Answer:
The answer is A. a tissue
Explanation:
Tissues are groups of similar cells that have a common function. An organ is a structure that is composed of at least two or more tissue types and performs a specific set of functions for the body.
Amino acids are the building blocks of proteins and are made from basic amino group (−NH2) and an acidic carboxyl group (−COOH) as well an organic R group (or side chain) that is unique to each amino acid. they are made from carbon, hydrogen, oxygen and nitrogen atoms
The ileum contains villi that project into the lumen and increase the amount of surface area.
Villi are small finger-like structures that project into the lumen of the small intestine. Villi increase the surface area of the intestinal walls for easy and quick absorption of digested food with the addition of digestive secretions. Villi vary in length from about 0.5 to 1 mm. They are usually found in large numbers at the beginning of the small intestine and they reduce toward the end of the tract.
The mechanism in which organisms best suited for their environment survive
and reproduce <u>NATURAL SELECTION.</u>
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Explanation:
When individuals in a population compete for resources or live in their environment, the individuals with the slightest advantage over the others have an increased chance of reaching maturity and reproducing to passing down their genes to the next generations.
Natural selection works on the variations of the population to ‘select’ the best alleles of genes in the population that offer an advantage in ‘survival for the fittest’. This how natural selection fits a population to its environment. The greater the variation within a population, the higher its capacity to adapt to changes in the environment.
Learn More:
For more on natural selection check out;
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