Answer: A). Active transport requires chemical energy to move nutrients from areas of low concentration to areas of high concentration.
Explanation:
Sometimes cells require nutrients such as sodium and potassium to be transported from an area where they are in low concentration to an area where they are in high concentration.
This goes against the concentration gradient where substances are transported from an area of high concentration to one with low concentration as is the case in processes such as osmosis.
This process is called Active transport and describes the use of chemical energy to move nutrients from areas of low concentration to areas of high concentration.
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An independent variable that is manipulated means to achieve a particular effect or tested to determine if it is the cause of the effect.
For example, to find out if your weight depends on the amount of calories you consume, you could lower your caloric intake (calories is the manipulated variable) for a period of time and see how your weight changes in response.
Explanation:
Homologous chromosomes are 2 physically different chromosomes that have the same genes but are not genetically identical. Sister chromatids are 2 copies of a single chromosome and so are genetically identical (they also are physically attached to one another).