Q1. Which four elements make up approximately 96% of living matter?

Background

Topic: Essential Elements of Life

This question tests your understanding of the most abundant elements in living organisms and their importance in biological molecules.

Key Terms:

• Essential elements: Elements required for an organism to survive, grow, and reproduce.

• Major elements: The elements that make up the majority of living matter by weight.

Step-by-Step Guidance

1. Recall that living organisms are primarily composed of a few key elements. Think about the main components of carbohydrates, proteins, lipids, and nucleic acids.

2. Review the periodic table and identify which elements are most commonly found in these biological macromolecules.

3. Compare the answer choices and eliminate any that include elements not typically found in large amounts in living organisms (e.g., sodium, calcium, phosphorus).

4. Focus on the elements that are present in all four major classes of biological macromolecules.

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Q2. How do fats differ from phospholipids?

Background

Topic: Lipids – Structure and Function

This question is about the structural differences between fats (triglycerides) and phospholipids, both of which are important types of lipids in biology.

Key Terms:

• Fat (triglyceride): A lipid molecule made of one glycerol and three fatty acid tails.

• Phospholipid: A lipid with a glycerol backbone, two fatty acid tails, and a phosphate group.

• Hydrophilic: Water-attracting (polar).

• Hydrophobic: Water-repelling (nonpolar).

Step-by-Step Guidance

1. Recall the basic structure of a fat (triglyceride) and a phospholipid. Draw or visualize their structures if it helps.

2. Identify the number of fatty acid tails in each molecule.

3. Consider the functional groups attached to the glycerol backbone in each molecule.

4. Think about where each type of molecule is found in cells and their biological roles.

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Q4. Scientists use a ________________ in their experimental study design to provide a baseline against which they can compare their experimentally treated group(s).

Background

Topic: Experimental Design – Controls

This question tests your understanding of the importance of controls in scientific experiments.

Key Terms:

• Control group: The group in an experiment that does not receive the experimental treatment and is used as a baseline for comparison.

• Experimental group: The group that receives the treatment or variable being tested.

Step-by-Step Guidance

1. Think about why scientists need a group that does not receive the experimental treatment.

2. Recall the term used for this group, which helps determine if the treatment has an effect.

3. Consider examples from experiments you have studied or performed in lab.

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Q5. When electrons are transferred from one atom to another (for example when Na gives up an electron to the more electronegative Cl), the resulting bond is referred to as a/an _____________ bond.

Background

Topic: Chemical Bonds – Ionic Bonds

This question is about the types of chemical bonds formed between atoms, specifically when electrons are transferred.

Key Terms:

• Ionic bond: A chemical bond formed when one or more electrons are transferred from one atom to another, resulting in oppositely charged ions.

• Electronegativity: The tendency of an atom to attract electrons.

Step-by-Step Guidance

1. Recall the main types of chemical bonds: covalent, ionic, hydrogen, and van der Waals.

2. Think about what happens when an atom like sodium (Na) transfers an electron to chlorine (Cl).

3. Identify the bond type that results from the attraction between oppositely charged ions.

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Q6. List two unique properties of water and explain how these properties are, in part, due to hydrogen bonding.

Background

Topic: Properties of Water and Hydrogen Bonding

This question tests your understanding of how hydrogen bonds give water its unique properties, which are essential for life.

Key Terms:

• Hydrogen bond: A weak bond between a hydrogen atom and an electronegative atom (like oxygen or nitrogen).

• Cohesion: Water molecules sticking to each other.

• Adhesion: Water molecules sticking to other substances.

• High specific heat: Water's ability to absorb a lot of heat without changing temperature much.

• Surface tension: The measure of how difficult it is to stretch or break the surface of a liquid.

Step-by-Step Guidance

1. Recall the unique properties of water that are important for life (e.g., cohesion, high specific heat, solvent abilities, density of ice, etc.).

2. Choose two properties and describe each one clearly.

3. Explain how hydrogen bonding between water molecules contributes to each property you selected.

4. Use examples or analogies if it helps clarify your explanation.

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Q7. Compare and contrast the structure of prokaryotic and eukaryotic cells. Include the major structures or organelles that differ between the two cell types, and describe the role of each of the structures that differ.

Background

Topic: Cell Structure – Prokaryotes vs. Eukaryotes

This question asks you to compare and contrast the main features of prokaryotic and eukaryotic cells, focusing on their structures and organelles.

Key Terms:

• Prokaryotic cell: A cell lacking a nucleus and membrane-bound organelles (e.g., bacteria, archaea).

• Eukaryotic cell: A cell with a nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).

• Organelle: Specialized structure within a cell that performs a specific function.

• Nucleus: Membrane-bound structure that contains the cell's DNA (present in eukaryotes only).

Step-by-Step Guidance

1. Start by defining prokaryotic and eukaryotic cells, noting the presence or absence of a nucleus.

2. List the major organelles or structures found in eukaryotic cells but not in prokaryotic cells (e.g., mitochondria, endoplasmic reticulum, Golgi apparatus).

3. Describe the function of each organelle or structure that differs between the two cell types.

4. Point out any similarities, such as the presence of a plasma membrane, cytoplasm, and ribosomes in both cell types.

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