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16 Cards in this Set
- Front
- Back
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The inorganic nutrient most often lacking in crops is __________.
phosphorus carbon potassium nitrogen |
nitrogen
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Micronutrients are needed in very small amounts because
only the most actively growing regions of the plants require micronutrients. most serve mainly as cofactors of enzymes. most are supplied in large enough quantities in seeds. they play only a minor role in the growth and health of the plant. most of them are mobile in the plant |
most serve mainly as cofactors of enzymes
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Some of the problems associated with intensive irrigation include all but
mineral runoff. soil salinization. overfertilization. land subsidence. |
overfertilization
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We would expect the greatest difference in plant health between two groups of plants of the same species, one group with mycorrhizae and one group without mycorrhizae, in an environment
in which the soil is relatively deficient in mineral nutrients. that is near a body of water, such as a pond or river. where nitrogen-fixing bacteria are abundant. that has hot summers and cold winters. that has soil with poor drainage. |
in which the soil is relatively deficient in mineral nutrients
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Topsoil _____.
is uniform in texture does not retain water is a mixture of rock fragments, living organisms, and humus is devoid of charged particles is the relatively inert upper layer of soil |
s a mixture of rock fragments, living organisms, and humus
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Two groups of tomatoes were grown under laboratory conditions, one with humus added to the soil and one a control without humus. The leaves of the plants grown without humus were yellowish (less green) compared with those of the plants grown in humus-enriched soil. The best explanation for this difference is that
the healthy plants used the food in the decomposing leaves of the humus for energy to make chlorophyll. the heat released by the decomposing leaves of the humus caused more rapid growth and chlorophyll synthesis. the humus contained minerals such as magnesium and iron, needed for the synthesis of chlorophyll. the healthy plants absorbed chlorophyll from the humus. the humus made the soil more loosely packed, so water penetrated more easily to the roots. |
the humus contained minerals such as magnesium and iron, needed for the synthesis of chlorophyll.
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A major long-term problem resulting from excessive irrigation is the _____.
accumulation of salts in the soil drowning (anoxia) of crop plants erosion of fine soil particles excessive cooling of the soil encroachment of water-consuming weeds |
accumulation of salts in the soil
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For an element to be considered a macronutrient _____.
it should consist of three or more subunits it must be a large atom it must have a high atomic mass it must be required in relatively large amount sit must be available in large amounts |
it must be required in relatively large amounts
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Nitrogen-fixing bacteria in the soil _____.
change ammonium into nitrates convert nitrate to ammonium convert nitrates to N2 use nitrates to make amino acids that plants can use convert atmospheric nitrogen to ammonia |
convert atmospheric nitrogen to ammonia
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The sundew plant has to digest insects because _____.
its flowers are fertilized by pollen in its digestive tract it's a method of self-cleaning to rid the plants of insects that get stuck in the plant it lives in a dry environment and uses moisture from the insects' bodies it has lost the ability to perform photosynthesis it obtains nitrogen from their bodies that it cannot get from the soil |
it obtains nitrogen from their bodies that it cannot get from the soil
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Plant hormones act by directly affecting the activities of _____.
signal transduction pathways genes enzymes membranes genes and enzymes |
signal transduction pathways
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Which of the following seedlings will probably bend toward light?
one whose tip is separated from its base by aluminum foil one whose tip is separated from its base by a gelatin block one whose tip is covered with a black plastic cap one whose tip is cut off and topped by a gelatin block containing no plant substances one whose tip is cut off |
one whose tip is separated from its base by a gelatin block
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Which of these plant hormones is not typically considered a growth-promoting substance?
brassin osteroids auxin cytokinin abscisic acid gibberellin |
abscisic acid
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The Pr form of the phytochrome pigment has maximum absorption in the _____ part of the spectrum.
red yellow far-red ultraviolet blue |
red
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Most plants flower when _____.
the nights are the right length a certain number of days have passed since they last flowered they deplete soil nutrients the soil reaches a certain temperature the days are the right length |
the nights are the right length
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If a long-day plant has a critical night length of 9 hours, which 24-hour cycle would prevent flowering?
4 hours light/8 hours dark/4 hours light/8 hours dark 14 hours light/10 hours dark 8 hours light/8 hours dark/light flash/8 hours dark 15.5 hours light/8.5 hours dark 16 hours light/8 hours dark |
14 hours light/10 hours dark
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