In order to conduct a research you should have an dependent variable, independent variable and the control variable. so in order to study phototropism, then you should need sun light and the growth of the plant and you must have a control that why you need a dark room.
A) DNA fulfils all three conditions:
<span>(1) copy itself precisely - in the process of replication, DNA copies itself and two molecules of DNA are formed. This process is very precise thanks to the great number of proteins involved in these process that prevents error occurring and proteins that can fix the error if it occurs.
(2) be stable but able to be changed - DNA is very stable molecule otherwise, it cannot be a genetic material. However, its chains can separate in a short length so the translational machinery can attach to it and the process of transcription can occur. Also, in crossing over, during meiosis, </span>the exchange of genetic material occurs and chromosomes change a bit.<span>
(3) be complex enough to determine the organism’s phenotype - it contains a number of genes responsible for different traits. All of this results in the </span>organism’s phenotype.
B) DNA copies itself. <span>Meselson and Stahl conducted the experiments on DNA replication in which they used </span>E. coli<span> bacteria as a model system. After they labelled all bacteria's DNA with heavy 15N by using medium with heavy 15N, they switched bacteria to medium with light 14N. After several generations, all bacteria's DNA was labelled with light 14N. This experiment evidenced that the self-replication of DNA is semi-conservative process.</span>
A simple example is the connection between the circulatory and respiratory systems. As blood circulates through your body, it eventually needs fresh oxygen (O2) from the air. When the blood reaches the lungs, part of the respiratory system, the blood is re-oxygenated.
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The most likely way that the lost fat left the body of a person on a strict diet and exercise regimen who lost 7 kg (about 15 pounds) of body fat in just two weeks is (A) It was released as CO₂ and H₂O.
Fats are the lipid molecules made of a glycerol backbone with 2 fatty acids and a phosphate head group. The body of an organism uses fat as an energy source, but it is the predominant form of storage of energy in the body. Fats can be of two types: good fat and bad fat. Only the food fat consumed in required amounts is beneficial for the body.
Strict diet is the calorie-restricted diet with fixed timings of meals. The restrictions and timings vary from person to person. When a person follows a strict diet along with exercise, beta-oxidation occurs inside the body where the fat is lost in the form of carbon dioxide and water.
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