SOLVED EXERCISE BIOLOGY CLASS 9 CHAPTER 2
Question#1 Describe the steps involved in biological method taking malaria as an example.
Answer. Study of malaria- an example of biological method.
In the last part of the 19th century many different causes of malaria were being suggested.
Observations about malaria:
1. By that time, there were four major observations about malaria.
2. Malaria and marshy areas have some relation.
3. Quinine is an effective drug for treating malaria.
4. Drinking the water of marshes does not cause malaria.
Plasmodium is seen in the blood of Malaria patients. We know that a scientist uses whatever information and observation he has and makes one or more hypotheses.
Hypothesis about malaria:
Hypothesis made in this case was “Plasmodium is the cause of malaria”.
Scientist does not know whether his hypothesis is true or not, but he accepts it may be true and makes deductions. One of the deductions from the above hypothesis was, if plasmodium is the cause of malaria then all person ill with malaria should have plasmodium in their blood.
Also Read this: Best O Level Schools in Karachi.
Experiment about malaria:
Next step was to test the direction through experiments which was designed.
Blood of hundred malarial patients examined under microscope, for the purpose of having control group the blood of the 100 healthy person also examined under microscope had plasmodium in their blood.
Results about malaria:
Results of the experiment showed that almost all Malaria patients had plasmodium in their blood while 7 out of hundred healthy persons also had plasmodium in their blood( now we know that plasmodium in the blood of healthy people was in incubation period i.e. the period between the entry of parasite in host and appearance of symptoms ). The results were quite convincing and proved bat hypothesis plasmodium is the cause of malaria was true.
Question#2 If a test shows that some people have plasmodium in their blood but they do not show any symptoms of malaria what hypothesis would you formulate to answer this problem.?
Answer: If some people have plasmodium in their blood but they do not show any symptoms of malaria then plasmodium is present in them in incubation period.
Question#3 How the principles of ratio and proportion are used in biological method?
Principles of ratio and proportion:
Proportion means to join two equal ratios by the sign of equality (=)
For example a:b=c:d is a proportion between the two ratios. This proportion may also be expressed as a:b::c:d.
In every proportion of two ratios, there are four terms the first and fourth terms are called extremes, the second and third are called means. So, in the above proportion ‘a’ and ‘d’ or extremes while ‘b’ and ‘c’ or means. The basic rule used to solve problems through ratios and proportion is that the product of extremes is equal to the product of means. When three values in proportion are known, the fourth one be calculated by using the rule.
For example, biologist can calculate how many birds would get malaria, when he allowed mosquitoes to bite 100 healthy sparrows. In the previous experiments he noted that when he allowed mosquitoes to bite 20 sparrows 14 out of them got malaria. Now he uses the proportion rule.
It means 70 out of 100 sparrows would get malaria. SOLVED EXERCISE BIOLOGY CLASS 9 CHAPTER 2
Question#4 Justify mathematics as an integral part of the scientific process.
Answer. Mathematics as an integral part of the scientific process.
Biological method also involves the use of Applied Mathematics to solve biological problems. Major biological problems in which knowledge of mathematics is used include gene finding, protein structure, and protein-protein interactions and the modelling of evolution.
Bioinformatics refers to the use of algorithm, computational and Statistical techniques for the analysis of biological data.
Computational biology refers to hypotheses-driven investigation of a specific biological problem using computers.
Q#1 Differentiate between theory and law?
The hypotheses that often tested and never rejected are ca called theories. A theory supported by a great deal of evidences. Productive theory keeps on suggesting new hypotheses and so testing goes on. Many biologists take it challenge and exert greater efforts to disprove the theory.
Law and Principle:
If a theory survives such doubtful approach and continues to be supported by experimental evidences. It becomes a law or principle. Scientific law is a uniform or constant fact of nature. It is an irrefutable theory. Examples of biological laws are Hardy-Weinberg law and Mendel’s laws of inheritance.
Question#2. Quantitative observations are better in biological method. How?
Answer. Quantitative observations are considered more accurate than qualitative ones because the former are invariable and measurable and can be recorded in terms of numbers.
Examples of qualitative and quantitative observations are given below;
1. The freezing point of water is colder than the boiling point.
2. A liter of water is heavier than a litre of ethanol (SOLVED EXERCISE BIOLOGY CLASS 9 CHAPTER 2)
1. The freezing point of water is 0°C and the boiling point is 100°C
2. A liter of water weighs 1000 grams and a liter of ethanol weighs 789 grams. film