List of top Questions asked in IISER- 2026

Which of the following schematics correctly depict a lac operon that can be negatively regulated?

Which one of the following correctly describes the mode of action of Follicle Stimulating Hormone (FSH) and estrogen?

Which one of the following correctly describes the sequence of events leading to muscle contraction following acetylcholine release at the neuromuscular junction?

In which one of the following cases, will an anti-Rh antibody treatment prevent erythroblastosis foetalis?

If cell wall was used as the only criterion for classifying organisms, then Mycoplasma would have belonged to which one of the following groups?

For which one of the following enzyme activity plots, will the K$_m$ of the enzyme for substrate ‘S' be 20? [S] indicates substrate concentration.

The pBR322 cloning vector has genes coding for tetracycline and ampicillin resistance. A foreign DNA to be cloned is inserted into the tetracycline resistance gene and the recombinant plasmid is then transformed into E. coli cells. Which one of the following choices is the most likely outcome of this cloning reaction?

Which of the following processes result in development of a proton gradient across the thylakoid membrane during photosynthesis?
i. Release of protons into the lumen of the thylakoid by plastoquinone
ii. Consumption of protons in the stroma during the reduction of NADP$^+$
iii. Release of protons into the lumen of the thylakoid by ATP synthase
iv. Release of protons into the lumen of the thylakoid by water splitting reaction

Which one of the following choices matches the organs in column I with their vascular system arrangement described in column II?

The graphs below depict the number of individuals of two organisms, named P and Q, when grown independently, and together. Based on these growth patterns, which one of the following statements is correct?