If the inner lining of the air sacs neither thin nor highly vascularized, then it can be inferred that AIR SACS ARE CANNOT BE THE SITES OF GASEOUS EXCHANGE BETWEEN AIR AND BLOOD. Air sacs are generally lined with mucus and surrounded with blood capillaries.
In case of birds, air sacs play an important role in respiratory system.
Answer: C. when food is abundant
Explanation:
<span>Unlike vascular plants, non-vascular plants do not have tissue specialised fro transport of fluids, so</span> they cannot control the rate of water loss. However, they have simple tissues that can perform this function. They also lack in true leaves, seeds, flowers, and roots. They usually live in moist environment so they can absorb water more efficiently.
It's true , because the nucleolus has always been inside the nucleus . It should be in your textbook
