Plant science chapter 11
Some plants can fling, squirt, or otherwise hurl their own seeds for some distance upon maturity. What is the maximum distance a seed is likely to travel using this mechanism?
12 meters
In addition to indolacetic acid (IAA) there are three other known naturally occurring auxins. What are they?
4-chloroindoleacetic acid Indolebutyric acid Phenylacetic acid
What is a tropism?
A movement in a plant caused primarily by external stimuli
When GA is applied to seeds, what is often eliminated?
A required period of cold before the seed will germinate
coconut
A substance from this plant's endosperm contained a compound that stimulated cell division.
corn
A substance similar to kinetin was isolated from seeds of this species.
How do auxins move through a plant?
ATP is expended to move auxin from cell to cell.
herring
An extract from heat-treated sperm of this organism was shown to stimulate cell division in tobacco.
Which of these were conclusions made by Kurosawa and colleagues in a series of experiments conducted starting in 1926?
An extract of the fungus that caused "foolish seedling" disease could be applied to uninfected seedlings and cause symptoms of the disease.
What kind of movement is considered "nodding" in a plant?
As legume seedlings germinate, the hypocotyl moves from side to side as it pushes through the soil.
What plant hormone (natural or synthesized) can promote uniform flowering on fruit trees, prevent premature fruit drop, and prevent the production of too many small fruits when applied to fruit trees?
Auxin
Brassinosteroids
Binding to receptors on cell surfaces, these compounds affect apical dominance, gravitropism, and germination.
Which lesser-known hormone (not one of the Classic Five) is known to affect apical dominance?
Brassinosteroids
Synthetic auxins at low concentration have been shown to effectively kill many kinds of weeds. Which type of weeds are most vulnerable to this type of herbicide?
Broad-leaved plants
By varying the amount of cytokinin in cell culture of tobacco pith cells, what two kinds of plant tissues can be produced?
Buds (that become stems) Roots
What kind of cells allow grasses to move in ways that help them conserve water?
Bulliform cells
What do we call cycles in plant metabolism, growth, and movements that seem to follow a 24-hour biological clock?
Circadian rhythms
What kind of movement allows bulbs to pull themselves deeper into the soil?
Contraction movement
Which plant hormone is produced in larger and larger amounts as fruits ripen?
Ethylene
Which of these are major types of plant hormones?
Ethylene Gibberellins Auxins
In 1926, Kurosawa and colleagues extracted a compound from a fungus that caused abnormal growth in rice seedlings that eventually led to the death of the plants. What plant hormone was found in the extract and was responsible for the disease symptoms?
Gibberellin
What plant hormone do most commercially available growth retardants block?
Gibberellin
What plant hormone, if applied to a plant, will speed the conversion of juvenile plants into adult plants that are capable of flowering? Multiple choice question.
Gibberellin
What is a growth response to the stimulus of gravity called?
Gravitropism
The auxin with the acronym_____was believed to be the only naturally occurring active auxin until PAA, IBA, and 4-chlorolAA were found.
IAA
Which of these studies were critical in the discovery of ethylene as a plant hormone?
In 1901, Neljubow saw that pea seedlings had unusual growth in a dark laboratory. In the fresh air the effects were reversed. In 1934, Gane discovered that fruits produced ethylene which promoted their own ripening.
Where is ABA synthesized in a plant?
In plastids
Which of these are typical responses of plants to GA?
Increased shoot growth (but not root growth). Increased plant growth in dicots.
Which of these are industrial uses for synthesized GA?
Increasing the size of seedless grapes Increasing yield of sugarcane Increasing the length of celery petioles
What effect does abscisic acid have on leaf abscission?
It has little if any effect.
Which of these are true of phytochrome?
It is responsible for controlling photoperiodism. It occurs in two stable forms that are readily converted to each other.
What effect does ABA have on seeds in a ripening fruit?
It prevents germination.
Which of these were discoveries that were important to the isolation of cytokinin and learning about its effect on cell division?
Johannes van Overbeek discovered that coconut milk contained a compound that stimulated cell division. A substance similar to kinetin was isolated from corn kernels. Kinetin was isolated from heat-treated herring sperm.
What is taxic movement?
Movement of whole organisms or reproductive cells that are propelled by cilia or flagella
What are the spiraling movements called that are made by the tip of a plant as it grows?
Nutations
What do we call a plant's ability to detect daylength and use it as a cue for growth and development?
Photoperiodism
Which of these are industrial uses of cytokinins?
Prolonging the shelf life of harvested vegetables Lengthening the life of cut flowers.
Oligosaccharins
Released from the cell wall, these compounds influence cell differentiation, reproduction, and growth.
Where are cytokinins synthesized in plants (choose all that apply)?
Root tips Germinating seeds
Which of these qualify as plant movements that cause seed dispersal?
Seed pods split with explosive force, flinging seeds. In the squirting cucumber, pressure builds up inside the fruit, until seeds are expelled out of one end, up to 10 meters.
What is the breakdown of cell components that leads to cell death called?
Senescence
What do cytokinins do in the presence of auxin?
Speed up the progression from the G2 phase to the mitosis phase
When water is in short supply, what happens to ABA in a plant?
The ABA causes stomata to close. As leaves wilt, ABA is produced in the leaves in larger amounts.
What did Charles Darwin observe about coleoptiles and light?
The coleoptiles bent toward the light.
What did Frits Went learn by putting coleoptiles on agar?
There was a growth factor in the coleoptiles that moved into the agar. Blocks of agar that had growth factor in it caused a plant growth response when they were put on decapitated coleoptiles.
How do gibberellins move through a plant?
They move through xylem and phloem, and the movement is not polar.
How did Charles Darwin and his son Francis test the hypothesis that coleoptiles of germinating grasses detected light, allowing plant shoots to grow toward it.
They put metal foil caps on the coleoptiles, and they did not grow toward the light.
What effect do cytokinins have on cell division?
They stimulate it.
What is it called when a plant develops a shorter, sturdier stem in response to mechanical stress such as high wind?
Thigmomorphogenesis
When plants are subject to mechanical stress such as high winds or repeated trampling, they can respond by developing a shorter, thicker stem than they would have. This response is called______
Thigmomorphogenesis
Why might you apply synthetic auxin to your lawn?
To kill broad-leaved weeds
Which of these are ways that auxins are used industrially to promote plant growth?
To promote uniform flowering and fruit set To stimulate root growth on cut stems
Which of these are commercial uses for ethylene in agriculture?
To ripen harvested green fruits To color up citrus fruits
Why might a farmer apply cytokinin to wheat as it's growing?
To shorten the straw length, making it sturdier in the wind.
Which of these are effects that auxin generally has on plants?
Triggering the production of ethylene. Stimulating the enlargement of cells.
______are movements in plants caused primarily by external stimuli coming from a specific direction.
Tropisms
What kind of plant movement allows a vine to grab onto a fence, trellis, or other plant it has touched?
Twining movement
Which of these can cause in increase in ethylene production (choose all that apply)?
When tissues are bruised or cut When a neighboring fruit ripens When auxin is applied When seedlings have trouble pushing through the soil
Select all of the following sites in plants where auxin is produced?
Young leaves Apical meristems
Strangely,_____acid is a plant hormone that has almost nothing to do with leaf abscission in plants.
abscisic
Unlike auxin, which is synthesized in embryonic tissues and moves in a polar fashion, the plant hormone___________ __________is synthesized in plastids, and its movement through the plant is nonpolar
abscisic acid
In many plants, the growth of lateral buds is suppressed by the presence of a branch tip. This is known as______dominance
apical
What condition is often broken in plants when the apical bud is removed?
apical dominance
Where are auxins primarily produced?
apical meristems
An application of GA will stimulate growth in many types of plants. What else needs to be present to maximize the results?
auxin
The first plant hormone discovered,_______has been shown to stimulate stem growth and cell elongation, inhibit lateral branching, and delay leaf abscission.
auxin
What was the first plant hormone to be discovered?
auxin
With the help of______cells, some grass species are able to roll their leaves to conserve water in dry times.
bulliform
Many plants exhibit patterns of metabolism and growth that follow a 24-hour cycle or biological clock. These patterns are called____rhythms and are common in animals as well.
circadian
The bulbs of a number of plants seek a soil depth that keeps differences between day and night time temperatures to a minimum. These bulbs have specialized_____roots that allow them to pull themselves deeper into the soil through______movements.
contractile contraction
In 1941, Johannes van Overbeek isolated a substance from coconut milk that promoted cell division. That substance was later shown to be ______.
cytokinin
In cell culture, auxins cause cells to enlarge, but what hormone must be applied to get cells to divide?
cytokinin
While plant hormones can have dramatic effects on their own, they can stimulate even more outcomes when acting in combination. For example,______need to have a small amount of auxin around to speed up the G2 phase of cell division.
cytokinins
Apples are available in supermarkets all year long because they are harvested before they are ripe and put in a sealed warehouse that is refrigerated and oxygen-free. Just before going to market, distributors can expose the apples to_______and they will ripen up as they are put onto store shelves. Listen to the complete question
ethylene
Before electric lights were widely available, gas lamps were used to light and heat many buildings. Because these lamps produced______as a by-product, they likely sped the discovery that this simple hydrocarbon could act as a plant hormone.
ethylene
Where do plants typically obtain their nutrients?
from the air and soil
If a growth retardant is applied to a plant, typically it is designed to inhibit or block the synthesis of_______resulting in shorter, thicker stems and generally smaller plants.
gibberellin
There are only a few types of plant hormones, but some types are made up of several specific chemicals. For example,_____is a group of more than 100 known compounds.
gibberellin
Which plant hormone can increase seed production in conifers, delay the aging of skin in citrus fruits, and increase the rate of malting in breweries?
gibberellin
he "classic five" plant hormones include auxins,_______cytokinins, abscisic acid, and ethylene.
gibberellins
Plant growth can respond to a number of external stimuli. For example, plant shoots may be positively phototrophic, growing toward a light source, or they may be positively__________growing toward gravity.
gravitropic, gravitropisms, or gravitropism
The biological process by which plants increase in size due to the division and enlargement of cells is called
growth
What process causes an irreversible change in plant size as a result of cell division and expansion?
growth
What is the main effect of auxin on plant growth?
it promotes growth
How many kinds of gibberellins are currently known to scientists?
more than 100
Legume seedlings make a slow oscillating movement as they push their hypocotyl through the soil following germination. What is the movement called?
nodding
Charles Darwin showed that the growing shoot tip of a plant makes______or spiral movements, as it grows taller.
nutations
Which of the following furnishes both the elements and energy for plant growth?
nutrients
Plants have the ability to sense the changing seasons by keeping track of the length of light and dark periods in each 14 hour cycle. This______allows plants to manifest major developmental changes, such as flowering, at the correct time of year.
photoperiodism
The movement of auxin is_____meaning that it is made in one part of the plant and moves away from its source.
polar
Unlike the_____movement of auxin through a plant, which involves active transport and consumption of ATP to move the chemical from its point of origin, gibberellins move through the xylem and_____
polar phloem
Most plants grow toward a light source, exhibiting_____phototropism. A plant that grows away from a light source would exhibit_________phototropism
positive negative
A plant that grows toward a light source is said to be demonstrating
positive phototropism
As plant cells age, their membranes and components will eventually break down, leading to______or the death of the cell.
senescence
What kind of movement involves either an entire plant or its reproductive cells being propelled by a cilia or flagella? This only occurs in fungi and non-flowering plants.
taxis
Cytokinins are synthesized in areas with a lot of cell division occurring, such as in root____and germinating seeds.
tips
Scientists can induce____and organ development, creating an entire new plant, by controlling cytokinin and auxin concentrations in a growth medium.
tissue
What is it called when a few cells are combined in a growth medium with the correct concentrations of auxin and cytokinin to create an entire new plant?
tissue culture
_______are movements in plants caused primarily by external stimuli coming from a specific direction.
tropisms
Vines with tendrils will elongate one side of the tendril in response to touch. The spiraling movement or______movement attaches the plant to fences, posts, or other plants nearby, adding additional support to the plant.
twining
