Exam 32: Plant Nutrition and Transport

In an attempt to determine the source of a growing plant's mass, van Helmont planted a willow seedling in a pot of soil. After 5 years, the willow weighed 76.8 kg, and the soil had lost 0.06 kg of weight. Only water had been added to the pot. Which conclusion should van Helmont have drawn?

Micronutrients function in plants mainly as

________ pulls water through a plant.

Much research is being done to increase the nitrogen-fixing ability of plants with root nodules. Why is this an important goal for agricultural researchers?

An example of an organism that parasitizes a host plant is

Which of these studies is a meta-analysis?

Plants are sometimes used for phytoremediation in areas where the soil has been contaminated with heavy metals. Suppose the Acme Remediation Company is proposing to remediate a contaminated area that you wish to restore. Acme presents you with the following data as evidence of their company's ability to remediate soil. -To decide if you want Acme to remediate the contaminated area, which question should you ask Acme about conclusions to be drawn from these data?

Compared to conventional agriculture, organic farming

A hot, dry summer will reduce crop yields in part because

Aphids are small insects that insert their mouthparts into a plant to obtain phloem sap. Which would be the best way to determine if aphids must actively draw phloem sap into their digestive tract or if hydrostatic pressure in the phloem tube could force the sap into them?

A peanut farmer decides that she can make more money growing cotton and so plants her fields with cotton. The terrific yield of her fields is so encouraging that she continues to plant cotton for several more years, but each year her cotton yield decreases. What advice could you give her to increase her yield?

Why don't the countries that most need high-protein crops grow them?

Over the next several decades, world population growth will necessitate as much as a 60% increase in food production, primarily in developing countries. These countries are often the most seriously affected by drought and salinity. Even if irrigation water is available, flooding fields with irrigation water leads to the gradual accumulation of sodium ions and other salts in the soil. To respond to this growing problem, scientists at the University of Connecticut have genetically engineered a plant that can survive in salty soil and withstand extended drought conditions. The new transgenic plant contains a gene for an ion pump. Salt ions are transported from the soil and stored in vacuoles in the cytoplasm. The enhanced uptake of ions into their vacuoles in turn improves water retention in the transgenic plants and their resistance to drought. The concentration of solutes inside and outside plant cells affects the direction of water movement through osmosis. The researchers found that the salt concentration in the cells of the new transgenic plants was significantly higher than in wild plants used as a control. In addition, the transgenic plants survived longer when deprived of water. -Planting these transgenic crops periodically would be beneficial to the environment because

What are the macronutrients present in most commercial fertilizers?

Plants are sometimes used for phytoremediation in areas where the soil has been contaminated with heavy metals. Suppose the Acme Remediation Company is proposing to remediate a contaminated area that you wish to restore. Acme presents you with the following data as evidence of their company's ability to remediate soil. -Which would provide the best evidence that Acme's phytoremediation really works?

What is most likely to be an epiphyte?

The sugar "sink" in roots is the result of

If you examine the soil profile revealed by a fresh road cut, which feature will you probably find in the B horizon?

What is the physical barrier in the root that regulates the flow of water to xylem via cell walls?

What is a potential problem with the use of transgenic varieties of plants that contain Bt toxin?