BSC 212 Exam 2 SG

what are the 2 principle types of root systems?

1) taproot root system
2) fibrous root system

how does the taproot RS differ from the fibrous RS?

-in taproot RS: the primary root is taproot, lateral roots are branching, and is in all seed plants BUT monocots

-in fibrous RS: adventitious roots (no taproot), lateral roots are fibrous, and is in monocots

what changes occur to the rootcap during elongation of the root?

-cells are replaced as root pushes through soil, new cells generated in root apical meristem, move towards RC
-newly formed cells elongate
-as cells move from RC, they differentiate

what are the functions of the rootcap?

protective parenchyma cells that control direction of movement & aid in protection

what tissues are found in a root at the end of primary growth? how are they arranged?

1) protoderm meristem in the epidermis

2) ground meristem in the ground tissue

3) procambium meristem in the vascular tissue

describe the effect of secondary growth on the primary body of the root

-increased thickness through production of secondary xylem & phloem by vascular cambium
-epidermis replaced by cork cambium
-lateral roots form
-enhanced transport & structural support

what are the principle functions of roots?

1) absorption
2) transport
3) hormone prod
4) storage
5) specialized roots

what are the roles of light in photosynthesis?

-provides photons absorbed by pigments in chloroplasts

-excites e- that eventually convert ADP to ATP & reduce NADP+ to NADPH (drive calvin cycle)

-splits water molecules to oxygen, protons, e- releasing oxygen as byproduct

what are the properties of light that suggest it is both a wave & a particle?

it can reflect, refract, interfere, and diffract

what are the principle pigments involved in photosynthesis?

1) chlorophyll a
2) chlorophyll b
3) chlorophyll c
4) carotenoids & phycobilins

why are leaves green?

chlorophyll absorbs blue-violet light, and reflects/transmits green light

what are the main products of light reactions in PS?

-oxygen
-ATP
-NADPH

what are the main products of carbon-fixation reactions in PS?

1) sucrose
2) starch

what are the main events associated with each of the 2 photosystems in light rxns?

PSI:

absorbs light energy exciting e- that are used to reduce NADP+ to NADPH

PSII:

water photolysis (split) yields oxygen & protons are released to lumen of thylakoid generating a proton gradient

what is the difference between antenna pigments & rxn center pigments?

antenna pigment molecules act as a funnel & rxn center pigments convert light to chemical energy

what are the principle differences between C3, C4, and CAM pathways for carbon fixation?

C3:

-uses rubisco

-low energy cost

-plants in cool/wet envir.

-prone to PR

C4:

-uses PEP carboxylase

-high energy cost

-plants in tropical envir.

-spatial sep avoids PR

CAM:

-temporal sep avoids PR

-stomata opens at night to reduce water loss

what are the similarities between C3, C4, and CAM pathways?

-C4 & CAM both use PEP carboxylase
-C4 & CAM both have low rates of PR

what is photophosphorylation?

process of converting light energy to chemical energy in form of ATP during PS

what is the relationship between photophosphorylation & the thylakoid membrane?

photophosphorylation takes place in the thylakoid membrane of chloroplast where light-dependent rxns take place

in what ways do C4 plants have an advantage over C3 plants?

spatial separation helps avoid photorespiration which C3 is prone to

explain temporal separation in CAM plants

at night CAM plants open their stomata for CO2 intake which is then converted to malic acid & stored in vacuoles

during day, stomata closes to minimize water loss: stored malic acid broken down to release CO2 used for the calvin cycle

why might CAM plants taste sweet during the day and sour at night?

during night, CO2 converted to organic acids
during day, acids break down to release CO2, sugars prod. during PS

what is the balanced equation for photosynthesis?

6CO2 + 6H2O -> C6H12O6 + 6O2

what is the overall equation for cellular respiration?

C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy (ATP)

what is the principle function of cellular respiration?

shifting stored energy to usable energy

what are the main events that occur during glycolysis?

glucose (6C molecule) is broken down to 2 pyruvate (3C each)

what is produced in glycolysis?

1) 2 NADH
2) 2 ATP
3) 2 pyruvate

where in the cell does the citric acid cycle occur?

matrix of mitochondria

what are the products of the citric acid cycle?

1) oxaloacetate
2) 2 ATP
3) 6 NADH
4) 2 FADH2

how does the flow of electrons in the electron transport chain result in the formation of ATP?

flow of electrons through ETC generates proton gradient & this energy is used by ATP synthase to produce ATP (oxidative phosphorylation)

how/why does the net energy yielded under aerobic conditions differ from that obtained under anaerobic conditions?

more NE yielded under aerobic compared to anaerobic

aerobic: oxygen is final e- acceptor in ETC which allows efficient prod of ATP through ox. phos.

no oxygen in anaerobic, ETC cant function, cells rely on fermentation (less efficient)

what is the central role of the citric acid cycle in cell metabolism?

glucose completely oxidized to CO2 & oxaloacetate regenerated

yields NADH & FADH2 for ATP prod. in ETC

what are the 6 major groups of plant hormones?

1) auxin
2) cytokinins
3) ethylene
4) abscisic acid
5) gibberellins
6) brassinosteroids

how do auxins contribute to plant development?

-signal devel. of lateral roots at pericycle
-vasc. tissue diff
-initiate adventitious roots

how do cytokinins contribute to plant development?

promote cell division

how does abscisic acid contribute to plant development?

prevents break in dormancy

how do gibberellins contribute to plant development?

-stimulate cell division & elongation
-hastens germination

how do brassinosteroids contribute to plant development?

vascular tissue differentiation

how does ethylene contribute to plant development?

regulates fruit ripening & leaf abscission

where is auxin synthesized?

shoot, roots, young leaves, seeds

where are cytokinins synthesized?

root tips, dividing seeds, fruits, leaves

where is abscisic acid synthesized?

leaves, roots, seeds

where are gibberellins synthesized?

young shoots, seeds

where are brassinosteroids synthesized?

throughout the plant, young tissue

where is ethylene synthesized?

ripening tissue

what is a tropism?

directional growth response of a plant part in response to external stimulus

by what mechanism do plants respond to light?

phototropism: shoot, petiole growth toward light

by what mechanism do plants respond to gravity?

gravitropism:
root growth downward, shoot growth upward

by what mechanism do plants respond to a moisture gradient?

hydrotropism

explain the starch-statolith hypothesis as it applies to roots:

amyloplasts in plants perceive gravity in the starch sheath (cells surrounding the vascular tissue)

why is it important that plants be able to "tell time"?

Important for resource allocation and processes locked around certain times of the day or a circadian rhythm

what are some characteristics of the circadian clock in plants?

-used to coordinate daily events & allow response to changing seasons by measuring daylength

-entrainment: periodic repetition of light & dark synchronize w/ an external factor

what precautions would you need to take to ensure that a chrysanthemum plant given to you in bloom & kept as a houseplant will bloom again?

-short day plants so need about 14hrs of dark and 10 hrs of light per day to trigger blooming

-avoid artificial light at night

-need cool environments

what type of effect does daylength have on flowering?

short-day plants: flower in shorter light periods

long-day plants:

require longer light periods to flower

day-neutral plants:

flower regardless

what is phytochrome?

photoreceptor that consists of a light-absorbing portion (chromatophore) & a protein

how is phytochrome involved in flowering?

influence timing of flowering by inhibiting gibberellin production

how is phytochrome involved in seed germination?

detects red light: when seeds exposed to light, PC promote germination by increasing gibberellins & breaking dormancy

how is phytochrome involved in stem growth?

inhibits elongation in presence of light when the plant has already had sufficient amount to ensure efficient energy use

what is dormancy?

period when seeds temporarily inactive to ensure germination in favorable conditions

what environmental cues may be necessary to break dormancy of seeds & buds?

stratification:
fire, winter, tumbling, rain, herbivores, disturbance

what advantages do molecular techniques have over comparative morphology & anatomy in assessing phylogenetic relationships?

ask

how do we classify organisms?

-cladistics: analyzes branching, produces cladogram

-molecular systematics: phylogenetic trees, DNA barcoding

what is taxonomy?

the science of naming and classifying organisms by organizing species into hierarchical groups based on shared characteristics & evolutionary relationships