In a stable ecosystem, which of the following limits the number of trophic levels?

(1) Biomass

(2) The number of nutrients

(3) Availability of nutrients

(4) Presence of contaminants that increase in concentration along the food chain

Most of the world's carbon is found:

1. As carbon dioxide in the atmosphere.

2. In living organisms.

3. As bicarbonate and carbonate ions dissolved in the oceans.

4. As carbonate minerals in sedimentary rock.

Photosynthesis and respiration are central to which cycle?
1. The nitrogen cycle 

2. The carbon cycle

3. The phosphorus cycle

4. The sulfur cycle

Which of the following changes would not result in an increase in net primary production?

(1) Increased precipitation in an and area

(2) Increased soil fertility

(3) Increased latitude (moving from the equator toward the poles)

(4) Moving down a mountain to warmer temperatures

Grasslands can support greater grazing rates by herbivores than forests because:

(1) Grasslands receive more sunlight

(2) The net production of grasslands is greater

(3) Grasslands produce less woody plant tissue

(4) More of the grassland production is above ground

The amount of energy reaching an upper trophic level is determined by:

1. Net primary production

2. Net primary production and the efficiencies with which food energy is converted to biomass

3. Gross primary production

4. Gross primary production and the efficiencies with which food energy is converted to biomass

Fill in the blanks, in the following simplified model of a nutrient cycle:

           1             2                    3                       4                  5

(1) Producers   Detritus         Soil solution      Decomposition    Weathering

(2) Producers   Detritus         Soil solution      Weathering         Decomposition

(3) Producers   Soil solution   Detritus            Decomposition    Weathering

(4) Producers   Soil solution   Detritus            Weathering         Decomposition

Which of the following is/are incorrect:

A. All ecosystems are constant in size
B. In nature food chains exist, not food web
C. Flow of energy in ecosystem is unidirectional
D. Gene flow occurs between 2 different population (of 2 species)

(1) A, C

(2) A, D

(3) A, B, D

(4) A, B, C, D

The important step in the process of decomposition in order is:

Which of the following is false?

I. Quantity of biomass in a trophical level at a particular period is called standing crop.
II. The energy content in a trophic level is determined by considering a few individuals of a species         in that trophic level.
III. The succession that occurs in nearly cooled lava is called primary succession.
IV. Rate of succession is faster in the secondary succession
V. Phytoplankton are the pioneers in aquatic succession

(1) Only II

(2) Only III

(3) Only V

(4) Only I and IV