The correct answer are valves. As lymphnodes become larger and deeper they turn into lymph vessels that develop one-way valves. These valves prevent the back flow of blood throughout the vessel and ensure that the lymph only flows in one direction.
Answer:
Height is affected by multiple pairs of genes on different chromosomes.
Explanation:
The height is a quantitative trait, it is a phenotypic feature that presents a continuous range of variation in the population. The cumulative effects of many genes and the environment produce a normal distribution bell-shaped curve when they are drawn, this being a characteristic of quantitative genetic traits. Examples of quantitative traits include, among others, height, metabolic rate and weight.
Mutualism , is the correct answer
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