Question 1

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

Accepted Answer

Termites produce methane as a byproduct of their digestive process, making them a significant contributor to global methane emissions.

Question 2

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 3

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 4

Most soil organisms are heterotrophs.

Accepted Answer

Most soil organisms rely on organic matter as a source of energy and carbon, making them heterotrophs.

Question 5

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 6

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 7

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

Soil fungi and actinomycetes produce antibiotics, many of which have been put to practical use in medicine and agriculture to control bacterial infections and diseases.

Question 8

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

Accepted Answer

Fungi are better adapted to grow in soils with low nutrient availability, such as acid, sandy soils, making them the dominant group of microorganisms in those environments.

Question 9

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

Accepted Answer

Mycorrhizae involve a symbiotic combination of certain fungi and plant cells, not bacteria.

Question 10

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 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

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 13

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 14

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 and is not kept sterile by the roots. In fact, plant roots actively release substances that attract and support a diverse population of microorganisms in the rhizosphere.

Question 15

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

Accepted Answer

Plant roots release carbon through root exudates, which serve as food for soil organisms such as bacteria and fungi. These organisms help to improve soil health and nutrient availability, ultimately benefiting the growth and health of plants.

Question 16

Most anaerobic organisms in soils are bacteria.

Accepted Answer

Anaerobic organisms in soils use anaerobic respiration, which is a type of respiration that does not require oxygen, and bacteria are the most common type of anaerobic organisms in soils.

Question 17

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

Accepted Answer

Actinomycetes tend to dominate soils that are rich in organic matter, neutral to slightly alkaline, and moist.

Question 18

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, which is exuded by the root cap cells, acts as a lubricant and helps the plant roots to penetrate the soil particles. It also helps in increasing the surface area of the roots, enabling them to absorb more water and nutrients from the soil. Therefore, it improves the contact between plant roots and soil particles, enhancing the plant's uptake of water and nutrients.

Question 19

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

Accepted Answer

Soil microorganisms can compete with higher plants for mineral nutrients, such as nitrogen, as they also require these nutrients for their growth and survival. This competition can affect the growth and productivity of plants, especially in nutrient-poor soils.

Question 20

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 and anaerobic respiration, fermentation, and photosynthesis, making them the most diverse group of soil organisms in terms of metabolism.

Quiz 10: Organisms and Ecology of the Soil