10 public questions tagged with this topic.
Frogs are cold-blooded (poikilothermic) animals that regulate their body temperature by using external heat sources.
Ref: NCERT Class 11 Biology Chapter 7: Structural Organisation in Animals Animal Tissues - Epithelial and Connective Tissue
Sweat glands in mammals help regulate body temperature through evaporative cooling (NCERT, Chapter 4, page 59). Scales are in reptiles, gills in fishes, and the clitellum in annelids.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Vertebrata - Aves and Mammalia
A lizard basking on a sun-warmed rock changes its location and posture to control heat exchange, an example of behavioural thermoregulation. Solar radiation and conduction from the rock raise body temperature, increasing enzyme activity, nerve conduction, muscle performance, digestion, and escape speed toward an optimal range. Once sufficiently warm, the lizard may move into shade, flatten or elevate its body, orient differently to the sun, or retreat into a burrow to avoid overheating. Most lizards are ectothermic: environmental sources provide the majority of their heat. This differs from endothermy, in which metabolic processes generate most regulatory heat, and from homeothermy, which refers to maintaining relatively constant temperature. Allen’s rule describes evolved geographic variation in appendage proportions, not an immediate behavioural response. Behaviour allows an ectotherm to maintain body temperature more precisely than ambient temperature alone would suggest, so “cold-blooded” does not mean passive thermal conformity. The effectiveness of basking depends on wind, substrate, colour, body size, predation risk, and access to thermal microhabitats, illustrating how physiology and habitat structure interact.
Ref: Evolutionary Analysis, Herron & Freeman, 5th Ed., Ch. 10
Long limbs and other elongated appendages increase surface area relative to body volume, facilitating heat dissipation in warm climates. This is the pattern summarized by Allen’s rule for many endothermic animals. Vascularized ears, tails, bills, and limbs can act as thermal radiators; vasodilation sends warm blood toward these surfaces, where heat is lost by radiation and convection. In cold climates, shorter appendages and compact bodies conserve heat and reduce frostbite risk. Fat accumulation adds insulation and therefore generally opposes heat loss. A compact body similarly lowers the surface-area-to-volume ratio and is more characteristic of cold adaptation. Pale pigmentation may occur in some hot, arid environments, but colour patterns depend on humidity, camouflage, ultraviolet exposure, and ancestry and are addressed more directly by Gloger’s rule. Long-limbed morphology is not universal because locomotion, feeding, sexual selection, and phylogenetic constraints also matter. Animals can combine structural traits with behavioural and physiological controls such as nocturnality, burrowing, panting, or evaporative cooling. The predicted warm-climate form follows basic heat-transfer geometry while remaining a statistical ecogeographic tendency rather than an absolute law.
Ref: Evolutionary Analysis, Herron & Freeman, 5th Ed., Ch. 10
Heat exchange occurs across body surface, while heat-producing tissue broadly scales with body volume or mass. As an animal becomes smaller, surface area decreases with the square of linear dimension but volume decreases with the cube. Small animals therefore have a high surface-area-to-volume ratio and lose heat rapidly per unit mass when their bodies are warmer than the environment. To maintain a stable temperature, small endotherms generally require high mass-specific metabolic rates, frequent feeding, insulation, or behaviours such as huddling and sheltering. High metabolic rate is mainly a compensatory response to rapid loss, not the geometric cause. “Lower surface area” considered alone is misleading because the relevant quantity is surface relative to volume. External temperature, wind, moisture, and insulation influence the actual rate, but they do not explain why small size intrinsically increases relative exchange. The same scaling principle affects water loss, gas exchange, and vulnerability to thermal extremes. Conversely, large animals have low surface-area-to-volume ratios and retain heat effectively, which can be advantageous in cold climates but creates challenges for dissipating heat in warm environments.
Ref: Evolutionary Analysis, Herron & Freeman, 5th Ed., Ch. 10
Eurythermal species tolerate a broad range of environmental temperatures. Their proteins, membranes, metabolic regulation, stress responses, and behaviour remain functional across wider thermal limits than those of stenothermal species. This breadth allows survival through seasonal fluctuations, movement among contrasting microhabitats, or occupation of geographically variable environments. It does not mean performance is equally high at every temperature. A tolerance curve still contains an optimum, zones of stress, and lethal lower and upper boundaries; eurythermal simply means those boundaries are relatively far apart. Reproduction only in summer describes a seasonal schedule, not thermal breadth. Migration and hibernation are possible strategies for avoiding unfavourable conditions, but neither is required in a species that tolerates them directly. Acclimatization may shift thermal performance within an individual’s plastic capacity, while evolutionary adaptation can alter the population’s range over generations. Thermal tolerance can also differ among eggs, larvae, and adults, so the most sensitive stage may set distribution limits. A broad tolerance often aids widespread species and biological invaders, although dispersal, moisture, food, and biotic interactions still constrain where they actually occur.
Ref: Evolutionary Analysis, Herron & Freeman, 5th Ed., Ch. 10
Endotherms generate most of the heat used to regulate body temperature through metabolism. Oxidation of carbohydrates and fats releases energy, much of which appears as heat rather than mechanical work. Birds and mammals can increase heat production through shivering muscles, non-shivering thermogenesis in brown adipose tissue, hormonal effects, and ordinary organ activity. Insulation and controlled blood flow then reduce or redistribute heat loss, while sweating or panting removes excess heat. Environmental heat can contribute, and many endotherms bask or seek shelter to reduce energetic costs, but it is not their primary heat source. Low oxygen would restrict aerobic metabolism and impair thermogenesis rather than support it. Reflective skin or covering may reduce solar heat gain but cannot replace heat generation. Sustained endothermy allows enzymes, nerves, and muscles to operate at relatively stable temperatures and enables activity in cold environments or at night. Its cost is high demand for oxygen and food. Endothermy should be distinguished from homeothermy: the former names the internal heat source, whereas the latter describes relative constancy of body temperature; hibernating endotherms may temporarily become heterothermic.
Ref: Evolutionary Analysis, Herron & Freeman, 5th Ed., Ch. 10
Answer: C) Increase. For Thermoregulation, once you lock onto the key mechanism or definition, Increase is the clear fit. If you restate the concept in your own words, Increase is the option that correctly names the structure, process, or principle asked for in Thermoregulation. So Increase is the clean, accurate selection. If a similar stem appears later, start from the same core fact and you will land on the same kind of answer. In class notes, highlight this same phrase next to the related diagram so the wording and the picture reinforce each other. When you practise, cover the choices first, write Increase from memory, then reveal the letter — that habit builds real recall for Thermoregulation.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.
Correct option is B, Cold receptors. In Thermoregulation, the accurate description is Cold receptors, and that is what you should commit to memory. Keep the definition tight and the role clear — Cold receptors is the option that correctly names the structure, process, or principle asked for in Thermoregulation. Then Cold receptors is the answer you can defend. Check yourself by covering the options and writing the answer first, then matching the letter — that builds confidence. If the wording feels dense, translate it into everyday language first, then map that plain sentence back onto Cold receptors. Remember that physiology questions reward precise language: name the process, the location, and the outcome, then match that to the option text.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.
Pick B: 0.5°C. Thinking about Thermoregulation in a practical way — what the structure does, or what the process achieves — leads you here. Clinically and academically, the same logic shows up again and again: 0.5°C is the option that correctly names the structure, process, or principle asked for in Thermoregulation. Hence 0.5°C is correct. Treat this as a building block for the rest of Thermoregulation; neighbouring topics often reuse the same principle. Keep a one-line summary card for this idea and revisit it before the paper; short, repeated review beats long cramming sessions. If the wording feels dense, translate it into everyday language first, then map that plain sentence back onto 0.5°C.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.
