The circuit for studying the V-I characteristics of a p-n junction diode typically includes:
- A variable DC power supply to provide different values of voltage \( V \),
- A p-n junction diode,
- A series resistor to limit the current through the diode, and
- A voltmeter and ammeter to measure the voltage across and the current through the diode, respectively.
Here is a simple diagram: \[ \begin{array}{c} \text{DC Power Supply} \quad \longrightarrow \quad \text{Series Resistor} \quad \longrightarrow \quad \text{P-N Junction Diode} \quad \longrightarrow \quad \text{Ammeter} \quad \longrightarrow \quad \text{Voltmeter} \end{array} \] The current and voltage are varied, and the corresponding V-I characteristics are plotted.
The process of copying the genetic information from one strand of DNA into RNA is termed as transcription. The principle of complementarity of bases governs the process of transcription, also except that uracil comes in place of thymine.
Study the complete transcription unit given below and answer the following questions:
(a) Name the main enzyme involved in the process of transcription.
(b) Identify coding strand and template strand of DNA in the transcription unit.
Attempt either sub-part (c) or (d):
(c) Identify (C) and (D) in the diagram, mention their significance in the process of transcription.
OR
(d) Describe the location of (C) and (D) in the transcription unit.}
Student to attempt either option (A) or (B).
(A)
(i) Describe the process of megasporogenesis in an angiosperm.
(ii) Draw a diagram of a mature embryo sac of the angiosperm. Label its any four parts.
OR
(B) The reproductive cycle in the female primates is called menstrual cycle. The first menstruation begins at puberty.
Answer the following questions:
(i) Name the four phases of menstrual cycle in a proper sequence.
(ii) How long does the menstrual phase last in a menstrual cycle?
(iii) When and why hormones estrogen and progesterone reach their peak levels respectively, in the menstrual cycle?
(iv) Give the significance of LH surge.