BIOL205 - Plant intro and energetics

Gas exchange in plants takes place in the

Stomata

Energy assimilation in plants takes place

throughout photosynthetic tissues

Nutrients are transported where in plants

Between cells and vascular tissues

Where does perception (light, pathogens etc) occus in plants?

Through receptors hormonal signaling

Where does support come from for plants?

Cell walls and hydrostatic pressure

Where does water and nutrient uptake take place in plants?

Across the root and sometimes shoot surfaces

Why is the terrestrial environment a difficult place to live as compared to an aquatic environment?

No buoyancy, water is scarce, extreme temperatures, excess light - including damaging UV light.

What are some examples of adaptations in leaves?

Green-ness, colour, toughness, reflectivity/shininess, leaf shape, orientation, leaf size, smell

What are some stressors that plants need to be able to respond to?

light, UV, water. temperature, ice, wind, herbivores, pathogens, nutrients, salt, heavy metals

Particular constraints of an organism shape adaptations - some with animals and some unique. What are some of them?

Resource requirements like water, light, nutrients. Structure like cell wall, modular, indeterminate growth. Sessile, sexual and asexual reproduction, endosymbiont-origin organelles, several important symbioses.

What are plants?

• Photosynthetic eukaryotes, mostly multi-cellular

• Almost all plants photosynthesize

• Not all things that photosynthesize are plants

Where does energy enter the biosphere?

Through photosynthesis

What does photosynthesis do?

Convert light energy to chemical energy which can then be converted to kinetic energy or other types of potential energy or heat

Why is chemical energy good to be converted into?

Can be stored and transported

What does movement of energy underlie much of?

Ecology

Where is the sweet spot of the light spectrum for plant photosynthesis?

400-700 nm

Where is chemical energy stored in plants?

Linking multiple sugars to make starch

Breaking the starch bonds causes what?

Energy release which is a catabolic reaction

What is respiration driven by?

Processes like an electron transport chain, ATP proton motive force

What is metabolism?

Controlled release and recapture of energy (respiration)

What is the energy loss between sugar and CO2 equal to?

Equal to energy gain by ATP plus heat

What is the organismal energy currency?

Sugars

Where is the energy stored in ATP?

In the bond between the second and third phosphates

What is ATP used to fuel?

Cellular processes such as ion movements to open stomata, uptake of nutrients from soil solution

What is NAD(P)H used for?

Another cellular energy currency. Energy stored as reducing power and electrons. Can be used to fuel cellular processes like anabolic reactions like synthesizing amino acids

What does the carbon reduced in photosynthesis become?

Carbon skeletons which are the physical building blocks of life

What is the net energy gain for plants?

Balance of energy stored via photosynthesis and lost via respiration

Carbon exchange is 0 sum, what are some different strategies for how plants use this carbon?

• Seeds/fruits

• Lost to herbivory

• Feed pollinators

• Exchange with symbionts

• Signals for other plants/insects/microbes (via volatile aromatic compounds for example)

Why might thermogenic plants exist?

Maybe a pollinator reward and to help disperse volatiles (smells for the plants to attract pollinators)

How do thermogenic plants exist?

Like in brown fat : a greater proportion of energy is lost as heat