The zone of atmosphere in which the ozone layer is present is called: 
The ozone (O3 ) found in upper part of the atmosphere, i.e., Stratosphere, is Good ozone, since, it acts as a shield for absorbing UV-radiations from sun.
Just as a person moving from Delhi to Shimla to escape the heat for the duration of hot summer, thousands of migratory birds from Siberia and other extremely cold northern regions move to: 
Given below is a simplified model of phosphorus cycling in a terrestrial ecosystem with four blanks (A-D). Identify the blanks: 
Phosphorus is an important element for living beings. Consumers obtain phosphorus directly or indirectly from plants. Phosphorus is also present in phosphatic rocks. It is released during the decomposition of plant and animal remains. The released phosphorus may reach the deeper layers of soil and gets deposited as phosphate rocks. All plants and animals eventually die and in due time, their organic remains or debris decay through the action of micro-organism and the phosphates are released into the water for recycling.
If 20 J of energy is trapped at the producer level, then how much energy will be available to peacock as food in the following chain? 
Plant → Mice → Snake → Peacock
Most animals are tree-dwellers in a: [2015 RS]
In tropical rain forest zone, most of the animals prefer to live on trees. The reason is that the floor of forest is full of humidity, decomposing leaves and other organic matters and is the habitat of insects etc.
A population will not exist in Hardy - Weinberg equilibrium if: [2015 RS]
The theory of Hardy- Weinberg equilibrium states that in the absence of disturbance on the level of genetic structure, a population’s existence will not continue. Thus mating should be in a random way.
Most animals that live in deep oceanic waters are: [2015 RS]
In which of the following interactions both partners are adversely affected? [2015 RS]
Competition occurs for light, food and space among organisms in which all partners are adversely affected in an ecosystom.
Gause's principle of competitive exclusion states that: 
When does the growth rate of a population following the logistic model equal zero? 
The logistic model is given as dN/dt = rN(1–N/K)
Logistic growth of a population size occurs when resources are limited. The formula we use to calculate logistic growth adds the carrying capacity as a moderating force in the growth rate.
The logistic model is given as dN/dt = rN(1-N/K)
When the value of N/K is one, then,
dN/dt = rN(1-N/K)
dN/dt = rN(1-1)
dN/dt = rN(0)
dN/dt = 0 (zero)
So, the growth rate of the population will be equal to zero.