Class 9th
Biology
Chapter 02
Solving a Biological Problem
Exercise Solution
Exercise MCQS
1. Which one is the first step in biological method?
a) Hypothesis
b) Experiment
c) Observations
d) Deduction
Solution: c. Observation
2. What is the correct experiment to know that Plasmodium destroys red blood cells?
a) Examine the blood of a single healthy person
b) Examine the blood of a single infected person
c) Allow mosquito to bite a healthy person and examine his blood
d) Examine the blood of some healthy and also some infected persons
Solution : d. Examine the blood of some healthy and some infected persons
3. What is the best way to analyze the data collected from experiments?
a) Reading the data and drawing conclusions
b) Discussion with scientists
c) Simple calculations on calculator
d) Application of statistical formulae
Solution : c. Simple calculation on calculator
4. People who slept near smoky fire had less chance to suffer from malaria. Why?
a) Smoke kills Plasmodium in their blood
b) Fire increases temperature and Plasmodia are killed in air
c) Mosquitoes cannot tolerate smoke and are repelled
d) Smoke kills Plasmodium present in mosquitoes
Solution : c. Mosquitoes can’t tolerate smoke and repelled
5. Which one of the following is NOT a characteristic of a hypothesis.
a) It must be consistent with all available data
b) It must be testable
c) It must be correct
d) Must make deductions
Sol: c. It must be correct
6. Deductions are made from;
a) Observations
b) Hypothesis
c) Experiment results
d) Solution of biological problem
Sol: b. Hypothesis
7. Which one of the following is true about the statement of hypothesis?
a)Logical
b) Possible answer
c) Based upon observations
d) All of them
Sol: d. All of them
8. The actual answer to scientific problem is:
a) Observations
b) Hypothesis
c) Data
d) Conclusion
Sol: d. Conclusion
9. Which mosquito can transmit Plasmodium in human beings?
a) Anopheles
b) Culex
c) Aedes
d)b All of these
Sol: a. Anopheles
10. For the first time, who found Plasmodium in the blood of malarial patient?
a) Ronald Ross
b) Laveran
c) F. A. King
d) Mendel
Sol: b. Laveran
Give short answers to the following questions:
1. What is a science? How does it work?
Science:
The word science is derived from Latin word Scientia which means “Knowledge”. It means, “Science is a knowledge in which, observations are made, experiments are done and results are drawn.”
OR
“The knowledge of Observations and Experiments” is called Science.
How does it works?
- Scientists use scientific methods to solve a biological problem, to find out the truth, to search causes and effects of natural phenomena.
2. Control group is important for scientific study, How?
Control group:
It is a group that remains constant throughout the experiment to test a hypothesis. But other variables are compared with it.
Importance:
- It is used to find more accurate and acceptable results of the experiments.
- It is used to compare these results with it.
- It is used to know the effects of treatment.
Example:
Blood of 100 healthy persons (Control group) compared with blood of 100 malarial patients.
3. What deductions were developed during the study of malaria?
There are two main deductions that were developed from the study of malaria.
a) Laveran’s deduction
b) A.F.A King’s deduction.
-
- Laveran’s deduction : ( If Plasmodium is the cause of malaria then all malarial patients should have plasmodium in their blood ).
- F.A King : ( If mosquitoes transmit plasmodium then plasmodium should be present in mosquitoes ).
4. How Ronald Ross conducted the experiment to prove that mosquitoes are Involved in the spread of malaria?
Ronald Ross allowed infected mosquitoes to bite the healthy sparrows. He found that these healthy sparrows got malaria. At the end when he examined the blood of these healthy sparrows, he found many Plasmodium in their blood. Thus from the above discussion, it is clear that mosquitoes carry plasmodium and are involved in the spread of malaria.
5. At what stage of the biological method, Hypothesis, is accepted or rejected?
The stage of biological method in which a hypothesis is accepted or rejected is experiment. Experimentation is the most basic step of biological method. In experiment we check our hypothesis whether it is true or false. After experimentation, the incorrect hypothesis are rejected and the ones that are proved correct are accepted.
Give detailed answers to the following Questions
1. Differentiate between inductive reasoning and deductive reasoning?
Inductive Reasoning:
A type of reasoning in which we moves from specific to general.
For example;
If pigeon has wings and it is a bird then all birds will have wings.
Deductive Reasoning:
In this type of reasoning, we moves from general to specific.
For example;
If birds have wings and pigeon is a bird then it must have wings.
2. Explain how biologists use scientific method to solve the mysteries of addressing the malarial problem?
Biological methods are used to solve the malarial problem.
Step 1 : Observations
Two main observations regarding the malarial problem are;
a) Old Observations
b) Modern Observations
a) Old Observations
The people and physicians in ancient times (more than 2000 years ago) had some observations on malaria. For example;
- The patients of this disease experienced recurring attacks of chills and fevers.
- The disease was more common among people who lived in low marshy areas.
- When some volunteers drank the water from marshes, they did not develop malaria. Thus a new observation was made i.e. the disease did not result from drinking the water of marshes.
- Now people thinks malaria is caused by poisoned air .
Mala means bad or poisonous and aria means air, so named it malaria .
b) Modern Observations / Observations of Laveran
Two hundred years later, it was proved that many diseases are caused by micro-organisms like bacteria. In 1878 a French Physician Laveran studied the ancient observations and work. He observed the blood of a malarial patient under microscope. He noticed some microorganisms in the blood. These microorganisms were called Plasmodium.
Step 2 : Hypothesis / Hypothesis of Laveran :
“Plasmodium is the cause of Malaria”.
Step3: Deduction/ Deduction of Laveran:
Before performing experiment to check hypothesis, biologists made deductions, “If plasmodium is the cause of Malaria, then all Malarial patients should have plasmodium in their blood.”
Step 4: Experiment/ Experiment of Laveran:
The following experiment was performed to test the hypothesis “Plasmodium is the cause of malaria”.
- They examined the blood of 100 malarial patients under microscope. It was labelled as the experimental group.
- They also examined the blood of 100 healthy persons under microscope. It was labelled as the control group.
Results:
- All the malarial patients had Plasmodium in their blood.
- The blood of healthy persons was free from Plasmodium.
- These results proved the hypothesis (Plasmodium is the cause of malaria) .
- After solving the problem “what is the cause of malaria” , the other problem is “how plasmodium transmit in human.”
Step 1: Observations: / Observations of A.F.A King :
In 1883, an American physician, Albert Freeman Africanus King (A. F. A. King), proposed 20 more observations about malaria. Some important observations are:
- People who slept in open places suffered from malaria more than the people who slept indoors.
- People who slept near a smoky place usually not get malaria.
- People who used mosquito nets less suffered from malaria than those who didn’t use nets.
Step 2 : Hypothesis / Hypothesis of A.F.A King :
“Mosquito transmit plasmodium” .
Step 3 : Deduction / Deduction of A.F.A King :
“If mosquito transmit plasmodium, then plasmodium should be present in mosquito”.
Step 4 : Experiment / Experiment of Ronald Ross on sparrow:
Ronald Ross was a British army physician who worked in India in 1880’s. He performed his experiment on sparrow.
First he allowed female Culex mosquito to bite a sparrow suffering from malaria. He killed some of the mosquitoes and studied them. He found that Plasmodium multiplied in the walls of the mosquitoes stomach and then moved into the salivary gland of mosquitoes. He allowed infected mosquitoes to bite healthy sparrows. Ross found that these healthy sparrows got malaria. At the end when he examined the blood of these previously healthy sparrows, he found many Plasmodium in their blood.
Results:
Results show that mosquito transmit plasmodium in sparrow.
Experiment on Human being:
An Italian biologist allowed Anopheles mosquito to bite a malarial patient. The infected mosquito was then allowed to bite a healthy man. This person later became ill with malaria.
Results :
The results proved the hypothesis “ Mosquito transmit Plasmodium in human being” was true.
3. Explain that how mathematics can be used to interpret the data obtained through experimentation.
Mathematics have important role in different fields of science. The mathematical rules are used in biology for many years.
For Example:
The research projects such as population studies, Drug studies, sequencing of DNA of plants and animals require mathematical knowledge for organizing and analyzing the data.
