Cells Flashcards
What is an organic compound?
A compound that always contains carbon and is typically found in living organisms.
Organic compounds are essential for life and include a wide variety of substances.
What is the purpose of a standard (control) in an experiment?
A part of an experiment that remains unchanged to provide a baseline for comparison.
Controls are crucial for validating experimental results.
What is an indicator?
A substance that changes color in the presence of a specific chemical, helping to detect its presence.
Indicators are often used in titrations and other chemical analyses.
What is a buffer?
Any substance that resists changes in pH by neutralizing added acids or bases.
Buffers are important in biological systems to maintain stable pH levels.
What is anthocyanin?
A pigment found in plants that can change color depending on the pH of a solution.
Anthocyanins are responsible for the red, purple, and blue colors in many fruits and flowers.
Which element do organic compounds always contain?
Carbon (C).
This is the defining characteristic of organic compounds.
Which other elements do organic compounds usually contain?
Hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), and sulfur (S).
These elements contribute to the diversity of organic molecules.
Who was the first to synthesize an organic substance?
Friedrich Wöhler in 1828, when he synthesized urea from an inorganic compound.
This event is often cited as a pivotal moment in organic chemistry.
What are the four classes of biological organic compounds?
Carbohydrates, Proteins, Lipids, Nucleic acids.
Each class plays a vital role in biological processes.
What does iodine test for and what is the positive result color change?
Tests for starch – Turns blue/black if starch is present.
Iodine is commonly used in food tests.
What does Benedict’s solution test for and what is the positive result color change?
Tests for sugars (must be heated) – Turns blue → green, yellow, orange, or brick-red if sugars are present.
This test is used to detect reducing sugars.
What does Biuret’s reagent test for and what is the positive result color change?
Tests for protein – Turns lilac/purple in the presence of proteins.
Biuret’s test is a common method for protein detection.
What does pH measure?
The concentration of hydrogen ions (H⁺) in a solution, indicating how acidic or basic it is.
pH is a critical measure in chemistry and biology.
What is the pH of acids?
Below 7.
Acids are substances that increase the concentration of H⁺ ions in a solution.
What is the pH of bases?
Above 7.
Bases are substances that decrease the concentration of H⁺ ions in a solution.
What is the pH of a neutral substance?
7 (e.g., pure water).
Neutral substances have equal concentrations of H⁺ and OH⁻ ions.
Each jump on the pH scale indicates how many times difference in the amount of H⁺ ions present?
10 times difference in H⁺ ion concentration per pH unit.
This logarithmic scale means small changes in pH represent significant changes in acidity or basicity.
What is the pH of human blood?
Around 7.35–7.45, which is slightly basic.
Maintaining blood pH within this range is essential for homeostasis.
