pmt master: a/r solution 2

Biology:

1. D

The mRNA attaches itself to the small subunit (30s) of the ribosome via its 5’ end. This attachment is assisted by the G-cap nucleotide and bases of sequence present on the mRNA systems where G-cap is present as in eukaryote

2. B

Lateral line system is a sensory system of fishes and aquatic and larval amphibians whose receptors are clusters of sensory cells derived from ectoderm. These clusters of sensory cells are called neuromast organs

3. A

The regulation of RBC production is accomplished by the hormone erythropoietin which is secreted by the juxtaglomerular cells of kidney. This hormone circulates to the red bone marrow, where it increase stem cell mitosis and speeds the development of RBC

4. C

To maintain unequal distribution of sodium and potassium ions, the neurons use chemical energy in form of ATP

5. B

During a wound germs are removed by the process of phagocytosis by WBC. WBCs accumulate at the wound site by diapedesis, which is the squeezing of leucocytes out from the endothelium of cappilaries to fight against foreign agent

Physics:

1. D

The billiards balls in an elastic collision are in a deformed state and their total energy is in the form of PE and KE. Thus, KE is less than the total energy. The energy used against friction is dissipated as heat and not available for doing work

2. C

Faraday’s laws involve conversion of mechanical energy into electrical energy. This in in accordance with the law of conservation of energy. We also know that, in pure resistance emf is in phase with the current

3. C

Colours are seen due to interference of light from both surfaces of thin layer

4. D

Magnetic poles always exist in pairs, however, one can imagine of a magnetic field configuration with three poles. When north poles of two magnets or south poles of two magnets are glued together, they provide a three poled configuration. Also a bar magnet does not exert a torque on itself due to its own field

5. B

A step-down transformer converts electrical energy from a high voltage to one at a low voltage. Accordingly the current in the secondary will be larger than that in the primary. In order to produce less heat in the secondary, we use a wire of lesser resistance i.e thick. We also know that when the plane of the armature is parallel to the lines of force of magnetic field, the rate of change of magnetic flux is the maximum. Therefore, emf induced is maximum

Chemistry:

1. C

In adiabatic process, no heat enters or leaves the system. The system is completely insulated from its surroundings. From first law, we know that change in internal energy is equal to the negative of work done, so, internal energy decreases and temperature of gas falls

2. A

The valence shell electrons in alkali metals is so losely held that ven low energy photons can easily emit electrons from the surface

3. C

In physical absorption, the substance absorbed is retained not only on the surface but also is uniformly distributed throughout the entire body. Absorbed molecules are not broken under ordinary conditions

4. C

Cuprous ion don’t have unpaired electrons and so is colourless. The unpaired electron of cupric ion can move from one set of d-orbital to other due to field of water molecules, thus, show blue colour in aqueous solution

5. D

Absorption spectrum is produced when white light is passed through a substance and transmitted light is analysed by spectrograph. The dark spaces corresponds to the light radiations absorbed by the substance.

Emission spectrum is produced by analysing the radiant energy emitted by an excited substance by a spectrograph. Thus discontinuous spectra consisting of a series of sharp lines and separated by dark bands are obtained