When fatty acid molecules are in water, they can self-organize into a bilayer (double layer) that surrounds an inner core of water. Where "middle" refers to the middle of the bilayer between the outer and inner layers of fatty acids, which of the following statements is correct? A. The polar heads of the outer layer face the middle; the polar heads of the inner layer face toward the middle.
B. The polar heads of the outer layer face outward; the polar heads of the inner layer face toward the middle.
C. The polar heads of the outer layer face outward; the polar heads of the inner layer face toward the inner water core.
D. The polar tails of the outer layer face toward the middle; the polar tails of the inner layer face toward the inner water core.
E. The polar tails of the outer layer face outward; the polar tails of the inner layer face toward the middle.

C. The polar heads of the outer layer face outward; the polar heads of the inner layer face toward the inner water core.

Explanation:

Lipids characterize for being amphipathic molecules, which means that they have a hydrophilic portion and a hydrophobic portion at the same time. These molecules have a lipidic head that corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion. They also have two lipidic tails that correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.  When fatty acid molecules are in water they are arranged with their hydrophilic polar heads facing the exterior and the interior of the core of water, while their hydrophobic tails are against each other, constituting the internal part (middle).  

1: most common garden plants prefer loam — soils with a balance of different-sized mineral particles (approximately 40% sand, 40% silt, and 20% clay) with ample organic matter and pore space. however, some plants grow better in sandy soils, while others are well-adapted to clay soils.

2: available water capacity is the maximum amount of plant available water a soil can provide. it is an indicator of a soil's ability to retain water and make it sufficiently available for plant use. available water capacity is the water held in soil between its field capacity and permanent wilting point.

3: it is the same for all living things (plants and animals). it also includes very tiny organisms that our eyes cannot see. they are known as microorganisms, and include viruses, bacteria and fungi.