PAG Extension Practice Test

The suitable temperature range for measuring Daphnia heart rate is just above freezing to room temperature, as this range ensures that Daphnia remain active and viable for accurate observations. At temperatures too close to freezing, Daphnia can become lethargic or may not respond adequately to stimuli, which can affect heart rate measurements. Conversely, temperatures exceeding room temperature can lead to stress and potential harm to the organisms, potentially skewing the results. Therefore, maintaining a temperature range that promotes normal physiological function is key to obtaining valid and reliable heart rate data.