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
In general, antiporters act as
exporters
In general, pumps for H+, or Ca2+ also act as
exporters
What is the difference between symporters and antiporters?
Movement of two molecules in the same vs opposite direction (respectively) through a protein channel
Define pumps and give two
examples
One of the main 3 channels of transport, pumps use chemical energy like ATP. Proton pumps
Define channels and give an example of a nutrient that is taken up by channels
selective pores in the membrane. potassium
Define cation exchange capacity
Soil particles have a negative surface charge and can bind
cations and make them available for plants.
What is the difference between general, interveinal and marginal chlorosis?
general=general yellowing of leaf
interveinal=yellowing between veins
marginal=yellows along leaf margins (outer edge)
Define necrosis
death of tissue through injury or disease, especially in a localized area. Such an area is usually brown or black.
Deficiency symptoms for N and S are similar (general chlorosis) how are the symptoms different?
Sulfur is not as mobile in the plant as N so S deficiency tends to show up on young leaves.
Mn and Fe deficiency symptoms are the same, what are they?
Interveinal chlorosis of young leaves.
Calcium and Boron deficiency symptoms are similar. What are they?
Necrosis of young tissues.
Zn and Mg have similar deficiency symptoms. What are they?
Both are mobile and under
deficiency conditions the plants have interveinal chlorosis of older leaves.
What enzyme is Ni required for?
Urease
What other nutrient deficiency leads to N deficiency?
Mo deficiency
Define morphogenesis
generation of the shape of the plant and its various organs
Define differentiation
the process of forming different specialized cell types
Define polarity
having two different ends, as in roots/shoot polarity
What are radial vs. bilateral symmetry?
Bilateral and radial symmetries. In bilateral symmetry only a single plane divides the organism into two identically reflected halves (reflective symmetry) , whereas a radially symmetric structure can be halved at multiple planes to produce identical parts (n-fold rotational symmetry)
Leaves have dorsiventral polarity, which side is dorsal and which is ventral?
Dorsal is the top side.
In the plant embryo the hypophysis develops into what tissue?
root cap
Describe the difference between determinate and indeterminate growth.
Determinate: having a defined limit. Indeterminate: Shoots and roots continue to grow until stopped by an environmental or internal signal.
What is a tropic response?
Tropism is oriented plant growth in response to a directional signal such as gravity, light or touch. The key work is “growth”.
Define photomorphogenesis, photoperiod and circadian rhythm.
Photomorphogenesis is a change in development due to light signals. Photoperiod is the amount of time during the day that a plant is exposed to light. Circadian rhythm is a biological activity that cycles independently of external stimuli with a period of about 24 hrs.
Give two examples of photomorphogenic processes.
Deetiolation and floral induction
(flowering)
What is phytochrome, what is the cofactor (chromophore)? Where is the cofactor synthesized?
Phytochrome, and all receptors that we discussed in class, is a protein. The cofactor is phytochromobilin which is synthesized in the chloroplast
Where is phytochrome synthesized?
t is a soluble protein synthesized in the cytoplasm.
Is Pr or Pfr considered to be the active form of phytochrome and Which form is first synthesized in the plant?
pfr and pr (respectively)
True or False. A seedling grown in the dark will have Pr and
when it perceives red light some will be converted to Pfr and then the plant will know that it has been exposed to red light
True
In seedlings, where is phytochrome most abundant?
Most abundant in the apical hook.
What is the fluence rate of full sunlight?
ound 2000 µmol m-2 sec-1
Indole-3-acetic acid (IAA) is the main native auxin in plants, what are some other auxins?
2,4-D is one, it is a common herbicide
Name three important effects of gibberellins in plants.
Regulation of plant height, promotes seed germination, is produced by the embryo and stimulates the aleurone layer to secrete amylase.
What are the three effects of ethylene in the “triple response”?
short hypocotyl, reduced root elongation, and exaggerated apical hook
Define a protist.
Diverse single celled or simple multicellular organisms (without much cellular differentiation) that cannot be classified as plant, fungal or animal. Not monophyletic.
Which protists have alveoli and what are alveoli?
Alveolates have tiny membranous sacs called alveoli
Land plants evolved from green algae. Name five characteristics that green algae and plants have in common
They both have chlorophyll A and B, both have cellulose cell walls, both store starch, both use phragmoplast formation during cell division.
Land plants evolved from green algae. Name five characteristics that green algae and plants have in common
They both have chlorophyll A and B, both have cellulose cell walls, both store starch, both use phragmoplast formation during cell division.
Land plants evolved from green algae. Name five characteristics that green algae and plants have in common
They both have chlorophyll A and B, both have cellulose cell walls, both store starch, both use phragmoplast formation during cell division.
