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Biology · Class 9 · Chapter 2: Solving a Biological Problem

8 min

Key points

Scientific method is a systematic approach to solve biological problems through observation, hypothesis formation, experimentation and conclusion
Observation is the first step where we notice and record phenomena using our five senses or scientific instruments
Hypothesis is a tentative explanation or educated guess about the observed phenomenon that can be tested experimentally
Controlled experiment involves independent variable (factor being tested), dependent variable (factor being measured), and controlled variables (kept constant)
Control group receives no treatment while experimental group receives the treatment being tested
Data collection involves recording observations in tables, graphs, and charts for analysis
Conclusion is drawn based on experimental results and either accepts or rejects the hypothesis
Theory is a well-tested hypothesis that explains many related observations and is supported by extensive evidence

Definitions

Scientific Method: Scientific method is a systematic approach used by scientists to investigate natural phenomena and solve problems through observation, hypothesis formation, experimentation, and drawing conclusions.
Hypothesis: A hypothesis is a tentative explanation or an educated guess about a natural phenomenon that can be tested through experimentation.
Variable: A variable is any factor that can change or be changed in an experiment.
Control Group: Control group is the group in an experiment that does not receive any treatment and serves as a standard for comparison.
Theory: A theory is a well-tested hypothesis that explains many related observations and is supported by extensive scientific evidence.

Worked example

Define hypothesis and explain the steps of scientific method used to solve biological problems. (6 marks)

Hypothesis is a tentative explanation or educated guess about the solution to a problem based on observations. Steps of Scientific Method: 1) Observation - noticing and studying phenomena 2) Question formulation - asking specific questions about observations 3) Hypothesis formation - making educated guess 4) Experimentation - testing hypothesis under controlled conditions 5) Data collection and analysis - recording and interpreting results 6) Conclusion - accepting or rejecting hypothesis based on evidence.

Common mistakes

Students confuse independent variable (cause) with dependent variable (effect)
Writing hypothesis as a question instead of a statement
Forgetting to mention control group in experimental design
Mixing up the sequence of scientific method steps
Not clearly distinguishing between observation and inference

Quick recap

Scientific method has 6 sequential steps: observation, question, hypothesis, experiment, data analysis, conclusion. Hypothesis is tentative explanation based on observations. Controlled experiments test hypothesis validity. Data must be analyzed objectively to reach valid conclusions about biological problems.

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