Question

1.which cause of habitat destruction is fastest-growing and most destructive?

a. Deforestationb. Mining and quarryingc. Urbanizationd. Damse. Draining wetlandsf. Conversion to agriculture

2.What percent of the world's land is used for crops and livestock pastures?

a. 73% b. 17% c. 7% d. 13% e. 37%

3.What is host plant resistance?

a. The ability to prevent herbivory through various defenses. b. Producing large quantities of seeds in some years. c. The secretion of chemicals that are toxic to competing plant species. d. A form of crypsis practiced by tropical rain forest plants. e. The ability of plants to grow taller than their competitors.

4. What do you think would result if nitrogen-fixing cyanobacteria populations suddenly declined?

a. Aquatic primary production would decline, particularly in regions not subject to fertilizer runoff. b. More nitrogen would become available for other aquatic autotrophs. c. Both the aquatic and terrestrial populations of autotrophs would collapse. d. Legumes would cease to grow, but other types of plants would be unaffected. e. Populations of denitrifying bacteria would expand to take over their role, creating only a temporary disruption.

5. The Intergovernmental Panel on Climate Change reported in 2007 that atmospheric carbon dioxide levels will nearly double by the end of this century. If this happens, what will be the atmospheric concentration of carbon dioxide?

a. 700 ppm b. 2.0 ppm c. 385 ppm d. 3.5 ppm e. 560 ppm

6.The eastern indigo snake often makes its home in abandoned gopher tortoise burrows. How would you characterize this relationship and its effect on each member?

a. amensalism neutral for snake, negative for tortoise b. commensalism positive for snake, neutral for tortoise c. amensalism negative for snake, neutral for tortoise d. commensalism neutral for snake, neutral for tortoise e. Parasitism positive for snake, negative for tortoise

7.Ecosystem diversity

a. is primarily associated with aquatic habitats. b. is the diversity of animal species within a defined geographical area. c. includes only species-rich ecosystems. d. refers to the structure and function within an ecosystem.

Answer 1

1. Clearing of habitats for the purpose of agriculture is the major cause of destruction of habitat today. All efforts to protect the natural habitats are competed by the growing demand for new agricultural lands.

2. The most appropriate answer is (c)

The total agricultural area use is divided into 3 types:

• Arable land which is 28% of the global agricultural area
• permanent crops 3% and
• permanent meadows and pastures 69%
• Permanent crops and pastures make 72% of total world agricultural area. The total agricultural area is 11% of total land area so, permanent crops and pastures will make 6.54545 % of total land area that is approximately 7%.

3. (a)

Host-plant resistance is an integrated pest management tactic that means intentional use of resistant crops only or in combination with other strategies to lower the impact of herbivores on crop yield or quality.

4.

a. d. Legumes would cease to grow, but other types of plants would be unaffected. as legumes cannot fix nitrogen from themselves and need cyanobacteria for survival. (note other plants would not be completely unaffected as there is always impact on the ecosystem of every change)

5. a CO2 levels in atmosphere in 2007 were 382ppm whole double is 766 approx. 700ppm will be the CO2 levels in atmosphere by end of century.

6. b. commensalism positive for snake as it gets shelter and as the tortoise already left it there is no effect on tortoise.

7. (b) Ecosystem diversity is the form of biodiversity that deals with variations in ecosystems in a limited geographical area and its overall impact on existence of humans and the environment.