Why is heart rate unreliable for measuring stress?

Living cells cannot use heat to provide the activation energy for biochemical reactions because which choice(s) complete the sentence correctly? a) answer choice ii. eliminate b) answer choices ii and iv. c) answer choice iii and iv. d) all answers can complete the sentence.

What are the two functions of the respiratory system

There are two tomato plantlets one of them is kept in an oxygen chamber with a light source and another is kept in sunlight. both of them are watered regularly what will be the observation after two weeks