Ornithologists observed decline in the bird population in an area near a lake after the setting of an industrial unit in the same area. Explain the cause responsible for the decline observed.

How has DDT caused decline in bird population?

Read the following passage and answer the questions. When colloidal solutions are viewed under a powerful ultramicroscope, the colloidal particles appear to be in a state of continuous zig-zag motion all over the field of view. This motion was first observed by the British botanist, Robert Brown, and is known as Brownian movement. This motion is independent of the nature of the colloid but depends on the size of the particles and viscosity of the solution. Smaller the size and lesser the viscosity, faster is the motion. The Brownian movement has been explained to be clue to the unbalanced bombardment of the particles by the molecules of the dispersion medium. The Brownian movement has a stirring effect which does not permit the particles to settle and thus, is responsible for the stability of sots. What is the cause of Brownian movement ?

The shells of crabs found around a particular coastal location in Japan seem mostly to resemble the legendary face of a Samurai. Given below are two explanations of this observed fact. Which of these strikes you as a scientific explanation? - (a) A tragic sea accident several centuries ago drowned a young Samurai. As a tribute to his bravery, nature through its inscrutable ways immortalised his face by imprinting it on the crab shells in that area. (b)After the sea tragedy, fishermen in that area, in a gesture of honour to their dead hero, let free any crab shell caught by them which accidentally had a shape resembling the face of a Samurai. Consequently, the particular shape of the crab shell survived longer and therefore in course of time the shape was genetically propagated. This is an example of evolution by artificial selection.

Explain with reason, why sun is observed earlier to actual sun rise and after sun set.

These questions consist of two statements each printed as Assertoin and Reason. While answering these questions, you are requied to choose any one of the following four responses. If both Assertion and Reason are true and Reason is correct explanation of Assertion If both Assertion and REason are true but Reason is not correct explanation of Assertion If Assertion is true but Reason is false If both Assertion and Reason are false Assertion: At climax age, perfect equilbrium between abiotic and biotic components of area cannot be observed. Reason: This is due to autogenic and allogenic succession.

Create an aquatic food chain in a water body into which effluents flow from a pesticide factory. Diagrammatically represent biomagnification in this food chain Explain why a decline in the predator bird population is expected when its feeds on the tertiary consumer of this food chain.

The graph shows species area relationship. If b denotes the relationship on log scale. What kind of slope will be observed for frugivorous birds and mammals in a tropical forest?