NEET Practice Questions (MCQs) with Answers & Solutions

The NCERT states, 'Joule heating is given by \(i^2R\) and depends on \(i^2\) (which is always positive whether i is positive or negative) and not on i. Thus, there is Joule heating and dissipation of electrical energy when an ac current passes through a resistor.'

The NCERT states, 'The magnitudes of phasors V and I represent the amplitudes or the peak values \(v_m\) and \(i_m\) of these oscillating quantities.' The direction of the phasor indicates the phase.

Given \(P = 100 W\) and \(V_{rms} = 220 V\). We know \(P = V_{rms}^2 / R\). Therefore, \(R = V_{rms}^2 / P = (220 V)^2 / 100 W = 48400 / 100 = 484 \Omega\). This is directly from Example 7.1 (a).

Given \(P = 100 W\) and \(V_{rms} = 220 V\). We know \(P = I_{rms} V_{rms}\). Therefore, \(I_{rms} = P / V_{rms} = 100 W / 220 V \approx 0.454 A\). This is directly from Example 7.1 (c).

The NCERT text derived this: 'Using the trigonometric identity, \(sin^2 \omega t = 1/2 (1– cos 2\omega t)\), we have \(\langle sin^2 \omega t \rangle = (1/2) (1– \langle cos 2\omega t \rangle)\) and since \(\langle cos 2\omega t \rangle = 0\), we have, \(\langle sin^2 \omega t \rangle = 1/2\)' (Eq. 7.5c).

The 'Points to Ponder' section clarifies: 'Though in a phasor diagram, voltage and current are represented by vectors, these quantities are not really vectors themselves. They are scalar quantities. It so happens that the amplitudes and phases of harmonically varying scalars combine mathematically in the same way as do the projections of rotating vectors... The ‘rotating vectors’ that represent harmonically varying scalar quantities are introduced only to provide us with a simple way of adding these quantities using a rule that we already know as the law of vector addition.'

According to the NCERT text, 'If any protein encoding gene is expressed in a heterologous host, it is called a recombinant protein.' This clearly defines what a recombinant protein is in the biotechnological context.

The NCERT text states: 'After having cloned the gene of interest and having optimised the conditions to induce the expression of the target protein, one has to consider producing it on a large scale.' This indicates the immediate next step.

The NCERT text explains: 'The cells can also be multiplied in a continuous culture system wherein the used medium is drained out from one side while fresh medium is added from the other to maintain the cells in their physiologically most active' phase (exponential phase). This maximizes the production of the desired protein.

The context lists 'Therapeutics, diagnostics, genetically modified crops for agriculture, processed food, bioremediation, waste treatment, and energy production' as applications of biotechnology. Weather forecasting is not mentioned.