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In a dicot stem, the cortex is differentiated into three sub-zones. Which of these provides mechanical strength to the young stem?
The NCERT states for dicotyledonous stem: 'The outer hypodermis, consists of a few layers of collenchymatous cells just below the epidermis, which provide mechanical strength to the young stem.'
Parenchymatous cells located between the xylem and phloem in a dicot root are referred to as:
The NCERT reads: 'The parenchymatous cells which lie between the xylem and the phloem are called conjuctive tissue.'
How does the size of vascular bundles in monocot leaves compare, particularly reflecting their venation pattern?
The NCERT states: 'The parallel venation in monocot leaves is reflected in the near similar sizes of vascular bundles (except in main veins) as seen in vertical sections of the leaves.'
Which primary difference in secondary growth ability exists between dicot and monocot roots and stems?
From the summary, it states: 'The secondary growth occurs in most of the dicotyledonous roots and stems.' And for monocotyledonous root: 'Monocotyledonous roots do not undergo any secondary growth.' For monocotyledonous stem, the text implies closed vascular bundles do not form secondary tissues. Thus, dicots generally exhibit secondary growth, while monocots typically do not.
Which of the following statements correctly describes the V-I characteristics of a p-n junction diode in forward bias?
According to the NCERT text, 'In forward bias, the current first increases very slowly, almost negligibly, till the voltage across the diode crosses a certain value. After the characteristic voltage, the diode current increases significantly (exponentially), even for a very small increase in the diode bias voltage.'
What is the approximate threshold voltage or cut-in voltage for a silicon diode?
The NCERT states, 'This voltage is called the threshold voltage or cut-in voltage (~0.2V for germanium diode and ~0.7 V for silicon diode).'
In reverse bias, the current flowing through a p-n junction diode is typically in the order of:
The NCERT text mentions, 'For the diode in reverse bias, the current is very small (~μA) and almost remains constant with change in bias. It is called reverse saturation current.'
The dynamic resistance ($r_d$) of a diode is defined as:
As per the NCERT, 'For diodes, we define a quantity called dynamic resistance as the ratio of small change in voltage ΔV to a small change in current ΔI: $r_d = \Delta V / \Delta I$ (14.6)'
What happens to the barrier potential of a p-n junction diode under forward bias?
The context states, 'The effective barrier height under forward bias is ($V_0 – V$).' Also, 'The barrier is decreased while the barrier increases in reverse bias.'
What happens to the depletion layer width of a p-n junction diode under reverse bias?
According to the NCERT, 'As a result, the barrier height increases and the depletion region widens due to the change in the electric field' in reverse bias.
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.