Short Questions & Answers : Class 9 - KP Boards - Unit: 2 - SOLVING A BIOLOGICAL PROBLEM

 Question B: Give short answers for the following questions.

i. What is a science? How does it work?
Answer:

Science can be defined as the study of the world through observations and experiments. It works in a very systematic and fantastic way known as scientific method, where first of all the scientific problem is identified and hypothesis are developed. Then, the hypothesis is tested through experiments. And in this way, most of the scientific problems are solved and discoveries are made.

ii. Control group is important for scientific study, how?
Answer:

Control group is important in scientific study as it allows the scientist to observe the difference in control and experimental group. It is important to corelate the results of experiments by comparing them with the control group to know the effects and whether the results support the hypothesis or not.

iii. What deductions were developed during the study of malaria?
Answer:

During the study of malaria, when the hypothesis. “Plasmodium is the cause of malaria” was made, to test this hypothesis the deduction developed was, “If Plasmodium is the cause of malaria, then all malarial patients should have Plasmodium in their blood”.

While when the hypothesis, “Mosquitoes transmit Plasmodium” was made, to test this hypothesis the deduction, “If Mosquitoes transmit Plasmodium, then Plasmodium should be present in mosquitoes” was made.

iv. How Ronald Ross conducted the experiment to prove that mosquitoes are involved in the spread of malaria?
Answer:

Ronald Ross was a British army physician, he performed an experiment in which he allowed a female anopheles mosquito to bite a malarial patient. He killed the mosquito and found Plasmodium in the stomach of mosquito. In his next experiment, he used sparrows instead of human beings as it was a risky approach. He allowed a female Culex mosquito to bite a sparrow suffering from malaria, he killed some of these mosquitoes and examined them. He found Plasmodium multiplied in the walls of the mosquito’s stomach and then moved to the mosquito’s salivary glands. He then allowed the infected Culex mosquito to bite a healthy sparrow and found that the priorly healthy sparrow got malaria and had Plasmodium in its blood. In this way, Ronald Ross proved that the hypothesis, “Mosquitoes transmit Plasmodium” is true and the problem was solved.

v. At what stage of the biological method, hypothesis is accepted or rejected?
Answer:

During biological method, after the experimental stage a hypothesis is accepted or rejected based on the results of the experiments. If the results of the experiments support the hypothesis, it is accepted while if the results of the experiment do not support the hypothesis, it is rejected.