KVPY Class-XII (SB/SX) - 05-11-2017

(i) a + b < c + d
(ii) b + c < d + e
(iii) c + d < e + a
(iv) d + e < a + b
From (i) and (iii),
a + b < e + a
⇒ b < e
From (ii) and (iv),
b + c < a + b
⇒ c < a
(i) - (ii):
a - c < c - e
⇒ c > e
(i) - (iv):
(a - e) + (b - d) < (c - a) + (d - b)
Thus, d > b
(i) + (iii) - (ii):
c > d

The conjugated chain in carotenoids means that they absorb the visible region and hence are coloured. Beta-carotene absorbs most strongly between 400-500 nm which is the green/blue part of the spectrum. Beta-carotene appears orange, because the red/yellow colours are reflected back to us.

NaCl + AgNO₃ → NaNO₃ + AgCl is not an oxidation-reduction reaction because there is no change in oxidation state of any element.

Thermal solubility of the carbonates of alkaline earth metals increases down the group due to increase in ionic character.
As the size of the cation increases, the polarising power of the cation decreases.

The metal with the lowest E^o (reduction potential) value is the strongest reducing agent.
This can also be estimated from the reactivity series of metals.
Among the given options, Zn is the most reactive metal and is the strongest reducing agent.

Due to steric hindrance, SF₆ is not hydrolysed by H₂O at 25ºC.

(NH₄)₂Cr₂O₇ →N₂ + Cr₂O₃ + H₂O

2NaN₃ →2Na + 3N₂

NH₄NO₂ →N₂ + H₂O

(NH₄)₂C₂O₄ →2NH₃ + H₂C₂O₄

A virus-infected cell releases interferons causing nearby cells to heighten their anti-viral defence. The name 'interferon' comes from their ability to interfere with the production of new virus particles.

Leydig cells release a class of hormones called androgens (19-carbon steroids). They secrete testosterone, androstenedione and dehydroepiandrosterone (DHEA), when stimulated by the pituitary hormone, luteinising hormone (LH).

Glucagon promotes breakdown of glycogen leading to release of glucose. This increases the level of glucose in blood.

Restriction enzyme has no role in polymerase chain reaction.

Carbon dioxide is nearly transparent to the solar radiation emitted from the sun, but partially opaque to the thermal radiation emitted by the Earth. As such, it allows incoming solar radiation from the sun to pass through it and warm the Earth's surface.

The species-area relationship or species-area curve describes the relationship between the area of a habitat, or of part of a habitat, and the number of species found within that area. The graph is a straight line on log-log axes.

The process of moving sodium and potassium ions across the cell membrane is an active transport process involving the hydrolysis of ATP to provide the necessary energy. It involves an enzyme referred to as Na⁺/K⁺-ATPase.

Enzyme decreases activation energy in reaction, thereby increasing the rate of catalysis.

Cellulose forms rod-like structures that will hydrogen bond together to form strong microfibrils (made of glucose) that make up the structures of cell walls and confer rigidity.

Antigens are bound to antibodies through weak and non-covalent interactions, such as electrostatic interactions, hydrogen bonds, Van der Waals forces, and hydrophobic interactions.

Under proper reducing conditions, three bands will be obtained corresponding to heavy, light and J chains.

Linkage is an exception to the law of independent assortment. Hence, linked genes do not obey this law.

Alleles are alternate forms of gene. They are present on the same locus and are inheritable.

Endonucleases do not cut from free ends. Exonucleases cut the DNA molecule from free ends.

Since glucose leads to two triose sugars in the preparatory phase, each reaction in the pay-off phase occurs twice per glucose molecule. This yields 2 NADH molecules and 4 ATP molecules, leading to a net gain of 2 NADH molecules and 2 ATP molecules from the glycolytic pathway per glucose.

Pyridoxal-6-phosphate is the active form of vitamin B₆. It acts as a co-enzyme in many enzymatic reactions. One of the reactions in which it functions as a co-enzyme is the conversion of L-alanine to a racemic mixture of D- and L-alanine. This reaction is catalysed by enzyme alanine racemase.

Under certain conditions, the photoexcited electrons take an alternative path called cyclic electron flow, which uses photosystem I (P700), but not photosystem II (P680). This process produces no NADPH and no O², but it does make ATP. This is called cyclic photophosphorylation.

Flame cells are for secretion and osmoregulation in flatworms. A planarian is one of many flatworms of the class Turbellaria.
Choanocytes (also known as collar cells) are cells that line the interior of asconoid, syconoid and leuconoid body type sponges that contain a central flagellum, or undulipodia, surrounded by a collar of microvilli, which are connected by a thin membrane.
The hydra's stinging cells are known as cnidocytes, which cover the outside of their tentacles.

Pressure gradient is essential for movement of gases in and out of the body, so that's why compared to the atmospheric air, the alveolar air has less pO₂ and less pCO₂.

Take a combination, such as x = 7, y = 1, z = 5.
Take a combination, such as x = 1, y = 7, z = 5; and verify for both cases.

1.013 = 0.742X_t + 1.8X_b

1.013 = 0.742(1 - X_b) + 1.8X_b

X_b = 0.256

∴ X_t = 1 - X_b = 0.744

Recombinants formed = 10% (AB 5% & ab 5%)

Proteins P, Q and R are associated with intact organellar membrane in a cell. If the intact organelle is treated with a high ionic strength buffer, only protein R remains associated with the membrane fraction. Based on this, one could conclude that P and Q are peripheral membrane proteins and they can be detached easily.

Photosystem II (PSII) is a specialised protein complex that uses light energy to drive the transfer of electrons from water to plastoquinone, resulting in the production of oxygen and the release of reduced plastoquinone into the photosynthetic membrane.

The number of distinct proteins containing n amino acids is 20^n. Hence, total number of proteins is 20¹⁰⁰.

Emigration is the movement of individuals out of a population. This can result when resources like food or nesting sites become scarce in an area.

The cysteine amino acid group is the only amino acid capable of forming disulphide bonds, and thus can only do so with other cysteine groups.

Number of plants with a particular genotype can be calculated by the formula 2^n, where n is the number of heterozygous genes in the desired genotype. Therefore, plants with genotype AabbCcDd = 2³ = 8. So, the correct answer is option 1.

After selfing, homozygous individual produces all white and red offspring and heterozygous ones also produces 50% red and white flowers. So, total percentage will be around 97%-100% of plants with red and white flowers in the final population consisting of a large number of individuals.