Science (English Medium) Class 12 - CBSE Important Questions

(a) Given below is a pyramid of biomass in an ecosystem where each bar represents the standing crop available in the trophic level. With the help of an example explain the conditions where this kind of pyramid is possible in nature.

(b) Will the pyramid of energy be also of the same shape in this situation? Give a reason for your response.

(a) Draw a pyramid of numbers where a large number of insects are feeding on the leaves of a tree. What is the shape of this pyramid?

(b) Will the pyramid of energy be also of the same shape in this situation? Give a reason for your response.

Observe the contents 1, 2, 3 and 4 of soil samples A, B and C shown in the graph. If the temperature and soil moisture of all soil samples are identical, which soil sample (s) will show faster decomposition?

1 indicates lignin content, 2 indicates chitin, 3 indicates nitrogen content, and 4 indicates sugar content

The biomass of a standing crop of phytoplankton is 4 kg/m², which supports a large standing crop of zooplankton having a biomass of 11 kg/m². This is consumed by small fishes having a biomass of 25 kg/m², which are then consumed by large fishes with a biomass of 37 kg/m².

Draw an ecological pyramid indicating the biomass at each stage and also name the trophic levels. Mention whether it is an upright or inverted pyramid.

Use the information provided in the table given below to answer the following questions:

1. Calculate the gross primary productivity.
2. Analyze the trend in the Net Production from Producers to Top Carnivore. Give a reason for your observation.

Why are scared groves highly protected?

Name the type of biodiversity represented by the following:

50,000 different strains of rice in India.

Mention the kind of biodiversity of more than a thousand varieties of mangoes in India represent. How is it possible?

There are many animals that have become extinct in the wild but continue to be maintained in Zoological parks.
(i) What type of biodiversity conservation is observed in this case?
(ii) Explain any other two ways which help in this type of conservation.

List six advantages of the "ex-situ' approach to conservation of biodiversity.

Suggest two practices giving one example of each, that help protect rare or threatened species.

Which of the following is an example of ex-situ conservation?

There was a loss of biodiversity in the ecosystem due to a new construction project in that area. What would be its impact on the ecosystem? State any three.

Which one of the following groups faces maximum threat of extinction? 

The sixth extinction in progress currently is different from all previous extinctions on earth as it is ______.

Give three reasons as to why the prokaryotes are not given any figures for their diversity by ecologists.

Iron (z=26) is highly ferromagnetic. Explain.

Silver crystallises in FCC structure. If density of silver is 10.51 gcm^-3, calculate the volume of unit cell. [Atomic mass of slive (Ag) = 108 gm^-1]

The major binding force in diamond is_______________ .

(a) Covalent bond                                                  

(b)  Ionic bond

(c) Metallic bond                                                   

(d)  Co-ordinate covalent bond

What is the covalency of nitrogen in N₂O₅?