Questions and Answers
What is the atomic number of an element?
The number of protons in the nucleus of one atom.
What is the tendency of water molecules to stick together called?
Cohesion
Cellulose cannot be digested by humans.
True
The fats in most foods we eat are ____________.
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A peptide bond is a ________ bond between two ________.
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What is the composition of the rail portion of DNA's ladder?
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The atomic number of hydrogen is _____.
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What are the unique properties of water that make it critical to life?
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Why are lipids insoluble in water?
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What are the amino acids that must come from your diet called?
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Which molecule contains carbon, nitrogen, oxygen, hydrogen, and phosphate?
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The atomic number of carbon is 6. Its nucleus must contain how many protons?
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What type of bond is responsible for water's cohesion?
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Polysaccharides always are a string of how many sugar molecules?
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Generally speaking, what happens to triglycerides with more double bonds?
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In addition to thymine, does RNA contain a unique base called uracil?
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The second orbital shell of an atom can hold how many electrons?
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How has the H+ ion concentration changed in a lake's pH drop from 7 to 5 due to acid rain?
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Study Notes
Atomic Structure and Properties
- Atomic number indicates the number of protons in the nucleus of an atom.
- The atomic number of hydrogen is 1; it contains 1 proton, 1 electron, and 0 neutrons.
- Carbon's atomic number is 6, meaning its nucleus must have 6 protons.
Water Properties
- Cohesion refers to the tendency of water molecules to stick together, facilitated by hydrogen bonds.
- Unique properties of water crucial for life include cohesion, large heat capacity, low density when solid, and its effectiveness as a solvent.
- Hydrogen bonds between oxygen in one water molecule and hydrogen in another account for its cohesive properties.
Organic Molecules
- Cellulose is indigestible by humans due to its molecular structure, despite being similar to starch.
- Triglycerides are fats consisting of three fatty acids linked to a glycerol molecule.
- Lipids are made of long hydrocarbon chains and are insoluble in water due to their non-polar nature.
- Polysaccharides, which are polymers, consist of three or more sugar molecules linked together.
Amino Acids and Proteins
- Peptide bonds are covalent bonds that connect amino acids, essential for protein formation.
- Essential amino acids must be obtained from the diet, while others can be synthesized by the body.
Nucleic Acids
- RNA contains carbon, nitrogen, oxygen, hydrogen, and phosphate, with uracil as its unique base (it does not contain thymine).
Chemical Bonds and Reactions
- The second orbital shell of an atom can hold up to 8 electrons, influencing its bonding behavior.
- A decrease in pH from 7 to 5 in a lake indicates a 100-fold increase in H+ ion concentration due to acid rain.
Triglycerides and Structural Properties
- The number of double bonds in a triglyceride affects its structure; more double bonds result in more "kinks" in the hydrocarbon tails, making it a liquid at room temperature.
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Test your knowledge of key concepts from Biology Chapter 2 with these flashcards. Each card covers crucial terms and definitions, such as atomic number and properties of water. Perfect for students looking to strengthen their understanding of biology fundamentals.
