Which of the following statements about innate immunity is true?
it involves the activity of b and t cells.
innate immunity is present at birth. innate immunity involves specific recognition of microorganisms via a memory response.
the innate immune response does not have a mechanism for detecting invading microorganisms.
it is activated only in response to tissue damage or a signal from an infected cell.

Innate immunity is present at birth.

Explanation:

The immune system is divided into two categories such as innate immunity and adaptive immunity. The innate immunity is present in an individual during birth. It does not depend on prior contact with microorganisms or immunization. It is present at birth and changes throughout the life of the individual. There are different barriers of innate immunity such as skin, mucous, lysozymes (present in the tears). This type of response is rapid and not specific. It has no memory. The cells of innate immunity are the phagocytic cell, dendritic cells.

condenser is used to focus in the light microscope.

the answer to the blank provided is “an autosomal gene that is required for the expression of genes on the x chromosome”.

testis-determining factor, abbreviated as td, which is more popularly known as sex-determining region y or sry protein, is a dna-binding protein or  gene-regulatory protein/transcription factor, encoded by the  sry gene. it is the gene responsible for the initiation of male gender determination in humans.