The Carbon and Nitrogen Cycle and Microorganisms

The Carbon and Nitrogen Cycle and Microorganisms

Multiple Choice

12D: This diagram demonstrates why the ocean is a large carbon sink. An increase in the amount of carbon dioxide in the atmosphere can cause atmospheric temperatures to increase. Which statement explains how this could affect the ocean as a carbon sink?

• Less atmospheric carbon dioxide would be available to phytoplankton

• Dissolved carbon dioxide gas in the ocean would increase because surface winds would cause a deeper circulation pattern, making more room for gas

• Less carbon dioxide gas would be contained in the ocean because increasing precipitation would dilute the carbon entering the ocean

• Less carbon dioxide would be dissolved in the ocean because increasing atmospheric temperatures would cause ocean temperatures to increase

Multiple Choice

12D What would be the most likely effect of a wildfire that burned a large area of a forest?

• More sugars and starches would be available for animals in the area.

• The availability of fossil fuels for use by industries in the area would be reduced.

• Less carbon dioxide would be removed from the atmosphere in the area by plants.

• An increase in animal respiration would increase the release of carbon dioxide in the area.

Multiple Choice

11B: An estuary collects sediment from the ocean and rivers that feed into it. The sediments swirl around and then settle to form a mudflat. Eel grass is then established on the mudflat. The ecosystem changes over time and ultimately develops into a salt marsh that contains mangrove trees. Which of the following is likely NOT involved in this example of ecological succession?

• The rotting remains of plants add to the fertility of the soil

• The soil becomes so fertile that eel grass is replaced by other plant species

• The roots from plants help stabilize the sediment, keeping it in place

• The concentration of salt becomes so high that all plant life is destroyed

Multiple Choice

12D: As part of the nitrogen cycle, animals acquire some amino acids by doing which of the following?

• Breathing air

• Eating plants

• Drinking water

• Producing waste

Multiple Choice

12D The diagram represents the nitrogen cycle in a student’s aquarium. Ammonia, nitrites, and, to a lesser degree, nitrates can be harmful to fish. The student wants to keep the nitrogen in this aquarium cycling normally without having to continually change the water.

Which of the following should the student add more of to help remove nitrates and improve the natural cycling of nitrogen in this aquarium?

• Fish

• Plants

• Nitrobacter

• Water

Multiple Choice

12D: Atmospheric nitrogen has to be combined with other elements, or fixed, in order to be used by plants. Lightning is one way that nitrogen is fixed. When lightning occurs, the extreme heat breaks the bonds in nitrogen molecules, allowing nitrogen to combine with oxygen and from nitrogen oxides. In what way is most of the nitrogen fixed by lightning made available for use by plants?

• It is moved by the wind toward dry areas

• It is incorporated into the exoskeletons of flying insects that eat plants

• It is inhaled and exhaled by birds roosting in trees during rainstorms

• It is carried by rain to the soil.

Multiple Choice

12D The photograph shows monarch butterflies landing on plants where there are thousands of other monarch butterflies. These butterflies feed on milkweed plants as they travel south for the winter, covering distances of 5,000 km or more each year. However, the population of these butterflies has been steadily declining over the last 20 years.

What is the most likely reason the population of these butterflies has been declining?

• The number of bird species evolving to prey on butterflies has increased.

• The butterflies are evolving to tolerate cold weather in the northern United States and southern Canada.

• The increase in yearly temperatures has warmed the northern habitats.

• The number of milkweed plants along the butterflies’ migratory route has decreased

Multiple Choice

11A Health professionals sometimes recommend nutritional supplements that contain a variety of species of bacteria to promote good digestive health. The product label for one of these supplements is shown.

Why does this type of bacteria-filled supplement benefit human health instead of causing illness?

• Stomach acids and digestive enzymes kill the bacteria in this type of supplement, protecting the person against future infections by live organisms.

• The human digestive system contains billions of beneficial bacteria that enhance digestion and nutrient absorption, synthesize vitamins, and help limit the growth of harmful bacteria.

• These species of bacteria remove all the other species of microorganisms living in the human digestive system and ensure that no microorganisms survive to contaminate the body.

• These bacteria are able to deactivate viruses that may inhabit the human digestive system and are used to protect against further viral infections

Multiple Choice

11A: A student researching bacteria concluded a report with the following claim: All bacteria disrupt the health of organisms they inhabit, including humans.

Which statement correctly addresses the validity of the claim?

• The claim is valid because many studies and experiments have shown that bacteria disrupt homeostasis

• The claim is invalid because there are many types of bacteria that help organisms maintain homeostasis.

• The claim is invalid because only microorganisms such as viruses disrupt the health of organisms.

• The claim is valid because bacteria cause disease

Multiple Choice

4C A person infected with the human immunodeficiency virus (HIV) may not have any symptoms for a period of time. During this period the virus affects the body by doing which of the following?

• The virus produces toxins that weaken immune cells and prevent them from reproducing.

• The virus damages immune cells while using their machinery to produce copies of itself.

• The virus uses nutrients meant for immune cells to fuel its own cellular respiration.

• The virus changes the identity of the nucleotides of immune cells to prevent the immune system from functioning normally.

Multiple Choice

4C In 1898 Friedrich Loeffler and Paul Frosch found evidence that the cause of the highly contagious hoof-and-mouth disease in livestock was a microscopic infectious particle. It was discovered that this particle requires a host cell to reproduce.

Which pathogen is most likely responsible for causing hoof-and-mouth disease in livestock?

• A bacterium, because it is contagious

• A fungus, because it infects livestock

• A protist, because it is microscopic

• A virus, because it requires a host cell to reproduce

Multiple Choice

4C A student produces a labeled drawing of a virus for a presentation. The student states that the capsid has a function similar to the nuclear membrane found in animal cells.

Which of these describes the similar functions of capsids and nuclear membranes?

• Both transport proteins throughout the structures.

• Both provide energy for activities in the structures.

• Both protect genetic information for the structures.

• Both code for the proteins needed for reproduction of the structures.

Multiple Choice

11A: Saprophytes are fungi that feed on dead and decomposing organisms. They secrete enzymes that digest components of cell walls, such as cellulose and lignin. Which statement explains why these fungi are an important part of the biogeochemical cycle?

• Saprophytes perform gas exchange that assists the cellular activities of autotrophs

• Saprophytes extract minerals from living tissue to recycle them back to the soil

• Saprophytes transport nutrients through the xylem and phloem in autotrophs

• Saprophytes return organic material to the soil for use by living organisms

Multiple Choice

11A Which role of protists has the most positive effect on maintaining the plant population in an ecosystem?

• Protists are a major food source for animals.

• Protists produce approximately 75 percent of the oxygen on Earth

• Protists decompose dead materials, returning nutrients to the soil.

• Protists found in the gut of animals assist in digestion.

Multiple Choice

Mode of Nutrition in Algae is

• Heterotrophic

• Autotrophic

• Both Autotrophic and Heterotrophic

• None

Multiple Choice

Why is algae not a plant?

• It does not have roots.

• It floats.

• It does not have roots and it floats.