BIO 102 exam 4

** According to the ABC model of floral development, which genes would be expressed in a showy ornamental flower with multiple sepals and petals but no stamens or carpels? A) A genes only. B) B genes only. C) C genes only. D) A and B genes only. E) A and C genes only.

D) A and B genes only.

Apoptosis is?

Genetically regulated form of cell death

Adventitious roots?

In stems with secondary growth these often originate in phloem parenchyma near the vascular cambium. In stem cuttings, sometimes also originates in the callus cells that form at the cut surface. Leaf cuttings of the Crassula form adventitious roots in the epidermis

** In general, which of the following is not a plant response to herbivores? A) Domestication, so that humans can protect the plant B) attracting predatory animals, such as parasitoid wasps C) chemical defenses, such as toxic compounds D) physical defenses, such as thorns E) production of volatile molecules

A) Domestication, so that humans can protect the plant

If you wanted to genetically engineer a plant to be more resistant to drought, increasing amounts of which of the following hormones might be a good first attempt? A) abscisic acid B) brassinosteroids C) gibberellins D) cytokinins

A) abscisic acid

The opening of stomata is thought to involve A) an increase in the osmotic concentration of the guard cells. B) a decrease in the osmotic concentration of the stoma. C) active transport of water out of the guard cells. D) decreased turgor pressure in guard cells. E) movement of K+ from the guard cells.

A) an increase in the osmotic concentration of the guard cells.

Which one of the following is not a direct function of either auxin or gibberellin? A) inducing semescence and ripening B) producing apical dominance C) producing positive geotropism of shoots D) stimulating cell elongation E) breaking dormancy in seeds

A) inducing semescence and ripening

What is the main function of petals in the plant?

Attracts insects to pollinate - typically produce nectar and are sometimes scented

Which of the following statements about plant hormones is false? A) The growth of plants in nature is probably regulated by a combination of growth-stimulating and growth-inhibiting hormones. B) Abscisic acid generally promotes growth. C) Gibberellins stimulate cell enlargement. D) Cytokinins promote cell division. E) Ethylene contributes to the aging of plants.

B) Abscisic acid generally promotes growth.

** What is the probable role of salicylic acid in the defense responses of plants? A) destroy pathogens directly B) activate systemic acquired resistance of plants C) close stomata, thus preventing the entry of pathogens D) activate heat-shock proteins E) sacrifice infected tissues by hydrolyzing cells

B) activate systemic acquired resistance of plants

** In systemic acquired resistance, salicylic acid probably A) destroys pathogens directly. B) activates defenses throughout the plant before infection spreads. C) closes stomata, thus preventing the entry of pathogens. D) activates heat-shock proteins. E) sacrifices infected tissues by hydrolyzing cells

B) activates defenses throughout the plant before infection spreads.

** The biological clock controlling circadian rhythms must ultimately A) depend on environmental cues. B) affect gene transcription. C) stabilize on a 24-hour cycle. D) speed up or slow down with increasing or decreasing temperature. E) do all of the above.

B) affect gene transcription.

Which plant hormones might be used to enhance stem elongation and fruit growth? A) brassinosteroids and oligosaccharides B) auxins and gibberellins C) abscisic acid and phytochrome D) ethylene and cytokinins E) phytochrome and flowering hormone

B) auxins and gibberellins

Which plant hormone(s) is (are) most closely associated with cell division? A) ethylene B) cytokinin C) abscisic acid

B) cytokinin

Axillary buds A) are initiated by the cork cambium. B) develop from meristematic cells left by the apical meristem. C) are composed of a series of internodes lacking nodes. D) grow immediately into shoot branches. E) do not form a vascular connection with the primary shoot.

B) develop from meristematic cells left by the apical meristem.

** The plant hormone involved in aging and ripening of fruit is A) auxin. B) ethylene. C) florigen. D) abscisic acid. E) gibberellin

B) ethylene.

Stomata open when guard cells A) sense an increase in CO2 in the air spaces of the leaf. B) open because of a decrease in turgor pressure. C) become more turgid because of an addition of K+, followed by the osmotic entry of water. D) close aquaporins, preventing uptake of

B) open because of a decrease in turgor pressure.

Based on the ABC model, what would be the structure of a flower that had normal expression of genes A and C and expression of gene B in all four whorls? A) carpel-petal-petal-carpel B) stamen-stamen-petal-petal C) sepal- carpel-carpel-sepal D) sepal-sepal-carpel-carpel E) carpel-carpel-carpel-carpel

B) stamen-stamen-petal-petal

__________ is to xylem as __________ is to phloem. A) Sclerenchyma cell; parenchyma cell B) Apical meristem; vascular cambium C) Vessel element; sieve-tube member D) Cortex; pith E) Vascular cambium; cork cambium

C) Vessel element; sieve-tube member

** ʺTotipotencyʺ is a term used to describe the ability of a cell to give rise to a complete new organism. In plants, this means that A) plant development is not under genetic control. B) the cells of shoots and the cells of roots have different genes. C) cell differentiation depends largely on the control of gene expression. D) a cellʹs environment has no effect on its differentiation. E) sexual reproduction is not necessary in plants.

C) cell differentiation depends largely on the control of gene expression.

If you were shipping green bananas to a supermarket thousands of miles away, which of the following chemicals would you want to eliminate from the plantsʹ environment? A) CO2 B) cytokinins C) ethylene D) auxin E) gibberellic acids

C) ethylene

Plant growth regulators can be characterized by all of the following except that they A) may act by altering gene expression. B) have a multiplicity of effects. C) function independently of other hormones. D) control plant growth and development. E) affect division, elongation, and differentiation of cells.

C) function independently of other hormones.

Incandescent light bulbs, which have high output of red light, are least effective in promoting A) photosynthesis. B) seed germination. C) phototropism. D) flowering. E) entrainment of circadian rhythms.

C) phototropism.

The transduction pathway that activates systemic acquired resistance in plants is initially signaled by A) antisense RNA. B) Pfr phytochrome. C) salicylic acid. D) abscisic acid. E) red, but not far-red, light.

C) salicylic acid.

** CO2 enters the inner the inner spaces of the leaf through the A) cuticle. B) epidermal trichomes. C) stoma. D) phloem. E) walls of guard cells.

C) stoma.

Buds and sprouts often form on tree stumps. Which of the following hormones would you expect to stimulate their formation? A) auxin B) cytokinins C) abscisic acid D) ethylene E) gibberellins

B) cytokinins

Which hormone is incorrectly paired with its function? A) auxin-promotes stem growth through cell elongation B) cytokinins- initiate programmed cell death C) gibberellins-stimulate seed germination D) abscisic acid-promotes seed dormancy E) ethylene-inhibits cell elongation

B) cytokinins-initiate programmed cell death

Cells elongate in response to auxin. All of the following are part of the acid growth hypothesis except A) Auxin stimulates proton pumps in cell membranes. B) Lowered pH results in the breakage of cross-links between cellulose microfibrils. C) The wall fabric becomes looser (more plastic). D) Auxin-activated proton pumps stimulate cell division in meristems. E) The turgor pressure of the cell exceeds the restraining pressure of the loosened cell wall, and the cell takes up water and elongates

D) Auxin-activated proton pumps stimulate cell division in meristems.

** Biological clocks cause organisms to perform daily activities on a regular basis. Which of the following is a false statement about this kind of ʺcircadian rhythmʺ? A) It may have the same signal transduction pathway in all organisms. B) It must be reset on a daily basis. C) It may help to cause photoperiodic responses. D) Once set, it is independent of external signals. E) The exact mechanism of biological clocks remains unknown.

D) Once set, it is independent of external signals.

Ethylene, as an example of a plant hormone, may have multiple effects on a plant, depending on all of the following except the A) site of action within the plant. B) developmental stage of the plant. C) concentration of ethylene. D) altered chemical structure of ethylene from a gas to a liquid. E) readiness of cell membrane receptors for the ethylene.

D) altered chemical structure of ethylene from a gas to a liquid.

Plant hormones can have different effects at different concentrations. This explains how A) some plants are long-day plants and others are short-day plants. B) signal transduction pathways in plants are different from those in animals. C) plant genes recognize pathogen genes. D) auxin can stimulate cell elongation in apical meristems, yet will inhibit the growth of axillary buds. E) they really donʹt fit the definition of ʺhormone.ʺ

D) auxin can stimulate cell elongation in apical meristems, yet will inhibit the growth of axillary buds.

When growing plants in culture, IAA is used to stimulate cell enlargement. Which plant growth regulator has to now be added to stimulate cell division? A) ethylene B) indoleacetic acid C) gibberellin D) cytokinin E) abscisic acid

D) cytokinin

** The ripening of fruit and the dropping of leaves and fruit are principally controlled by A) auxins B) cytokinins C) indole acetic acid D) ethylene E) carbon dioxide concentration (in air)

D) ethylene

** In attempting to make a seed break dormancy, one logically could treat it with A) IAA. B) 2, 4-D. C) CO2. D) gibberellins. E) abscisic acid

D) gibberellins.

A short-day plant will flower only when A) days are shorter than nights. B) days are shorter than a certain critical value. C) nights are shorter than a certain critical value. D) nights are longer than a certain critical value. E) days and nights are of equal length.

D) nights are longer than a certain critical value.

Plants that have their flowering inhibited by being exposed to bright lights at night are A) day-neutral plants. B) short-night plants. C) devoid of phytochrome. D) short-day plants. E) long-day plants.

D) short-day plants.

A long-day plant will flower if A) the duration of continuous light exceeds a critical length. B) the duration of continuous light is less than a critical length. C) the duration of continuous darkness exceeds a critical length. D) the duration of continuous darkness is less than a critical length. E) it is kept in continuous far-red light.

D) the duration of continuous darkness is less than a critical length.

** Which of the following are the water-conducting cells of xylem, have thick walls, and are dead at functional maturity? A) parenchyma cells B) collenchyma cells C) clerenchyma cells D) tracheids and vessel elements E) sieve-tube elements

D) tracheids and vessel elements

According to modern ideas about phototropism in plants, A) light causes auxin to accumulate on the shaded side of a plant stem. B) auxin stimulates elongation of plant stem cells. C) auxin is produced by the tip of the coleoptile and moves downward. D) A and B only E) A, B and C

E) A, B and C

Negative gravitropism of plant shoots A) depends upon auxin distribution. B) depends upon the aggregation of statoliths. C) results from relatively rapid elongation of some stem cells. D) A and B only E) A, B and C

E) A, B and C

Which of the following are examples or parts of plantsʹ systemic acquired resistance against infection? A) phytoalexins B) salicylic acid C) alarm hormones D) A and B only E) A, B, and C

E) A, B, and C

Regarding positive gravitropism exhibited by plant roots, A) it is mediated by auxin as for phototropism. B) it depends on more rapid elongation of some cells than other cells. C) gravity causes auxins to accumulate on the lower side of roots. D) the phenomenon depends upon inhibition of cell elongation of certain root cells by auxins. E) All of the above are correct.

E) All of the above are correct.

The hormone that helps plants respond to drought is A) auxin. B) gibberellin. C) cytokinin. D) ethylene. E) abscisic acid.

E) abscisic acid.

** How may a plant respond to severe heat stress? A) by orienting leaves toward the sun, increases evaporative cooling B) by producing ethylene, which kills some cortex cells and creates air tubes for ventilation C) by producing salicylic acid, which initiates a systemic acquired resistance response D) by increasing the proportion of unsaturated fatty acids in cell membranes reducing their fluidity E) by producing heat-shock proteins, which may protect the plantʹs proteins from denaturing

E) by producing heat-shock proteins, which may protect the plantʹs proteins from denaturing

Which of the following are sugar-transporting cells in angiosperms? A) parenchyma cells B) collenchyma cells C) clerenchyma cells D) tracheids and vessel elements E) sieve-tube elements

E) sieve-tube elements

** Plant cells begin synthesizing large quantities of heat-shock proteins A) after the induction of chaperone proteins. B) in response to the lack of CO2 following the closing of stomata by ethylene. C) when desert plants are quickly removed from high temperatures. D) when they are subjected to moist heat (steam) followed by electric shock. E) when the air around species from temperate regions is above 40°C.

E) when the air around species from temperate regions is above 40°C.

Phloem?

Vascular tissue in plants that conducts sugars and other metabolic products downward from the leaves

Xylem?

Vascular tissue in plants that conducts water and dissolved nutrients upward from the root and also helps to form the woody element in the stem

Abscission layer?

Layer of cells that is formed at the bases of fruits, flowers, and leaves.

Role of florigens?

Leaves produce to signal flowering

Cuticle?

Non-cellular protective layer covering the outer cell layer of the green aerial parts of land plants

Role of organ identity genes?

Plant homeotic gene that use positional information to determine which emerging leaves develop into which types of floral organs

Role of meristems?

Regions of tissue consisting of plant stem cells

Trichomes?

Small hair or other outgrowth from the epidermis of a plant

Petioles?

Small portion of plant that attaches to the leaf stem