Answer:
Speeding up chemical reactions by lowering the activation energy.
Explanation:
<span>As the pollen tube penetrates the ovule, it releases two sperm cells. As in gymnosperms, the ovule becomes a seed, encasing the embryo and endosperm in a seed coat. But unlike gymnosperms, in angiosperms the ovary containing the ovules develops into a fruit after fertilization.</span>
The answer is : linea aspera
The circulatory system - hemoglobin in the blood transports oxygen :)
They might be deep inside
