Mutations are positive occasionally, beneficial occasionally and omission of information.
Answer: Options 1, 3 and 4.
<u>Explanation:</u>
Mutations are more or less permanent changes. These changes are heritable in the phenotype of an individual. These changes occur because of the alteration in the number, kind or the sequence of nucleotide of the genetic material which is DNA in most of the cases.
Mutations occur at some times in the life of people and they are present in only some cells of the human body. They are not present in all the cells of the human body. These changes can also occur because of environmental factors like ultraviolet radiation from the sun.
Answer: True. Selective media can be used to separate gram negative from gram positive bacteria.
Explanation: Selective media allow certain types of organisms to grow, and inhibit the growth of other organisms.
For example: Media containing potassium tellurite will inhibit the growth of gram negative bacteria while media supplemented with penicillin will inhibit the growth of gram positive bacteria.
The second phase of the body's immune response to a foreign substance involves initiation of the body's defenses.
The producers would grow more food to be eaten but the secondary/tertiary etc consumers would have nothing to eat and so numbers would drop on that side
Answer:
1. Wind
When strong winds blow, the topsoil along with the organic matter is carried away by the wind. This happens more often when the land is not covered with grass or plants. Such conditions are very common in desert and semi-desert regions where strong winds blow very frequently.
2. Water
When it rains in the hilly areas, the soil gets washed away towards the plains. The running water deposits the mineral-rich soil in the riverbed and over the years this deposition of soil can change the course of the river. This can lead to floods which cause the destruction of life and property. Water erosion leads to loss of agriculture potential.
3. Overgrazing
When cattle are allowed to graze on the same field repeatedly, all the available grass, including the roots are eaten by them. This makes the topsoil vulnerable to wind and flowing water, leading to soil erosion.
4. Deforestation
Humans have taken land from the forest to cultivate in order to feed the ever-increasing population and to build houses, industries, etc. Cutting down of trees on a large scale for these purposes is deforestation. The roots of trees hold the soil together, thus preventing the soil from getting uprooted. When large areas of the forest are cleared, the topsoil gets eroded by wind and flowing water.
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