plant phys exam 4 | Quizlet

Growth

Irreversible increase in size and/or volume

Differentiation

Changes in properties other than size

Development

Sum of growth and differentiation

During embryogenesis, cell fate is determined by:

-Cell position within the embryo

-Hormone gradients in the embryo

-Cell lineage within the embryo

-Intercellular signaling through plasmodesmata

Look at this flower. Pretty crazy, eh? This is called fasciation, and may result from inappropriate proliferation of the meristem during early development in the embryo. If this did indeed start during embryogenesis, from the list below, which is the most likely cause?

WUSCHEL activity became uncoupled from control by CLAVATA3

Auxin is considered a weak acid because the carboxylic acid of the acetic acid can be

-CH2-COOH (neutral) at pH 5 and -CH2-COOH+ (cation) at pH 7

-CH2-COOH+(cation) at pH 5 and -CH2-COOH (neutral) at pH 7

-CH2-COO-(anion) at pH 5 and -CH2-COOH (neutral) at pH 7

-CH2-COOH+(cation) at pH 5 and -CH2-COO- (anion) at pH 7

-CH2-COOH (neutral) at pH 5 and -CH2-COO- (anion) at pH 7

-CH2-COOH (neutral) at pH 5 and -CH2-COO- (anion) at pH 7

Shoot and root apical meristems need to be established in the embryo before differentiated tissues can develop

False

Embryo development is commonly grouped into stages based roughly on the shape of the developing embryo. Place the five widely recognized stages of Arabidopsis embryogenesis in the correct order:

First stage:

Second stage:

Third stage:

Fourth stage:

Fifth stage:

First stage: Zygotic

Second stage: Globular

Third stage: Heart

Fourth stage: Torpedo

Fifth stage: Mature

Match the color in this embryo with the organ(s) in the mature shoot

Dark green:

Orange:

Red:

Blue:

Beige:

(looking at the late heart stage)

Dark green: cotyledons and shoot

Orange: hypocotyl

Red: most of the root

Blue: root cap

Beige: suspensor

In botanical terms, a mature seed is a

dormant embryo, nutritive tissue, and a protective coat (integuments)

Monocot seeds are exceptionally important to modern human diets and our need to feed 9 billion people by 2050. Consider this wheat seed, and match the letters with the structure.

Seed coat (testa and pericarp)

Aleurone layer

Endosperm

Scutellum

Coleoptile and embryonic leaves

Radicle

When auxin promotes root bending in response to gravity, it does so by

migrating along the lower side of the root to inhibit cell elongation on the lower side

Germination in some species is stimulated if the seed first passes through the gut of a bird or other animal. This implies that germination in these species is mostly likely controlled by

Seed-coat imposed dormancy

Which statement is most true about seed dormancy and germination

Auxin promotes dormancy; cytokinin promotes vivipary

ABA promotes dormancy; GA promotes germination

Auxin promotes dormancy; cytokinin promotes germination

cytokinin promotes dormancy; auxin promotes germination

GA promotes dormancy; ABA promotes germination

ABA promotes dormancy; GA promotes germination

If I wanted to make a thousand gallons of corn whiskey in a forested region several miles from the nearest paved road, what plant hormone should I include in my nefarious operation?

Gibberellic acid

During germination, when does MAJOR mobilization of nutrient reserves start?

Shortly after the radicle emerges

Modern varieties of corn are more productive than those of ~70 years ago in large part because breeding affected the gibberellin signaling pathway to

Produce more healthy plants per acre

With respect to seed gemination, water impermeability, mechanical constraints, interference with gas exchange and retention of inhibitors are examples of

Seed-coat imposed dormancy

When it comes to seeds, a seed being in a quiescent state, and a seed being in a dormant state, are synonymous terms.

False

quiescent implies the plant will start to germinate eventually

dormant implies you need a trigger (such as a cold treatment) to cause germination

Photoblasty

Exposure to light

stratification

An extended cold treatment in a moist environment to promote germination

after ripening

A period of dry storage

imbibition

Water uptake

vernalization is not

Not related to germination

A hormone that can substitute for most of these (dormancy) signals

auxin

An important hormone not directly related to germination

gibberellic acid

A state where dormancy is not achieved

vivipary

Referring back to the question above, most of those treatments are thought to impact (directly or indirectly) the balance of hormones in the seed and thus, treating dormant seeds with ___________ can generally substitute for each of the treatments that promote germination.

Gibberellic acid

During germination, when do cell divisions start in the seedling?

Shortly after the radicle emerges

During a gravitropic response in roots, which is most true

1. Auxin is mobilized along the top of the root to cause cell expansion and downward bending

2. Gibberellic acid is mobilized along the top of the root to cause cell expansion and downward bending

3. Auxin is mobilized along the bottom of the root to inhibit cell expansion and downward bending

4. Gibberellic acid is mobilized along the bottom of the root to inhibit cell expansion and downward bending

3. Auxin is mobilized along the bottom of the root to inhibit cell expansion and downward bending

compound palmate leaf

leaves arise from a single point

Boundaries between different organs or tissues during development are commonly formed and maintained by

Mutual antagonism between development genes in each domain

The "top" side of a leaf is referred to as the _____________ side and develops _______________ the meristem; the "bottom" side of the leaf is referred to as the ____________ side and forms _________________ the meristem.

adaxial; toward; abaxial; away from

The position of where a new leaf will form on a growing stem correlates with

An auxin maximum in the peripheral zone of the shoot apical meristem

Vernalization is one example of signaling processes in which the response is manifest

In months or the span of seasons

The graft transmissible, phloem mobile signal called 'florigen' is thought to be

A protein

This is a mesquite leaf that I plucked from a mesquite tree outside the EESAT building. Note that it has a distinctive bifurcation and compound pinnate structure. Also note that the leaflets I have separated from the leaf show aberrant morphology and developed additional leaflets on the leaflets. If this development resulted from aberrant hormone distribution, the new leaflets likely correspond to localized increases in

Cytokinin

When a new leaf grows on a stem, the vascular system

starts within the new leaf and cells differentiate down toward the pre-existing vascular system in the stem

Senescence is best described as

A genetically controlled, developmental process of cell death and resource recycling or reutilization

A plant that dedicates all its resources to a single reproductive event and then dies, regardless of how many seasons lead up to that event, is best described as

Monocarpic

In the days of gas-powered street lights, a curious thing happened in London: Every year, towards the end of summer, the leaves of trees in the city would fall earlier than the leaves of the same types of trees out in the country. This was because the gas street lights increase the amount of __________ in the city.

Ethylene

The genes that are active in maintaining the meristematic nature of the shoot apical meristem are also the genes that are re-activated to allow compound leaves to generate leaflet. Those genes are

STM/KNOX

The formation of the vascular network in an expanding leaf blade, and the formation of a new vascular strand from a growing leaf to the existing vascular strand in the stem is attributed to

Auxin

Mature monocot and dicot seeds differ from each other with respect to:

nutrient reserves: monocots have food stored in the endosperm while most dicots store nutrients in the cotyledons at maturity

A horticultural technique commonly used in apple orchards allows a shoot with high quality fruit to be grown on top of a pest and stress resistant rootstock. This technique is called

Grafting

The phloem mobile signal called 'florigen' is thought to be

a protein

When the timing of flowering is controlled fully or at least partially by photoperiod, the signal to induce flowering at the meristem comes from

Leaves

Vernalization is one example of signaling processes in which the response is manifest

In months or the span of seasons

A mutation that impacts whorls 1 and 2 of the flower would be described as having

A function

A mutation in all three floral organ identity gene functions will most likely result in a floral structure derived entirely of

Leaves

If you grow an apple tree from a seed, you likely will not get flowers or fruits for four to eight years because

A juvenile period must be passed through

Arabidopsis is a facultative long day plant. This means that Arabidopsis

plants will flower earlier if exposed to long days

LEAFY (lfy) is a

Meristem identity gene

The fertilization of angiosperm flowers includes all of the following except

the pollen lands on the moist stigma and the two sperm cells swim toward the egg cell

when pollen reaches the stigma of a flower it begins to grow a pollen tube that pierces the style

pollen is transported to a stigma of a flower

double fertilization produces an embryo and the endosperm

the pollen tube grows until it reaches the ovule in the ovary

the pollen lands on the moist stigma and the two sperm cells swim toward the egg cell

Which of the following best describes the function of fruits?

storage of food for the plant to consume through the winter

protection and dispersal of seeds

protection from pollinators

rewards for pollinators

deterrent to herbivores, stopping them from eating leaves

protection and dispersal of seeds

When plants flower in response to seasonal daylength, they are responding to

The length of the dark/night period

True or False: In the coincidence model for induction of flowering, daylength signals need to coincide with signals intrinsic to the plant's circadian clock.

TRUE

Land plants have a reproductive cycle called "alternation of generation" in which there are both multicellular diploid and haploid stages. In organism with an alternation of generation life cycle, gametes (egg and sperm) are produced by

Mitosis

"Fruit" is best described as

the remaining floral structures which undergo further development rather abscising after pollination

When the radicle emerges from the seed, how does it know which direction it should grow?

The radicle respond to gravity and demonstrates gravitropism

Describe how auxin contributes to the direction of shoot growth in response to directional light - be sure to explain where the auxin levels are higher and lower in relation to that growth

Auxins promote root initiation. As more native auxin is transported down the stem to the roots, the overall development of the roots is stimulated. If the source of auxin is removed, such as by trimming the tips of stems, the roots are less stimulated accordingly, and growth of stem is supported instead. Auxin plays an important role in the gravitropism of plant roots. Auxin transmits the gravity signal from sensing cells, that is, columella cells, to the root elongation zone. When gravity is sensed, auxin is transported preferentially to the lower side of the root, which leads to the accumulation of auxin in the elongation zone. When seedlings are treated with inhibitors of either auxin influx or efflux, gravitropism is severely inhibited.

In a classic experiment, Ian Sussex carefully separated a leaf primordia from the adjacent apical meristem. What was observed?

The leaf primordia transitioned into a second apical meristem

Double pinnately compound leaf

In the tissue surrounding the apical meristem of a growing shoot, a local accumulation of __________________ will determine where the next new leaf will form.

Auxin

Formation of a distinct organ, tissue or cell type requires a boundary between the material that will form the organ tissue, or cell, and that which will not. Explain how such a boundary may arise (1 points) and give an example of such a boundary in plants (1 point).

Formation of a distinct organ, tissue or cell type requires a boundary between the material that will form the organ tissue or cell. Such boundary may arise because of the existence of molecular pre-pattern that is present in precursor tissues, or from inductive signals emanating from neighboring regions.

Example: Meristem/leaf boundary antagonism between KNOX and ARP gene

The formation of the vascular network in an expanding leaf blade, and the formation of a new vascular strand from a growing leaf to the existing vascular strand in the stem is attributed to

Auxin

Several genes in the strigolactone signaling pathway have the name "MAXIMUM AXILLARY BRANCHING" (MAX1, MAX2, etc.). Based on these gene names, strigolactone most likely

Inhibits outgrowth of axillary branches

In hormone research, if you hypothesized that a signal is produced in the root and influences growth in the shoot (or vice versa) describe a common experiment that you would do. Your answer should give the name of the technique, AND the outcome if your hypothesis is correct or incorrect.

Avena Curvature Test - performed on oat plants

In plant biology, "indeterminate growth" and "determinate growth" are important concepts. Define each term AND give an example of an ORGAN for each

Indeterminate growth: continual generation of new growth; stem cell population is regenerated. Example: stem or root.

Determinate growth: termination; stem cell population eventually undergoes terminal differentiation. Example: flower or fruit.

True or False: In large-scale, commercial tomato production (canned tomatoes, ketchup, etc), varieties that produce flowers and fruits continually throughout the growing season are preferred.

False

In the field of plant development, how a plant monitors its age is not well understood, a leading model discussed in lecture involves an age-related gradient of

microRNA 156/microRNA172

You are presented with a variety of chrysanthemum that is a typical short day plant and you are tasked with determining if phytochrome (red light receptors) or cryptochrome (blue light receptors) are involved in the response. Describe the experiments you would do

Expose short-day chrysanthemums to night-break pulses of red, far-red, or blue light. If red light inhibits flowering and far-red reverses it, phytochrome is involved. If blue light inhibits flowering, cryptochrome is likely responsible

A cold treatment that is required in some plants to signal the transition to flowering is called

Vernalization <- for flowering

At the molecular level, the speed with which a plant responds to vernalization can be understood as

Changes in histone structure and packaging of the genomic DNA at specific loci.

Describe the coincidence model of how the circadian clock works with photoperiod to induce flowering in Arabidopsis. Use pictures if it helps.

This model requires overlap between light signal and circadian oscillations.

During long days, illuminated periods overlap with CO protein expression, CO is NOT degraded, activated FT (flowering).

During short days, illuminated periods do not overlap CO protein expression, CO is degraded, no flowering.

A mutation in a Type B organ identity gene (homeotic gene) will alter the nature of the organs developing in

Whorls 2 and 3

In the ABC model of floral development, describe the function and location of "A function" genes, and what an Arabidopsis flower would look like if it had a "A function" mutation.

A function genes control sepal formation and a mutation in this would cause the formation of only carpels and stamens.

During Angiosperm development, pollen is made up of

Gametophyte tissue only

Some plant species self-pollinate very efficiently. Others have evolved morphological traits to limit self-pollination and promote outcrossing. Describe two such morphological adaptations to promote outcrossing (2 points, technical names of the processes are not required, but I'll give you bonus marks if know them; genetic mechanisms of self-incompatibility will not be accepted).

Dichogamy - the ripening of the stamens and pistils of a flower at different times, so that self-fertilization is prevented.

Heterostyly - is a genetic polymorphism in which flowers differ between individual plants of a species in heights at which the stamens and style are positioned

Sporophytic self-incompatibility involves genetic "communication" between the sporophyte that provides the pollen and the stigma of the sporophyte that harbors the egg cells. This signaling is possible because the pollen is

Two gametophyte sperm cells and a maternal pollen tube cell

During gametophytic self-incompatibility, RNases from the receiving style enter the growing pollen tube and degrade all the RNA in the pollen tube IF the RNase is recognized as "self"; this kills the pollen tube. If the RNase is recognized as "non-self"

Non-self RNases are tagged with ubiquitin and targeted to the proteosome for degradation.

reduces chromosome number to create spores (not gametes)

Meiosis

ABC model:

• A genes specify sepals (whorl 1)

• A and B genes specify petals (whorl 2)

• B and C specify stamens (whorl 3)

• C genes specify carpels (whorl 4)