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A student set up an experiment as shown - HSC - SSCE Biology - Question 27 - 2014 - Paper 1
Question 27
A student set up an experiment as shown. Set-up 1: Rat - core body temperature sensor - data logger - cooling unit - food bowl - carbon dioxide sensor Set-up 2: S... show full transcript
Worked Solution & Example Answer:A student set up an experiment as shown - HSC - SSCE Biology - Question 27 - 2014 - Paper 1
Step 1
Explain why the carbon dioxide concentrations rose in each of the incubators.
Answer
The rise in carbon dioxide concentrations in the incubators can be attributed to the process of cellular respiration occurring in both the rat and snake. As these animals metabolize food to generate energy, carbon dioxide (CO₂) is produced as a waste product. Therefore, the more active the animals are, or the higher their metabolic rate, the more CO₂ they release into the incubator, leading to an increase in the overall concentration.
Step 2
Sketches both lines showing the correct starting points and the correct trends.
Answer
For the rat, the core body temperature starts at 37°C at 25°C and should maintain a relatively stable level near this temperature until the environment becomes significantly cooler. The graph will show a slight decline as the temperature decreases.
For the snake, the core body temperature starts at 25°C at 25°C. As the temperature decreases, the snake’s temperature will likely drop more noticeably due to its ectothermic nature, suggesting a steady decline in its body temperature as the incubator temperature falls.
Step 3
Predict two physiological or behavioural observations in the rat.
Answer
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The rat may increase its food intake as it attempts to generate more body heat through increased metabolism and energy production. This compensates for the cooler incubator environment.
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Observably, the rat might exhibit behaviors typical of trying to maintain warmth, such as huddling or seeking out warm areas within its incubator as the temperature decreases.