Chapter 21 Homework

If a wetland like the one depicted in the infographic covered an area of 1,500 m2, what would be the grams of biomass from primary producers for that wetland in a year? (Infographic)

( 1,500 square meters) * (2,620 grams per square meter) = 3,930,000

Instead of a wetland, calculate the biomass produced for a desert of the same size (1,500 m2) in one year. (Infographic)

(150 grams per square meter) * (1,500 square meters) = 225,000

Scientists have become greatly concerned that ocean productivity has been dropping as the oceans warm due to climate change. In this energy pyramid, how many calories would be available for the tertiary consumer if the phytoplankton only produced 1,000 calories? (Figure 21.3)

1

The animation depicts the flow of energy through an aquatic food chain as a pyramid. If there were a quaternary consumer level on the pyramid in the animation, how much energy would be available to the quaternary consumers?

1 Kcal

Scientists know that, on average, 90 percent of the available energy at a trophic level is lost through metabolic heat and inefficient consumption and is not passed on to the next trophic level. Consider a food chain found in the Konza Prairie in Manhattan, Kansas. The various producers (prairie grasses and flowers) in an area of the prairie have 14,300 Kcal of energy available for the food chain. The prairie food chain consists of voles that eat these producers, snakes that eat the voles, hawks that eat the snakes, and bald eagles that eat the hawks. How much energy is available at the level of the primary consumer in this food chain?

1,430 Kcal

Now consider the Konza Prairie food chain again, except with a different amount of energy available. It has been an exceptionally good summer for plant growth, so the amount of energy available from primary producers is now 78,640 Kcal. How much energy is available for the quaternary consumers?

7.864 Kcal

Sort only the following components of the ecosystem depicted at the beginning of the animation as either biotic or abiotic. (Not all choices will be used.)

Abiotic ◽ Earth's crust ◽ Atmosphere ◽ Water Biotic ◽ Grasses ◽ Bacteria ◽ Cardinals ◽ Owls

In the following graph, focus on the data collected between 2000 and 2005. What did scientists conclude about the correlation between ocean temperature and chlorophyll concentration over this period? (Figure 21.10)

Average ocean temperature increased over this period, and chlorophyll concentration decreased with it.

Match the marine ecosystem description to its name.

Coastal region ◽ From shoreline to edge of continental shelf, highly productive, majority of marine species live here Estuary ◽ Shallowest, but most productive, where rivers flow into the ocean, constant ebb and flow of fresh and salt water Intertidal zone ◽ Closest to shore, challenging environment due to twice-daily cycle of submergence and exposure Open ocean ◽ Begins 40 miles offshore, low productivity

Why does the arrow in the nutrient cycle between decomposers and producers point in both directions while the other arrows only point one way? (Figure 21.5)

Decomposers obtain nutrients through consumption but also return nutrients to producers.

Contrast energy and nutrient movement in an ecosystem.

Energy transfers in a one-way flow, whereas nutrients cycle through an ecosystem.

Rank the biomes depicted in this graphic from most productive (in grams of biomass produced per square meter per year) to least productive. (Infographic)

Most productive 1. Wetlands 2. Grassland, tropical 3. Grassland, temperate 4. Lakes and streams 5. Tundra 6. Desert Least productive

Rank the biomes in terms of their productivity from most productive to least productive. (Infographic)

Most productive 1. Wetlands 2. Tropical grassland 3. Temperate grassland 4. Lakes and streams 5. Tundra 6. Desert Least productive

Climate change has been significantly affecting the Arctic, home of the tundra biome. As temperatures warm, more water becomes available, especially as the permafrost continues to melt. Grasslands do not support tree growth because of low moisture levels. Although trees do not currently grow in the tundra, would the Arctic tundra be able to support tree growth if water becomes more available due to climate change?

No, the growing season is too short to support widespread tree growth and that does not change with climate change.

The flow of nutrients is a cycle in ecosystems, and nutrients are returned to the ecosystem by the activity of decomposers. Without decomposers, nutrient cycling would stop and life as we know it would also cease. By what primary route do nutrients re-enter the food web?

Nutrients pass through the decomposers to the soil, water, and atmosphere where they are absorbed by producers and incorporated into organic molecules.

Daniel Boyce and his collaborators only used chlorophyll measurements taken where the ocean floor is deeper than 25 meters. What was wrong with data taken in shallower waters?

Sediment runoff from the land can affect the measurements of water transparency, so these measurements could be inaccurate and skew the data.

How could warming oceans affect phytoplankton productivity?

Warmer oceans could decrease productivity because warmer oceans mix less, bringing fewer nutrients to the surface.

Patterns of net primary productivity (NPP) differ between the land and the oceans. On land, NPP __________ as you move toward the poles. In the oceans, NPP __________ as you move away from land. (Figure 21.9)

decreases; decreases

This biome has the lowest production on the planet, due to extremely low precipitation levels. Extremely low moisture levels also result in exceedingly high daytime temperatures with plunging nighttime temperatures. Plants in this biome are adapted to the low moisture levels, with most having spines instead of leaves and many storing water in their leaves and stems. Because of the intense daytime heat, most animals in this biome are nocturnal (active at night) and stay in their burrows during the day. This biome encompasses one-third of the Earth's land surface, an area that is increasing annually. (Figure 21.8)

desert

Dr. Siu is conducting research on the coral reefs around St. John's Island in the U.S. Virgin Islands, which are part of the Virgin Islands Coral Reef National Monument. Dr. Siu is studying fish diversity, identifying the species of fish living in and around the coral reef, and quantifying their abundance. The coral reef and its inhabitants are a(n) ________, and Dr. Siu is studying a(n) _____ component of the reef.

ecosystem; biotic

The base of an energy pyramid is occupied by

primary producers.

Identify the biome that is found at the poles and mountaintops, where trees are absent or scarce and the vegetation is dominated by low-growing plants like mosses and lichens. Because of the low productivity, very few large animals live in these areas, although rodents provide food for foxes and wolves. (Figure 21.8)

tundra

Which biome is not present on the content of Africa?

tundra

Ecosystems depend on the activity of producers to provide energy and nutrients for all other organisms in the food web of the ecosystem. Any reduction of productivity therefore has significant impacts throughout the ecosystem. Daniel Boyce's findings of a 50 percent loss in phytoplankton rocked the scientific world for this very reason, but there are reasons why the loss of phytoplankton is especially worrisome. What are those reasons?

✔ Phytoplankton take in carbon dioxide, which helps to offset the greenhouse effect and global warming. ✔ Phytoplankton produce half of the oxygen we breathe. ✔ Phytoplankton support fisheries.

According to this map, which areas feature abundant phytoplankton in the oceans? (Figure 21.6)

✔ along the coasts of the continental land masses ✔ at high latitudes ✔ at the equator