Questenaتدريب يوضح لك ما ينبغي مراجعته لاحقًا
السؤال 113

Pollen has landed on a stigma. How does material from that pollen grain reach an ovule inside the ovary?

  1. The whole grain slides down into the ovary
  2. The grain is carried down by water moving in the xylem
  3. The ovule grows upwards to meet the grain on the stigma
  4. A tube grows from the grain down through the styleالإجابة الصحيحة

الشرح

The grain itself cannot move, and only the tube it grows can travel through the style: that pollen tube pushes down through the tissue beneath the stigma until it reaches an ovule, carrying a nucleus with it. Picturing the whole grain making the journey leaves it with no route to take, because the style is solid tissue rather than an open passage.

تابع هذا الاختبار

بدء التدريب
السؤال 113: Pollen has landed on a stigma. How does material from that… · Plants and Photosynthesis · Questena