Exam 2 (Ecology) by Branna Campbell

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What is physiology?


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What is physiology?

branch of biology concerns with understanding the function of tissues, organs, and organ systems

physiological ecology

the study of how organisms are physiologically adapted to their environment; an organism's ability to carry out it's vital functions (or the efficiency with which it performs these function; depends on environmental conditions

What are the limitations of life?

energy, water, and temperature

What is the source of carbon from which life is constructed?

the atmosphere

Plants are...

autotrophs; make their own carbon

Humans are...

heterotrophs; have to eat their carbon


light energy from the sun fuels a series of reactions that result in the fixation of CO2 and the release of O2

cellular respiration

plants use this in order to convert the energy in sugars and other molecules into ATP; producing CO2

net photosynthesis

photosynthesis - respiration

What happens in shaded environments?

low light limits the rate of photosynthesis; leaf respiration is lower

shade intolerant plants vs shade tolerant plants

adaptations to sun and shade environments; show fundamental difference in patters of photosynthesis in response to different levels of available light

What happens when you move a shade-tolerant plant to a high light environment?

its maximum rate of photosynthesis is limited

specific leaf area (SLA)

ratio of surface areas in cm2 to weight in g; the surface areas of leaf produced per gram of biomass allocated to leaf production

Shade tolerant plants have...

greater SLA; shorter

Shade intolerant plants have...

lower SLA; longer


openings on the leaf surface that allows CO2 to enter; gas diffuses from higher concentration in the air to lower concentrations in the leaf

Stomata is found in...

terrestrial plants

How is diffusion controlled in terrestrial plants?

the stomata opens and closes

stomata are usually closed when...

photosynthesis and the demand for CO2 are reduced for any reason

stomata are open when...

the concentration of CO2 in the air outs the leaf is greater than that inside the leaf


when the stomata are open, water vapor in the leaf diffuses out

transpiration rate depends on..

the diffusion gradient and stomatal conductin of H2O

How is the water in plants replaced?

plants take up water form the soil by the roots and transport that water to their leaves

What kind of transport happens in plants?

passive; does not require energy

Water loss through transpiration will continue as long as...

light energy striking leaf supplies enough heat for evaporation, moisture in available in the soil, and the roots are able too maintain a more negative water potential than the soil

What affects the water potential of the soil?


water use efficiency

the ratio of carbon fixed per unit of water loss

What plants have the least water use efficiency

plants in the rainforest; because there is a lot of rain

What plants have the most water use efficiency?

plants in the desert; b/c there isn't as much rain

CO2 concentrations in the atmosphere are increasing. Should this lead to an increase or decrease in the amount of time a plant must leave its stomata open?


CO2 concentrations in the atmosphere are increasing allowing plants to keep their stomata closed more of the time. Is this change accompanied by an increase or decrease of the water use efficiency of the plant?


Temperature effects...

photosynthesis and cellular respiration

Does photosynthesis increase or decrease as temperature increases?


The max temperature for photosynthesis is higher or lower than the max temperature of respiration?


Tmin =

min. temperature

Tmax =

max. temperature

Topt =

range of temperatures over which net carbon uptake is highest

As air temperature rises...

the rate of transpiration rises

plant acclimation

reversible changes to different environments

Topt lower

for plants grown under cooler conditions

Topt higher

for plants grown under warmer conditions

How do most plants acquire energy?

through the sun & photosynthesis

How do animals acquire energy?

through different types of organisms

What impacts structure/function relationships in animals?


Surface area of a cube

6 x LsĀ²

Volume of a cube

L x W x H

Why does the relationship between surface area and volume impose a critical constraint on the evolution of animals?

Many basic physiological and biochemical processes require the transfer of materials and energy between the exterior (environment) and interior of the organism


plants that make their own food


A consumer that eats only plants.