Q-4
Answer correctly.
(1) How does the vaccine help to prevent disease?
(2) Why do birds migrate?
(3) Which irrigation system is useful in water scarcity area? Why?
Answers
Answer:
1.When the familiar antigens are detected, B-lymphocytes produce antibodies to attack them. Vaccines prevent diseases that can be dangerous, or even deadly. Vaccines greatly reduce the risk of infection by working with the body's natural defenses to safely develop immunity to disease.
2.Migratory birds fly hundreds and thousands of kilometres to find the best ecological conditions and habitats for feeding, breeding and raising their young. When conditions at breeding sites become unfavourable, it is time to fly to regions where conditions are better. There are many different migration patterns.
3.Therefore agriculture is often criticised as a wasteful water user, especially in water scarce areas. Drip irrigation is widely recognised as the most efficient irrigation technique and often portrayed as the best solution to increase agricultural production whilst reducing the demand for water.
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Answer:
1)Vaccines work because of a remarkable property of the human immune system: Once infected with a particular pathogen, your antibodies get to work. “’Memory’ cells develop when you get sick with a new virus so you don’t get the viral infection again,” said Van G. Wilson, PhD, associate dean for research and graduate studies and professor of microbial pathogenesis and immunology at the Texas A&M College of Medicine. “The second infection is dealt with quickly, before you even feel sick.”
2)Migratory birds fly hundreds and thousands of kilometres to find the best ecological conditions and habitats for feeding, breeding and raising their young. When conditions at breeding sites become unfavourable, it is time to fly to regions where conditions are better. There are many different migration patterns.
3)Drip irrigation is one such technology that has been introduced to reduce water consumption in the agriculture sector, leading to sustainability of this sector. It allows farmers to cultivate crops without moisture stress even under water-scarce conditions, thereby increasing farm productivity.
Explanation:
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