Answer:
Antibiotic resistance can evolved in bacterial population in the following ways:
Explanation:
- In response to constant exposure to antibiotics some members of a bacterial population develop some beneficial mutations in some essential genes that gives them survival advantage in terms of food and space over the sensitive bacterial strains and hence they are capable of out-competing the sensitive bacteria.
- This happens due to the process of Natural Selection.
- These genes are called antibiotic resistance genes and bacteria usually carry them on plasmids in form of cassettes where genes resistant to multiple drugs are incorporated. These plasmids are called the MDR or Multi-Drug Resistance Plasmids.
- These resistant plasmids can be easily transferred among bacterial populations by conjugation, transformation or transduction or direct plasmid transfer.
- The resistant genes encode for proteins that render the drug ineffective by promoting their efflux from the cells, preventing their entry into the cell, chemically modifying them such that they become non-functional or altering the target site of the drug.
Answer:
The correct answer is: A. Only the best-adapted animals in a population survive.
Explanation:
- Natural Selection is the process by which the individuals of a species which has the potential to sustain and survive in adverse or changing environment gets a survival advantage over those individuals which are unable to adapt themselves to altered environmental conditions.
- As the less potent individuals die in altered environmental conditions the adaptable individuals escapes competition with them for natural resources.
- Evolution causes species to alter their characteristics depending upon the demand of the conditions. These changes can vary, can be less or drastic.
- Animals pass all the newly adapted traits to the successive generations either as genetic traits or as acquired traits, as this is necessary for the offspring to survive in the altered environment.
- Natural selection is best defined as "the survival of the fittest".
Pull Of Gravity , that is why you have weight or else without gravitational pull you only have mass hence the equation w = mg
