21.

The normal boiling point of a of a solvent (whose vapour pressure curve is shown in the figure) on a planet whose normal atmospheric pressure is 3 bar, is about

• 400K

• 273K

• 100K

• 500K

A ball is dropped from a height h above the surface of the earth. Ignoring air drag, the curve that best represents its variation of acceleration is

Recent studies on Archaea suggest that life could have orginated:

• Extra-terrestrially and seeded through meteorite impact.

• In shallow coastal area

• In deep hydrothermal vents

• In, hot terrestrial habitats

Standing on a polished stone floor one feels colder than on a rough floor of the same stone. This is because

• Thermal conductivity of the stone depends on the surface smoothness

• Specific heat of the stone changes by polishing it

• The temperature of the polished floor is lower than that of the rough floor

• There is greater heat loss from the soles of the feet when in contact with the polished floor than with the rough floor

The acidity of normal rain water due

• SO₂

• CO₂

• NO₂

• NO

If the ratio of the number of non‐synonymous to synonymous substitutions per site in protein coding gene is greater than one, it is a an evidence of selection that is

• Positive

• Negative

• Netural

• Random

The following is the biochemical pathway for purple pigment production in flowers of sweet pea:

$\mathrm{Colorless} \mathrm{Precursor}1 \stackrel{\mathrm{Allele} \mathrm{A}}{\to } \mathrm{colorless} \mathrm{precursor} 2\stackrel{\mathrm{Allele} \mathrm{B}}{\to } \mathrm{Purple} \mathrm{pigments}$

Recessive mutation of either gene A or B leads to the formation of white flowers. A cross is made between two parents with the genotype: AaBb x aabb. Considering that the two genes are not linked, the phenotypes of the expected progenies are

• 9 purple: 7white

• 3 white: 1purple

• 1 purple: 1white

• 9 purple: 6light puple: 1 white

The frequencies of alleles ‘A’ and ‘a’ in a population at Hardy‐Weinberg equilibrium are 0.7 and 0.3 respectively. In a random sample of 250 individuals taken from the pupation, how many are expected to be heterozygous?

• 112

• 81

• 105

• 145

The transition to flowering in plants requires

• Growth of plants under long – day conditions

• Growth of plants under short‐day conditions

• Reprogramming of the shoot apical meristem

• Synthesis of the flowering hormone florigen

Both halophytes and glycophytes compartmentalize cytotoxic ions into the intracellular compartment or actively pump them out of the cell to the apoplasts with the help of membrane transport proteins. Among these, the Na⁺‐H⁺ antiporter, NHX1, is localized in

• The plasma membrane

• Chloroplast (inner envelope)

• Mitochondria (outer membrane)

• Tonoplast