Biology Chapter 37 – Flashcards
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Topsoil _____.
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is a mixture of rock fragments, living organisms, and humus
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Humus consists of _____.
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decomposing organic material
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A major long-term problem resulting from excessive irrigation is the _____.
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accumulation of salts in the soil
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Mineral nutrients _____.
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contribute little to a plant's overall mass
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For an element to be considered a macronutrient _____.
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it must be required in relatively large amounts
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Which of the following is a symptom of magnesium deficiency in plants?
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chlorosis
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Nitrogen-fixing bacteria in the soil _____.
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convert atmospheric nitrogen to ammonia
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Mycorrhizae enhance plant nutrition mainly by
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absorbing water and minerals through the fungal hyphae.
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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
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in which the soil is relatively deficient in mineral nutrients.
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How do plants obtain organic molecules?
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Plants synthesize their own organic molecules.
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The relationship between legumes and Rhizobium is _____.
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mutualistic
(Both the legume and the Rhizobium benefit from this relationship. The legume gains a supply of fixed nitrogen from Rhizobium, and Rhizobium gains organic nutrients from the legume.)
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Mutualistic associations between roots and soil fungi are called _____.
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mycorrhizae
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The sundew plant has to digest insects because _____.
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it obtains nitrogen from their bodies that it cannot get from the soil
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The inorganic nutrient most often lacking in crops is __________.
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nitrogen
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Micronutrients are needed in very small amounts because
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most serve mainly as cofactors of enzymes.
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Epiphytes are
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plants that grow on other plants.
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Some of the problems associated with intensive irrigation include all but
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overfertilization
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A mineral deficiency is likely to affect older leaves more than younger leaves if
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the mineral is very mobile within the plant.
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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
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the humus contained minerals such as magnesium and iron, needed for the synthesis of chlorophyll.
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Identify the components of the rhizosphere, the soil layer that surrounds plant roots.
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dirt, bacteria, fungi
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Select the correct statement(s) about plant nutrition.
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Mineral deficiency symptoms vary with the mobility of the mineral within the plant.
