Final answer:
In the text, tension is heightened by the character waking up to a peculiar noise and the subsequent discovery of a medicine's altered taste and texture, suggesting possible tampering.
Step-by-step explanation:
The two events in the text that work together to build tension are (1) the character waking up and peering about due to a strange noise, and (3) the discovery that the powder is unexpectedly tasteless and different in texture from what was expected. The first event sets a scene of wary alertness, while the third raises suspicion and doubt about something being amiss, especially with the medicinal powders that seem to have been tampered with. Both these elements introduce a sense of unease and anticipation of something going wrong, effectively building tension in the narrative.