The 5-week-old human embryo has external gill slits (grooves). they do not develop into gills, so what happens to them?

As the gills does not develop into gills, they are likely to contribute to the development of the lower jaw of the human embryo though after the embryonic stage, the gill slits won’t be retained or won’t be a part of a human as they only appear during embryonic stage for the development of the lower jaw.

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.