What is torpor? (2)
- a state in which an animal reduces its body temperature and metabolic rate to conserve energy.
- It is a key part of hibernation.
How does hibernation differ from normal sleep?
hibernation is a prolonged period of torpor, where an animal reduces activity, body temperature and metabolism to survive cold and food shortages whereas normal sleep is controlled by the brain
What metabolic changes occur during hibernation?
Decrease in metabolism, body temperature, heart rate, and oxygen consumption.
What chemical is linked to sleep and potentially triggers torpor?
Adenosine — it slows brain activity and is linked to both sleep and torpor regulation.
Q: Why does body temperature drop during hibernation (link to enzymes)?
A: Reduced temperature slows enzyme activity, conserving energy by decreasing biochemical reaction rates.
Q: How does reduced metabolism during hibernation relate to respiration rate?
A: Slower metabolism means lower respiration rate, conserving energy and oxygen.
Q: Explain how homeostasis is still maintained during hibernation.
A: Core physiological processes like minimal heart rate and respiration are stabilised at low levels to maintain internal balance.
Q: How can comparing hibernators and non-hibernators’ genomes help medicine?
A: It helps identify genes linked to disease resistance or metabolic suppression, which may be useful for human therapies.
Q: Explain how the activation of certain genes leads to reduced metabolism during torpor.
A: Transcription factors activate genes that suppress metabolism, producing proteins that reduce ATP production and heat production.
Q: Describe how differences in gene expression lead to changes in cell function in hibernating animals.
A: Genes for energy conservation are expressed more, while genes for active metabolism are expressed less, altering cell function.
Q: Suggest how environmental factors like day length or temperature affect gene expression in hibernators.
A: Environmental cues like day length affect hormone levels such as melatonin, which affect hypothalamic control of gene expression for torpor.
Q: Explain how regulation of gene expression allows entry and exit from torpor.
A: External stimuli like cold activate transcription factors that switch on/off metabolic genes, enabling reversible metabolic suppression.
Q: What survival advantages does hibernation give animals?
A: Conserves energy in cold or food-scarce environments, and may offer protection against conditions like stroke or heart attack.
Q: Which human diseases might benefit from hibernation-based treatments?
A: Heart disease, stroke, Alzheimer’s disease.
Q: Describe how hibernator genetics could help develop treatments for stroke or heart disease.
A: Genes that protect tissues in torpor could be used to design drugs that prevent damage during strokes or cardiac events.
Q: Explain how hibernation research could help develop stroke treatments.
A: Lowered metabolism during torpor protects brain cells during periods of low oxygen, which is useful in strokes.
Q: What is one ethical concern with inducing torpor in mammals for research?
A: Potential for distress or harm to animals during experimental procedures.
Q: Explain how hormonal signals could contribute to torpor.
A: Hormones like melatonin or cortisol influence gene expression via the hypothalamus, helping initiate metabolic suppression and torpor.
Q: Explain the role of the hypothalamus in controlling body temperature during hibernation.
A: The hypothalamus detects body temperature changes and sends signals to suppress thermogenesis while maintaining low, stable temperatures.
Q: Design an investigation to test the effect of temperature on adenosine pathway activation.
A: Use two groups of mammals exposed to different temperatures. Administer adenosine. Measure changes in metabolic rate or core body temperature. Control variables like species, age, and drug dosage.
Q: What is one risk if metabolic rate drops too low during experimental torpor?
A: Risk of organ failure or death due to insufficient energy supply.
Q: Suggest improvements for an experiment on hypothalamus thermoregulation.
A: Increase sample size; use non-invasive imaging techniques; include proper control groups.
The article mentions that Arctic ground squirrels can survive core temperatures below 0°C. Suggest two physiological adaptations that might allow this. (4 marks)
- Presence of antifreeze proteins to prevent ice crystal formation inside cells.
- Accumulation of glucose or urea to lower the freezing point of body fluids.
- Stabilisation of cell membranes at low temperatures.
- Efficient vasoconstriction to protect vital organs from freezing.
Evaluate how hibernation research could contribute to extending human lifespan. (6 marks)
Hibernation reduces metabolic rate, lowering oxidative stress.
Enhances DNA repair and reduces accumulation of damage.
Mimics caloric restriction, linked to increased lifespan.
Potential to reduce risk of age-related diseases.
Challenges include ethical concerns and lack of full human applicability.
More research is needed to ensure safety and long-term benefits.
