AP Bio unit 8.1-8.4

What does an organism’s response depend on?

environmental cues!

• stimulus (an external/internal signal) → response (behavioral/physiological change)

Taxis vs kinesis

Taxis: change in direction ← automatic movement towards/away from a stimulus

kinesis: change in rate of movement in response to a stimulus

Phototropism

directional response that allows plants to grow towards/away from a source of light

photoperiodism

regulation of physiology or developmental process in response to day length

How does communication to others in a species or a predator occur?

signaling! → could be audible, visual, tactile, electrical, or chemical

• can convey dominance, food location, territory establishment, and reproduction

What kind of behaviors do natural selection favor

innate and learned behaviors that increase reproductive fitness

cooperative behaviors

increases individual fitness which leads to better survival of population

What is required by the highly complex living organization of living systems?

the constant input of energy and the exchange of macromolecules

How do organisms acquire and use energy?

• regulation of body temperature and metabolism (endo vs ecto therms)

• reproductive strategies based on energy availability

• use energy based on change in net energy

endotherms

use thermal energy generated internally by metabolism to regulate body temp

ectotherms

use external heat energy via behavioral adaptations to regulate body temp

life-history strategy

a way an organism makes trade-offs between survival and reproduction (r selection vs k selection)

life-history strategy trade-offs

1: # of offspring produced and amt of energy put into each one

2: timing of 1st reproduction → earlier lowers chance of dying without offspring, later = healthier babies

3: # of reproductive opportunities → semelparity vs iteroparity

semelparity vs iteroparity

reproducing once (semelparity) vs more than once (iteroparity)

r selection vs k selection

reproductive strategies based on energy availability

• r = intrinsic rate of increase → occurs to maximize the exponential phase of population growth when there is little competition (Ex: unstable environment, small organism, low energy use to reproduce, many offspring, short life expectancy, one cycle)

• k = carrying capacity → occurs when populations are near max capacity in a certain area and competition is high (Ex: stable environment, large organism, high energy use to reproduce, few offspring, long life expectancy, many cycles)

reproductive diapause

• when there’s not enough energy to reproduce

temporary cessation of reproduction in certain species of animals and insects, in response to environmental cues such as food availability, temp, and photoperiod

What are the effects of body mass on metabolic rate?

small body mass = associated w/ higher metabolic rates

large body mass = associated w/ lower metabolic rate

body mass vs metabolic rate

inversely proportional (higher metabolic rate = higher oxygen requirement)

net gain in energy vs net loss in energy of organism

gain: results in growth or storage

loss: results in loss of mass, decrease in reproduction output → death

How do changes in energy availability affect populations and ecosystems?

change in energy resources/producer level can affect the # and size of other trophic levels

What limits the number of trophic levels in the food pyramid?

some energy cannot be consumed → some is lost as heat in waste

How do autotrophs capture energy?

from physical/cehmical sources in the environment

How do heterotrophs get energy?

by metabolizing macromolecules as a source of energy from carbon compounds

Where does energy flow?

through an ecosystem

where do matter and nutrients flow?

through biogeochemical cycles (nitrogen, carbon, phosphorus, water cycle)

carbon cycle

dead organisms and waste products → fossil fuels → factory emissions → CO2 cycle → photosynthesis

water cycle

evaporation → condensation → precipitation → transpiration

Nitrogen cycle

driven by microbes

• Fixation: N2 → NH3

• ammonification: NH3 → NH4+

• nitrification: NH4 → NO2 + NO3

• denitrification: NO3 → N2

Phosphorous cycle

rocks release phosphate in soil → producers take it in → consumers consume→ consumers die restarting the cycle

photosynthetic organisms

capture energy present in sunlight contributing to primary productivity

chemosynthetic organisms

capture energy from small inorganic molecules present in their environment, can occur without oxygen