Ar 1

Biology: 1. D Anaphase I involves the separation of homologous chromosomes into different daughter cells. So, meiosis I is called reductional division. But each chromosome is still formed of two sister chromatids joined at the common centromere. Anaphase I results in reduction in number of chromosomes but each chromosome has double amount of dna, so, meiosis II occurs, during which chromatids of each chromosome separate into different cells. Main aim of meiosis ii is to separate genetically modified chromatids of each homologous chromosome formed during crossing over in meiosis i 2. B Milk secretion is maintained as long as breast feeding, and hence , hormone production continues. A woman does not conceive during the lactation period because lactation stimulates prolactin secretion which inhibits GnRH secretion, and ovulation is inhibited 3. A The heart wood of Cedrus deodara is strongly resistant to insect and fungi due to oils and thus is very suitable for commercial use 4. D Cycas seeds remain viable for a few months only. Germination in Cycas is hypogeal 5. C Ammensalism is (-,0) effect, i.e, one species suffer and other not effected. Allelopathy is a phenomenon associated with plants, in which one plant produce some chemical substances which inhibits the growth of other plant species. Eg, Juglans nigra (black walnut) produce juglone that inhibits growth of other plants near it Mycorrhizal association is an example of mutualism (+,+)

Physics: 1. A R=
 

 

A= mass number The volume of nucleus is

Now, as the mass of proton and neutron is equal, say m, the mass of a nucleus is roughly proportional to the mass number A, M= Am

Hence, density within a nucleus

That is, ρ is independent of A 2. C Red colour is always used for danger signals, because red have longest wavelength and so is least scattered and can be seen from a very long distance 3. A As the polar ice melts, it will flow towards the equator, thereby increasing the moment of inertia. Hence, angular velocity decreases, so, days will be longer 4. A The focal length of a lens in a medium of refractive index μ is given by

Where µ is the refractive index of glass In air,

So,

That is, focal length of convex lens in water increases thereby reducing its convergent power 5. D Eddy currents are produced when a metal sheet is placed in a changing magnetic field. In a metal sheet, we can consider closed loops through which an induced current flows due to a change of magnetic flux. This current is called eddy current and give rise to loss of thermal energy Chemistry: 1. A Dissociation constant for

Can be given as

2. 3.

4.

5.

Therefore we can say that dissociation constant is a measure of its ability to furnish protons in the solution A Due to intermolecular bonding p-nitrophenol has higher boiling point than o-nitrophenol C Due to presence of hydroxyl group, there is extensive hydrogen bonding between ethanol molecules, but there is no hydrogen bonds in dimethyl ether. So, boiling point of dimethyl ether is lower than ethanol A Oxygen is most electronegative element after fluorine. Therefore, in compounds between O and F , O is found to have positive oxidation stage B When s-electrons of outermost shell do not participate in bonding, it is called inert pair effect. Since, the inert pair effect increases down the group, so Pb 2+ compounds are more stable than Pb 4+ which thus, act as oxidising agents Pb 2+ Is paramagnetic