NEET Practice Questions (MCQs) with Answers & Solutions

The NCERT text states: 'All animals belonging to various phyla are assigned to the highest category called Kingdom Animalia in the classification system of animals.'

The context mentions: 'The scope of systematics was later enlarged to include identification, nomenclature and classification. Systematics takes into account evolutionary relationships between organisms.' This implies all four aspects are included.

The text explicitly states: 'Classification is not a single step process but involves hierarchy of steps...'. Therefore, the statement 'Classification is a single-step process' is incorrect.

From Table 1.1: Mango (Mangifera indica) and Wheat (Triticum aestivum) both belong to Division Angiospermae. Their classes (Dicotyledonae and Monocotyledonae respectively), orders, families, genus, and species are different.

Referencing Figure 1.1 and general biological knowledge, the ascending hierarchical order is Species, Genus, Family, Order, Class, Phylum/Division, Kingdom. Option (d) presents the full correct sequence, although other options in the exercise question (not the provided options) were incomplete or incorrect.

According to the NCERT text, 'The path taken by a fluid particle under a steady flow is a streamline. It is defined as a curve whose tangent at any point is in the direction of the fluid velocity at that point.' Option o1 is false because 'No two streamlines can cross, for if they do, an oncoming fluid particle can go either one way or the other and the flow would not be steady.' Option o2 is false because 'The velocity of a particular particle may change as it moves from one point to another.' Option o4 is false; streamlines are closer together where velocity is higher and can converge/diverge.

The equation of continuity for incompressible fluids states $Av = ext{constant}$. Here, $Av$ represents the volume flux or flow rate, which remains constant throughout the pipe of flow. While the density of an incompressible fluid is constant, the question asks what remains constant in the flow, and volume flux is directly derived from the continuity equation applied to the flow.

The NCERT text explicitly states, 'Equation (9.10) ... is called the equation of continuity and it is a statement of conservation of mass in flow of incompressible fluids.'

From the equation of continuity, $Av = ext{constant}$. If A decreases, then v must increase to maintain the constant product. The text says, 'Thus, at narrower portions where the streamlines are closely spaced, velocity increases and its vice versa.'

The NCERT text states, 'No two streamlines can cross, for if they do, an oncoming fluid particle can go either one way or the other and the flow would not be steady. Hence, in steady flow, the map of flow is stationary in time.' This precisely defines steady flow.