List of top Biological Science Questions

An E. coli cell with an internal volume of 2 femtolitres contains 10 molecules of a repressor protein in its cytosol. The concentration of the repressor protein is ............ nM (round off to 1 decimal place)

Tryptophan (Trp) is encoded by UGG, phenylalanine (Phe) is encoded by UUU and UUC, isoleucine (Ile) is encoded by AUU, AUC, and AUA, and glycine (Gly) is encoded by GGU, GGC, GGA and GGG. The maximum number of RNA segments with unique sequences that can encode the polypeptide Ile-Phe-Trp-Ile-Gly-Trp would be ............

In an examination consisting of 100 multiple choice questions, each question has four choices out of which only one is correct. A student scores +1 for each correct answer and a negative mark of -1/5 for each wrong answer. The correct choices are uniformly distributed across the four choices. If an unprepared student always selects the first choice for each question, then the expected value of the student’s total score in the examination would be ............ (round off to 1 decimal place)

Values of \( \Delta G_f^0 \) (standard Gibbs free energy of formation) for molecules A, B, and C are \[ \Delta G_f^0(A) = -34 \, \text{kJ/mol}, \quad \Delta G_f^0(B) = 84 \, \text{kJ/mol}, \quad \Delta G_f^0(C) = -100 \, \text{kJ/mol}, \] respectively. The \( \Delta G^0 \) for the reaction \( A + B \rightarrow C \) would be ............ kJ/mol (round off to 1 decimal place)

A bacterial population in the log-phase grows from \( 4 \times 10^6 \) cells to \( 8.64 \times 10^6 \) cells in 20 minutes. The doubling time of the bacterium is ............ minutes (round off to 1 decimal place)

The growth rate of a bacterial culture is given by \( x \left( 1 - \frac{x}{100} \right) \), where \( x \) is the density of the culture. The growth rate is maximum when the density is equal to ............ (round off to 1 decimal place)

A hypothetical plant forms 10 leaves, each of which is perfectly circular with 10 cm diameter. If the total number of stomata made by all these leaves is \( 7.85 \times 10^6 \), then the stomatal density in these leaves would be ............ / mm\(^2\) (round off to 1 decimal place)

The function \( f(x) = \sin(x) e^{-x} \) is equal to zero in the range \( 0<x<2\pi \) for \( x = ............ \) radians (round off to 2 decimal places)

Which of the following disorders in humans is/are due to a defect/deficiency in enzymes involved in the urea cycle?

A spherical bacterium has a diameter of 2 µm. Its volume to surface area ratio is equal to ............ µm (round off to 2 decimal places)

Ricin, a protein from castor beans, causes toxicity in humans by

The velocity of an enzyme-catalysed reaction following Michaelis–Menten kinetics, at the substrate concentration equal to \( 0.3 \times K_m \), is equal to ............ \( \times V_{\max} \) (round off to 2 decimal places)

During photosynthesis in higher plants, oxygen is produced

The value of the integral \( \int_0^\infty e^{-y} \, dy \) is equal to ......... (round off to 2 decimal places)

The function \( f(x) = x^2 - 6x + 8 \) is positive when

Which of the following coenzymes is/are present in the pyruvate dehydrogenase complex?

A typical \( \alpha \)-helix in a native polypeptide chain has

Insulin action on a target cell causes an increase in

In this system of two reactions, \( A \to 2B \) and \( B \to 2C \), which of the following statements is/are TRUE at steady-state?

Which one of the following statements is TRUE about flagella?

Caffeine is a plant-based drug that

2,4-Dinitrophenol (DNP) is an uncoupler that

Which is the CORRECT chronological order, from the least recent to the most recent, of the four evolutionary events listed below?
P. Earliest evidence of terrestrial arthropods
Q. Appearance of Ediacaran fauna
R. Extinction of the large, non-flying dinosaurs
S. Origin of mammals

Which one of the following statements is INCORRECT about the prokaryotic and eukaryotic organisms on the Earth?

Which of the following changes would cause a shift in the membrane potential of a neuronal cell from -70 mV to -50 mV?