EES 152: Ecology Exam 2

blue

Within PAR. what color light is used most by photosynthesis?

45%

What percentage does PAR make up of all solar radiation?

photon flux density

What is PAR measured in?

ATP and NADPH

energy from these two molecules is used to build organic molecules, using CO2 as a carbon source

carbon fixation

the process in which inorganic carbon, usually in the form of CO2, is converted into organic molecules, including carbohydrates

C3, C4, and CAM

What are the three was photosynthesis is done?

mesophyll cells 

Where do all C3 reactions take place?

rubisco

In C3 plants, what enzyme is used to initially fix CO2?

open; large

Do C3 plants need to keep their stomata open or closed? Do they have a small or large amount of stomata?

mesophyll and bundle sheath cells

What two different cells are involved or related to C4 plants?

pepco

In C4 plants, what enzyme is used to initially fix CO2?

less

Compared to C3 plants, do more or less stomata need to be open to bring in the same number of CO2 molecules in C4 plants?

lacking in C3 plants; present in C4 plants

Do the bundle sheath cells in C3 plants have chloroplasts? What about in C4 plants?

CAM plants

plants where stomata close during the day and open at night

lower temperatures reduce the vapor pressure deficit

Why do CAM plants fix carbon at night?

mesophyll, PEP

All reactions in CAM plants occur in ______ cells, like C3 plants, but CO2 is combined initially with _______, like C4.

large vacuoles in mesophyll cells

CAM plant leaves have what?

pepco

In CAM plants, what enzyme is used to initially fix CO2?

C3 plants are more competitive; C4 inefficient at low light intensities, ineffective as shade plants, takes more energy

Why aren’t C4 plants more abundant than C3 plants?

shaded regions: C4 does poorly (less light); C3 does well; opposite for sunny habitats

Plants that occur in shaded habitats versus a plant that occurs in open, sunny habitats. Difference between a C4 and C3 species in these conditions?

the rate is limited

The rate at which photosynthetic organisms can take in energy always levels off with increasing light. What does this mean?

true

TRUE OR FALSE: The current rise in CO2 has potential direct effects on energy acquisition and nutrients

heterotrophs

organisms that obtain their energy by capturing organic molecules manufactured by other organisms

93-97%

How much of biomass is made up of CHONP?

nitrogen

Which nutrient is particularly limiting?

carbon

What other element do ecologists use in ratio with nitrogen?

food

C:N ratio describes the quality of what to consumers?

describes quality of food (plants have high C:N; animals, fungi, bacteria have low C:N)

herbivores need to eat more plants to get enough N and energy; N is used to make DNA, RNA, proteins

Why does the C:N ratio of a food source matter?

toxins and chemical defenses (in tropical plants: mustard oil, capsaicin), symbiosis with ants and trees

What adaptaions have plants developed in response to herbivory?

cellulose; it is not digestible by any animal

What defense do ALL plants have against herbivores, and why?

nitrification

the oxidation of ammonia (NH4) to nitrite (NO2-) to nitrate (NO3-)

camouflage, spines and shells, repellents and poisons, behavior

What defenses have prey evolved in response to predation?

Mullerian mimicry

two or more toxic or harmful species evolve to resemble each other’s warning signals, such as the same pattern or bright colors

Batesian mimicry

a harmless species resembles a harmful one

type I functional response

feeding increases linearly with food supply up to a point and then levels off abruptly; only animals that need little to no time to process food

type II functional response

feeding increases linearly at low densities, rises more slowly at intermediate densities, and then levels off at high densities

time spent finding food

At low food density, feeding rate is limited by what?

time spent finding and handling food

At mid-food-density, feeding rate is limited by what?

time spent handling food

At high food denisty, feeding rate is limited by what?

type III functional response

S-shaped curve; low densities may afford prey more protected hiding spaces

type II

What type functional response is most common?

principle of allocation

a principle that states an organism has a limited quantity of resources that it can use for life processes

How does the principle of allocation relate to life histories and what trade-offs exist?

greater energy expenditure

High mortality rate; reproduction at earlier age. What does this mean in terms of energy expenditure?

semelparous

breeds once

iteroparous

breeds multiple times

r-selection

reproduce rapidly, high mortality, rapid turnover of generations, many offspring, semelparity

k-selection

at carrying capacity, stable, large, late maturity, iteroparity

intensity of disturbance (process limiting plants by destroying biomass); intensity of stress (external constraints limiting rate of growth 

What variables are important in Grime’s life history classification of plants? What are the three end-member categories, what are their characteristics, and how are they related to environmental conditions? Compare and contrast Grime’s scheme with the classic r and k classifications.

distinct differences that results due to competition for mates

Define sexual selection.

intrasexual selection

males compete among themselves for mates (larger size, antlers)

intersexual selection

females choose mates based on particular traits (peacock tail feathers; good health hypothesis)

Define the handicap hypothesis