<span>Damming a river has a variety of effects on the freshwater ecosystem, more than just altering the flow from A to B. Dams create calm bodies of water, changing overall temperature regimes and sediment transport, leading to conditions which tend to favour generalist species. Loss of specialist species, particularly endemics, changes the community structure and leads to biotic homogenization. A dam will withhold sediment in the reservoir, not just decreasing the amount of substrate available to local freshwater species, but even impacting diadromous, estuarine and marine species much further downstream. The competition between resident species for food and breeding sites will increase as damming isolates populations, and perhaps more importantly, damming completely restricts migratory fish species. Isolation may lead to decreases in genetic diversity and therefore puts species at greater risk from disease. All of these effects may be exacerbated by changes in the surrounding land use. Overall, damming river flow will lead to both a loss of native species, but also an increase in exotic species which are more likely to become established in degraded habitats. For this reason, dams are one of the greatest global threats to freshwater biodiversity.</span>
Answer:
DNA ligase
Explanation:
DNA replication is an enzyme mediated, 3-step process during which the DNA molecule produces a copy of itself. The 3 steps involved are as follows;
- initiation
- elongation
- termination
<em>Initiation </em>involves the unwinding of the double helix structure of the DNA using DNA helicase enzyme
<em>Elongation</em> involves binding of RNA primer to the DNA strands and addition of bases to the primer<em> </em>to elongate the new chains. Bases are added to the leading strand continuously while the lagging strand is replicated in short segments (okazaki segments).
<em>Termination</em> involves the unbinding of RNA primer and substitution of its bases by DNA bases. The Okazaki fragments are then joined together using the DNA ligase enzyme.
<em>The short, numerous segments of DNA observed in the mixture is the Okazaki fragments of the lagging strand. This is due to the absence of the enzyme involved in the joining of these fragments.</em>
Hence, the answer is DNA ligase.
<span>B- tree > insect > frog> snake> hawk
The food chains are represented by organisms interconnected by red arrows that point in the direction of the one that's eating. So, the relation that is explicit by the arrow is that the organism from where the arrow departs is eaten by the organism where the arrow is pointing towards to. So, the food chain that can be observed accurately in the food web is: the tree is eaten by the insect, the insect is eaten by the frog, the frog is eaten by the snake, and the snake is eaten by the hawk.
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<h2>Least desirable method for processing the crime scene</h2>
You are at a crime scene, collecting glass evidence. Following are the least desirable methods for processing the crime scene for glass fragments as: At a crime scene, a person should be very concerned at the gathering and organization of mirror pieces.
- Proper accumulation and protection methods should be utilized for getting a specimen from glass pieces.
- Put on latex gloves.
- Use clean forceps.
The data should be typed accurately.
D- species
A biological species is a group of organisms that can reproduce with one another in nature and produce fertile offspring.
