Studyguide Exam 2 Flashcards
Sucrose is a main storage form of fixed carbon. What are the two monosaccharide components
of sucrose?
Glucose and Fructose
What are the two enzymes that degrade sucrose in plants?
Invertase and sucrose synthase
What are the four main steps of respiration?
Mobilization, glycolysis, TCA cycle and electron
transport
If oxygen is not present how many steps are there in respiration, and what are they?
Three, mobilization, glycolysis, and anaerobic fermentation.
What are the products of glycolysis?
2 pyruvate + 2 ATP and 2 NADH
What happens to the pyruvate after glycolysis?
It depends on whether oxygen is available
In respiration, if oxygen is not available, then pyruvate is used in anaerobic fermentation. What is the purpose
of anaerobic fermentation?
To oxidize NADH to produce NAD+ so that glycolysis can continue.
What are the products of anaerobic fermentation?
CO2, ethanol and NAD+
Does fermentation produce energy?
Not directly, it produces NAD+ so that glycolysis can happen and glycolysis produces ATP.
OK, in respiration, if oxygen is available then what is the fate of pyruvate?
Pyruvate is transported into the
mitochondria and enters the TCA cycle
What is the purpose of the TCA cycle?
To decarboxylate pyruvate (releasing CO2), and to produce reduced NADH and FADH2 that can be used by the electron transport chain. The TCA cycle also produces a small amount of ATP
Where does the TCA cycle take place?
In the mitochondrial matrix
How does the mitochondria use NADH and FADH2 to produce ATP?
NADH and FADH2 are produced by the TCA cycle in the matrix. These feed electrons to the electron transport chain, that pumps protons from the matrix into the intermembrane space and forms a proton gradient (form of energy). The proton gradient drive ATP production as protons flow back into the matrix through the ATP synthetase.
NADH and FADH2 are the electron donors in the mitochondria, what is the terminal electron acceptor?
Oxygen accepts electrons and water is produced.
What is the function of the alternate oxidase (AOX)?
Alternate oxidase reduces oxygen earlier in the electron transport chain. Its function is to produce heat, by wasting some energy. it is the mechanism that plants use to produce
heat by wasting energy in their mitochondria.
What are the three criteria that must be met for an element to be classified as an essential plant nutrient?
1) Elements must be necessary for complete normal plant
development for a full life cycle,
2) No element can substitute for an essential nutrient, and
3) The element must be active within the plant (not outside the plant).
Both uptake transporters and efflux transporters are required for a nutrient to move from the soil solution to the xylem. Please explain why
The xylem tracheids and vessel elements are dead at maturity and for conducting tubes that are continuous with the cell wall space. Water and nutrients cannot move in the cell wall space (apoplast) from the soil solution to the xylem because of the casparian strip at the endodermis. Water and nutrients need to be taken up into the cytoplasm and then exported into the wall space within the vascular cylinder to get into the xylem. It is a system that allows plants to have selective nutrient uptake because transporter proteins are selective.
What are the two types of essential nutrients?
micronutrients and macronutrients
Which elements are the macronutrients?
nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), Sulfur (S), and magnesium (Mg), and for some plants Silicon (Si)
Which elements are the micronutrients?
boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni). and cobalt (Co)
Why are plant nutrient deficiencies unusual in natural ecosystems?
Because in nature, plants are adapted to their environment, including the soil.
Why are plant nutrient deficiencies common in horticultural or agricultural ecosystems?
In horticulture, plants are introduced to environments where they might not be well adapted. In agriculture, soils can be depleted of nutrients because crops are harvested and nutrients not recycled into the soil.
Some nutrients can be taken up by ion channels. This is only true for some cations. Why are anions not taken up by ion channels?
Because the membrane potential is negative and would
attract the positively charged cations but would repel anions.
In general, symporters act as
nutrient uptake transporters