Do tardigrades in an ametabolic (cryptobiotic) state meet the definition of life according to standard biological criteria?

• A. Yes, because all non-living things can become living under the right conditions.
• B. No, because they are completely inactive and do not exhibit any characteristics of life during ametabolic states.
• C. No, because they lose all cellular structure during ametabolic states.
• D. Yes, because they retain the potential to resume metabolism and reproduction when conditions improve.

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by reviewing the standard biological criteria for defining life. These typically include characteristics such as metabolism, reproduction, response to stimuli, growth, and cellular organization.
2. Step 2: Understand the concept of cryptobiosis (ametabolic state). Cryptobiosis is a state in which an organism's metabolic processes are halted due to extreme environmental conditions, such as desiccation, freezing, or lack of oxygen.
3. Step 3: Analyze whether tardigrades in a cryptobiotic state retain the potential to exhibit characteristics of life. Even though they are inactive, they maintain cellular structure and the ability to resume metabolism and reproduction when favorable conditions return.
4. Step 4: Compare the options provided in the problem. Eliminate incorrect answers based on the biological criteria for life and the nature of cryptobiosis. For example, the statement that tardigrades lose all cellular structure during ametabolic states is false.
5. Step 5: Conclude that the correct answer is: 'Yes, because they retain the potential to resume metabolism and reproduction when conditions improve,' as this aligns with the biological definition of life and the unique survival mechanisms of tardigrades.