback
when system deviates from desired state; internal response mechanisms act to restore that desired state
- ex: hypothalamus gland in brain regulates body temp
Kidneys:
remove salts and nitrogenous waste from blood in all mammals
- Solutes dissolved in water
the loop of Henle
helps recover some before secretion, concentrates urine
- Direct relationship to kidney size
4 sources of heat exchange:
radiation, conduction, convection, evaporation
Radiation
emission of electromagnetic energy from sun
Conduction
transfer of kinetic energy of heat b/w substance in contact
- Depends on surface area, resistance to heat transfer, temp diff
Convection
transfer of heat by mvmt of liquids and gases
Evaporation
transformation of water from liquid –> gas w/ energy input
Surface area =
length^2
volume =
length^3
Thermal inertia
resistance to change temp due to large body volume
Thermoregulation
ability of organism to maintain body temp
Homeotherm
organism maintains constant temp w/in cells
Poikilotherm
organism w/o constant body temp
Blood shunting
adaptation that allows blood vessels to shut off so less of animal’s warm blood flows to cold extremities
- ex: humans hands/legs stay cold, while stomach/brain stay warm
Independent variable
causes other variables to change
dependent variable
effect by change/changing
evolutionary adaptation!!
the process of changing physiology, anatomy, and behavior to become more suited to an environment
how do kangaroo rats get their water? (in dry environments)
- through food they eat; adaptation to maximize use of water
plants need to obtain ___ from their environment (other than from soil)
carbon
matric potential = 0 MPa
saturated soil
matric potential = -0.01 MPa
field capacity of soil
- plants can’t extract anymore water
matric potential = -1.5
wilting point of soil
sand, silt, and clay: order by which holds the most water
most–>least: clay, silt, sand
- smaller particles = holds more water
3 components of soil:
sand, silt, clay
If a root cell has a higher solute concentration than soil water, __ will draw water into root cells
osmosis
roots have ___ that prevent larger solutes from leaving the root; allows ions and small molecules to enter
semipermeable membranes
most plants use ___ photosynthesis…
C3
capillarity action; in plants?
movement of water up a narrow tube
- xylem tissue acts as capillary
surface tension
a pull that exists on water molecules at an air-water interface
as water moves up the tree, ___ decrease
water potential decreases as you move up the tree
guard cells in stomata allow for exchange of:
CO2 entry, O2 exit
For every 1g of CO2, the plant loses ___ of water.
500g
Rubisco (RuBP)
enzyme that incorporates CO2 into plants
- open stomata, lower oxygen
- closed stomata = too much O2 = stops
cacti adaptations to reduce heat loading:
- increase surface area (more loss of heat)
- increase reflectivity
adaptations to grow in poor soil
- symbiosis (relationship w/ fungi)
- grow slowly
- keep leaves (ex: evergreen)
- storage
- grow more roots than shoots; root hairs
Epiphytic Plants (Epiphytes)
- adapted to grow in the absence of soil
- absorb most nutrients from: rainwater, dust, and particles that collect in/on bark
how do mammals conserve water in hot environments
evaporative cooling, reduce activity, seek shade, only come out at night, migrate seasonally, produce concentrated urine, eliminate evaporation losses from lungs
extremely hot temps cause…
- denaturing of proteins
- accelerated chemical processes
- affect properties of lipids/membranes
endotherm
warm-blooded
ectotherm
cold-blooded
