Ecology (Chapter 5)

What is C4 photosynthesis?

-Spatial separation of where CO2 uptake and processing occurs (Pepcase near surface) -Developed in conditions where CO2 conc. low relative to O2 and high temps.

Why does photorespiration increase at higher temperature?

-Stomata closes so less CO2 uptake -CO2 doesn't enter via cytoplasm (solubility of CO@ decreases more than O2) -O2 uptake by rubisco increases

What are the benefits of C4 photosynthesis?

-lower photorespiration -stomata partly close which means less water loss and lower co2 intake -PEPcase can uptake CO2 at lower levels compared to rubisco -Photosynthesis can continue at lower CO2 levels than possible in C3

What is the light saturation point?

-point of light level that maximizes photosynthetic rate -greater light does not equal greater photosynthesis rate -below this light, plant is light limited (>light= >photosynthesis)

Why hasn't rubisco evolved to reduce O2 uptake?

-remember plant experiment -altered plants to enhance or reduce ability to photorespire then exposed them to high intensity light Results: 1) Plants with enhanced photorespiration maintained higher ETC 2) greater ETC = less energy stored 3) less energy stored=less damage to tissues Conclusion: The more you photorespire, the greater the ETC and the less energy is stored in your tissues, so there is less damage. The less you photorespire, the less the ETC and the more energy will build up which = more damage

What is the optimal foraging theory?

-seeks explanations for decisions made while foraging -assumes that natural selection acts on foraging behaviors that maximize energy gains

Explain the light response curve.

-summarizes relationship between light availability and photosynthesis rate (CO2 VS Light Level)

What is CAM photosynthesis?

-temporal separation of when co2 uptake and processing occurs

What does optimal foraging theory predict?

-that foraging animals will maximize their energy gain

Describe the mechanisms of CAM photosynthesis

1) *Close stomata during day* to prevent H2O loss 2) *Open stomata at night* for CO2 uptake via PEPcase. CO2 is converted to C4 acid and stores it 3) *Convert acid back to usable CO2* for Calvin cycle during day

Describe the mechanisms of C4 photosynthesis.

1) CO2 initially taken up by PEPcase which has greater capacity to take up CO2 than rubisco 2) PEPcase reacts with CO2 to form 4-carbon molecule 3) This 4C molecule is pumped to lower tissues where RuBisCo is where it is then converted to CO2 and enters Calvin Cycle

CAM photosynthesis is an adaptation to reduce?

1) H2O loss in dry environments

Why is too much sun for a plant bad?

1) Overheating ->metabolic functions not efficient 2) Water loss 3) Damage photosynthetic membranes

Which of the following are ways heterotrophs have evolved mechanisms to acquire and assimilate energy efficiently from a variety of organic sources.

1) Predator 2) Parasite 3) Herbivore 4) Detritivore

How can some CAM plants switch to C3?

1) When H2O is abundant (no need to close stomatas) 2) Different life stages Basically when h2o is abundant it switches to c3 and when temps get hot or dry they become CAM

What are some short-term morphological responses that help regulate light input?

1) change orientation of leaf 2) alter location of chloroplasts 3) change ratio of photosynthetic pigments throughout the day -violaxanthin maximizes photosynthetic efficiency in low light -breaks into (zeaxanthin + antheraxanthin) in hotter and sunny conditions b/c its good at dissipating heat

What are some long-term morphological responses that help regulate light input?

1) increase/decrease # of chloroplasts 2) thicker leaves reduce light penetration (acclimatization)

C4 photosynthesis is an adaptation to reduce what?

1) photorespiration 2) H2O loss in *HOT* environments

NET PROFITIBAILITY

ADD

Different photosynthetic enzymes that optimize function are an _____ to a specific environment

Adaptation

What was found in the crosbill beak morphology study?

Bill of crosbill bird depended on the type of conifer it was eating. It was found that each species had an optimal shape and size of beak to most efficiently extract seeds from confier (for optimal survival rate). The *conclusion* was that crosbills are currently undergoing evolutionary divergence (speciation) because of diff. in available food resources and effects of those difference on bill morphology

What is the light compensation point?

CO2 lost via respiration = CO2 gained via photosynthetic uptake

Do plants growing in low light have more or less chloroplasts than those in high light?

Fewer because more chloroplasts means more energy needed to sustain them which low light plant doesn't have. Less chloroplasts so they can reallocate energy to something else

Name some types of plants that undergo photosynthesis.

succulents (cacti) or epiphytes (bromeliad and spanish moss) also pineapple!

Explain what rubisco does?

-1st step of typical photosynthesis (C3) -5 carbon molecule (RuBp) combines with CO2 to form two 3 carbon molecules -catalyzes photosynthesis AND respiration