ICAR AICE-JRF/SRF (PhD) · India · NTA for ICAR
Original practice questions written to the published syllabus · not past papersDigestion in monogastrics, birds and ruminants, muscle and nerve, hormones, reproduction and lactation, growth, and the animal's response to climate and work.
In the exams: Same exams as Physiology I: ICAR JRF 08, AIEEA-PG 14, PRC, NLEV, China, AVE
ICAR AIEEA (PG) (Code 14 Animal Sciences: Physiology) and ICAR AICE-JRF/SRF core group 08
Mechanisms and species comparisons: rumen VFA and methane stoichiometry, oesophageal groove, avian proventriculus and gizzard, excitation-contraction coupling, synaptic transmitters, hypothalamic-pituitary hormones, maternal recognition of pregnancy, placental types, lactose and milk fat synthesis, GH-IGF-1 axis, thermoneutral zone, and THI.
How our questions for ICAR AICE-JRF/SRF spread across the units of Veterinary Physiology II: Digestion, Muscle, Nerve, Endocrinology, Reproduction, Lactation, Growth and Climate. Difficulty: 0 easy, 11 medium, 19 hard.
| Ruminant fermentative digestion | 4 | |
| Smooth and skeletal muscle contraction | 3 | |
| Reproductive physiology | 3 | |
| Lactation physiology | 3 | |
| Growth physiology | 3 | |
| Digestion in monogastric animals | 2 | |
| Digestion in birds | 2 | |
| Nervous system physiology | 2 | |
| Endocrinology | 2 | |
| Environmental physiology and heat stress | 2 | |
| Physiology of work and exercise | 2 | |
| Physiological basis of animal behaviour | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Which function belongs to the secondary cycle of forestomach motility?
A. Moving gas towards the cardia for eructation
The secondary (eructation) cycle is a ruminal contraction sequence that clears gas forward; its failure leads to bloat. Mixing is the primary cycle; regurgitation is an extra reticular contraction linked to rumination; milk is directed by the reticular groove.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
In a nylon-bag study, a protein supplement has a soluble fraction a = 0.20, a slowly degradable fraction b = 0.60 and a degradation rate c = 0.08 per hour. If rumen outflow rate k is 0.02 per hour, what is the effective degradability using ED = a + bc/(c + k)?
B. 0.68
ED = 0.20 + (0.60 x 0.08)/(0.08 + 0.02) = 0.20 + 0.048/0.10 = 0.20 + 0.48 = 0.68. Reporting a + b = 0.80 ignores outflow; 0.48 forgets the soluble fraction; 0.32 uses k in the numerator instead of c.
Further reading: McDonald P et al., Animal Nutrition, 7th ed.
In smooth muscle, the calcium-calmodulin complex causes contraction mainly by:
B. Activating myosin light-chain kinase, which phosphorylates myosin's regulatory light chain
Smooth muscle lacks troponin; regulation is on the thick filament through myosin light-chain phosphorylation. Myosin light-chain phosphatase reverses it. Troponin C is the skeletal and cardiac mechanism.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
Which property allows smooth muscle of the gut and blood vessels to maintain tone for long periods with low ATP use?
C. The latch state, in which dephosphorylated cross-bridges remain attached and cycle slowly
In the latch state cross-bridges stay attached after dephosphorylation and detach slowly, holding force cheaply. Smooth muscle remains calcium-dependent; the long refractory period is a cardiac feature that prevents tetanus.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
Using the Nernst equation simplified to E = 61.5 log10(Co/Ci) mV at 37 degrees C, what is the potassium equilibrium potential when extracellular K+ is 4 mmol/L and intracellular K+ is 140 mmol/L?
D. About -95 mV
E = 61.5 x log10(4/140) = 61.5 x (-1.544) = -95 mV. Inverting the ratio (140/4) gives +95 mV, the usual slip. -61 mV treats the log term as if the gradient were tenfold; -219 mV uses the natural log with the log10 constant (61.5 x ln(4/140)). Potassium's equilibrium potential lies close to, and slightly more negative than, the resting potential.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
Which hormone acts mainly through an intracellular (nuclear) receptor?
D. Triiodothyronine (T3)
T3, like steroids, enters the cell and binds a nuclear receptor that regulates transcription. Adrenaline, glucagon and oxytocin act on cell-surface G-protein-coupled receptors.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
A broiler chick grows from 0.04 kg at hatch to 2.4 kg at 42 days. What is its specific growth rate, SGR = 100 x ln(W2/W1)/t?
A. About 9.7% per day
ln(2.4/0.04) = ln 60 = 4.094; 100 x 4.094/42 = 9.75% per day. Using log10 (1.778) gives 4.2%; omitting the logarithm (100 x 60/42) gives about 143%; dividing by 6 weeks instead of 42 days gives about 68%, which is a weekly rate, not a daily one. SGR is useful precisely because growth of young animals is roughly exponential.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
Using Kleiber's relation (basal metabolic rate proportional to W^0.75), how does the basal metabolic rate per kilogram of body weight of a 20 kg dog compare with that of a 500 kg cow?
A. About 2.2 times higher in the dog
Per-kg rate scales as W^-0.25, so the ratio is (500/20)^0.25 = 25^0.25 = 2.24. Check: 70 x 20^0.75/20 = 33.1 kcal/kg/day; 70 x 500^0.75/500 = 14.8; 33.1/14.8 = 2.24. Twenty-five is the body weight ratio; 11 comes from comparing total metabolic weights (105.7/9.46) the wrong way round.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
At the canter and gallop, horses take one breath per stride. This locomotor-respiratory coupling means that, at a gallop:
D. Respiratory rate rises with stride frequency, so extra ventilation relies partly on larger tidal volume at longer strides
Because breaths are locked to strides, respiratory rate equals stride frequency; ventilation rises with speed through both. Horses do not breath-hold during galloping.
Further reading: Hinchcliff KW et al. (eds), Equine Sports Medicine and Surgery, 2nd ed.
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