C. The cell took in another ancient prokaryotic cell, which began living inside it.
Answer:
Usually, Populations have a genetic variation among individuals, which is important to the population's ability to survive in different situations that have an effect on the natural selection. There are different factors which can increase or decrease the genetic diversity, and influencing natural selection.
These factors include an environmental factor, one of the major factors, which may cause changes in the genetic variation of a population and influence the natural selection. A famous and important example of environmental factors affecting natural selection was during the Industrial Revolution, when many more grey moths made up the moth population.
This was so that they could blend in with the soot from factories to avoid predators.
Answer:
Hemoglobin is responsible for binding and transporting oxygen in the body. It is a tetrameric protein that is found in high concentration in red blood cells (erythrocytes, red blood cells). Each hemoglobin molecule is made up of four subunits: two of the alpha type and two of the beta type, and each subunit can bind an oxygen molecule through its heme group.
Structure studies have shown that hemoglobin can adopt two conformations, called T (tense) and R (relaxed). Deoxyhemoglobin (in blue) is in state T, and the union of oxygen (in red) causes the transition to state R. The animation shows a close view of the heme group (in white, balls and rods) of one of the subunits of hemoglobin. In the deoxygenated state (T), the iron atom is not coplanar with the rest of the heme group due to its association with the histidine side chain. The union of oxygen displaces the iron atom so that it remains coplanar with the rest of the heme group, which in turn drags histidine, producing a larger-scale conformational change that affects the entire protein.
Hemoglobin can be considered as a tetramer formed by two alpha-beta dimers. The conformational change associated with the transition from T to R mainly affects the relative position of these two dimers (rather than the interactions between the alpha and beta subunits within a dimer). This is illustrated in the last stretch of the animation (drawn in black and white).
Answer:
<em>The correct option is D) How is the number of frogs in Massachusetts affected by pollution</em>
Explanation:
A scientific question can be described as a question which can be answered through the scientific method of research. Based on the scientific question, a hypothesis can be formulated. For example, for the option D, the hypothesis can be 'if the pollution increases, then the number of frogs decreases.' A hypothesis is a tentative statement which can be tested through experiments. Based on these experiments, results are formulated and conclusions are drawn. The question mentioned in option D can be answered through this method hence, it is the correct option.
Answer:
b) By mixing weak base with its conjugate acid and then adjusting the pH with strong acid.
Explanation:
Hello,
In this case, considering that the buffer required a pH greater than 7 where the basic conditions are present, we need a weak base and its conjugate base in order to assure such pH greater than 7. Moreover, by using a strong acid, we can gently add it in order to decrease the pH up to 7.4 via a properly measured neutralization of the necessary moles of base up to a hydrogen concentration of 3.98x10⁻⁸ (pH). Therefore, answer is b) By mixing weak base with its conjugate acid and then adjusting the pH with strong acid.
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