BIS 2B Properties of Life Midterm 1

What are the properties of life?

Order and Organization

Energy Processing

Growth and Development

Evolutionary Adaptation

Regulation (Homeostasis)

Reproduction

Response to Stimuli

Of Every Girl Everywhere Rarely Risks Relationships

What is the smallest possible unit of life?

Cell

What is ecology?

Study of how organisms interact with each other, and with the environment in which they live

What is evolution?

Study of changes in heritable characteristics of biological populations over successive generations

What is the biosphere?

All life lives within 10km within the surface of the earth

Why is the biosphere so compatible for life?

Water, Sunlight, Temperature

What is latitude

How north or south of the equator you are
each degree ~69 miles

What are the precipitation trends?

Rain near equator, dry 30 degrees north and south

What are hadley cells

patterns of atmospheric ciruclation with air rising near the equator (rain) and descending as dry air at 30degrees north and south

equator hot → warm moist air rises → cooler atmosphere condenses cloud → rain → cool dry air descends → desert

How does the earth’s tilt change affect temperature/season

when northern hemisphere tilted away → winter

northern hemisphere tilted towards → summer

what is the intertropical convergence zone?

thermal equator:

• band of clouds that shifts up and down throughout seasons

• if above equator, june/july

• if below, january

What does windward mean?

air rises, cools, and rains

side of mountain facing ocean

What does leeward mean?

dry air decends and warms

What is weather?

current, short-term atmospheric conditions

What is climate?

average atmospheric conditions/patterns/cycle over a longer period of time

How does visible light from the Sun interact with the Earth?

50% absorbed by the surface, 20% absorbed by the atmosphere, 30% reflected

How does infrared radiation from the Earth interact with the atmosphere/surface?

visible light/solar radiation → hitting Earth → Earth emits infrared radiation → atmosphere absorbs infrared radiation → radiates it back to Earth

What is the greenhouse effect?

Infrared radiation emitted by the Earth → getting absorbed by atmospheric gas → radiating back to earth

Why did CFCs decrease over time, also why was it bad?

World governments came together to ban the substance

CFCs depleted the ozone layer

What is the cryosphere?

all the frozen water on earth’s surface

How does thermal expansion contribute to sea level rise?

Warmer things are bigger

Ocean absorption vs Atmospheric Absorption

Ocean acts like a thermal sink, can absorb more heat but temperature raises less

What is ocean acidification?

ocean absorbing CO2 → creates carbonic acid → fewer carbonate ions → reduced coral health

What is the value of biodiversity?

market value, ecosystem services (bee pollination, wetlands, erosion control), tourism/recreation, life satisfaction, sceince/research, cultural/intrinsic value

What is genetic or trait diversity

different genes or traits within the same species

What is species diversity?

different species occupying same habitat at same time

What is diversity index composed of?

Species richness and species evenness

What does principle of allocation mean?

the limited amount of energy each organism can use for all life processes
• Obtaining food
• Escaping predators/pathogens
• Reproduction
• Growth and metabolic functions

Energy allocated to one function cannot be used for another function

What is C3 photosynthesis?

Most common pathway, 85% of plants use
All mesophyll cells take up CO2 and build sugar
Light reaction and carbon fixation occur at same time

Problems with C3 Photosynthesis

Water escapes from stomata that are open to allow CO2 to enter
C3 Plants perform carbon fixation during the daytime so water loss is unavoidable
Photorespiration occurs if they close stomata

• oxygen binds onto rubisco, depletes carbon rather than fixing it

• Wastes ATP

What is C4 Photosynthesis

Occurs in 3% of plants
Uses PEP-C and Rubisco
Carbon fixation and sugar building are separated
- CO2 + PEP-C → C4 → Moves C4 into different location → C4 + Rubisco → Glucose
Able to concentrate CO2 in area near Rubisco to reduce photorespiration waste

Problems with C4 Photosynthesis

Requires 2 extra ATP per sugar molecule

What is CAM Photosynthesis?

Occurs in 7% of Plants

CO2 and Sugar-building are separate in time

• Open stomata at night, store CO2 as acid in vacuole

• Close stomata during day, convert acid back to CO2 to build sugar

Night: CO2 + PEP-C → Malate (acid)

Day: Malate + Rubisco → Glucose

Very water efficient, less photorespiration than c3

good for plants with few competition and low water

Problems with CAM Photosynthesis

Requires 2 extra ATP per sugar molecule
slows growth due to temporal restriction

What is the relationship between nitrogen legumes and rhizobium?

(mutualistic relationship) rhizobium bacteria live in the roots of legumes that help fix nitrogen (converts nitrogen gas into ammonia)

allows legumes to thrive in soils with limited availble nitrogen

bacteria creates fertilizer for the legume

What is the relationship between plants and mycorrhizal fungi?

Mutualistic relationship, allows plants roots to stretch further to access additional water/nutrients (phosphorous)

Fungal cells penetrate/wrap around root

Fungi get sugars from plant

80-90% of plants have this

What is Liebig’s law of the minimum?

Plant growth is determined by the amount of the resource that is most scarce compared to what the plant needs

autotrophs vs heterotrophs

autotrophs must grow

heterotrophs must move (time management)

What determines foraging decisions?

Guiding principles: optimize rate of benefits through time

• trade-off between handling time and calorie amount

• E1/H1 and E2/H2

• E1 and E2 are the energy values of large prey and small prey

• H1 and H2 are the handing times of large prey and small prey

What are fundamental niches?

The abiotic conditions in which a species can survive and reproduce (ex. temperature, precipitation, soil type)

What are realized niches?

The biotic conditions that determines where the species occurs (interactions with other species)

What are some responses to abiotic stress?

Acclimation

• physiological changes in response to experienced conditions

Adaptation

• Heritable evolutionary changes in populations over generations driven by natural selection

What is the Root:Shoot ratio?

More sun → More Shoots
More water → More roots

Root/Shoot

Why does temperature matter?

Affects:

• rates of reactions

• shapes of proteins

• membrane properties

Endotherms vs Ectotherms

Endotherm: constant body temperature, metabolism decreases with temperature

Ectotherm: body temperature equilibrates with room temperature, metabolism increases with temperature

How do ectotherms reduce temperature stress?

Behavioral strategies such as burrowing and basking

How do plants thermally regulate?

• Water travels up the xylem and evaporates through open stomata

• Orient their leaves vertically

• Highly reflective leaves

• Leaves are far away from ground to reduce radiation

• Open wide structure for more wind

Describe the stress and risk of predation biotic favotr

P(predator eating prey) = P(detection) x P(capture) x P(Consumption)

Detection: Prey camouflage

• drawbacks: less productive/optimized, restricted to location

Capture: Prey travel in large schools (Fish)

Consumption: Prey are hard to eat

• Physical: porcupine/thorns

• Chemical: Poison/Toxicity

What are the growth-defense trade offs?

More tannin = less growth

What is the life history strategy?

The way organisms allocate resources to growth, reproduction, and survival based on genetic and environmental factors

What is the life history/allocation of resources in young organisms?

Mostly growth, some maintenance, low storage

What is the life history/allocation of resources in old organisms?

Mostly reproduction, some maintenance, some storage, low growth

What does semelparous mean?

Organisms that reproduce once and then die

What doe iteroparous mean?

Organisms that reproduce many times throughout their lifespan

R strategist behaviors

• Survivorship

  • short life span

  • density independent mortality

  • type 3 curve

• Reproductive strategy

  • reproduce once

  • large number of offspring

  • large allocation of resources to reproduction

• Population growth

  • exponential growth followed by periodic/seasonal decline

k strategist behaviors

• Survivorship

  • long life span

  • density dependent mortality

  • type 1 or 2

• Reproductive strategy

  • reproduce more than once

  • greater allocation of resources to growth rather than reproduction

  • fewer offspring

• population growth

  • slow rising

  • stabilizes at/near carrying capacity

What is fecundity?

average amount of offspring a group will produce during that age class

What is the net reproductive
rate?

the mean number of offspring produced per individual across their lifetime

sum of lxmx

What is generation time?

G = sum of xlxmx / sum of lxmx

What is the formula for r?

ln(R0)/G