How many alleles (letters) do each person carry for a trait?

Two letters are used represent a trait. An offspring gets one letter/ allele from each parent. - each parent contributes 50% to an offspring. A dominant allele always shows up in an organism, even when the other allele is present.

Explanation:

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.