Lec 4-6 Flashcards
1
Q
Physiological processes are affected by _________
A
Temperature
2
Q
Why are physiological processes affected by temperature?
A
Enzyme-catalyzed processes rely on steady temperatures
3
Q
Physiological processes affected by temp
A
Photosynthesis
Cellular respiration
4
Q
Enzymes catalyze reactions faster at __________ temperatures
A
HIGHER
5
Q
Low temperatures therefore _______ support physiological processes well
A
Do NOT
6
Q
Enzymes at extremely high temperatures?
A
Get DENATURED
High temps do NOT support processes
7
Q
Physiological Age
A
Developmental time
Measured as number of degree-days above threshold temp
8
Q
Developmental time
A
Time it takes to reach a certain stage of development
Depends on temperature in certain organisms (many insects are examples)
9
Q
Developmental time is _________ when temperature is HIGHER; ________ when temperature is COOLER
A
FASTER; SLOWER
10
Q
Grasshopper eggs require _____ degree-days above a threshold temperature of ____ in order to develop
A
70; 16
11
Q
At daily mean of _____, grasshopper eggs take _____ days to develop
A
23C; 10
70/(23-16) = 10 days
12
Q
Degree-days equation
A
degree-days/(daily mean temp - threshold temp)
13
Q
Mechanisms by which organisms gain or lose heat
A
Solar Radiation
Sensible Heat
Latent Heat
Metabolic Heat
14
Q
Solar Radiation
A
Sun’s energy input
15
Q
Sensible Heat
A
Convection
- Heat exchange between a gas or liquid circulating around a solid
- COOLING mechanism
- All water circulates around organism’s body, heated by body, rises, leaves body cooler behind
Conduction
-Heat exchange between two solids in contact with each other
16
Q
Latent Heat
A
Heat exchange that occurs during a CHANGE OF PHASE
Evaporation
- Conversion of liquid to gas
- COOLING
Condensation
- Conversion of gas to liquid
- WARMING
17
Q
Adaptations of PLANTS to HEAT
A
Decrease solar radiation
-Pubescence, waxy cuticle (reflects sun rays), curled or vertical orientation (less sun able to strike)
Increase sensible heat (CONVECTION)
-Compound leave to increase surface area-to-volume ratio for more air contact and heat exchange
Increase latent heat (EVAPORATION)
- Evaporation is TRANSPIRATION in plants
- Requires LARGE water supply, so plants have deep/wide-spreading roots or be able to store water (succulents)
18
Q
Adaptations of PLANTS to COLD
A
Annual life history strategy:
-Seeds resistant to cold, so annual plants survive cold seasons by existing exclusively as seeds
Supercooling
-Production of excess sugars within cells, which increases their solute concentration and lowers their freezing point
19
Q
“Types of animals” with respect to temperature
A
Ectotherms
Endotherms
Heterotherms
20
Q
Animal Temperatures: Ectotherms
A
Regulate the amount of solar radiation they receive to maintain a fairly constant body temperature
-Examples include fishes, amphibians, reptiles, and most invertebrates
Ectotherms with HIGH SA-V ratio better able to exchange heat with surroundings (smaller)
- As body size increases, SA-V decreases
- -Large ectotherms UNCOMMON
- –Dinosaurs likely endotherms
21
Q
Animal Temperatures: Endotherms
A
Regulate temperature METABOLICALLY (use metabolic heat)
-Maintain CONSTANT body temperature
VERY effective: Trade-off = High energy consumption
Examples: Birds and mammals
Tolerate temperature extremes:
- Insulation
- –Fur, feathers, fat (all reflect solar radiation)
- Shivering
- –Involuntary muscle activity to increase heat production
- Evaporative Cooling
- –Sweating, panting, breathing
22
Q
Animal Temperatures: Heterotherms
A
ACTUALLY ENDOTHERMS
ENDOTHERMS that are able to relax control of metabolism during inactive periods, allowing body temp to drop near environmental temperature
Torpor: Metabolism relaxed daily
- –Bats during the day
- –Hummingbirds at night
Hibernation: Metabolism relaxed seasonally
- –NOT bears
- –Many rodents - squirrels, mice, hamsters
23
Q
Importance of Light for Organisms
A
Light is the energy source for photosynthesis in ALL ecosystems
Light provides a cue that environmental conditions are changing
24
Q
Light and Photosynthesis
A
Stages of Photosynthesis:
1) Light Reactions:
- -Light energy is used to oxidize water into oxygen, providing the electrons required to generate high-energy ATP and NADPH
2) Calvin Cycle:
- -ATP and NADPH energy is used to reduce carbon dioxide (GAIN e-) into glucose and other carbohydrates, which are high in chemical energy
PAR:
- -Photosynthetically Active Radiation
- -Solar radiation wavelengths that provide the energy for photosynthesis (specifically light reactions)
- –All visible light wavelengths EXCEPT green
- —-Plants appear green because that’s the energy being reflected, all others are absorbed
Light Response Curves:
–Graphs showing the relationship between light levels and photosynthetic rate
Compensation Point:
- -The minimum PAR required for positive net photosynthesis
- —The point at which CO2 uptake for photosynthesis is balanced by CO2 loss from cellular respiration
Saturation Point:
- -The maximum PAR that plants can use for increased rates of photosynthesis
- –When plants are saturated with sunlight
Photoinhibition:
- -Reduced photosynthesis rates at very high lights levels, due to damage caused by excessive solar radiation
- -Too much light is generally not a problem for most plants
SHADE-TOLERANT PLANTS
- -Those plants able to maintain positive net photosynthesis even in very low light conditions
- -Plants found in forest understories where most light is blocked by the canopy above
25
Adaptations of Shade-Tolerant Plants
1) General characteristic:
- -Low compensation point (exceptionally)
- -Low saturation point (handle shade well, not)
- -Susceptible to photoinhibition
2) Mechanisms of shade tolerance:
- -Allocation of more resources to the light reactions than to the Calvin Cycle
- -Allocation of more resources to the leaves than to the stems or roots
- -Thinner but wider leaves
26
Light as an Environmental Cue
Circadian Rhythms:
- -Daily pattern of activity that correspond to a 24 hour cycle of light and dark
- -Best demonstrated by diurnal and nocturnal oorganisms
- -The adaptive value of circadian rhythms can be physical or biological
Physical:
- -Insects are ectotherms, so they are diurnal to "soak up the sun"
- -Rabbits are nocturnal to avoid the heat of the day
Biological:
- -Plants are diurnal and open their flowers during the daw when their pollinating insects are active
- -Owls are nocturnal because their prey are active at night
Photoperiodism:
- -A response to changing daylengths throughout the year
- -Not seen in equatorial organisms
Changes in light levels are the most reliable cues of upcoming seasonal changes
27
Importance of Water for Organisms
Polarity of water ad the hydrogen bonds that forms between water molecules lead to water's life-supporting properties:
1) Water molecules stick to each other (COHESION) and to other molecules (ADHESION)
- Necessary for the transport of water up plant stems
2) High specific heat capacity
- Helps organisms maintain fairly constant body temperatures
- Moderates the temperature o f the environments in which organisms live
- High boling point and low freezing point, so liquid at ambient Earth temperatures
3) Excellent solvent for dissolving solutes
- Common aqueous solutions include the cytosol of cells, the blood of animals, and the sap of plants (H2O + sugar)
- Water also trasnports solutes well because it flows easily (is not viscous)
- -Solution where water is solvents: AQUEOUS SOLUTION
28
Types of Plants with respect to water
Mesophytes
Xerophytes
Hydrophytes
29
Opening of stomata on leaves is necessary for photosynthesis, allowing ____ to enter plant
CO2
30
H2O is lost through open stomata, dduring the process of ___________
Transpiration
31
A plant's _________ relates the amount of CO2 entering a plant to the amount of H2O lost
Water Use Efficiency (WUE)
32
_________ means much CO2 taken in with minimal H2O lost
High WUE
33
Major enzyme that brings CO2 into Calvin Cycle:
Rubisco
34
Rubisco:
a) is efficient
b) is NOT efficient
c) brings in O2 into Calvin Cycle
d) Brings in CO2 to Calvin Cycle
e) b, c, and d
f) All of the above
e) NOT efficient, brings O2 and CO2 into Calvin Cycle
35
Rubisco inefficiency yields NO photosynthetic output and wastes the CO2 present because the Calvin Cycle is "occupied" by O2: Consequence - WUE is ______-
LOWERED
36
Most plants are _____ plants and must deal with problem of PHOTORESPIRATION
C3:
-Undergo normal photosynthesis (Mesophytes and Hydrophytes)
Photorespiration:
-CO2 and O2 produced
37
Xerophytes
Evolved alternative photosynthetic pathways to increase WUE:
- C4 pathway
- CAM pathway
38
Examples of C4 plants
Corn and Sugarcane
39
In C4 plants, CO2 is first bound to a different enzyme, PEP carboxylase (PEPcase), which has ____________
NO affinity for O2
This bound CO2 is transported to the bundle sheath cells, the only cells in which the Calvin cycle occurs
40
CO2 is unloaded in the bundle sheath cells and becomes so concentrated that any O2 is ______________
"swamped out"
41
The C4 strategy
Increases WUE by efficiently utilizing all of the CO2 taken into the plant
Still loses some H2O
NONE of CO2 is wasted
42
Examples of CAM plants
Cactus and Pineapple
43
CAM plants open stomata at _______
Night
When there is LESS transpirational pull on H2O (not losing water to surroundings)
44
CO2 is first bound to PEPcase (NOT rubisco), and is stored in the cell's _______ overnight
Vacuole
45
Stomata __________ when transpiration would be greatest
Close during the day
46
CO2 is released from the ________ to go through the Calvin cycle while the light reactions are proceeding
Vacuole
47
The CAM strategy
Increases WUE by minimizing the amount of H2O lost from the plant
48
Why haven't all plants evolved a C4 or CAM strategy?
More energy is required for these pathways, so there is a trade-off involved
Benefits outweigh costs for xerophytes in very dry, hot environments
49
Animal-Water Relations
Adaptations of TERRESTRIAL animals to DRY habitats:
- -Avoid adverse conditions
- -Reduce water loss
- -Obtain water from food
50
Avoid Adverse Conditions:
1) Become nocturnal (many desert animals)
2) Migrate out during dry season (African savanna ungulates)
3) Go dormant during the dry season
- -Diapause: Hibernation due to water stress rather than temperature stress
- -Estivation: Belowground "cocoon" (toads and snails)
51
Reduce water loss:
1) Reabsorb water in kidneys and intestines to redce water lost with urine and feces (kangaroo rats)
2) Reduce evaporative water loss by suppressing panting and sweating (African savanna ungulates)
3) Waterproofing scales (reptiles) or exoskeletons (arthropods)
52
Obtain water from food:
1) Desert insects derive water from feeding of succulent plants
2) Desert birds and lizards derive water from feeding on the insects
3) Kangaroo rats metabolically produce water from dry seeds: they convert the carbohydrates into CO2 and HsO
53
Osmoregulation
Aquatic animals must maintain a proper solute concentration in order to regulate the amount of water gained or lost
54
Marine invertebrates are _____ to their environment
ISOTONIC: Same salt concentration relative to environment
Solute concentrations inside the animals are equal solute concentrations in the surrounding water
NO special adaptations are needed for osmoregulation
55
Marine vertebrates are __________ to their environment
HYPOTONIC
Solute concentrations inside the animals are LESS tahn solute concentrations in the surrounding water
Water concentration inside the animals is GREATER than water concentration in the surroundings (per unit volume)
They will LOSE water to the environment: Challenge for osmoregulation
56
Marine vertebrates must actively ____________________
Drink water and excrete salt from the gills and kidneys
57
Freshwater animals (invertebrates and vertebrates) are ________ to their environment
HYPERTONIC
Solute concentrations inside the animals are GREATER than solute concentrations in the surrounding water
Water concentration inside the animals is LOWER than water concentration in surroundings -> These animals GAIN water (challenge for osmoregulation)
58
Freshwater animals constantly
EXPEL water with their urine (freshwater is essentially fish pee)
59
How do Organisms Obtain Organic Nutrients?
Autotophes synthesize thier own organic nutrients by wat of photosynthesis or chemosunthesis (bacteria in hydrothermal vents)
Heterotrophs must consume autotrophs or other heterotrophs to obtain organic nutrients
Both autotrophs and heterotrophs undergo cellular respirations
Nutrients taken up from soil (contains humus - decaying organic matter)
60
Cellular respiration
3 stages:
1) Glycolysis
- -Glucose and other carbohydrates are oxidized into pyruvic acid, providing the electrons required to generate high-energy ATP and NADH (NOT NADPH)
- -Glucose split apart
2) Citric Acid Cycle (AKA Kreb's Cycle)
- -Pyruvic acid oxidized into CO2 providing the electrons required to generate more ATP and NADH (plus FADH2)
3) Electron Transport Chain
- -In the presence of O2, which is reduced to H2O, the high-energy NADH and FADH2 molecules are used to generate even more ATP molecules
61
Soil Particles classified by Size:
Sand (Largest)
Silt
Clay (smallest)
62
Optimal Soil Characteristics: Soil Particles
SAND has LARGE pore spaces between particles -> water and minerals are LEACHED (drained) through sand and are unavailable to plant roots; BUT large pore spaces enable efficient diffusion of oxygen through sand to roots (roots need oxygen)
SILT and CLAY have SMALL pore spaces between particles -> water and minerals are NOT leached; BUT water drains so slowly, soil saturated, LITTLE oxygen = suffocate roots
OPTIMAL: LOAM
--Equal mixture of SAND, SILT, and CLAY
63
Optimal Soil Characteristics: Live Organisms
Live organisms are necessary for decomposition and soil mixing
Bacteria, fungi, arthropods, worms, and the plant roots themselves live within and shape the soil
64
Optimal Soil Characteristics: Water
Although excessive water can have negative consequences, a water deficiency is of course harmful as well
Minterals are dissolved in solution
Very dry soil therefore leads to a lack of both water and nutrients
65
Optimal Soil Characteristics: pH
Soil particles are negatively charged
Majority of plant's essential nutrients are positively charges ions (cations), which adhere to these negatively charged particles
ACIDIC soil has a high hydrogen ion concentration
- H ions adhere to soil particles, displacing essential cations
- Cations leached through soil; unavailable to plant roots
NEUTRAL or SLIGHTLY BASIC soil is the optimal pH for plant nutrient acquisition
66
Plants increase the surgace area of their roots for increased nutrient absorption by way of __________-
millions of tiny root hairs
67
Plant roots involved in _______ relationships with ______ and nitrogen-fixing bacteria
MUTUALISTIC; MYCORRHIZAE
68
Mycoorhizae
Mutualism between plant roots and fungi
Very common
Fungi wrap around plant roots and spread out into the soil, increasing the surface area for nutrient contact and absorption
Fungi receive photosynthates from plants
69
Nitrogen-fixing bacteria
Bacteria that live mutualistically within root nodules
Only in certain plants (legumes)
Bacteria convert nitrogen gas (N2) into usable forms of nitrogen for the plant
Bacteria receive photosynthates and shelter from the plant
70
Nonmutualistic Plant Relationships
With other plants or with animals
Parasitic plants obtain organic and inorganic nutrients from a host plant, harming the host in the process
Carnivorous plants are photosynthetic but supplement their nitrogen supply by digesting insects and other small animals
--Generally live in marshes, bogs, swamps: Low nitrogen, must obtain from animals
71
Parasitic Plants
Hemiparasite:
- -Capable of photosynthesis but still obtain much of their water and nutrients by parasitizing a host plant
- -MISTLETOE
Holoparasites:
- -CANNOT photosynthesize and therefore extract all of their nutrients from a host plant
- -DODDER
72
Carnivorous Plants
Generally found in bogs with nitrogen-poor soil
Trap, kill, and digest prey using highly modified LEAVES
Examples:
- -Venus Fly Trap
- -Sundews
- -Pitcher Plants
73
Animals take in nutrients by ingesting other organisms (though _________ is obtained from the atmosphere)
Oxygen
74
Herbivore eat ________
Plants or algae
75
Carnivores eat ________
Other animals
76
______________ eat both plants and animals
Omnivores
77
Advantages of Herbivory:
More energy is available since they feed lower on the food chains than carnivores feeding higher up
Herbivores expend significantly less energy obtaining food (don't need to chase or capture prey)
78
Challenges of Herbivory:
Physical defenses (spines (leaf) and thorns (branch)) and chemical defenses (toxins)
Plants a high carbon-to-nitrogen ratio, while animals have a low carbon-to-nitrogen ratio
--To obtain sufficient nitrogen herbivores by eat lots of plants
Plant proteins are "incomplete"
--They lack one or more of an animal's essential amino acids
Sodium is an essential nutrient for ANIMALS but NOT for PLANTS
--Salt licks
Plants have cellulose and other indigestible material
Mutualistic microorganisms (bacteria, protozoans) within an herbivore's digestive tract break down cellulose for the herbivore
- -Ruminants and their four-chambered stomach
- -Rabbits and coprophagy
79
Evolution is biology's _______ and there for ecology's _________
Unifying theme (both)
80
Much of evolution has an ___________
Ecological foundation
81
Ecology and evolution are _________________
Highly related and interdependent
82
Charles Darwin was an ecologist, though he predated the term; instead, he was termed ________
Naturalist
Voyage of Beagle: 1831-1836
Origin of Species: 1859
83
Evolution can be considered on a smaller, shorter time scale (______________), as well as on a larger, longer time scale (______________)
Microevolution, macroevolution
84
Background Terms:
1) Alleles: Alternative forms of genes
2) Genotype: Genetic make-up of an organism (collection of alleles)
3) Phenotype: The physical expression of an organisms' genotype (its morphology, anatomy, physiology, and behavior)
4) Fitness: Number offspring produced by an individual relative to number offspring produced by all other individuals in population; an individual's relative contribution to the next generation
85
Microevolution
Allele frequency changes in a POPULATION over time
86
Mechanisms of Microevolution:
1) Mutations
2) Sexual reproduction
3) Genetic drift
4) Gene flow
5) Natural Selection
87
Mutations
Changes in genes due to changes in the nucleotide sequences of DNA
Caused by errors during cell division (mutagens) usually resulting from exposure to chemicals or high-energy radiation
The ultimate source of new alleles within a population
88
Sexual Reproduction
Rearranges existing alleles into new combinations by way of crossing over, independent assortment of chromosomes, and random fertilization
Reproduction is a greater contributor to genetic variability than are mutations in sexual organisms
89
Genetic Drift
Change in allele frequencies of SMALL populations due solely to chance
90
Gene Flow
Change in allele frequencies due to immigration into or emigration out of a population
91
Natural Selection
There exists variation among the individuals within a population
- Most of this variation is genetically inherited
- -Some environmentally acquired, MOT inherited
92
Overproduction of Offspring
All populations have the potential to produce far more offspring than the environment can support with its limited resources
Offspring will therefore compete for these resources
93
Unequal Reproductive Success
Those individuals with the inherited traits that make them stronger competitors in their environment will obtain the limited resources, survive, and reproduce to pass the traits o n to their offspring (they will have the greatest fitness)
Allele frequencies change as certain traits increase while others are eliminated
94
Adaptations are features that
Improve an organisms ability to survive and reprodues in its environment
95
_____________ involved adaptations increasing in frequency within a population over time
Adaptive evolution
96
_____________ is the only mechanism of microevolution that consistently promotes adaptive evolution
Natural Selection
Other mechansisms change allele frequencies, but may increase frequency of harmful alleles as well as adaptive ones
97
Macroevolution
Defined by Darwin as DESCENT WITH MODIFICATION
--All current species are descended from a common ancestor, but modified from that ancestor
Also known as SPECIATION - the process by which an ancestral species evolves into 2 or more descendant species; NOT synonymous with macroevolution; a COMPONENT of macroevolution
98
Definition of a Species:
2 Organisms belong to same species if they have potential to mate in the WILD and produce viable, fertile offspring
Formation of new species involves formation of reproductive barriers
99
Mechanisms of Macroevolution
1) Allopatric Speciation
| 2) Sympatric Speciation
100
Allopatric Speciation
More common
Geographic barrier physically splits a population in two and prevents gene flow between the new populations
Each population undergoes microevolution independent of the other population
If the two populations are brought back together and can no longer interbreed, they have evolved into separate species
101
Sympatric Speciation
NOT very common
Part of population becomes reproductively isolated in the midst of its parent population
NO geographic barrier
Due to MUTATIONS
Most frequently seen in PLANTS (polyploidy, so mutations common)
102
Convergent Evolution
When natural selection produces similar phenotypes in organisms that are NOT closely related
Due to same environmental selection pressures
103
Coevolution
When 2 species exert selective pressures on each other, resulting in both evolving together
Due to interactions such as mutualism and parasitism
104
Sexual Selection
A type of natural selection in which limited resource for which individuals compete is mates, and the "environment" that selects for advantageous traits is the opposite sex
105
Note that a ________ evolves, NOT an __________
Population; individual organism
An individual organism either survives and reproduces or dies
A population changes over time as individuals with particular traits become more or less abundant
106
Acclimatization
An individual organism can respond to changing conditions by altering its physiological processes
Informal: Acclimation
107
Adaptation
A population (species) respongs to changing conditions by evolving
108
Phenotypic Plasticity
Single organism with one genotype but MULTIPLE PHENOTYPES based on that ONE genotype
Common in PLANTS
109
Note close relationship between ecology and evolution
Ecology is DEFINED as the interactions between organisms and their environment
Evolution is DRIVEN by the interactions between organisms and their environment
Ecology is the driving force behind evolution
Note that many evolutionary terms (adaptation, population, competition, etc.) are actually ecological terms
