The main driver of a climate zone is the amount and directness of sunlight that reaches the Earth's surface. In the tropical regions, there is a fairly constant amount of sunlight throughout the year. The maximum sun angle is also higher above the horizon.
I would guess it just means that the population just stays the same, no growth.
Polyunsaturated fats. The four types<span> have different chemical structures and physical properties. The bad fats, saturated and trans fats, tend to be more solid at room temperature (like a stick of butter), while monounsaturated and polyunsaturated fats tend to be more liquid (like liquid vegetable oil).</span>
Function. There, the villi and the microvilli increase intestinal absorptive surface area approximately 30-fold and 600-fold, respectively, providing exceptionally efficient absorption ofnutrients in the lumen. There are alsoenzymes (enterocyte digestive enzyme) on the surface for digestion.
I hope helping with this answer