Answer:
They are stimulated by an antigen.
Explanation:
Natural killer cells are cytotoxic cells that help our body in innate immune response. These are an critical and important component of the innate immune system of our body. These natural killer cells provide a rapid response towards the virus infected cells. These cells have capability to detect MHC that are present on the infected cells. Natural killer cells do not require activation for killing those cells which are missing MHC I. Due to this feature, they are named as the Natural killer cells. These cells can directly induce the death of tumor cells and play an important role in immunosurveillance.
Chloroplast makes Photosynthesis
Answer: Option (c) is the correct answer.
Explanation:
A long hydrocarbon chain that consists a terminal carboxylic group is known as a fatty acid.
An unsaturated fatty acid consists a double bond within the fatty acid chain. If a fatty acid contains more than one double bond then it is known as polyunsaturated fatty acid.
For example, oelic acid has chemical formula
is an unsaturated fatty acid.
Therefore, we can conclude that option (c) represents an unsaturated fatty acid.