Homework Assignment: Due 1.30.23

Which organisms and set of characteristics are correctly paired?

• fungi—carry out photosynthesis and heterotrophic nutrition

• plants—carry out respiration and autotrophic nutrition

• decomposers—carry out photosynthesis and autotrophic nutrition

• animals—carry out autotrophic nutrition and heterotrophic nutrition

Answer explanation

Through the process of photosynthesis, plants capture the energy of the sun and use it to convert carbon dioxide and water into molecules of glucose. The plant uses the energy from the molecules of glucose to carry out its own life processes. All living organisms, through cellular respiration, release the energy contained in molecules of glucose and use this energy to carry out their life processes.

Humans have an effect on ecosystems when they use native grasslands or forested areas for farming or urban use. One negative effect of these changes on the ecosystem is that there will be

• less biodiversity

• more homes

• successful economic growth

• increased food production

Answer explanation

After feeding at the surface of the ocean during the day, many ocean organisms migrate to deeper waters. While there, they release ammonia in their urine. Many bacteria use the nitrogen from the ammonia as they make amino acids, which eventually end up in food chains on both land and water. These amino acids may even be used in humans. Which statement best explains these observations?

• Chemical elements, including nitrogen, pass through food webs and are combined and recombined in different ways.

• Chemical elements, including nitrogen, are removed from food webs and eliminated from ecosystems.

• Nitrogen is transferred directly from bacteria to humans.

• All elements in the ocean remain there and are not transferred to other ecosystems.

Answer explanation

Because of actions of decomposers, the atoms and molecules in living things cycle through both the nonliving and living parts of the biosphere. As they do, chemical elements, such as carbon, hydrogen, oxygen, and nitrogen, that make up the bodies of living things pass through food webs and are combined and recombined in different ways in different living organisms. For example, plants trap carbon dioxide and water molecules in energy-rich compounds (such as glucose and starch) during photosynthesis.

Based on this information, which ecosystem is likely to be the most stable?

• A

• B

• C

• D

Answer explanation

Biodiversity (a variety of species) ensures the stability of an ecosystem. If we look at this graph, we see that ecosystem C has a greater number of different species than the other ecosystems, which makes ecosystem C the best choice.

Carbon dioxide and oxygen are important resources in ecosystems and are

• recycled through the activity of living and nonliving systems

• stored in the animals of the ecosystem

• lost due to the activities of decomposers

• released by the process of photosynthesis

Answer explanation

Because of actions of decomposers, the atoms and molecules in living things cycle through both the nonliving and living parts of the biosphere. As they do, chemical elements, such as carbon, hydrogen, oxygen, and nitrogen, that make up the bodies of living things pass through food webs and are combined and recombined in different ways in different living organisms. For example, plants trap carbon dioxide and water molecules in energy-rich compounds (such as glucose and starch) during photosynthesis.

During which month would the bears in the area have the most fish available?

• May

• July

• August

• October

Answer explanation

If we take a look at the first graph, we see that the fish population is the greatest when the lake is at a temperature of 25 degrees Celsius. The second graph shows us that in the month of July the lake is 25 degrees Celsius. Thus, there will be more fish in the lake during the month of July.

One of the best ways to represent the interdependence of all of the organisms in this ecosystem is

• an evolutionary tree

• a food chain

• an electrophoresis gel

• a food web

Answer explanation

Interdependence- the dependence of two or more people or things on each other.

A food web shows more complex feeding relationships among organisms in an ecosystem. There are many food chains in a single food web, and it is a great representation of how different populations rely on each other.

Rafflesia arnoldii is a bright red and yellow flowering plant that has no leaves, roots, or stems. Rafflesia do not carry out photosynthesis. They take nutrients from the cells of grapevines. Rafflesia arnoldii is an example of a

• producer

• carnivore

• omnivore

• parasite

Answer explanation

Parasitism- A relationship where one organism benefits but the other is harmed

During the last century, human impacts on our planet have led to an increasing and alarming loss of biodiversity in rainforest ecosystems. Scientists estimate that current extinction rates exceed those of some prehistoric mass extinctions. This loss of biodiversity also means loss of genetic diversity and loss of ecosystems. What could be done to minimize this loss of biodiversity?

• Introduce new species to rainforest ecosystems.

• Write and pass new environmental protection laws specific to rainforest ecosystems.

• Build barriers around rainforest ecosystems to keep animals and plants contained.

• Move all rainforest animals to new ecosystems where they will be safe.

The number of white-tailed deer in certain areas of Long Island, NY has increased signifi cantly. Homeowners and farmers have put up tall fencing to protect their gardens and crops from the deer. One reason why the white tailed-deer might have increased significantly in certain areas of Long Island is

• the lack of natural predators

• an increase in deer pathogens

• a shortage of biotic resources needed by the deer

• that carrying capacity has no effect on deer populations

Answer explanation

Remember, predator and prey relationships are an example of a limiting factor that can keep a population size in check. Lack of predators can be why the deer population continues to increase.