An Introduction to Ecology and the Biosphere

Explain how the sun’s unequal heating of Earth’s surface results in deserts near 30° north and south of the equator.

Some arctic tundra ecosystems receive as little rainfall as deserts but have much more dense vegetation. What climatic factor could cause this difference? Explain.

Based on the climograph in Figure 52.10, what mainly differentiates temperate grassland from temperate broadleaf forest?

Why are phytoplankton, and not benthic algae or rooted aquatic plants, the dominant photosynthetic organisms of the oceanic pelagic zone? (See Figure 52.15.)

Make a bar graph of the data from the field experiment. (For additional information about graphs, see the Scientific Skills Review in Appendix F.) What do these data indicate about the salinity tolerances of S. patens and T. angustifolia?

Describe a scenario showing how ecological change and evolution can affect one another.

Which of the following areas of study focuses on the exchange of energy, organisms, and materials between ecosystems?

(A) organismal ecology

(B) landscape ecology

(C) ecosystem ecology

(D) community ecology

What are some of the differences in microclimate between an unplanted agricultural field and a nearby stream corridor with trees?

Using Figure 52.12, identify the natural biome in which you live, and summarize its abiotic and biotic characteristics. Do these reflect your actual surroundings? Explain.

Many organisms living in estuaries experience freshwater and saltwater conditions each day with the rising and falling of tides. Explain how these changing conditions challenge the survival of these organisms (see Concept 44.1).

What do the data from the field experiment indicate about the effect of competition on the growth of these two species? Which species was limited more by competition?

Which lake zone would be absent in a very shallow lake?

(A) benthic zone

(B) aphotic zone

(C) pelagic zone

(D) littoral zone

If global warming increases average temperatures on earth by 4°C in this century, predict which biome is most likely to replace tundra in some locations as a result. Explain your answer.

As noted in Figure 52.15, the addition of nutrients to a lake can cause an algal bloom. When these algae die, complex molecules in their bodies are broken down by decomposers using aerobic respiration. Explain why this would reduce the lake's oxygen levels (see Concept 9.1).

Focusing just on the effects of temperature, would you expect the global distribution of C₄ plants to expand or contract as Earth becomes warmer? Why?

The oceans affect the biosphere in all of the following ways except

(A) producing a substantial amount of the biosphere’s oxygen.

(B) removing carbon dioxide from the atmosphere.

(C) moderating the climate of terrestrial biomes.

(D) regulating the pH of freshwater biomes and terrestrial groundwater.

When climbing a mountain, we can observe transitions in biological communities that are analogous to the changes

(A) in biomes at different latitudes.

(B) in different depths in the ocean.

(C) in a community through different seasons.

(D) in an ecosystem as it evolves over time.

Suppose that the number of bird species is determined mainly by the number of vertical strata found in the environment. If so, in which of the following biomes would you find the greatest number of bird species?

(A) tropical rain forest

(B) savanna

(C) desert

(D) temperate broadleaf forest

After examining Figure 52.19, you decide to study feeding relationships among sea otters, sea urchins, and kelp. You know that sea otters prey on sea urchins and that urchins eat kelp. At four coastal sites, you measure kelp abundance. Then you spend one day at each site and mark whether otters are present or absent every 5 minutes during the day. Graph kelp abundance (on the y-axis) versus otter density (on the x-axis), using the data below. Then formulate a hypothesis to explain any pattern you observe.

Discuss how the distribution of a species can be affected both by its evolutionary history and by ecological factors. Could ongoing evolutionary change also affect its distribution? Explain.

If you were to hike up MountKilimanjaro in Tanzania, you would pass through several habitats, including savanna at the base, forest on the slopes, and alpine tundra near the top. Explain how such diverse habitats can be found at one location near the equator.

Explain how the sun’s unequal heating of Earth’s surface results in deserts near 30° north and south of the equator.

What are some of the differences in microclimate between an unplanted agricultural field and a nearby stream corridor with trees?

WHAT IF? Changes in Earth's climate at the end of the last ice age happened gradually, taking centuries to thousands of years. If the current global warminghappens very quickly, as predicted, how may this rapid climate change affect the evolution of long-lived trees compared with that of annual plants, which have muchshorter generation times?

Focusing just on the effects of temperature, would you expect the global distribution of C₄ plants to expand or contract as Earth becomes warmer? Why?

Some arctic tundra ecosystems receive as little rainfall as deserts but have much more dense vegetation. What climatic factor could cause this difference? Explain.

Based on the climograph in Figure 52.10, what mainly differentiates temperate grassland from temperate broadleaf forest?

Using Figure 52.12, identify the natural biome in which you live, and summarize its abiotic and biotic characteristics. Do these reflect your actual surroundings? Explain.

If global warming increases average temperatures on earth by 4°C in this century, predict which biome is most likely to replace tundra in some locations as a result. Explain your answer.

Why are phytoplankton, and not benthic algae or rooted aquatic plants, the dominant photosynthetic organisms of the oceanic pelagic zone? (See Figure 52.15.)

Many organisms living in estuaries experience freshwater and saltwater conditions each day with the rising and falling of tides. Explain how these changing conditions challenge the survival of these organisms (see Concept 44.1).

As noted in Figure 52.15, the addition of nutrients to a lake can cause an algal bloom. When these algae die, complex molecules in their bodies are broken down by decomposers using aerobic respiration. Explain why this would reduce the lake's oxygen levels (see Concept 9.1).

Make a bar graph of the data from the field experiment. (For additional information about graphs, see the Scientific Skills Review in Appendix F.) What do these data indicate about the salinity tolerances of S. patens and T. angustifolia?

What do the data from the field experiment indicate about the effect of competition on the growth of these two species? Which species was limited more by competition?

Make a line graph of the data from the greenhouse experiment. Decide which values constitute the dependent and independent variables, and use these values to set up the axes of your graph.

(a) In the field, S. patens is typically absent from freshwater marshes. Based on the data, does this appear to be due to salinity or competition? Explain your answer. (b) T. angustifolia does not grow in salt marshes. Does this appear to be due to salinity or competition? Explain your answer.

Give examples of human actions that could expand a species' distribution by changing its (a) dispersal or (b) biotic interactions.

Describe a scenario showing how ecological change and evolution can affect one another.