Answer:
When the required direction of transport is opposed to concentration levels, a cell <u>will </u> expend energy to force<u> ions</u> across its membrane.
Explanation:
If the concentration gradient is opposite to the direction of transport of minerals, then the cell will use energy to transport mineral ions from a lower concentration to a higher concentration. The most common process through which this happens is termed as the active transport.
The process of active transport is opposite to passive transport. In passive transport, molecules move from a higher concentration to a lower concentration.
'Red shift' is a key concept for astronomers. The term can be understood literally - the wavelength of the light is stretched, so the light is seen as 'shifted' towards the red part of the spectrum.
Hope this helps.
Answer:
The hershey chase experiment on bacteriophages showed the genetic information is carried in <u>DNA.</u>
Explanation:
In 1952 Alfred Hershey and Martha Chase provided evidence that DNA is the genetic material. These scientists carried out an experimental work with the T2 virus, a bacteriophage that infects the Escherichia coli bacteria, which reproduces by attaching itself to the outer wall of the bacteria, injecting its DNA into it where it replicates and directs, the synthesis of phage proteins. Phage DNA is encapsulated within proteins and produces phages, which lyse or break the cell and releasing phage from the progeny. They used radioactive forms (isotopes) of phosphorus and sulfur. A radioactive isotope can be used as a marker to identify the location of a specific molecule, because any molecule that contains the isotope is radioactive and therefore easy to detect. The DNA contains phosphorus, but doesn't contain sulfur, therefore phosphorus-32 was used to mark the DNA, instead the protein has sulfur, but not phosphorus, so sulfur-35 was used. Hershey and Chase found that sulfur-35 is outside the cell while phosphorus-32 was inside, indicating that DNA was the physical support of the inheritance. This work allowed the scientists to conclude that it's the DNA and not the protein that enters the bacteria during phage reproduction and that only the DNA is transmitted to the phage of the progeny.
