Question

17. Acid Rain has an effect on natural systems (lakes, forests, etc) when the pH of the (rain or snow) is

A. less than 8 on the pH scale   B. greater than 8 on the pH scale  C. less than 7 on the pH scale

D. less than 5.6 on the pH scale  E. greater than 9 on the pH scale

18. Natural selection will ultimately lead to a species that is:

A. more intelligent. B. physically bigger.  C. adapted to its environment.

D. more aggressive.  E. less vulnerable to its predators.

19. Carbon sequestration refers to what?

A. uncut tropical rain forests holding vast amounts of carbon in their vegetation

B. humans attempting to capture carbon from the burning of fossil fuels and storing that carbon underground  

C. the oceans holding carbon and keeping it out of the atmosphere

D. all of the above may be considered carbon sequestration

E. only a and b

20. A bluebird and a tree swallow are living in the same territory and are using some of the same resources (feeding on flying insects). These two birds would be members of the same trophic level.     A. True.           B. False.         

Answer 1

Answer for question no 17 : Option (D) - less than 5.6 in the pH scale.

Explanation : Natural range of pH of normal rain is between 5 and 5.5. But when sulphur dioxide, nitrogen oxides etc are mixed with rain, it becomes acidic and the pH value falls down to more or less 4.

The other options represent the pH values more than the pH value of normal rain and somewhat towards alkaline range. So, these values can't be considered as the pH of acidic rain.

So, Option (D) is the right answer and option (A), (B), (C) and (E) are not.

Answer for question no 18 - Option (C) - adapted to its environment.

Explanation : Natural selection will ultimately lead to a species which are better adapted to its environment as explained in the principle ; 'Survival of the fittest'.

The species being more or less intelligent has no preference in natural selection.

The physical size of the species also plays no role in natural selection.

The species being more or less aggressive doesn't provide more chance of getting naturally selected.

A species which is being vulnerable to its predator doesn't affect its chance of being naturally selected or natural selection doesn't have a direction that would lead to a species which is less vulnerable to its predator,it is dependent on the adaptibility of the species.

So, Option (C) is the right answer and rest are not.

Answer for question no 19 - Option (D) - All of the above may be considered carbon sequestration.

​​​​​​Explanation : Carbon sequestration is the process by which carbon is stored in a long term manner as carbon Di oxide or other form of carbon to reduce global warming or other climatic changes.

Uncut tropical forest is a place of carbon sequestration.

Industry or power station with CO2 capture facility is also a mode of carbon sequestration.

The ocean ecosystem also captures a large amount of carbon.

So, all of the above system are examples of carbon sequestration. Hence Option (D) is the right answer.

Answer for question no 20 - Option ( A) - True

Explanation : If both blue bird and tree swallow feed on flying insect,they share a common trophic level. As trophic level is the position in which any species feed on In food Web.

So the statement is true.