If the humidity of the atmosphere suddenly increases substantially, the water flow in the xylem will –

(A)  increase

(B)  decrease

(C)  remain unaltered

(D)  increase sharply and then reduce slowly to the preexisting level 

A large number of random snap shots using a camera are taken of a particle in simple harmonic motion between x = – x₀ and x = + x₀ with origin x = 0 as the mean position . A histogram of the total number of times the particle is recorded about a given position (Event no.) would most closely resemble 

Which of the following statements correctly describes a codon? 

(a) A length of DNA which codes for a particular protein 

(b) A part of the transfer RNA molecule to which a specific amino acid is attached 

(c) A part of the transfer RNA molecule which recognises the triplet code on the messenger RNA 

(d) A part of the messenger RNA molecule that has a sequence of bases coding for an amino acid

Which one of the following is a modified leaf ?

(A)  Sweet potato

(B)  Ginger

(C)  Onion

(D)  Carrot

The pair of atoms having the same number of neutrons is

(a) ¹²₆C, ²⁴₁₂Mg

(b) ²³₁₁Na, ¹⁹₉F

(c) ²³₁₁Na, ²⁴₁₂Mg

(d) ²³₁₁Na, ³⁹₁₉K

The rate constant of a chemical reaction at a very high temperature will approach

(A)  Arrhenius frequency factor divided by the ideal gas constant

(B)  activation energy

(C)  Arrhenius frequency factor

(D)  activation energy divided by the ideal gas constant  

Three cellular processes are listed below. Choose the correct combination of processes that involve proton gradient across the membrane.

I. Photosynthesis

II. Aerobic respiration

III. Anaerobic respiration

(a) II and III

(b) I and II

(c) I, II and III

(d) I and III

A new life form discovered on a distant planet has a genetic code consisting of five unique nucleotides and only one stop codon. If each codon has four bases, what is the maximum number of unique amino acids this life form can use ?

(A)  624

(B)  20

(C)  124

(D)  3124

A graph of species richness vs area on log-log axes is

(A)  linear

(B)  sigmoidal

(C)  oscillatory

(D)  parabolic 

At 298 K, assuming ideal behaviour, the average kinetic energy of a deuterium molecule is

(a) two times that of a hydrogen molecule

(b) four times that of a hydrogen molecule

(c) half of that of a hydrogen molecule

(d) same as that of a hydrogen molecule