List of top Questions asked in NEST

Consider the following table of three lanthanoid ions X, Y, and Z and their properties.

Atomic numbers of Ce, Eu, and Lu are 58, 63, and 71, respectively. Given these atomic numbers, the lanthanoid ions X, Y, and Z, respectively, are:

Consider the following compound.

The compound undergoes reaction with two equivalents of diisobutyl aluminium hydride followed by acid hydrolysis to provide P as the major product. The structure of P is:

Acetylene is passed through red hot iron tube at 873 K to produce P. P reacts with chlorine gas in the presence of anhydrous $\text{AlCl}_3$ to produce Q. Q reacts with benzyl chloride and sodium to produce R as the major product. The structure of R is:

tert-Butylbenzene reacts with 1-chloro-2-methylpropane in the presence of anhydrous $\text{AlCl}_3$. The major product in this reaction is:

Consider the following compound.

The compound reacts with $\text{SOCl}_2$ to produce P. P reacts with dimethyl cadmium to produce Q. Q upon reaction with ethyl magnesium bromide (3 equiv) followed by water workup produces R. The structure of R is:

The reaction that produces butanoic acid as a product is:

The compound that produces aromatic species upon deprotonation of the indicated hydrogen is:

Two students (P and Q) independently made three measurements (denoted by I, II, and III) of the same property. The expected correct value is 9.0. The observed values by the students are provided in the given table.

Based on the given data, the correct statement is:

Species that are both isoelectronic and isostructural are:

Two galvanic cells, Cell I and Cell II, operate at the same temperature and involve two different redox systems. It is observed that at a particular value of the reaction quotient $\text{Q}_{\text{I}} = \text{Q}_{\text{II}} = \text{Q}_0$, the ratio of EMF of the two cells ($\text{E}_{\text{I}}/\text{E}_{\text{II}}$) as well as the ratio of change of Gibbs free energy for the two cells ($\Delta\text{G}_{\text{I}}/\Delta\text{G}_{\text{II}}$) are both 1/3. Assuming standard cell reactions written in the spontaneous direction and reversible operation, the pair of cells can satisfy these conditions is:

Desert ants are known to use landmarks (reference points), pedometers (memorising step counts), and optic flow (rate of passing objects across its eye to estimate navigation speed) to navigate across deserts. A desert ant is trained to walk 100 m from its nest to a feeder in an artificial arena as depicted in the schematic. The arena had a single tall landmark placed at 40 m from the nest.

At the feeder, certain manipulations were performed before allowing the ant to return to its nest with the food.
Manipulation 1: Stilts were attached to its legs, which doubled the step length.
Manipulation 2: The optic flow of the arena was doubled.
While the ant uses the landmark exclusively for long-distance ($\gt $55 m) navigation, it switches to optic flow and pedometer simultaneously and exclusively for short-distance navigation. Due to the manipulations, the distance from the feeder where the ant will search its nest is:

The trophic relationships between species in a habitat can be represented in the form of a food web matrix where, rows represent consumers/ predators, and columns represent resources/prey. If the organism of a species in the row eats the organism of a particular species in the column, then a `1' is placed in the intersection. Otherwise a `0' is placed in the intersection. Such a matrix for species M - Q is given below.

Based on the matrix, the correct statement is:

The table shows the presence (+) / absence (-) of features 1 - 5 for animals P - U.

Based on the table, the correct statement is:

A researcher wants to insert a linear DNA fragment into a plasmid DNA. The linear DNA fragment has two MfeI restriction sites at its ends. The plasmid DNA has only one EcoRI restriction site. The plasmid was digested with EcoRI and the DNA fragment was digested with MfeI. The recognition sequences of the restriction enzymes on one strand are given.

(arrow indicates enzyme cut sites)
Based on this information, the DNA fragments generated by EcoRI and MfeI

Consider a mitochondrion in which the $\text{F}_0$ subunit of ATP synthase is mutated, such that it can still passively conduct protons but is mechanically uncoupled from the $\text{F}_1$ subunit. If such a mitochondrion is provided with succinate, ADP, and Pi in aerobic conditions, the correct outcome based on chemiosmotic theory is:

There is a difference between the predicted and observed global carbon budget. The possible reason is:

Three different bacterial strains (P, Q, and R) when grown independently in a culture medium showed typical growth curves. Equal number of cells from all three actively growing cultures are mixed and grown together for 10 days. The number of bacteria (N) are counted each day and plotted.

Assuming nutrients are not limiting, the correct explanation for the observed trend is:

The fundamental niche of a species is the full range of environmental conditions and resources a species can potentially occupy in the absence of limitations. The realized niche is the actual, smaller subset of the fundamental niche that the species occupies due to biotic limitations. The distribution of populations of Species 1 and Species 2 over various levels towards the shore of an aquatic habitat is shown in the figure.

Consider the following statements based on the distribution.
(i) Competition for resources between Species 1 and Species 2 is mainly in the zones M and N.
(ii) Species 2 is a stronger competitor as compared to Species 1.
(iii) In absence of Species 2, Species 1 could prevail in zone O.
(iv) Species 2 probably has predators who thrive in zone O.
The correct statement(s) is(are):

In the axon of a giant squid neuron,
(i) The resting membrane potential is -70 mV.
(ii) At the equilibrium potential of $\text{Na}^+$ ($\text{E}_{\text{Na}^+} = +55$ mV) there is no net movement of $\text{Na}^+$ ions across the membrane.
In an experiment, when the axon is stimulated, the voltage-gated $\text{Na}^+$ channels open. The membrane potential peaks at +30 mV, where the resistance of the axonal membrane for $\text{Na}^+$ flow is $1 \times 10^6\ \Omega$. The net $\text{Na}^+$ current ($\text{I}_{\text{Na}^+}$) across the membrane and the direction of ionic movement at the peak is:

In a haplodiploid ant species, sons are haploid and produced from unfertilized eggs, while daughters are diploid and produced from fertilized eggs. A single queen establishes a colony after mating with three different unrelated males. The queen uses the sperm from all three males equally to produce her female offspring. The average genetic relatedness between two randomly selected female offspring in this colony will be:

In a population of 1000 moths, 450 moths were brown-colored with homozygous genotype and 350 albino moths that were homozygous for the recessive allele. Assuming random mating within the population, the frequency of heterozygotes in the next generation would be:

Events occurring during signal propagation in a chemical synapse are given below.
P: Postsynaptic membrane potential changes.
Q: Synaptic vesicle fuses with the presynaptic membrane.
R: Action potential depolarizes the presynaptic terminal.
S: Neurotransmitter binds to receptors on the postsynaptic membrane.
T: Neurotransmitter is released into the synaptic cleft.
The correct sequence of occurrence of these events is:

In the roots of plants, casparian strip made of suberin forms a ring around the cells of the endodermis. It effectively blocks the entry of water and mineral ions into the stele via the apoplast. A defect in the casparian strip leads to

In an experiment, bacteria were grown for 500 generations in a medium containing $^{14}\text{N}$ (light isotope), then transferred to a medium with $^{15}\text{N}$ (heavy isotope) for one generation, and finally transferred back to the $^{14}\text{N}$ medium for one more generation. Assuming all cells divide synchronously and replication is semi-conservative, the ratio of $^{14}\text{N}^{15}\text{N}$ to $^{14}\text{N}^{14}\text{N}$ double-stranded DNA at the end of the experiment is:

The ability of phloem to distribute sugar depends on the companion cell and sieve element working as a complex. Consider the following statements with regard to possible effects of reduction in companion cell plasmodesmata.
(i) Sugar loading into sieve tubes reduces due to collapse in osmotic pressure gradient.
(ii) Water moves from companion cells into the xylem to maintain osmotic balance.
(iii) The sieve tubes collapse structurally due to loss of turgor pressure.
(iv) Reverse loading of sugar in phloem begins immediately due to pressure inversion.
Under the given condition, the correct statements are: