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Reported or indirect speech is usually used to talk about the past, so we normally change the tense of the words spoken. We use reporting verbs like 'say', 'tell', 'ask', and we may use the word 'that' to introduce the reported words. Inverted commas are not used.
Answer:
Enzyme
Explanation:
Enzymes are the bio-catalyst that serve to accelerate the metabolic reactions occurring in a living cell. All the metabolic reactions of organisms are catalyzed by enzymes. Each metabolic reaction is catalyzed by specific enzyme. Absence of that particular enzyme leads to absence of the respective product. Since genes code for protein which regulate the specific trait, absence of enzyme does not allow the expression of that trait.
Example: Absence of enzymes for chlorophyll synthesis would lead to absence of chlorophyll from leaves of the green plants.
Answer:
The correct option is <u><em>A. they evolved from land mammals.</em></u>
Explanation:
The process of evolution explains how closely one organism is to another based on their common ancestors. Scientists believe that those organisms which show many similarities in their structures or functions might have evolved from a common ancestor in the past.
As in the above-mentioned question, scientists have observed that cetaceans lack gills and breath air, this is a property of land mammals. The cetaceans have fin bones which are similar to the limb bones. As limb bones are present in land mammals, hence they cetaceans and land mammals might have common ancestors in the past.
