The correct statement regarding the electric field due to static charges is that it is conservative and field lines do not form closed loops.
An electric field is said to be conservative if the work done by the electric field on a test charge is independent of the path taken and depends only on the initial and final positions. This implies that the work done around any closed path is zero, a property of a conservative field. Mathematically, for a conservative field, we have:
\(∮C E · dl = 0\)
where ∮C indicates the integral around a closed path and E is the electric field. Therefore, the electric field created by static charges is conservative.
Additionally, the electric field lines of static charges start at positive charges and end at negative charges, without forming closed loops. This is in contrast to the magnetic field lines, which do form closed loops. Therefore, the statement that the electric field is conservative and field lines do not form closed loops is correct.
Regulation of lac operon by repressor is referred to as:
Explain how the addition of lactose in the medium regulates the switching on of the lac operon in bacteria.
Read the following passage and answer the questions that follow. According to evolutionary theory, every evolutionary change involves the substitution of a new gene for the old one and the new allele arises from the old one. Continuous accumulation of changes in the DNA coding for proteins leads to evolutionary differences. The chemical composition of DNA is basically the same in all living beings, except for differences in the sequence of nitrogenous bases. Given below are percentage relative similarities between human DNA and DNA of other vertebrates:
(a) What is the term used for the substitution of a new gene for the old one and the new allele arising from the old one during evolutionary process?
(b) Which one of the following holds true for the data provided in the above table?
(c) [(i)] To which category of evolution (divergent or convergent) does the following relationship belong? Justify your answer.
Human and Rhesus Monkey
OR
[(ii)] Differentiate between Convergent and Divergent evolution.
Answer the following questions:
[(i)] Explain the structure of a mature embryo sac of a typical flowering plant.
[(ii)] How is triple fusion achieved in these plants?
OR
[(i)] Describe the changes in the ovary and the uterus as induced by the changes in the level of pituitary and ovarian hormones during menstrual cycle in a human female.