Unit 1 Test Review

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Questions and Answers

What is the total number of points for the Unit 1 Test?

50 points

30 points

60 points (correct)

40 points

Which type of bond is characterized by the complete transfer of electrons?

Hydrogen bond

Ionic bond (correct)

Metallic bond

Covalent bond

Which of the following represents a polar covalent bond?

C-C bond in ethane

O-O bond in oxygen gas

N-H bond in ammonia (correct)

C-H bond in methane

What is the primary characteristic of hydrocarbons?

They only contain carbon and hydrogen. Signup and view all the answers

What is the primary reason that hydrogen bonds can form between molecules?

Hydrogen is part of a polar covalent bond. Signup and view all the answers

Why do fatty acid tails in phospholipids exhibit hydrophobic behavior?

Electrons are evenly distributed, leading to no net charges. Signup and view all the answers

What is a characteristic of Van der Waals forces?

They are due to transient dipoles. Signup and view all the answers

Which property of water is explained by hydrogen bonding?

Low density of ice Signup and view all the answers

How do isomers differ from one another?

They have the same molecular formula but different structures. Signup and view all the answers

Why can carbon not form hydrogen bonds?

Carbon lacks sufficient electronegativity. Signup and view all the answers

What is a key feature of enantiomers?

They are mirror images of each other. Signup and view all the answers

Which of the following accurately describes a characteristic of a compound?

It is formed from more than one type of atom. Signup and view all the answers

What determines the specific arrangement of enantiomers?

Chiral centers where a carbon is bound to four different substituents. Signup and view all the answers

What impact can the arrangement of a molecule have biologically?

It can significantly alter the molecule's emergent properties. Signup and view all the answers

What type of bond joins nucleotides in nucleic acids?

Phosphodiester linkages Signup and view all the answers

Which nitrogenous base is found in RNA but not in DNA?

Uracil Signup and view all the answers

What type of isomer maintains the same covalent bonds but has a different spatial arrangement due to double bonds?

Geometric isomers Signup and view all the answers

Which statement correctly describes the central dogma of biology?

DNA → RNA → Protein Signup and view all the answers

What is a common feature of fatty acids and phospholipids?

Both can store and release energy. Signup and view all the answers

What is the main function of transfer RNA (tRNA)?

Brings amino acids to ribosomes Signup and view all the answers

How many hydrogen bonds are formed between guanine and cytosine when they bond?

3 Signup and view all the answers

What significant event marked the increase of oxygen levels in Earth's atmosphere?

The oxygen revolution Signup and view all the answers

What does the Miller-Urey experiment demonstrate regarding the origins of life?

Abiotic synthesis of small organic molecules Signup and view all the answers

Which process led to the formation of protocells?

Vesicles formed from lipids Signup and view all the answers

What characteristic of RNA allows it to act as a self-replicating molecule?

Ability to bend and form complex shapes Signup and view all the answers

Which of the following was NOT a consequence of the oxygen revolution?

Development of multicellular eukaryotes Signup and view all the answers

What determines the properties of organic molecules?

The carbon skeleton and the functional group attached Signup and view all the answers

Which of the following statements is true about saturated fats?

They are solid at room temperature and have a linear structure Signup and view all the answers

What is a characteristic of unsaturated fats?

They contain cis bonds causing kinks Signup and view all the answers

What type of biological molecule are steroids categorized as?

4-carbon ring lipids Signup and view all the answers

What forms a peptide bond between amino acids?

Dehydration synthesis Signup and view all the answers

What determines the tertiary structure of a protein?

Interactions between R-groups Signup and view all the answers

Which functional groups are present in an amino acid?

Amino and carboxyl groups Signup and view all the answers

What is the optimal condition for enzyme activity in our stomach?

Slightly acidic pH and moderate temperature Signup and view all the answers

Study Notes

Test Information

Unit 1 Test Review: September 22, 2024
Exam Date: September 24, 2024 (In-person)
Accounts for 12% of total grade
Format: Canvas Quiz featuring 18 multiple-choice questions (1.5 pts each) and 3 free-response questions (total 33 pts)
Total exam score: 60 points
Proctored via Respondus; practice exam required
Exam duration: 60 minutes (9:30 am - 10:30 am)

Chemistry Basics

Element: A substance made of only one type of atom (e.g., Na)
Compound: A substance made of more than one type of atom (e.g., NaCl)
Covalent Bonds: Formed by sharing valence electrons between non-metals (e.g., CH4 - methane)
- Non-polar: Equal electron sharing (e.g., C-H bond)
- Polar: Unequal sharing due to differences in electronegativity
Ionic Bonds: Formed by complete transfer of electrons, resulting in ions (e.g., NaCl)

Intermolecular Forces

Van der Waals Forces: Weak attractions due to transient dipoles in molecules
Hydrogen Bonds: Formed between hydrogen covalently bound to F, O, or N and similar atoms in another molecule; crucial in water and DNA

Properties of Water

Hydrogen bonding in water facilitates life through:
- Cohesion: Attraction between water molecules
- Adhesion: Interaction of water with other substances

Hydrocarbons and Isomers

Hydrocarbons: Organic compounds consisting solely of C and H; significant for energy storage and release (e.g., combustion)
Isomers: Molecules with the same formula but different structures and properties
- Geometric Isomers (Cis/Trans): Same bonds but different spatial arrangements; restricted rotation due to double bonds
- Enantiomers: Mirror images of each other, significant due to chiral centers (carbon with four different substituents)

Functional Groups and Lipids

Organic molecule properties depend on carbon skeleton and functional groups:
- Lipids: Not true polymers; consist of smaller units (e.g., fatty acids, glycerol)
- Types of Lipids:
  - Fats: Formed via ester linkages between glycerol and fatty acids
  - Phospholipids: Composed of 2 fatty acids and a phosphate group
  - Sterols: Four-carbon ring structure (e.g., cholesterol)

Saturated vs. Unsaturated Fats

Saturated Fats: Solid at room temperature; linear structure
Unsaturated Fats: Liquid at room temperature; contain kinks from cis bonds

Proteins

Composed of 20 amino acids distinguished by R groups
Peptide Bonds: Formed through dehydration synthesis between two amino acids
Protein Structure Levels:
- Primary: Unique amino acid sequence
- Secondary: Coils and folds in polypeptide chains
- Tertiary: Interactions among side chains
- Quaternary: Multiple polypeptide chains together
Protein function is shaped by environmental factors such as pH and temperature

Nucleic Acids

Polymers of nucleotides linked by phosphodiester bonds; essential for genetic information
Central Dogma: DNA → RNA → Protein
- DNA stores information; RNA transmits and helps express it; proteins perform cellular functions

RNA vs. DNA

RNA: Single-stranded; contains uracil instead of thymine; ribose sugar
DNA: Double-stranded helix; stores genetic material; deoxyribose sugar

Geological Record and Life's Origin

Fossil record exhibits significant extinction events; biased towards long-lived, abundant species
Miller-Urey Experiment: Showed abiotic synthesis of organic compounds; small molecules can form macromolecules
Cyanobacteria: Contributed to oxygen accumulation through photosynthesis
- Resulted in the "Oxygen Revolution," allowing for aerobic respiration but also posing risks to early life

Evolutionary Milestones

Evolution from prokaryotes to multicellular eukaryotes involved:
- Oxygen accumulation enabling aerobic organisms
- Colonization of land by plants and fungi, followed by animals during the Cambrian Explosion

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Description

Prepare for your Unit 1 Test with this review session. The exam includes multiple-choice and free-response questions, and is worth 12% of your total grade. Make sure to check out the recording on Canvas under the 'Zoom' tab for additional support.