They observe it, run tests on many different things, and do expirments
Answer:
C) production of sperm and eggs
Explanation:
Sperms and eggs are the male and female gametes respectively. Formation of sperms and egg cells require meiotic cell division. Meiosis in sperm mother cells and egg mother cells reduces the chromosome number of half in the sperms and eggs. Meiosis also adds new gene combinations in these gametes by the process of crossing over.
Mitosis cannot reduce the chromosome number to half in the sperms and eggs. Absence of crossing over in mitosis leads to the formation of genetically identical progeny cells from mitosis.
Hence, mitosis can not form sperms and egg cells. If it does, the sperms and egg cells would not have genetic variations and there would be doubling of chromosome number with each round of sexual reproduction.
Answer:
The fish did not yet exist when the old layers of rocks were deposited. In fact, animals with hard parts did not evolve until about 600 million years ago, which is only about 13% of the 4.5 billion year age of the Earth. Multicellular animals without hard parts left tracks in older sediments, but had no fossilize-able body parts.
Explanation:
Answer:
<h2>Ethylene is a gaseous hormone in plants, it is a fruit ripening hormone.</h2>
Explanation:
Ethylene is a chemical signal through which ripening fruits trigger the ripening process in fruits, Studies on components of ethylene signaling have shown a linear transduction pathway leading to the activation of ethylene response factors. However, the whole pathway by which ethylene selects the ripening-related genes and interacts with other signaling pathways to regulate the ripening process still not yet fully known. Most fruits produce ethylene that starts the ripening process. Its level in under-ripe fruit is very low, but as fruit develop, the production of ethylene become larger that speed up the ripening process of fruit.
Answer:
Runoff is nothing more than water "running off" the land surface.
<h3>Explenation:</h3>
Just as the water you wash your car with runs off down the driveway as you work, the rain that Mother Nature covers the landscape with runs off downhill, too (due to gravity). Runoff is an important component of the natural water cycle.
