Soil consists of inorganic particles and organic ________. silt clay humus 1 2 3 4 5

Layers of soil that are identified by distinct properties are called ________. leaching weathering horizons ecosystems 1 2 3 4 5

Topsoil is not ________. the horizon most essential for plant growth the horizon closest to bedrock deeper in some places than in others a soil with decomposed organic matter 1 2 3 4 5

Bacteria in root nodules produce a biologically active form of the essential nutrient ________. nitrogen oxygen carbon hydrogen 1 2 3 4 5

Mycorrhizae are ________. very small roots that absorb nutrients a bacterial infection of roots a mutualism between roots and fungi responsible for nitrogen fixation 1 2 3 4 5

Root hairs are extensions of ________ cells. epidermal endodermal vascular pericycle 1 2 3 4 5

endodermal transport proteins sieve tubes in phloem The control point where plants adjust the quantity and types of solutes absorbed from soil water are the ________. root hairs root nodules endodermal transport proteins sieve tubes in phloem 1 2 3 4 5

The Casparian strip is a barrier to unrestricted ________ flow into the vascular cylinder. water and gas water and solute solute and ATP oxygen and ATP 1 2 3 4 5

Which of the following is an identifying characteristic of xylem tracheids and vessel members? their cells are dead at maturity they carry organic products of photosynthesis they are discontinuous from roots to leaves they operate under high fluid pressure 1 2 3 4 5

Which is not true of xylem tracheids and vessel members? they are perforated with pectin-coated pits they consist of dead, mature cells they move nutrients from leaves downward they have rigid lignin-filled walls 1 2 3 4 5

According to cohesion-tension theory, ________. energy is expended to raise water from roots to leaves negative pressure from evaporation pulls water toward the leaves pressure from the vascular cylinder pushes water toward the leaves tension between tracheids pushes water upward from the roots 1 2 3 4 5

In water conservation, the essential principle of osmosis is ________. water follows the light ions follow the water water follows the concentration gradient water follows the ions 1 2 3 4 5

Plant structures directly responsible for maintaining turgor include ________. roots and periderm cuticle and stomata petioles and endoderm meristem and phloem 1 2 3 4 5

the tracheid structure blue light carbon dioxide levels In stomata, all of the following influence the opening and closing of guard cells except ________. the tracheid structure blue light carbon dioxide levels the hormone ABA 1 2 3 4 5

Smog pollution directly affects plants by ________. clogging stomata blocking sunlight reducing photosynthesis all of the choices 1 2 3 4 5

The primary function of phloem is to distribute ________ through the plant. groundwater minerals organic products inorganic nutrients 1 2 3 4 5

In translocation, companion cells in ________ load sucrose into ________. veins, sieve-tube members veins, tracheids sieve-tube members, xylem xylem, phloem 1 2 3 4 5

According to pressure flow theory, the mechanisms that increase fluid pressure are ________. gravity and diffusion gravity and osmosis active transport and osmosis diffusion and concentration gradient 1 2 3 4 5

loading by companion cells unloading at sinks decreased turgor All of the following conditions are required to maintain a pressure gradient in phloem except ________. photosynthesis loading by companion cells unloading at sinks decreased turgor 1 2 3 4 5

All of the following are sink regions except ________. flowers photosynthetic tissues fruits growing roots 1 2 3 4 5