They can grow tall, 60 cm plus
The stem has more things to transport that's why it has more vascular bundles. The roots only get water from the ground and moving nutrients from the soil to transfer it to the stem. Having more vascular bundles helps the stems to transfer things to leaves and other parts of the plants.
The answer is "A hypothesis is tentative statement" and "A theory has a strong predictive power."
The most abundant protein is dead epidermal structures such as hair and melanin.