Sexually transmitted infections could be prevented by:
(A) Use of condoms
(B) Use of intra uterine devices
(C) Use of pills
(D) Avoiding sex with multiple partners
Choose the correct answer from the options given below:

Identify the correct statements for pollen grains
(A) Pollen grain represents male gametophyte.
(B) Pollen grain is a haploid unicellular body.
(C) The hard exine of the pollen is made up of sporopollenin.
(D) The intine of the pollen is composed of oxidative polymers of
carotenoids or carotenoid esters.
Choose the correct answer from the options given below:

Read the following passage carefully and answer the given questions.
During anaerobic sludge digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide. These gases form biogas and can be used as source of energy as it is inflammable. The bioactive molecule, cyclosporin A, that is used as an immunosuppressive agent in organ-transplant patients, is produced by the fungus Trichoderma polysporum. You must have noticed that bottled fruit juices bought from the market are clearer as compared to those made at home. This is because the bottled juices are clarified by the use of pectinases and proteases. Statins produced by the yeast Monascus purpureus have been commercialised as blood-cholesterol lowering agents. It acts by competitively inhibiting the enzyme responsible for synthesis of cholesterol. The BOD test measures the rate of uptake of oxygen by micro-organisms in a sample of water and thus, indirectly, BOD is a measure of the organic matter present in the water.
The bottled juices are clarified by the combination of -

Which one of the following is a result of convergent evolution?

What are seen as "beads on string" structure when viewed under an electron microscope ?

The rate of biomass production is called productivity. It is expressed in terms of _______ to compare the productivity of different ecosystems.

Arrange the given organisms involved in an ecosystem in correct sequence from lower to higher order.
(A) Fish
(B) Phytoplankton
(C) Man
(D) Zooplankton
Choose the correct answer from the options given below:

Ferromagnetic material in transformers should have :

In which of the following interval the function \(f(x)=x^x, x>0\) is strictly increasing?

Three charges, +Q, q and +Q are placed with q at mid point of the line joining the other two charges. For the system of charges to be in equilibrium, the value of q is

The differential equation \(\frac{d y}{d x}+\frac{x}{y}=0\), represents the family of curves:

When a mixture of NaCl and \(K _2 Cr _2 O _7\) is gently warmed with conc. \(H _2 SO _4\) ?
(A) Deep red vapours are evolved.
(B) The Vapours when passed through NaOH solution give yellow solution of \(Na _2 CrO _4\).
(C) Chlorine gas is evolved.
(D) Chromyl chloride is formed.
Choose the correct answer from the options given below :

If \(\vec{a}, \vec{b}\) and \(\sqrt{3} \vec{a}-\vec{b}\) are three unit vectors, then the angle between \(\vec{a}\) and \(\vec{b}\) is :