Question 1

A significant portion of the global production of methane comes from the activity of termites.

Accepted Answer

Termites are known to produce methane as a byproduct of their digestion process, and this is a significant source of methane emissions globally.

Question 2

Most anaerobic organisms in soils are bacteria.

Accepted Answer

Most anaerobic organisms in soils are indeed bacteria, such as Clostridium, Methanogens, and Sulfate-reducing bacteria. However, there are also some anaerobic fungi and protozoa present in the soil.

Question 3

Plant roots are an important source of carbon for many soil organisms which are beneficial to plants.

Accepted Answer

Many soil organisms such as bacteria and fungi obtain carbon from plant roots through symbiotic relationships, which can benefit the plants by increasing nutrient availability and disease resistance.

Question 4

The total number of microorganisms in a hectare of soil is far greater than the number of macroorganisms, but the reverse is true for biomass of the two groups.

Accepted Answer

Although there are far more microorganisms than macroorganisms in a hectare of soil in terms of numbers, the biomass of macroorganisms can still be greater due to their much larger individual sizes.

Question 5

The deeper that they are placed in the soil, the more rapidly organic compounds such as pesticides are decomposed by the soil microflora.

Accepted Answer

Organic compounds such as pesticides decompose more slowly in deeper soil layers due to reduced microbial activity and oxygen levels compared to the surface layers.

Question 6

Of all the groups of soil organisms, bacteria have the most diverse metabolic capabilities.

Accepted Answer

Bacteria have a wide range of metabolic capabilities including aerobic respiration, anaerobic respiration, fermentation, photosynthesis, chemosynthesis, and nitrogen fixation, among others. This diversity in metabolism contributes to their ability to thrive in a wide range of environments and play crucial roles in nutrient cycling and soil fertility.

Question 7

Research has shown that most herbicides and insecticides used in agriculture drastically reduce the numbers of living meso- and microorganisms in soils for several years after the application of these chemicals.

Accepted Answer

The answer of Research has shown that most herbicides and...

Question 8

All but a few nematodes are pests, attacking either economic or wild plants.

Accepted Answer

Many nematodes are beneficial, playing crucial roles in soil health, nutrient cycling, and controlling pest populations. Only a minority are pests to plants.

Question 9

Compared to the rest of the soil, the rhizosphere is kept relatively sterile by the action of plant roots.

Accepted Answer

The rhizosphere is actually a hotspot for microbial activity, as the roots release various organic compounds and sugars that attract beneficial bacteria and fungi. This creates a complex and diverse soil community that helps support plant growth and health.

Question 10

Mucigel is thought to improve the contact between plant roots and soil particles, thus enhancing the plant uptake of water and nutrients.

Accepted Answer

Mucigel is a slimy substance secreted by root tips that helps improve the adhesion between roots and soil particles, improving nutrient and water uptake by plants.

Question 11

Mycorrhizae do not normally kill their host plants, but merely reduce the efficiency of the plant root system.

Accepted Answer

Mycorrhizae form a mutualistic relationship with plants, enhancing nutrient and water uptake, rather than reducing the efficiency of the plant root system.

Question 12

Termites tend to enrich soils in the tropics much the same way as earthworms do in temperate region soils.

Accepted Answer

The answer of Termites tend to enrich soils in the...

Question 13

Where conditions are favorable, earthworms are known to add several hundred kg/ha of several important nutrients to the soil system.

Accepted Answer

The answer of Where conditions are favorable, earthworms are known...

Question 14

Algae are single-celled plants that function principally as primary producers in the soil ecosystem.

Accepted Answer

The answer of Algae are single-celled plants that function principally...

Question 15

Mycorrhizae involve a symbiotic combination of certain bacteria and plant cells.

Accepted Answer

Mycorrhizae involve a symbiotic combination of fungi and plant cells.

Question 16

Certain soil fungi and actinomycetes are known to produce specialized organic compounds that inhibit or kill other, competing microorganisms in the soil, but so far scientists have not been able to put any of these compounds to practical use.

Accepted Answer

There have been some soil fungi and actinomycetes compounds that have been put to practical use, such as the antibiotic streptomycin derived from Streptomyces griseus. However, not all compounds have found practical applications.

Question 17

Soil microorganisms often compete with higher plants for mineral nutrients, such as nitrogen.

Accepted Answer

Soil microorganisms are known to compete with higher plants for essential mineral nutrients, including nitrogen. This competition can be particularly intense in nutrient-poor soils, and can have important implications for plant growth and ecosystem functioning.

Question 18

Fungi tend to be the dominant group of microorganisms in acid, sandy soils.

Accepted Answer

Fungi are well-adapted to survive and thrive in acidic, nutrient-poor soils. They are able to obtain nutrients by breaking down organic matter and forming mutualistic relationships with plants. In sandy soils, which are low in water-holding capacity, fungi can increase soil aggregation and improve water infiltration. Therefore, fungi tend to be the dominant group of microorganisms in acid, sandy soils.

Question 19

Actinomycetes tend to dominate soils that are either very acid, very cold, or very dry.

Accepted Answer

Actinomycetes tend to dominate soils that are neutral to slightly acidic, moist, and high in organic matter. They are less commonly found in very acidic, very cold, or very dry soils.

Question 20

Most soil organisms are heterotrophs.

Accepted Answer

Most soil organisms rely on consuming other organic matter as a source of energy, making them heterotrophs. This includes bacteria, fungi, protozoa, and many soil invertebrates such as earthworms and insects.

Quiz 11: Organisms and Ecology of the Soil