The correct answer is option A, that is, theories.
A restricted explanation of a phenomenon is referred to as a hypothesis. A statement regarding an observed phenomenon or a unifying concept is considered as a law. A law differs from a scientific theory in that they do not postulate an explanation or mechanism of the phenomenon, they are just a filtration of the outcomes of recurrent observation.
However, a scientific theory refers to a thorough explanation of the observed phenomenon.
Answer
Photosynthesis yield sugar in two main steps
1. Light reaction
In this step plant absorb sunlight which cause photolysis of water and excitation of electron. this electron flow through Z-scheme and atlast enter into NADH, the end product of light reaction is ATP and NADH₂.
2. DArk reaction.
In this step ATP and NADH₂ are used as raw materials. it occurs in stroma of chloroplast. here CO₂ is used through Calvin cycle and at the end glucose is prepared.
External Stimulus is the answer
Answer: Codon
Explanation:
Codon refers to nucleotide triplets of mRNA that serve to specify the amino acid sequence of proteins. There are total 64 genetic code that specify 20 standard amino acids found in proteins. All codon together make genetic code. For example: AUG is codon that specify amino acid "methionine". AUG codon also serve as initiation codon during initiation of protein synthesis.