Answer:
When fresh water reaches lakes and shores , it becomes dirty and less diverse in living organism.
Explanation:
Fresh water originating from a given source is usually cooler at upstream side. Also it has high oxygen content and fresh water fauna such as fishes. In the middle of its course, its width and species diversity increases. With further progression, sediments and dust adds to the water thereby reducing its clarity and hence the penetration of sunlight. By the time this water reaches streams and ponds, it is full of mud, sand, and other sediments.
The correct answer is: b) directional selection
Directional selection is a type of natural selection in which an extreme phenotype is favored over other phenotypes. In this case, phenotype of large crickets will be favored, because they cannot be eaten by lizards. Large crickets are advantageous in surviving and reproduction. This will cause the allele frequency to shift over time in the direction of that large size phenotype.
Answer:
The problems that can be caused by Expansion or Contraction a;long with the solutions are:
Explanation:
- The railway tracks made of steel expand during the summer and contract during the winter. This can cause them to become curved during the summer thereby causing rail derailment.In order to prevent this, an air gap is kept in between the railway lines so that they get the space to expand without getting curved.
- The electric wires linking the telegraph posts are made up of metals and so they expand in the summer and contract in the winter, which can cause them to tear. This is why the wires are loosely fixed so that they can expand and sag in the summer and contract and tighten in the winter.
- Bridges are constructed with joints where some space is maintained to allow the easy expansion and contraction in summer and winter respectively.
Answer:
I think it is a because the oldest things would be farther down in the ground and the youngest would be upper to the ground if that makes sense
