Answer:
Option (B)
Explanation:
A river that is diverted to the irrigating farmland during a drought is an example of the human-caused disturbances to an ecosystem.
An ecosystem refers to a particular community within which the organisms exist and interact with each other. For example, fresh water ecosystem, desert ecosystem and forest ecosystem.
In the given situation, the river channel is disturbed by changing its flow direction. This is caused by the human activity, that changes the course of the river channel to the farmlands during a flood, so that the water can provide nutrient to the soil and prevent the soil from getting eroded.
Thus, by doing this, the river ecosystem gets affected, as a result of which the organisms existing in this ecosystem such as fishes are affected.
Hence, the correct answer is option (B).
The amount of chromosomes are fairly constant
Answer:
Origin of Viruses. ... Small viruses started as runaway pieces of nucleic acid that originally came from living cells such as bacteria. Large viruses were once parasitic cells inside bigger host cells. Over time, genes needed to survive and reproduce outside host cells were lost.
NUCLEAR ENERGY
Every second of every day our Sun converts about 4.2 million metric tons (4,200,000,000 kilograms) of hydrogen into helium using a nuclear <span>fusion </span>process. During this nuclear reaction, a small portion of matter is converted to an enormous amount of energy. It is this output that provides the energy for photosynthesis and for heating our atmosphere and oceans.
In this lesson, you will learn the details of the nuclear fusion process. You will also learn about another important nuclear reaction called fission and some useful applications of it.
OBJECTIVES<span>Describe the process of nuclear fusion.Describe the process of nuclear fission.Identify some applications for nuclear reactions.List positive and negative factors associated with nuclear reactions.</span><span>VOCABULARY</span>
