Two human activities that could contribute to the introduction of invasive species.

Invasive species or alien species is the term referred to the organisms which are introduced in an ecosystem due to man made or any environmental activity. Humans play primary role in the introduction of invasive species in a certain ecosystem.

Explanation:

These activities may include the ships and boats flowing in aquatic regions of the world that carry novel aquatic organisms in their ballast water and propellers respectively. The small insects present into their shipping pallets and wooden parts are carried from one place to another place where they cause threat for the availability of food and nutrients to the already existing populations.

Another human activity that can contribute to the introduction of invasive species is the enhanced fuel consumption which leads to environmental pollution around the globe. This environmental pollution gets so immense in some areas that it can make the survival of existing species difficult and thus they move to new location for their survival.

Therefore, it can be seen that human activities have potential role in the spread and introduction of invasive species.

Hope it helps!

you are certainly talking about this picture:

a: is the label of the white square, it is showing the  replication fork, formed by helicase (d) ==> so it is the site of dna separation and replication 

b: is a new dna brand that is following directly the replication fork, so it is continuous ==> built continuously from 5' to 3

c: dna polymerase cannot replicate dna on its own, it needs the of their proteins, and one of them plays the role of a clamp which fixes  the dna with the dna template and increases  the processivity of the enzyme. ==>   stops polymerase from falling off the  template.

d: is the enzyme responsible for forming the replication fork (helicase) ==> unwinds and separates dna into two strands

e: is the delayed strand, it is built  in the opposite sense of the helicase, so dna will be built in fragments ==> built  fragments from 5' to 3 joins

and finally f: is the enzyme that builds  the new dna strand (dna polymerase) ==>   adds nucleotides to make a new dna helix.

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