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Before viruses can reproduce, they must infect a host cell.
Viruses need a way to enter the body before they can infect a host cell.
<u>Answer</u>: option B they have a random gene mutation that affects their fur colour.
<u>Explanation</u> :-
- <em>Variation</em> is the phenomena which occurs in all populations.
- These variations result in slight differences in the phenotypes of individuals .
- These variations only arise due to <em>random mutations </em>that arise in the individuals’ genome and then can be inherited by their offspring.
- There is always a probability of one particular trait to make the individuals survive better in the environment as compared to other trait.
- The individuals having the trait that helps them to survive better in the environment tend to survive more and leave more progeny. This is termed as <em>survival of the fittest</em>.
- Thus, according to the question it can be inferred that the dark fur colour arose due to a <em>random mutation </em>since it is the only source of variation. Since, in the given environmental conditions the mice having the dark fur colour were less susceptible to the predators they are better fitted to survive.
- The dark brown fur coat mice, survive better, leave more progeny and hence, increase their population with time. However, the orginal source of origin of this trait was a random mutation. Had this mutation not occured, the dark coloured fur mice would not have been there.
So, a <em>random gene mutation affecting the fur colour made the dark coloured mice first appear in the population.</em>
Answer: Both the mouse and human beings are encoding the proteins having similar functions.
Explanation:
The CFTR gene in the mouse and CFTR gene in the human beings encode proteins that perform similar function,this is so because if the results are same then it means that both mouse and human beings are encoding the protein that have similar function.
Option A is incorrect because both humans and mouse are eukaryotes so they have introns and because of that even if the gene sequences are different they can still encode protein.
Option B is incorrect because amino acid sequences can be similar inorder to have the similar function. If glutamic acid is replaced by aspartic acid, it won't have different function the function will remain same. So, identical amino acid sequences are not required. They can be similar too.
The answer: Yes, because plants photosynthesis to absorb Carbon Dioxide and convert it in to Oxygen. We humans breathe the oxygen that is produced from plants.
