CSIR NET 2024 | Life Science: System Physiology Animals | 2 April

Most people who are completely blind have circadian rhythms that are 'free-running;' that is, their rhythms are not synchronized to environmental time cues and they oscillate on a cycle of about 24.5 hours.
Consider the following statements:
A) A specialized group of cells in the hypothalamus - the cells of the suprachiasmatic nucleus (SCN) -regulates our circadian rhythm.
B) SCN receives neural cues from the retina, although not from rods and cones - the light receptor for vision - but from a subset of retinal ganglion cells that responds to light. The retinal signals entrain the cells of the SCN to the daily cycle of light and dark.
C) In totally blind people, information about the light and dark cycle does not reach the SCN cells. As consequences, they operate their own inherent rhythm, which is slightly longer than 24 hours.
D) Blind peoples do not have problem in entraining their circadian rhythms in phase with normal 24-hour cycles due to special light receptors termed as cryptochromes

Which of the following statements is correct?

Myoglobin shows a hyperbolic response, while hemoglobin shows a sigmoidal response for oxygen binding.
 
Which of the following statements are true with respect to this observation?
P. Haemoglobin binds 2, 3-BPG while myoglobin does not
Q. Haemoglobin exists in two different conformational states while myoglobin does not
R. Haemoglobin is a tetramer while myoglobin is a monomer
S. Haemoglobin is present in RBCs while myoglobin is present in the muscle

Increasing estradiol (E2) hormone from ovarian follicles prior to ovulation has been hypothesized to play a critical role for induction of pheromones. These pheromones render females sexually receptive to males to facilitate mating. An investigator performs experiments in sheep in which females are gonadectomized, then treated with E2 or vehicle alone and allowed to breed.
 
Which one of the findings listed below will validate the hypothesis that pheromones are induced by E2?

Amphibian oocytes remain for years in the diplotene stage of meiotic prophase. Resumption of meiosis is initiated by:

Match the hormones in Group I with their metabolic precursor in Group II

Group I
 P. 17-estradiol
 Q. Thromboxane A2
 R. Epinephrine
 S. Retinoic acid

Group II
 1. Arachidonic acid
 2. Tyrosine
 3. β-carotene
 4. Cholesterol