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Botany Test 3 > Test 3 > Flashcards

Test 3 Flashcards

(61 cards)

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1
Q

List 4 tissues that make up the angiosperm seed

A

The seed coat (testa)
An aleurone layer (functional or not)
Variable amounts of endosperm (or none)
The embryo

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2
Q

Give 3 functions for seeds

A

Seeds are a means of reproduction
Seeds result in dispersal of the species
Seeds protect the species through bad times

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3
Q

The root quiescent center and distal initials are formed from the ________

A

hypophyseal cell

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4
Q

Give 4 functions for the seed coat

A

Physical protection of the embryo
A barrier to prevent water entry into the dry seed
A barrier to fungal or bacterial invasion
Sometimes it is designed to help seed dispersal

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5
Q

List in order 3 events that occur during seed maturation

A

The seed detaches from the parent plant and desiccates
The integuments harden and form the seed coat
ABA is expressed in the seed to enforce dormancy

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6
Q

The plant hormone ______ enforces dormancy while the plant hormone _____ induces germination

A

ABA

GA

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7
Q

Differentiate between seed imbibition and seed germination

A

Seed Imbibition is when a quiescent seed comes into contact with water and water is taken up by purely physical force

Seed Germination starts with the restart of central metabolism and ends when one part of the embryo escapes from the seed coat, usually the radicle.

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8
Q

The outermost layer of endosperm develops into an aleurone layer. Describe how the aleurone layer functions.

A

After germination, GA synthesized and secreted by the embryo diffuses to the aleurone layer where it induces the synthesis and secretion of hydrolytic enzymes that digest the endosperm to nourish the developing seedling

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9
Q

Ovules develop into seeds and the ovary wall develops into the _____

A

fruit

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10
Q

Differentiate between a true fruit and an accessory fruit

A

True fruit - only the ovary wall is incorporated into the fruit

Accessory fruit - other floral parts are also incorporated into the fruit - examples are sepals, petals, and receptacles

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11
Q

Fruits can be classified in part based upon the arrangement and union of pistils. Define what is meant by simple fruits, aggregate fruits, and multiple fruits.

A

Simple - result from a single flower with one pistil

Aggregate - results from several pistils aggregated in a single flower

Multiple - result from multiple flowers, an inflorescence, with each flower producing a fruit, with these fruits maturing into a single mass

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12
Q

The ovary wall or pericarp often consists of three distinct layers. List these layers from the outside of the fruit towards the inside

A

Exocarp
Mesocarp
Endocarp

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13
Q

A dry dehiscent fruit derived from one carpel that splits down two sides is called a ______

A

legume

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14
Q

Describe a silique

A

Fruits of the mustard family, Brassicaceae
A dry dehiscent fruit from 2 carpels separated by a septum
More than twice as long as wide

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15
Q

The pepo is an accessory fruit, describe how it is formed

A

Pepo is a berry from an inferior ovary sunken into receptacle tissue, so the accessory fruit that results is from the ovary fused with the receptacle

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16
Q

Describe in order 3 steps involved in fleshy fruit ripening

A

Changes in texture (cell wall loosening and a decrease in turgor pressure)
Changes in appearance (chlorophyll is degraded and carotenoids accumulate)
Changes in flavor and aroma (starch converted to sugar, volatiles synthesized and released)

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17
Q

What are climacteric fruits

A
  • Have an increase in ethylene production and then an increase in respiration during later stages of ripening
  • The burst in respiration provides energy for fruit ripening
  • Examples include tomato, apple, banana, most stone fruits
  • The ethylene affects the transcription and translation of many ripening related genes
  • An ethylene- independent pathway may also be operating similar to what occurs in non-climacteric fruits
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18
Q

Respiration can be thought of as occurring in 4 steps. List these steps in the order they occur

A

Breakdown of storage and translocation forms of carbs
Glycolysis
Krebs cycle
Electron transport chain

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19
Q

Starch, sucrose, and fractans are broken down to _______ for entry into glycolysis

A

fructose-6- phosphate

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20
Q

List the 3 products of glycolysis, and indicate their fate

A

Pyruvate -to mitochondria used by Krebs cycle
NADH - to mitochondria used by ETC
ATP - to cell to do work within the cell

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21
Q

Give the products of the Krebs Cycle that are used by the electron transport chain

A

NADH and UQH2

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22
Q

List the components of the plant electron transport chain in the order of their engagement

A
  • matrix NADH dehydrogenase complex
  • ubiquinone
  • cytochrome bc1 complex
  • cytochrome c
  • cytochrome oxidase
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23
Q

The plant ETC results in protons being pumped into the ___________ ____ and this proton gradient is eventually used for _____ _________

A

intermembrane space

ATP synthesis

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24
Q

The plant ETC is called a branched pathway. Explain what this means and give the primary function of each branch

A

ubiquinone pool can be used by 2 pathways
When used by cytochrome pathway - ATP produced
When used by alternative pathway - heat produced

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25
List the end products of the ETC
ATP and water
26
Plants that are thermogenic have lots of the _______ _______
alternative pathway
27
When O2 becomes limiting, What happens to the ETC and the Krebs cycle?
They stop, ETC stops first then the Krebs Cycle stops
28
Define visible light and give the wavelength range involved
light that a human can see 400- 700 nm
29
The PETC can be thought of as occurring in via 6 ordered components. List these in the order they become involved
- PS II - plastoquinone - cyt b6f complex - plastocyanin - PS I - ATPase
30
In reference to the above question, explain where proton pumping occurs
- 2 protons in lumen as result of splitting water - 4 protons are pumped into lumen by plastoquinone and the cyt b6f complex - 1 proton is consumed in stroma through formation of NADPH
31
Give the three products of the light reactions of photosynthesis
O2, ATP, NADPH
32
The dark reaction of PS can be thought of as occurring in 3 steps. List these steps and indicate where the products of the light reactions are used
- Fixation of CO2 into 3-phosphoglycerate - Reduction of 3-phosphoglycerate to 3-phosphoglyceraldehyde (uses NADPH and ATP) - Regeneration of RuBP for the cycle to continue (uses ATP)
33
What is the most prevalent protein on earth?
Rubisco
34
Give 3 fates for 3- phosphoglyceraldehyde
- turned into starch inside of the chloroplast - shipped out of the chloroplast and turned into sucrose - shipped out of the chloroplast and used in the same cell for respiration
35
Give the 2 reactions that the most prevalent protein catalyzes
Fixes CO2 - RuBP+CO2 ------> 2 molecules of 3-PGA Fixes O2 - RuBP+O2 ----> 1 molecule of 3-PGA and 1 molecule of phosphoglycolate
36
Why is photorespiration a bad thing for plants
- no CO2 fixed - something has to be done with the 2C molecules - CO2 is released
37
Compare C3, C4, and CAM types of photosynthesis
C3- rubisco in the chloroplasts of mesophyll cells during the day C4 - PEPcase in chlorooplasts of mesophyll cells during day, then rubisco in chloroplasts of bundle sheath cells during the same day CAM- PEPcase in cytosol of mesophyll cells during the night, then rubisco in chloroplasts of mesophyll cells the next day
38
Plant growth and development can be thought of as occurring as the result of 5 processes. List these in order
cell division cell enlargement cell maturation patterned differentiation of cells into tissues organization of tissues into organes and then the whole plant
39
Define growth
Permanent increase in the size of an organism
40
Define development
genetically programmed progression from a simpler to a more advanced or complex form
41
Define what a plant hormone is
organic molecule or a small protein produced in small amounts, usually synthesized in one region and transported to another region to have its effect, the effect can inhibit or promote a process
42
Explain how cells are differentially responsive to plant hormones
- cells need receptors for hormones to be effective - receptor then initiates a signal transduction pathway to regulate gene expression and/ or enzyme activity - 2 things determine a cell's differential response to a plant hormone, concentration of hormone, and presence or absence of receptors
43
List the 5 traditional plant hormones
``` Auxins Cytokinins Gibberellins Abscisic Ethylene ```
44
Explain the mechanism behind phototropism
- initiated by blue light - blue light causes phosphorylation of a flavin-containing protein called phototropin - this starts a signal transduction pathway that results in auxin being transported to the dark side where auxin effects cell elongation - this results in stem bending toward the light and roots grow away from light, into soil
45
Describe polar auxin transport from the apical meristem
- auxin is often produced in apical meristems and moves down the plant through parenchyma cells within the vascular bundles - auxin influx carriers are usually located at top of cells, whereas auxin efflux carriers usually located at bottom of cells. The action of these transporters moves auxin down the stem in a polar manner - auxin transport requires energy and is slow at about 1 cm/ hr
46
Explain the roles of auxins and cytokinins in apical dominance
- balance of cytokinins from root tip and auxins for shoot apical meristem - auxins inhibit axillary bud growth and stimulate root growth - cytokinins stimulate axillary bud growth and inhibit root growth
47
Describe the discovery of gibberellins
- discovered by Eiichi Kurosawa in Japan in 1926 - discovered through investigation of "foolish seedling" disease in rice (seedlings elongate too much then fall over) - elongation caused association of a fungus with the roots - an extract of this fungus also caused the stem elongation - fungus was of genus Gibberellia
48
Which plant hormone is produced in plastids from carotenoids?
Abscisic acid (ABA)
49
The synthesis of ethylene is autocatalytic. Explain the significance of this. Use a diagram if helpful.
- one rotten apple spoils the whole bunch - ethylene stimulates its own synthesis, so when little is produced, its production increases exponentially - Since it is a gas, it spreads to other regions of the plant, or to other plants, where it stimulates ethylene production
50
Auxins have a role in phototropism and gravitropism. Describe the common mode of action
- result from uneven growth - Specific auxin transporters are used to concentrate in specific regions - - in shoot phototropism, auxins moved to dark side, thus that side elongates - - in shoot gravitropism, auxins move to new lower side, thus that side elongates - Auxin influx carriers stay in the same position while auxin efflux carriers change positions
51
Starting with the plant embryo at the 8-cell stage, describe what parts of the embryo are formed from the upper tier and from the lower tier of cells
Upper tier- shoot apical meristem, most of the cotyledon Lower tier- lower shoulder of cotyledon, hypocotyl, root, proximal initials of the root meristem
52
In the apical domain of the plant embryo explain what happens after initiation of the first cotyledon
- 2nd cotyledon is produced opposite of it - Shoot apical meristem is formed - First leaf is formed perpendicular to the 2 cotyledons - 2nd leaf is formed opposite of first leaf - phyllotaxy pattern is established
53
Capsules can dehisce in several ways. List 3.
- along the mid vein of a carpel - along the union of 2 carpels - through the formation of pores
54
Plants that are rapidly growing have high respiration rates. Explain
- central metabolism provides carbon skeletons for synthesis of materials for growth - as these molecules are removed from central metabolism, respiration increases to replace them - so high respiration rate is associated with rapid growth
55
Pyruvate and NADH from glycolysis are used in fermentation when not enough O2 is present. Explain how this occurs in plants.
- Initially they are used to make lactic acid - That drops the pH of the cytosol - This activates alcohol dehydrogenase - Ethanol is produced from pyruvate and NADH - This converts NADH back to NAD which is used to keep glycolysis going - this provides some ATP for the cell, usually just enough to keep the cell alive
56
The Krebs Cycle can be thought of as occurring in 3 steps. List these along with their products that leave the cell.
1. Conversion of pyruvate to acetyl CoA which releases 1 CO2 and produces 1 NADH 2. Condensation of acetyl CoA with OAA to form citrate which yields no products 3. Regeneration of OAA for the cycle to continue which forms 3 NADH, 1 ATP, and 1 UQH2 and releases 2 CO2
57
For sucrose, starch, and fructans give the following: where are they synthesized, what is the nature of the molecule, and where are they used for storage or translocation
Starch- plastids, large polymer of glucose, storage Sucrose- cytosol, disaccharide of glucose and fructose, translocation Fructans- vacuole, small polymer of fructose, storage
58
Explain how light harvesting complexes function. What components are present?
- several chlorophyll molecules, along with carotenoids and xyanthophylls, are used as an antennae to enlarge the area for reception of a photon of light - once the energy of a photon of light has been captured, it is transferred from 1 pigment molecule to the next until it reaches the reaction center. It is called an exciton as it is being transferred - at the reaction center the energy of the exciton is used to move an electron out of P680 or P700. In PSII this electron goes to plastoquinone and in PSI the electron goes to ferridoxin
59
Starting with the absorption of light by the light harvesting complex of PSII, describe the electron flow through to NADP reduction
- light is absorbed by PSII and takes electron from the splitting of water to PQ - PQ carries 2 electrons and 2 protons, so after it receives 2 electrons it picks up 2 protons from the stroma - PQ carries them to the lumen side and passes the electrons to cyt b6f complex - cyt b6f complex along with PQ conducts a Q-cycle, doubling the number of protons pumped to 4 - electrons pass from b6f complex to plastocyanin which carries them to PSI - at PSI, light is absorbed and transfers the electrons to ferridoxin - Ferridoxin gives the electrons to NADP forming NADPH
60
The acid growth hypothesis is important for expansion of cells that have secondary cell walls. Explain this hypothesis
- plasma membrane ATPase pumps protons into cell wall space, where they lower the pH and activate cell wall loosening enzymes - once cell wall loosened, solutes are put into the vacuole and this results in water entering osmotically and puts pressure on the cell wall enlarging the cell
61
Explain senescence of a leaf
- extended form of programmed cell death - extra time is used to mine plant organs - chloroplasts are broken down first - nucleus is the last to go - proteins leave as amino acids, carbohydrates as sucrose - only the cell wall and some starch are left and the leaf senesces

Botany Test 3 (1 decks)

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