Question

Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene

(A) normally leads to the formation of head structures.

(B) normally leads to formation of tail structures.

(C) is transcribed in the early embryo.

(D) is a protein present in all head structures.

Short answer

(A)The option “normally leads to the formation of head structures” is true.

(B)The option “normally leads to the formation of tall structures” is false.

(C)The option “is transcribed in the early embryo” is false.

(D)The option “is a protein present in all head structures” is false.

Step-by-step solution

mRNA

mRNA is the messenger RNA formed from the transcription process that uses the DNA as a template strand. mRNA is responsible for coding the protein that is responsible for performing different metabolic functioning necessary for the organism's survival.

Explanation of option “(A)”

The bicoid mRNA codes for an essential protein known as the bicoid protein. This protein is important for the development of Drosophila insects. Mainly, it works as an anterior body part organizer in Drosophila.

Thus, the absence of the bicoid gene leads to the absence of anterior parts in Drosophila. It is confirmed that the bicoid is responsible for forming anterior or head parts in the Drosophila.

Therefore, the given option is true.

Explanation of option “(B)”

The formation of tail structures also happens in the development of Drosophila. In the given condition, the mirror image duplication of posterior structures is formed.

The mirror image duplication is not a normal formation of the posterior parts. So, the absence of the bicoid gene does not form normal posterior or tail structures.

Therefore, the given option is false.

Explanation of option “(C)”

Transcription is the process that happens throughout the lifetime to produce essential proteins. It does happen alone in the early embryo. The absence of the bicoid gene cannot result in the transcription of the particular protein.

The transcription in the early embryo does not occur due to the absence of the bicoid gene.

Therefore, the given option is false.

Explanation of option “(D)”

The bicoid protein is responsible for the development of the anterior structure. It is not the structural component for all head structures.

Bicoid protein is not the protein component present in all the head structures.

Therefore, the given option is false.