SA citizens vaccinated against yellow fever is yes because now we have different vaccinations in each other and created new medicine for the human being.
Answer:
Water erosion refers to the removal of the top most or surface layer of soil by the flow of water. The long term effect of water erosion can be because of drastic rain fall and may be because of flood. These two reasons can adversely effect the human life. The water erosion is responsible for the removal of fertile layer of soil, therefore, the region will not be appropriate to grow vegetation. The long term effect may result in stagnation of water, therefore, long time is required so that the region gets dried. The long term accumulation of water over an agricultural field can spoil the crop production.
Prevention that can be taken to reduce long term effect of water erosion:
1. Plantation of long root bearing trees over flood prone regions and around the agricultural field: This will allow the trees to tightly hold up soil and prevent it's erosion.
2. Add rocks over the soil: In an agricultural field or flood prone area, the rocks will act as barrier for the movement of run off water, hence, will prevent water erosion. It will increase the absorption of water by soil.
3. Building of walls: This will also act as a barrier in a flood prone region and will prevent the water being added up to the agricultural land.
4.Remove soil compaction: If the soil compaction of the effected region is removed, the water retention property of the soil can be improved. Machines, animals and humans can be used for this purpose to remove the compaction of upper layer of soil.
Explanation: hope this helps.
9 : a. # of seeds
10 : d. amount of time given
<u>Answer</u>:
Science is not limited to the laboratory because it has done in a laboratory to study the physical, chemical and biological aspects of the natural system. It mean that science presents everywhere and happening at all times. It also mean that anyone can become a scientist and they can conduct the experiments with the data and a hypothesis.
<u>Explanation</u>:
Science is the study of the physical, chemical, biological, and mathematical study of nature. The science is studied in laboratory conditions to validate the various reaction and principles occurring in natural systems.
In a laboratory, small system or model is made to study the particular aspect of a large system. Thereby, science in the laboratory helps to find out the science of the actual world. Various principles, machines and designs are inspired by the natural systems.
