Matric Notes Biology Class 9th Ch 2 Solving a Biological Problem Extra Short & Long Questions

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Short Questions

Q.1) What is a science? How does it work?

Answer: Science:

The knowledge which is based on observation, experiments and facts is called science.

Biology is classified as natural science.

Systematic approach to science:

Science involves more than just gaining of the knowledge, and thus it is the systematic and organized inquiry into the natural world and its phenomenon. The scientific method is a process for experimentation that is used to explore observations and answer to questions. Scientists use the scientific method to search for the cause, effect, and relationships in nature. In other words, they design an experiment so that changes to one item cause something else to vary in a predictable manner. So, science works on the phenomenon of scientific methods, which helps biologist to focus on science project fair questions, construct a hypothesis, design, execute and evaluate the problem.

Q.2) Control group is important for scientific study, How?

Answer: Control group:

“Control group is the standard to which comparisons are made in an experiment.”

“Or”

“Control group is a group separated from the rest of an experiment where the independent variable being tested cannot influence the results.”

It can be positive control groups where the conditions guarantee a positive result and negative control groups where conditions produce a negative outcome.

During experiments, a researcher made two arrangements i.e, “experimental group” and “control group”. Both groups are kept under the same condition except for the condition which is being tested.

For example:

If you want to do an experiment to test the necessity of carbon dioxide for the process of photosynthesis. you will arrange two similar plants and will provide soil, water, and sunlight to both plants. you will not provide carbon dioxide to one plant (experimental group) and provide carbon dioxide to the other plant (control group). The necessity of carbon dioxide will be proved when photosynthesis does not occur in the experimental group but occur in the control group.

Q.3) What deductions were developed during the study of malaria?

Answer: Deductions made during the study of malaria:

Biologists further built upon the ancient observations and discovery of Laveran. They developed a hypothesis i.e. “Plasmodium is the cause of malaria.”

For testing this hypothesis through experiment, biologists made a deduction;

“If Plasmodium is the cause of malaria, then all malarial patients should have Plasmodium in their blood.”

Q.4) How Ronald Ross conducted the experiment to prove that mosquitoes are involved in the spread of malaria?

Answer: Experiment by Ronald Ross:

Ronald Ross was a British army physician who worked in India in the 1880s. He performed important experiments to test the deduction that “If mosquitoes transmit Plasmodium, then Plasmodium should be present in mosquitoes.”

He also received Nobel Prize for his work on the transmission of Plasmodium. He allowed a female Anopheles mosquito to bite a malarial patient. He killed the mosquito and found Plasmodium multiplying in mosquito’s stomach.

In the next experiment, he allows an infected mosquito (having Plasmodium) to bite a healthy person. If the hypothesis was true, the healthy person would have gotten malaria. But he did not use human beings for such a risky experiment.

Ross experiment on sparrows:

Ross performed his experiment again but used sparrows instead of human beings. He allowed a 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 mosquito’s stomach and then moved into the mosquito’s salivary glands. He allowed infected mosquitoes to bite healthy sparrows. Ross found that these healthy sparrows got malaria. When he examined the blood of these previously healthy sparrows, he found many Plasmodium in it. In this way, biologists had got the solution of the 2nd biological problem (How Plasmodium is transmitted to human beings?). The hypothesis (Mosquitoes transmit Plasmodium.) was proved true and taken as the solution of a biological problem.

Q.5) At what stage of the biological method, hypothesis, is accepted or rejected?

Answer: Experimentation:

Biologist performs experiments on his hypothesis and checks the deductions. Through experiments he can find that deductions of some hypothesis have come true while other have not. In this way, the hypothesis are proved as true or false.

The false hypothesis are rejected while the true one are accepted. Biologists make new deductions from the accepted hypothesis. Then he perform further experiments and confirms the correctness of hypothesis. There is a possibility that the results of experiments do not support any hypothesis. Under these conditions, new hypothesis are developed and tested.

Long Questions

Q.1) Differentiate between inductive reasoning and deductive reasoning?

Answer:

Deductive Reasoning	Inductive Reasoning
Deductive reasoning starts with a general theory, statement, or hypothesis and then works its way down to a conclusion based on evidence.	Inductive reasoning starts with a small observation or question and works its way to formulate a theory by examining the related issues
Deductive reasoning is the observation from general to specific	Inductive reasoning is the observation from specific to general
It moves from broader information to specific information	It moves from specific information to broader information
Moves from theory to observation	Moves from observation to theory
Also called a top-down approach	Also called bottom-up approach
Example:  If all organisms have cells and human is also an organism, then we conclude that all humans should have cells	Example:  We observe that pigeon has wings and pigeon is a bird, so we conclude that all birds have wings.

Q.2) Explain how biologists use a scientific method to solve the mysteries of addressing the malarial problem?

Answer: Biological Problem:

“What is the cause of malaria.?”

Step 1: 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.

Then they began thinking that stagnant water of marshes poisoned the air. When people breathed in this bad air, they got malaria. That is why they gave the name malaria to this disease. The Italian words mala means “bad” and aria means “air”.

These observations did not help much for solving the problem i.e. “What is the cause of malaria?”

Work 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 a microscope. He noticed some microorganisms in the blood. He won the Nobel Prize for his discoveries.

Five years after Laveran, the same microorganisms were observed in the blood of malarial patients and this microorganism was given a name of Plasmodium.

Step 3: Experiment and Results:

In order to test the hypothesis, “Plasmodium is the cause of malaria”, carried out the following experiment.

They examined the blood of 100 malarial patients under a microscope. It was labeled as the experimental group.

They also examined the blood of 100 healthy persons under a microscope. It was labeled as the control group.

Results:

It was observed that all the malarial patients had Plasmodium in their blood; whereas the blood of healthy persons was free from Plasmodium. These results supported the hypothesis that Plasmodium is the cause of malaria. So it was taken as the solution to a biological problem.

Q.3) Explain that how mathematics can be used to interpret the data obtained through experimentations.

Answer: Biometry/ biostatistics is the application of statistical and mathematical formulas in the study of biology. so experiments can be interpreted or solved by the application of biometry.

Data Organization:

The researchers collect and analyze the data (information such as names, dates, numbers, values etc.) at various steps in the scientific method. This data helps them to make a hypothesis from observations and to conclude results from experiments. In order to use data in a scientific method, scientists have to organize and analyze it.

Scientists organize the collected data in the form of graphs, tables, flowcharts, maps, and diagrams.

Data Analysis:

The collected data is analyzed by using statistical methods like ratios and proportions. A ratio is a relationship with respect to relative size between two quantities of the same kind. A pure number to a pure number; an amount of money to an amount of money; a number of people to a number of people. Proportion means to join two equal ratios.

a:b=c:d

“a” and “d” is called the extremes, “b” and “c” are called the means. The product of the extremes is equal to the product of means. When three values in a proportion are known, the fourth one (a) can be calculated by using this rule.

For example:

If a biologist wants to know how many sparrows would be infected with malaria if he allows Culex mosquito to bite 50 sparrows. Previously in one of his findings, he already noticed that 6 out of 10 sparrows get malaria if bitten by Culex mosquito.

Here he applies proportion rule.

a: b= c:d

a: 50 = 6:10

a/50 = 6/10

a x 10= 50×6

a= 30

It means that if he allows Culex mosquito to bite 50 sparrows, 30 out of them will get malaria. Proportion method can be used to draw conclusions. As in the above case, we can find the fourth proportion of the data if three proportions are already available.