Biology: Macromolecules and Life Organization

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Questions and Answers

Which of the following options best characterizes the hierarchical organization of life?

Molecule, atom, organelle, organism, ecosystem

Organism, community, population, ecosystem, cell

Population, organism, community, ecosystem, organ

Cell, organ, organ system, organism, population (correct)

What distinguishes prokaryotic cells from eukaryotic cells?

Prokaryotic cells lack a nucleus and organelles, while eukaryotic cells have both (correct)

Prokaryotic cells have a defined nucleus, while eukaryotic cells do not

Prokaryotic cells are typically larger than eukaryotic cells

Prokaryotic cells cannot reproduce independently, while eukaryotic cells can

Which statement correctly explains the formation of covalent bonds in carbon-containing macromolecules?

Carbon has 4 valence electrons and forms a maximum of 4 covalent bonds to complete its octet (correct)

Carbon can only form double bonds which do not count toward its valence

Carbon can form a maximum of 6 bonds due to its electron configuration

Carbon bonds to other elements exclusively through ionic bonds

In the context of macromolecules, what is the relationship between monomers and polymers?

Polymers consist of numerous repeating monomers, similar to building blocks of larger structures Signup and view all the answers

Which of the following accurately describes the four major classes of organic compounds?

Proteins are made of amino acids and serve primarily as structural components Signup and view all the answers

What is the primary role of the sodium-potassium pump in neuronal action potential generation?

To create a concentration gradient of sodium and potassium ions Signup and view all the answers

Where does glycolysis take place within a cell?

Cytoplasm Signup and view all the answers

Which of the following accurately describes facilitated diffusion in neuronal signaling?

It occurs via ion channels that open upon stimulation Signup and view all the answers

During the light-dependent reactions of photosynthesis, which of the following products is generated?

Oxygen Signup and view all the answers

What is the final step of the electron transport chain in cellular respiration?

Reduction of oxygen to form water Signup and view all the answers

Which mechanism facilitates neurotransmitter release at a synapse?

Exocytosis Signup and view all the answers

Which component of cellular respiration is specifically responsible for producing the majority of ATP?

Electron Transport Chain Signup and view all the answers

What role do NADH and FADH2 play in the electron transport chain?

They deliver electrons from the Krebs cycle to the ETC Signup and view all the answers

What is the main product formed during the Calvin cycle of photosynthesis?

Glucose Signup and view all the answers

How do calcium ions contribute to neurotransmission?

They trigger exocytosis of neurotransmitters Signup and view all the answers

What happens during repolarization of a neuron?

Sodium channels close and potassium channels open Signup and view all the answers

What is the role of pigments in photosynthesis?

They absorb sunlight to energize electrons Signup and view all the answers

Which statement accurately describes the process of endocytosis?

Large molecules are absorbed into the cell Signup and view all the answers

What main outcome results from active transport during cellular processes?

Creation of an electrochemical gradient Signup and view all the answers

What is the main function of proteins in biological systems?

Enzymatic activity Signup and view all the answers

What distinguishes unsaturated fatty acids from saturated fatty acids?

The presence of at least one double or triple bond Signup and view all the answers

Which of the following best represents a hydrolysis reaction?

Object ab + water -> Object a + Object b Signup and view all the answers

What is the composition of a triglyceride?

1 glycerol and 3 fatty acids Signup and view all the answers

Which environmental factor is known to denature enzymes, altering their function?

pH levels Signup and view all the answers

What does the term 'active site' refer to in enzymology?

The specific region where a substrate binds to the enzyme Signup and view all the answers

How does a change in substrate concentration affect enzyme activity?

Increasing concentration leads to increased activity until saturation Signup and view all the answers

What is a common role of carbohydrates in living organisms?

Immediate and stored energy use Signup and view all the answers

Which structural formula best represents a monosaccharide?

Single ring with a 1:2:1 CHO ratio Signup and view all the answers

What typically occurs in a dehydration synthesis reaction?

Monomers are linked to form a larger molecule Signup and view all the answers

What defines a primary consumer in an ecological context?

Organisms that feed on primary producers Signup and view all the answers

Which type of lipids primarily make up the cell membrane?

Phospholipids Signup and view all the answers

Which of the following compounds is classified as a polysaccharide?

Cellulose Signup and view all the answers

How does temperature affect enzyme activity?

Extreme temperatures can denature enzymes, reducing activity Signup and view all the answers

What is the primary role of secondary consumers in an ecosystem?

They consume either producers or primary consumers for energy. Signup and view all the answers

How much of the initial energy does a primary consumer retain from the producer it consumes, according to the 10% rule?

10% Signup and view all the answers

Why do food webs provide a more comprehensive understanding of ecosystems compared to food chains?

Food webs incorporate multiple feeding relationships. Signup and view all the answers

What is biomass in an ecosystem?

The dry weight of living organisms in a given area. Signup and view all the answers

Which two processes are primarily responsible for maintaining stable CO2 levels in the biosphere?

Photosynthesis and cellular respiration. Signup and view all the answers

What is a primary consequence of combustion in terms of the carbon cycle?

It significantly increases atmospheric CO2 levels. Signup and view all the answers

Which chemical form of nitrogen is converted by nitrogen-fixing bacteria into ammonia?

Nitrogen gas (N2) Signup and view all the answers

What structural component of the plasma membrane allows for selective permeability?

Phospholipids with hydrophilic heads and hydrophobic tails. Signup and view all the answers

How is the plasma membrane described as a 'fluid mosaic'?

It contains various proteins and phospholipids that can move laterally. Signup and view all the answers

What is the primary difference between simple diffusion and facilitated diffusion?

Facilitated diffusion requires specific transport proteins. Signup and view all the answers

In an isotonic solution, how does water movement behave relative to the cell?

Water moves in and out of the cell at equal rates. Signup and view all the answers

What characterizes hypertonic solutions in relation to cells?

Higher concentration of solutes outside the cell than inside. Signup and view all the answers

Which of the following best differentiates passive transport from active transport?

Passive transport does not require cellular energy. Signup and view all the answers

What drives osmosis in the context of a cell placed in a solute-rich environment?

Water will move toward an area of higher solute concentration. Signup and view all the answers

Signup and view all the answers

Study Notes

Characteristics of Life

Made of Cells: Organisms are composed of one or more cells, which can be prokaryotic (lacking a nucleus and organelles) or eukaryotic (containing a nucleus and organelles). Examples include bacteria (prokaryotic) and plants (eukaryotic).
Hierarchical Organization: Living things exhibit a complex organization, from atoms to ecosystems. This includes atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms, populations, communities, and ecosystems.
Reproduction: Organisms reproduce either asexually or sexually, creating new individuals.
Growth and Development: Organisms increase in size and complexity over time.
Evolution: Populations of organisms change over time, adapting to their environment.
Energy Requirements: Organisms require energy to power life processes (e.g., metabolism, movement). Organisms can be photoautotrophs (use sunlight), chemoautotrophs (use inorganic chemicals), or heterotrophs (consume other organisms for energy).
Homeostasis: Maintaining stable internal conditions despite changing external environments. Examples include shivering when cold or pupils dilating in response to light.

Prokaryotic vs. Eukaryotic Cells

Prokaryotic Cells: Lack a nucleus and membrane-bound organelles.
Eukaryotic Cells: Contain a nucleus and membrane-bound organelles.

Animal, Plant, and Bacterial Cells

Animal and plant cells are eukaryotic and multicellular.
Bacterial cells are prokaryotic and unicellular. They differ in size, complexity, and internal structure.

Biochemistry

Covalent Bonds in Macromolecules

Covalent bonds hold atoms together in macromolecules by sharing electrons.

Carbon Atoms and Covalent Bonds

Carbon forms a maximum of four covalent bonds because it has four valence electrons. It needs to share four more electrons to achieve a stable octet configuration.

Monomers and Polymers

Polymers are long chains of repeating monomers.

Organic Compounds

Carbohydrates: Function in short-term and long-term energy storage.
- Monomer: Monosaccharides (e.g., glucose)
- Polymer: Polysaccharides (e.g., starch, glycogen, cellulose, chitin)
Lipids: Function in long-term energy storage, insulation, and lubrication, with types like:
- Triglycerides: Glycerol + fatty acid chains (e.g., oils, body fats)
- Phospholipids: Phosphate group + two fatty acid chains (e.g., cell membranes)
- Steroids: Four fused carbon rings (e.g., some hormones, cholesterol)
Proteins: Function as enzymes, structural components, transport molecules, and more.
- Monomer: Amino acids
- Polymer: Polypeptides (proteins)
Nucleic Acids: Function in storing and transmitting genetic information (DNA and RNA)
- Monomer: Nucleotides
- Polymer: Nucleic acids (DNA, RNA)

Structural Formulas

Specific structural formulas for each class of organic compounds can vary. Key characteristics for differentiation would include the number of carbon atoms, the presence of double or triple bonds, and the general structural shape they form. The ratio of parts (CHOs, or CNH2n+2) in each compound.

Dehydration Synthesis and Hydrolysis

Dehydration Synthesis: Combining monomers to form a polymer by removing a water molecule.
Hydrolysis: Breaking a polymer into monomers by adding a water molecule.

Enzymes

Enzymes: Biological catalysts that speed up chemical reactions by lowering activation energy.
- Substrate: The molecule upon which an enzyme acts.
- Active Site: Region of an enzyme where the substrate binds.
- Activation Energy: The initial energy required to start a reaction.
Enzyme Specificity: The precise shape of the active site allows only specific substrates to bind.
Effect on Reaction Rate: Enzymes increase the reaction rate by lowering the activation energy needed. A graph would illustrate a faster reaction with an enzyme.
Denaturation: Changing the shape of an enzyme's active site, typically by changes in temperature or pH, preventing it from binding to its substrate.

Environmental Factors and Enzyme Activity

pH and Temperature: Extreme pH or temperature levels can denature enzymes by changing their active site shape.

Enzyme and Substrate Concentration

Increasing substrate concentration, while enzyme concentration stays constant helps raise the rate of reaction until all enzymes are fully utilized and have a substrate attached. After that, even if more substrate is added, activity will not change. Decreasing substrate will decrease the reaction rate.

Ecosystems and Cycles

Trophic Levels in an Ecosystem

Producer: Autotrophs that create their own energy (e.g., grass).
Primary Consumer: Herbivores that eat producers (e.g., bunny).
Secondary Consumer: Omnivores or carnivores that eat producers or primary consumers (e.g., frogs, some insects).
Tertiary Consumer: Carnivores that eat primary or secondary consumers (e.g., wolves).

Biotic and Abiotic Factors

Biotic Factors: Living organisms in an ecosystem.
Abiotic Factors: Nonliving components of an ecosystem (e.g., sunlight, temperature, water).

Food Chains and Food Webs

Food Chain: A linear sequence of feeding relationships.
Food Web: A network of interconnected food chains.

Biomass

Biomass: The total mass of living and/or once-living organic matter within a given area. Changes in the biomass of one trophic level affect biomass in other trophic levels.

Carbon Cycle

Carbon Cycle: The natural process where carbon cycles through the atmosphere, land, water, and organisms.
Processes maintaining CO2 levels: Photosynthesis and cellular respiration.
Human Alterations: Combustion of fossil fuels increases atmospheric carbon dioxide.

Nitrogen Cycle

Nitrogen Cycle: The natural process where nitrogen cycles through the atmosphere, soil, water, and organisms.
Organic compounds requiring nitrogen: Nucleic acids.
Chemical Forms of Nitrogen: Nitrogen gas (N2), ammonia (NH3), nitrite (NO2-), nitrate (NO3-).
Microorganisms/Reactions: Nitrogen-fixing bacteria convert N2 to NH3; nitrifying bacteria convert NH3 to NO2- and NO3-; denitrifying bacteria convert NO3- back to N2.

Cell Transport

Plasma Membrane

Structure: Phospholipid bilayer with embedded proteins, forming a semi-permeable barrier.
Semi-permeable: Selectively allows certain substances to pass through.
Hydrophobic and Hydrophilic: Nonpolar "tails" of phospholipids are hydrophobic (repel water) and polar "heads" are hydrophilic (attract water).
Importance: Regulates the passage of materials in and out of the cell.

Fluid Mosaic Model

The plasma membrane is a fluid structure with embedded proteins.

Diffusion

Diffusion: Passive movement of molecules from high to low concentration.

Factors Determining Passive Diffusion

Size, charge, and polarity of the molecule

Osmosis

Osmosis: Passive transport of water across a semi-permeable membrane. Water moves from low solute concentration to high solute concentration.

Hypotonic, Isotonic, and Hypertonic Solutions

Hypotonic: Lower solute concentration outside the cell than inside; water moves into the cell.
Isotonic: Equal solute concentration inside and outside the cell; no net water movement.
Hypertonic: Higher solute concentration outside the cell than inside; water moves out of the cell.

Passive vs. Active Transport

Passive Transport: Requires no energy; moves substances from high to low concentration.
Active Transport: Requires energy; moves substances from low to high concentration.

Simple vs. Facilitated Diffusion

Simple Diffusion: Does not require protein channels or carriers.
Facilitated Diffusion: Uses protein channels or carriers to assist the movement of molecules or ions across a membrane.

Endocytosis and Exocytosis

Endocytosis: Taking material into the cell by enclosing it in a vesicle.
Exocytosis: Releasing material from the cell by fusing a vesicle with the plasma membrane.

Neurology

Neuron Structure and Function

Dendrites: Receive signals.
Cell Body: Contains nucleus and other organelles.
Axon: Conducts electrical signals.
Axon Terminals: Release signals to other cells.

Sodium-Potassium Pump

Active transport mechanism that maintains a sodium (Na+) and potassium (K+) gradient across a neuron membrane.

Resting Membrane Potential

The electrical potential difference across the neuron membrane when the neuron is at rest.

Action Potential Transmission

Action Potential: Electrical signal traveling down the neuron, generated by regulated movement of ions.

Synaptic Transmission

Neurotransmitter: Chemical messenger released at synapses to transmit signals between neurons.
Synaptic Vesicles: Membrane-bound sacs containing neurotransmitters in a presynaptic neuron.
Exocytosis: Process of releasing neurotransmitters from synaptic vesicles to the synaptic cleft.

Membrane Proteins

Sodium-potassium pump, voltage-gated sodium, potassium, and calcium channels, and ligand-gated channels play roles in producing electrical and chemical signals in neurons.

Cell Energy

Cellular Respiration

Equation: 6O2 + C6H12O6 → 6H2O + 6CO2 + ATP
Reactants: Glucose and oxygen.
Products: Carbon dioxide, water, and ATP.
Location/Process: Glycolysis (cytoplasm); Pyruvate oxidation, Krebs cycle, and Oxidative phosphorylation (electron transport chain) occur in mitochondria.

ATP Production

ATP is produced in mitochondria via oxidative phosphorylation (chemiosmosis).

Cellular Respiration Steps

Glycolysis: Cytoplasm
Pyruvate Oxidation: Mitochondria
Krebs Cycle: Mitochondria
Oxidative Phosphorylation/Electron Transport Chain: Mitochondria

Electron Transport Chain and NADH/FADH2

NADH and FADH2: Electron carriers that deliver electrons from the Krebs cycle to the electron transport chain to start the ETC at oxidative phosphorylation.

Photosynthesis

Equation: 6CO2 + 6H2O + sunlight → 6O2 + C6H12O6

Photosynthesis Pigments

Pigments absorb light energy for photosynthesis (e.g., chlorophyll).

Light-Dependent and Light-Independent Reactions

Light-dependent: Capture light energy to produce ATP and NADPH, splitting water. Products are O2, ATP and NADPH.
Light-independent: Use ATP and NADPH to fix carbon dioxide and synthesize glucose, this produces glucose.

Cellular Respiration and Photosynthesis Relationship

Photosynthesis and cellular respiration are linked; their reactant/products are largely opposite. Electrons are passed and then ultimately create chemical energy known as ATP

Experimental Design

Independent and Dependent Variables

Independent Variable: The variable that is manipulated or changed in an experiment.
Dependent Variable: The variable that is measured in an experiment.

Controlling Variables

Holding some variables constant to ensure the results are due only to the independent variable.

Supporting Claims with Data

Using data collected from the experiment to support statements, or claims, conclusions, etc.

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Description

This quiz explores key concepts in biology, particularly focusing on the hierarchical organization of life, cell types, and the formation of covalent bonds in macromolecules. It also examines the relationship between monomers and polymers and the four major classes of organic compounds. Test your understanding of these essential biological principles.