single crossing over tetrad

例句：

1. 1. The researchers conducteda single crossing over tetrad to study the effects of genetic variation on disease resistance.
   研究人员进行了一次单次穿越四分体实验，以研究遗传变异对疾病抵抗力的影响。
2. 2. During the experiment, the scientists observed a single crossing over tetrad that led to a significant increase in productivity.
   在实验期间，科学家们观察到了一次单次穿越四分体，导致生产力显著提高。
3. 3. The team successfully performed a single crossing over tetrad to create a new strain of bacteria with enhanced antibiotic resistance.
   团队成功地执行了一次单次穿越四分体，以创造一种具有增强的抗生素抗性的新细菌菌株。