Answer:
The correct answer to the question, 'which of the following scenarios is representative of how agricultural practice can affect the environment' is A. Option A is chosen because it is the only option that refer to another environment which is different from that of the farm. When fertilizers are washed to nearby ponds as a result of erosion, it causes a lot of negative changes in the pond. For instance, the chemicals in the fertilizer can be poisonous to some of the smaller organisms in the pond, this will result in the death of these organisms. Fertilizer run off can also cause excessive growth of plants such as algae in the pond. This may block out the light necessary for the survival of the organisms in the ponds and may also reduce the amount of oxygen available to the organisms living in the pond.
Explanation:
In Eukaryotes, the DNA replication can start at several sites or places in the DNA molecule or DNA strand. The only important factor for DNA replication to start is that it starts at replication fork.
The replication of DNA is semi-conservative in nature because each strand acts as a template for synthesizing a new complementary strand of the double helix.
The new DNA is made with the help of the enzyme DNA polymerase which requires a primer for starting the DNA synthesis.
Replication occurs only at specific regions of DNA known as origin of replication and these are short sequences of nucleotides which are recognized by the enzyme for the replication.
The special enzymes or proteins recognize the specific sites and then binds to them. After binding, the DNA is opened up forming the replication forks which are two Y- shaped structures.
<h3><u>
The following events are identified as chemical weathering:</u></h3>
- The minerals in a marble statue react with water to form acids and pores in the structure.
- The rocks in a region are streaked orange after being exposed to repeated rains.
<em><u>Reason: </u></em>
When the weathering process occurs due to <em>chemical reaction</em>, then it is considered as chemical weathering.
In <em>the first case</em>, minerals of marble statue are <em>reacting</em> with water to cause weathering. In the <em>second case</em>, due to the <em>acidificaion reaction</em>, the change of the color has happened after exposure to the repeated rains.
<h3><u>
The following events are identified as Mechanical weathering:</u></h3>
- A piece of rock crumbles after being constantly thrashed by strong waves.
- Industrial runoff forms cracks in a rocky structure in its path.
<em><u>Reason:</u></em>
When the rock is broken into simple pieces <em>without any chemical reaction </em>it is considered as mechanical weathering.
In the <em>first cause</em>, due to the <em>abrasion</em> caused by the strong waves, weathering has happened, in the <em>second case</em> industrial run off may be of varying temperature and thus may cause <em>heating or cooling</em> of the rock and causes weathering.
1 H2SO4 + 2 NaNO2 ---> 2 HNO2 + 1 Na2SO4
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