Answer:
The Miller and Urey experiment is a well-known classic experiment in which hypothetical conditions of the early Earth's evolution were simulated to test the possibility of chemical evolution. In fact, this was an experimental test of the hypothesis previously expressed by Alexander Oparin and John Haldane that the conditions that existed on primitive Earth promoted chemical reactions that could lead to the synthesis of organic molecules from inorganic ones. It was held in 1953 by Stanley Miller and Harold Urey. The apparatus designed for the experiment included a mixture of gases corresponding to the notion of the composition of the atmosphere of the early Earth in the 1950s, and electric discharges passing through it (simulating lightning strikes on the ground). The Miller and Urey experiment is considered one of the most important experiments in the study of the origin of life on Earth.
Answer:
Humoral immunity protects the body against extracellular pathogens and their toxins. Cell-mediated immunity protects the body against intracellular pathogens. Recognises pathogens in circulating in blood or lymph.
celluler immunity is very specific compared with humoral
Answer:
Structurally, proteins are different from carbohydrates because all proteins contain nitrogen (option C).
Explanation:
The basis of the chemical composition of proteins is carbon, hydrogen, oxygen and nitrogen, so all proteins have nitrogen in their structure. Some proteins also possess phosphorus and sulfur atoms, among others.
Proteins are biomolecules formed by the union of multiple amino acids through carboxyl-amino bonds, called petidic bonds. Their content of nitrogen and other atoms in their structure is what makes them different from carbohydrates.
The other options are not possible because:
- <em>Only some proteins contain </em><u><em>iron</em></u><em> in their composition.</em>
- <u><em>Potassium and helium</em></u><em> are not part of the protein structure.
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Answer:
they have cell walls as an outer boundry
Explanation:
the cells of all living things do not have cell wall. animal cells do not have cell wall. protozoans also do not have cell wall. while cells of plants algae fungi and bacteria have cell wall.
Brachiopoda hope this helps :)
