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Questions and Answers
What must an organism do to be considered a living being?
Which macromolecule is largest and comprises about 20% of human body weight?
Which of the following is true about molecular weight?
How is density calculated?
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Which statement accurately describes the relationship between states of matter and density?
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Which measurement unit is not commonly used to measure molecules?
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Which molecule is commonly found in all living organisms?
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What is the formula to calculate density?
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Which method is used to determine the volume of an irregular shaped solid?
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Which statement best describes Archimedes' Principle?
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What does accuracy in data indicate?
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If the density of an object is greater than the density of the fluid it is placed in, what will happen?
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Which type of variable is affected by changes in other variables?
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Which of the following is NOT a step in the scientific method?
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In which situation would a bar chart be most appropriate?
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What is the significance of conducting background research in the scientific method?
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What defines the independent variable in an experiment?
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What is the best description of a line of best fit?
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Which measure of central tendency is defined as the number found most frequently in a data set?
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What can a bias in an experiment lead to?
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What does a scatter plot primarily illustrate?
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Which of the following best illustrates the concept of buoyancy?
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Which statement is true concerning controlled variables in experiments?
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What does the term 'correlation does not imply causation' mean?
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What is indicated by the median value in a data set?
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Study Notes
Molecules and Living Organisms
- Molecules consist of two or more chemically bonded atoms, essential in both living and nonliving entities.
- Homonuclear diatomic molecules include O2, while heteronuclear diatomic ones include NaCl.
- Carbon is a fundamental organic molecule present in all living organisms.
- Criteria for defining a living organism include growth, evolution, environmental response, cellular composition, reproduction, genetic code, homeostasis, and energy utilization.
- Four essential macromolecules: proteins, lipids, carbohydrates, and nucleic acids, with proteins being the largest, constituting about 20% of human body weight.
- Water, a common molecule in living organisms, measures only 0.27 nanometers in width.
- Measurement of molecules can utilize nanometers and angstroms; one nanometer equals one-billionth of a meter and is typically invisible to the naked eye.
- Molecular weight, the total mass of a molecule's atoms, is determined using atomic masses from the periodic table.
Density
- Density measures the compactness of matter; it represents how tightly molecules are packed into space.
- Everyday applications of density include its effects on cloud altitude, buoyancy in water, and atmospheric gas behavior.
- Dense materials, such as lead, gold, and most metals, have a greater density than liquids and gases.
- The formula for density is density = mass / volume (ρ = m/V), typically expressed in kilograms per cubic meter.
Buoyancy
- Buoyancy refers to an object's ability to float in a fluid; it's influenced by fluid pressure, which increases with depth.
- Archimedes' Principle states that the buoyant force equals the weight of the fluid displaced.
- Calculating buoyant force involves considering density, volume of displaced fluid, and Earth's gravitational acceleration (9.8 m/s²).
- To determine if an object will sink or float, compare the object's density with that of the fluid; if the object is denser, it will sink, and if it's less dense, it will float.
Scientific Method
- The scientific method is a structured procedure for investigating questions and generating explanations.
- Key steps include: defining a question, conducting background research, formulating a hypothesis, performing experiments, analyzing data, and concluding.
- Validity is crucial, as biases can compromise experimental integrity.
Experimental Design
- The experimental design consists of initial observations leading to questions and hypotheses.
- Five key steps include defining variables, formulating hypotheses, designing experiments, assigning subjects, and measuring dependent variables.
- Careful planning allows for replicable and informative experimentation.
Data Accuracy and Precision
- Data accuracy signifies correctness, while precision refers to the closeness of measurements.
- Scientific graphs display relationships between independent and dependent variables with various methods for clarity:
- Line graphs depict trends over time.
- Bar charts compare differences among groups.
- Pie charts represent proportions.
- Flow charts illustrate processes.
Central Tendency
- Central tendency summarizes data with a single number, with three main measures:
- Mode: the most frequently occurring value.
- Mean: the average, computed by summing values and dividing by their count.
- Median: the middle value, adjusted for even or odd counts.
Variables in Experiments
- independent variables are manipulated by the scientist; dependent variables respond to changes; controlled variables remain constant.
- The relationship between variables can be linear (straight line) or non-linear (curved). Regression analysis helps interpret these relationships.
- Experiments systematically observe and measure to prove or disprove hypotheses, using variable manipulation as a core principle.
Scientific Analysis and Calculations
- Scientific analysis often requires calculating unknown values from known data, involving formula rearrangement to facilitate accurate results.
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Description
This quiz summarizes the essential properties of molecules and their significance in forming living organisms. It outlines the difference between homonuclear and heteronuclear diatomic molecules and highlights the eight criteria that define living organisms. Test your understanding of the fundamental concepts of biology related to molecular structures.
