Well, Carbon has 4 Valence Electrons. I'm sure you know this, but valance electrons allow electrons to covalently bond with one another. The elements, when sharing the electrons, want to have 8 valance electrons. So carbon has 4 valance electrons so it can bond with itself, or another say 4 hydrogen [becuase hydrogen can live with 2 valance electrons]. Hope this helps. Remember: Electrons <3 8 valance electron bonds Carbon's 4 + Carbon's 4= 8 true love at first bond! OR Carbon's 4+ Hydrogen's 1 [x4] = 8 hope this help
Ans.
Paper waste prevention is defined as a practice to reduce or eliminate use of paper, which is potential for the efficient use or disposal of paper. It decreases the environmental impacts due to both paper manufacturing and paper recycling, such as demands on forest resources).
Use of advance technologies, such as E-mail (electronic mail) can help in cut down on paper waste. Nowadays, E-mail has replaced conventional letters and faxes as it is more eco-friendly than letters and faxes, which needs paper consumption.
Thus, the correct answer is 'option d). E-mail.'
<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:
The selenium particles when coated on paper towels were extremely effective and continuously inhibited (about a 90% reduction) the growth of gram-positive bacteria including S. aureus and S. epidermidis after 24, 48, or 72 hours.
