Question 1

In hundreds of years we have released large quantities of fossil fuels that took millions of years to form.

Accepted Answer

Over the course of industrialization and modernization, we have increased our consumption of fossil fuels like coal, oil, and gas which were formed over millions of years.

Question 2

The reason we observe a "pyramid" of energy flow instead of an energy flow "cube" is because the low ecological efficiency of biological systems limits the numbers of organism in the higher trophic levels.

Accepted Answer

The ecological efficiency of biological systems is low because energy is lost at each trophic level through metabolic processes and heat production. This limits the amount of energy available to support organisms in the higher trophic levels, resulting in fewer individuals and a pyramid-shaped energy flow.

Question 3

Over land, most water that reaches the atmosphere comes from transpiration.

Accepted Answer

Transpiration is the process by which water is lost from the leaves of plants and enters the atmosphere. It is a major source of water vapor in the atmosphere over land.

Question 4

Transfer of energy through food chains or webs is very efficient, making a lot of energy available to organisms.

Accepted Answer

Energy transfer through food chains or webs is actually quite inefficient, with only a small fraction of the energy from one level being passed on to the next level. This is due to factors such as metabolism, digestion, and waste production. As a result, there is relatively little energy available to organisms at higher trophic levels.

Question 5

All microbes are pathogenic (disease causing) or otherwise dangerous.

Accepted Answer

This statement is false. While there are some microbes that are pathogenic and can cause diseases, the majority of microbes are actually beneficial and essential for our survival. For example, microbes in the gut help with digestion and the immune system. Only a small percentage of microbes are pathogenic or harmful to humans.

Question 6

Agricultural runoffs containing phosphates cause huge blooms of algae in streams and lakes.

Accepted Answer

Agricultural runoffs containing phosphates can cause eutrophication, which is the process by which excessive nutrients, particularly phosphorus and nitrogen, stimulate excessive plant growth (algae) in aquatic ecosystems. This can deplete oxygen levels and harm other organisms in the water, leading to serious ecological problems.

Question 7

Because the soil contains a sufficient amount of phosphates, phosphorus is not usually a limiting plant nutrient.

Accepted Answer

Although phosphates may be present in soil, they may not always be available in a form that can be readily absorbed by plants. Additionally, certain environmental factors such as soil pH can affect the availability of phosphorus to plants. Therefore, phosphorus can still be a limiting plant nutrient even if there is a sufficient amount of phosphates in the soil.

Question 8

Since 1950 human activities have more than doubled the annual release of nitrogen into the environment.

Accepted Answer

Various human activities such as agriculture, transportation, and industrial processes have significantly increased the amount of nitrogen released into the environment since 1950, leading to various environmental issues such as eutrophication, water pollution, and greenhouse gas emissions. This increase in nitrogen release has been more than double compared to the pre-1950 era.

Question 9

Gross primary productivity (GPP) is the biomass produced by photosynthesis minus the rate at which biomass is used for aerobic respiration.

Accepted Answer

Gross primary productivity (GPP) is the total amount of biomass produced by photosynthesis, without subtracting the biomass used for aerobic respiration. Net primary productivity (NPP) is calculated by subtracting the rate at which biomass is used for aerobic respiration from GPP.

Question 10

A larger number of humans could be supported on the earth if more of them consumed grains, vegetables, and fruits rather than eating meat.

Accepted Answer

Meat production requires more resources such as water, land, and energy compared to the production of plant-based food. Therefore, if more people shift towards a plant-based diet, the earth could support a larger number of humans.

Question 11

Nitrogen gas, the major component of the atmosphere, cannot directly be used by plants and animals.

Accepted Answer

Although nitrogen gas makes up 78% of the atmosphere, it is not biologically available for most organisms. The nitrogen must first be converted into a usable form such as ammonia or nitrates, which can be done through a process called nitrogen fixation.

Question 12

Ecologists do not make use of most new technologies, preferring to continue the "muddy-boots biology" style of research.

Accepted Answer

Ecologists make extensive use of technology such as remote sensing, GPS, and modeling software in their research. While fieldwork and observation are still important, modern ecological research is heavily reliant on cutting-edge technology.

Question 13

Most producers capture sunlight to produce energy-rich carbohydrates through photosynthesis.

Accepted Answer

This is a basic concept of biology - producers such as plants, algae, and some bacteria use sunlight to produce energy-rich carbohydrates through the process of photosynthesis.

Question 14

Autotroph is another word for a consumer in a trophic system.

Accepted Answer

Autotrophs are actually producers, not consumers. They are able to create their own food through processes like photosynthesis, while consumers rely on other organisms for their food.

Question 15

The larger the number of trophic levels in a food chain or web, the greater the accumulated loss of energy.

Accepted Answer

Each trophic level in a food chain or web represents a transfer of energy from one organism to another. However, not all of the energy is transferred as some is lost as heat during respiration or as indigestible waste. As a result, each successive trophic level receives less energy than the one before it, meaning that the larger the number of trophic levels, the greater the accumulated loss of energy. This is known as ecological pyramid of energy.

Question 16

Because carbon makes up such a small amount of the earth's atmosphere, even a small change, caused by nature or by humans, affects the earth's climate.

Accepted Answer

Carbon dioxide (CO2) makes up only about 0.04% of the earth's atmosphere, but it plays a crucial role in regulating the planet's temperature. Even small changes in atmospheric CO2 levels can lead to significant changes in the climate. Both natural and human activities, such as volcanic eruptions and burning fossil fuels, contribute to changes in atmospheric CO2 levels.

Question 17

The hydrologic cycle is a way nature renews water quality.

Accepted Answer

The hydrologic cycle is a natural process that involves the evaporation, condensation, and precipitation of water. Through this cycle, water is purified and renewed, which helps to maintain water quality.

Question 18

Nutrient cycles connect past, present, and future forms of life.

Accepted Answer

Nutrient cycles, such as the carbon and nitrogen cycles, involve the movement and transformation of essential elements among the living and nonliving components of ecosystems. These cycles connect the past, present, and future forms of life as the nutrients are continuously recycled and made available for use by different organisms over time.

Question 19

An ecosystem is defined as a community of different populations of species interacting with one another and their nonliving environment.

Accepted Answer

This is the correct definition of an ecosystem. It includes both living (biotic) and nonliving (abiotic) components and their interactions.

Question 20

Deep sea habitats are an exception to the first principle of sustainability, in that they use a non-solar source of energy.

Accepted Answer

Deep sea habitats use chemosynthesis as the primary source of energy, which does not rely on solar energy. This makes them an exception to the first principle of sustainability which focuses on the use of renewable energy sources.

Quiz 3: Ecosystems: What Are They and How Do They Work