Ch 37 Plant Nutrition

Question 1

Limiting factor

Answer 1

Anything that limits the amount of growth ie., insufficient light, CO2, water, and other mineral nutrients.

Question 2

Chlorosis

Answer 2

The yellowing of leaves as a result of a mineral deficiency.

Question 3

Leaching

Answer 3

Dissolution and removal of inorganic ions as water percolates through materials. Heavy rainfall can remove a lot of nutrients.

Question 4

Weathering

Answer 4

Inorganic materials in soil a derived from the physical and chemical breakdown of rock. Lichens and plant roots can contribute to the breakdown of rock.

Question 5

Loam

Answer 5

A type of soil that contains a mixture of sand, silt, and clay and is ideal for the cultivation of most plants.

Question 6

Humus

Answer 6

Organic constituents of soils

Question 7

Cation Exchange

Answer 7

H+ in acid rain falls and binds to clay, thereby release other mineral cations into the soil water (Al, Fe, Ca). This allows mineral uptake by plant roots. However, the minerals are now very susceptible to runoff. This is why acid rain is erosive and pollutes streams with toxic chemicals.

Question 8

Fertilizer

Answer 8

Soil additions that enhance plant growth by providing essential elements that may otherwise be deficient in the soil. They come in organic and inorganic varieties. Inorganic are mostly composed of N, P, and K.

Question 9

Organic Farming

Answer 9

The production of crops without using inorganic fertilizers, growth substances, and pesticides. Manure and compost. Organic fertilizers have most of the minerals bound to organic molecules that are released slowly.

Question 10

Fixed Nitrogen

Answer 10

Compounds that are useful in delivering Nitrogen to plants. These compounds include NH3, NH4+, and NO3-.

Question 11

Mineralization

Answer 11

Plants can secrete phosphatase enzymes from their roots. These enzymes release phosphorus from organic compounds in the soil. This process can be applied to P, N, CO2, and others.

Question 12

Nodule

Answer 12

Rhizobia (root bacteria) can only fix nitrogen when they are on these lumpy formations of legume roots.

Question 13

Nod factor

Answer 13

A type of secretion made by Rhizobia that only works on its preferred host species. When the host is found, the rhizobia can enter the host through the host’s root hairs.

Question 14

Nodulins

Answer 14

Within 18-30 hours after infection, these proteins cause root cortex cells to divide to form root nodules.

Question 15

Bacteroids

Answer 15

Environmental conditions in developing nodules cause rhizobia to change their structure and gene expression patterns. The new rhizobian forms are called…

Question 16

Leghemoglobin

Answer 16

Legume nodules typically produce this pink protein that helps to regulate local oxygen concentrations, transporting enough oxygen to bacteroids to support respiration but prevent oxygen from disabling nitrogenase.