BIOL107 Practice Exam 1

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Questions and Answers

What is the primary function of mitochondria?

fold and package proteins

provide structural support

produce energy for the cell (correct)

produce proteins

Which of the following is NOT one of the principles of cell theory?

all cells come from other cells

all cells contain DNA (correct)

the cell is the basic unit of life

all living things are made of cells

In the described experiment, which of the following is an independent variable?

type of culture media

pH of the media (correct)

amount of growth

incubation time

What is the process through which electrical energy is generated by chemical reactions?

electrochemical cell function Signup and view all the answers

Which of the following components is found in all cell types, including plant, animal, and bacterial cells?

plasma membrane Signup and view all the answers

Which class of macromolecules is NOT a polymer?

Lipids Signup and view all the answers

How does the polarity of water impact its physical and chemical properties?

It creates cohesion between water molecules which contributes to water's surface tension and capillary action. Signup and view all the answers

The plasma membrane is best described as:

A fluid structure that controls what comes in and out of the cell. Signup and view all the answers

The energy for primary active transport comes from and the energy for secondary active transport comes from .

ATP; electrochemical gradient Signup and view all the answers

Which subatomic particle has negligible mass and determines the chemical behavior of an atom?

Electron Signup and view all the answers

Is a solution that has a [H+] concentration of 1x10-4 acidic or basic and what is the pH of the solution?

Acidic; pH = 4 Signup and view all the answers

Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly?

O2 Signup and view all the answers

In animals, glucose molecules are stored in liver and fat cells in the form of:

Glycogen Signup and view all the answers

What do anions do to electrons and what type of charge do they carry?

gain; negative Signup and view all the answers

Which four elements are most organisms primarily made of?

oxygen, carbon, hydrogen, nitrogen Signup and view all the answers

Why can ruminant animals break down cellulose effectively?

microbes in their rumen produce the required enzyme Signup and view all the answers

How many subatomic particles, in its most abundant form, are in an atom of cobalt?

27 protons, 32 neutrons, 27 electrons Signup and view all the answers

What is required for a hypothesis?

testable and falsifiable Signup and view all the answers

Which organelle is primarily responsible for breaking down macromolecules in animal cells?

lysosomes Signup and view all the answers

What is the molecular weight of glucose (C6H12O6)?

174g/mol Signup and view all the answers

How does the electrochemical gradient function?

It is based on the selective transport of ions across the cell membrane. Signup and view all the answers

When a transport vesicle carries a newly synthesized protein to the plasma membrane, where it fuses with it and releases the protein out of the cell, this is an example of ____________________.

exocytosis Signup and view all the answers

Approximately how much carbon-14 remains after 11,400 years if an organism has 25g of carbon-14 at its time of death?

6.25g Signup and view all the answers

Which class of macromolecules provides structural support, catalyzes biochemical reactions, and transports other molecules?

proteins Signup and view all the answers

The main 'fabric' of the plasma membrane is composed of ____________________ with a mosaic of other molecules.

phospholipids Signup and view all the answers

Cells placed in a hypertonic solution would most likely ____________________.

shrink Signup and view all the answers

All of the following contain polar covalent bonds EXCEPT

CH4 Signup and view all the answers

Mitochondria are found in

plant and animal cells. Signup and view all the answers

Which component of the plasma membrane is found only in animal cells?

cholesterol Signup and view all the answers

What differs between the four stable isotopes of naturally occurring iron (Fe)?

number of neutrons Signup and view all the answers

Which option accurately describes deductive reasoning in scientific practice?

hypothesis based science that utilizes the scientific method Signup and view all the answers

Which term best describes the field that outlines evolutionary relationships among organisms?

phylogeny Signup and view all the answers

What is the best description of diffusion?

movement of substances from an area of high concentration to an area of low concentration across the plasma membrane Signup and view all the answers

What is the valency of carbon?

4 Signup and view all the answers

What is the most common pathway taken by a protein that will be secreted by a cell?

rough ER → Golgi → transport vesicle → plasma membrane Signup and view all the answers

Under the 3 domain system, what is the defining characteristic separating bacteria from archaea?

different ribosomal RNA sequences Signup and view all the answers

What primarily stabilizes membrane fluidity and prevents freezing at low temperatures?

Cholesterol molecules Signup and view all the answers

What mechanism requires energy to move substances against their concentration gradient?

Active transport Signup and view all the answers

What feature describes the cell membrane as a flexible layer with proteins embedded within it?

Fluid mosaic model Signup and view all the answers

Which of the following is a role of membrane proteins?

Cell communication Signup and view all the answers

Which transport mechanism involves the engulfing of substances into the cell by vesicle formation?

Phagocytosis Signup and view all the answers

Which type of signaling affects nearby cells?

Paracrine signaling Signup and view all the answers

What is the primary function of the barrier created by the cell membrane?

Regulation of substance entry and exit Signup and view all the answers

What can trigger intracellular responses when bound to membrane proteins?

Signaling molecules (ligands) Signup and view all the answers

What type of carbohydrate consists of two monosaccharides linked together?

Disaccharides Signup and view all the answers

Which level of protein structure is defined by the sequence of amino acids?

Primary Signup and view all the answers

What is the primary function of DNA in cells?

Genetic information storage and transmission Signup and view all the answers

What is the role of phospholipids in cell membranes?

Structural components of cell membranes Signup and view all the answers

Which factor can significantly influence enzyme activity?

Temperature and pH Signup and view all the answers

Which structure is involved in the synthesis of proteins from amino acids?

RNA Signup and view all the answers

What type of macromolecule is primarily involved in catalyzing biochemical reactions?

Proteins Signup and view all the answers

What is the term for the complex formed when an enzyme binds to its substrate?

Enzyme-Substrate Complex Signup and view all the answers

What characterizes ionic compounds in terms of their physical properties?

High melting and boiling points due to strong ionic bonds. Signup and view all the answers

How does VSEPR theory influence molecular geometry?

It predicts molecular shape based on electron pair attraction. Signup and view all the answers

What does the dissociation of ionic compounds in a solvent typically lead to?

A mixture of free cations and anions. Signup and view all the answers

Which statement best describes the properties of molecules based on polarity?

Polarity influences interactions and solubility of the molecules. Signup and view all the answers

In comparing ionic and covalent bonding, which statement is accurate?

Ionic bonds result from the transfer of electrons, creating charged ions. Signup and view all the answers

Which type of cholesterol is primarily considered 'good'?

High-Density Lipoprotein (HDL) Signup and view all the answers

What effect do saturated fatty acids typically have on cholesterol levels?

Elevate 'bad' cholesterol levels Signup and view all the answers

What is a distinguishing feature of trans fatty acids compared to cis fatty acids?

Trans fatty acids have a straight structure Signup and view all the answers

Which statement correctly describes the structure of a phospholipid?

It has a hydrophilic phosphorus head and two hydrophobic fatty acid tails Signup and view all the answers

How does the structure of steroids differ from other lipids?

Steroids are composed of three fused hydrocarbon rings Signup and view all the answers

Which of the following is NOT a characteristic that makes something alive?

Creation of energy from scratch Signup and view all the answers

What is the correct order of taxonomic sublevels from broadest to most specific?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species Signup and view all the answers

Which reasoning approach is primarily associated with hypothesis-driven research?

Deductive reasoning Signup and view all the answers

What unifying concept describes the gradual process by which populations evolve over time?

Theory of evolution Signup and view all the answers

Which term best describes the study of evolutionary relationships among organisms?

Phylogeny Signup and view all the answers

Study Notes

Isotopes and Atomic Structure

Iron (Fe) has four stable isotopes differing in the number of neutrons.
Electrons and protons remain constant across isotopes, defining an element’s chemical identity.

Reasoning and Scientific Method

Deductive reasoning starts with a general statement and examines possibilities to reach a specific conclusion.
Inductive reasoning makes generalizations based on specific observations.

Biological Classification

Taxonomy organizes living organisms into categories based on evolutionary relationships.
Phylogeny refers specifically to the evolutionary history of a species.

Diffusion and Transport

Diffusion involves the movement of substances from high to low concentration across membranes.
Active transport requires energy; primary transport uses ATP, while secondary transport derives energy from electrochemical gradients.

Cellular Components and Processes

Carbon has a valency of 4, allowing it to form bonds with various elements.
Proteins are synthesized in ribosomes, with newly made proteins transported via vesicles from rough ER to Golgi apparatus then to the plasma membrane for secretion (exocytosis).

Osmosis and Solutions

Cells in a hypertonic solution lose water, leading to cell shriveling.
Solutions with pH < 7 are acidic; pH of 4 indicates high hydrogen ion concentration.

Macromolecules

Lipids are not polymers, whereas carbohydrates, proteins, and nucleic acids are.
Proteins serve multiple functions: providing structure, catalyzing reactions, and transporting molecules.

Energy Sources and Cell Structures

Mitochondria produce energy through cellular respiration, present in both plant and animal cells but not bacteria.
The plasma membrane consists mainly of phospholipids, allowing selective permeability for nutrients and waste.

Chemical Behavior and Reactions

Electrons in atoms determine chemical behavior; anions gain electrons and carry a negative charge.
The atomic mass of glucose is 180 g/mol (C6H12O6).

Cell Theory and Functionality

Cell theory states all organisms are composed of cells, which arise from pre-existing cells.
Lysosomes are responsible for breaking down macromolecules.

Experimentation Variables

In experimental design, independent variables are manipulated to observe effects on dependent variables; in this case, the pH of media is the independent variable.

Essential Elements in Biology

Organisms primarily consist of carbon, hydrogen, oxygen, and nitrogen, essential for forming macromolecules necessary for life.

Structure Of Cell Membrane

Cell membrane primarily consists of a phospholipid bilayer, fundamental for its structure.
Phospholipids have hydrophilic heads that attract water and hydrophobic tails that repel it, creating a barrier.
Integral and peripheral proteins are embedded in the bilayer, facilitating various cellular functions such as transport and signaling.
Cholesterol molecules are interspersed within the bilayer, enhancing fluidity and preventing membrane freezing at lower temperatures.
Glycolipids and glycoproteins are crucial for cell recognition and communication with other cells.

Functions Of Cell Membrane

Acts as a barrier, effectively separating the cell's internal environment from external conditions.
Regulates transport, controlling the entry of nutrients and the exit of waste products.
Contains signaling receptors that enable communication with hormones and neurotransmitters.
Provides structural support, giving shape to the cell and maintaining integrity.
Offers protection as a physical shield against pathogens and harmful toxins.

Membrane Transport Mechanisms

Passive Transport:
- Occurs without energy (ATP) expenditure, relying on natural concentration gradients.
- Includes diffusion (movement from high to low concentration) and facilitated diffusion through transport proteins.
Active Transport:
- Requires energy to transport substances against their concentration gradient, utilizing pump proteins like the sodium-potassium pump.
Endocytosis:
- Engulfs substances into the cell via vesicle formation, with subtypes like phagocytosis (cellular "eating") and pinocytosis (cellular "drinking").
Exocytosis:
- The process of releasing substances from the cell by fusing vesicles with the membrane.

Fluid Mosaic Model

Describes the cell membrane's dynamic and flexible nature, emphasizing its patchwork-like structure.
The "mosaic" aspect highlights the diverse array of proteins that float within the fluid phospholipid bilayer.
Membrane proteins can move laterally, contributing to the fluidity and functionality of the membrane.
Lipids and proteins are responsive to environmental changes, allowing for adaptation to maintain cell operations.

Cell Membrane And Signaling

Membrane proteins function as receptors for signaling molecules (ligands), initiating cellular responses.
Ligand binding can trigger a series of intracellular reactions (signal transduction), impacting various cellular processes.
Types of signaling include:
- Autocrine: A cell signals itself to regulate its activities.
- Paracrine: Signals affect nearby cells, facilitating local communication.
- Endocrine: Hormones are released into the bloodstream, reaching distant target cells.
Common signaling mechanisms involve G-protein coupled receptors (GPCRs) and ion channel receptors.
Signal amplification ensures that one ligand-receptor interaction can activate multiple downstream signaling pathways.

Carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen, typically with a 1:2:1 ratio.
Monosaccharides are simple sugars, examples include glucose and fructose.
Disaccharides are formed by linking two monosaccharides, with examples like sucrose and lactose.
Polysaccharides consist of long chains of monosaccharides, including starch, glycogen, and cellulose.
Functions include energy storage (glucose for quick energy, starch for plants) and structural support (cellulose in plant cell walls, chitin in fungi and arthropods).

Proteins

Polymers made of amino acids connected by peptide bonds.
Primary structure refers to the linear sequence of amino acids.
Secondary structure includes shapes like alpha-helices and beta-pleated sheets formed by hydrogen bonds.
Tertiary structure is the three-dimensional shape resulting from interactions among side chains.
Quaternary structure involves the assembly of multiple polypeptide chains.
Functions encompass enzymatic activity (catalyzing biochemical reactions), structural roles (e.g., collagen in connective tissue), and transport (e.g., hemoglobin carries oxygen).

Nucleic Acids

Polymers made of nucleotide monomers, consisting of a sugar, phosphate group, and nitrogenous base.
DNA (Deoxyribonucleic Acid) is a double helix that stores genetic information.
RNA (Ribonucleic Acid) is single-stranded and plays a crucial role in protein synthesis.
Functions include storing and transmitting genetic information (DNA), facilitating protein synthesis (mRNA, tRNA, rRNA), and regulating gene expression.

Lipids

A diverse group of hydrophobic molecules, primarily composed of hydrocarbons.
Fats and oils are triglycerides made of glycerol and fatty acids, serving as energy storage.
Phospholipids form cell membranes due to their amphipathic nature, having a hydrophilic head and hydrophobic tails.
Steroids, characterized by four carbon rings, include hormones such as cholesterol.
Functions of lipids include energy storage (fats), forming structural components of cell membranes (phospholipids), and acting as signaling molecules (steroid hormones).

Enzyme Function

Biological catalysts that accelerate chemical reactions without being consumed.
The active site is the specific region where substrates bind to the enzyme.
Substrates are the reactant molecules that enzymes transform into products.
The enzyme-substrate complex is formed when substrates bind, leading to product generation.
Factors influencing enzyme activity include:
- Temperature, where each enzyme has an optimal temperature range for function.
- pH levels that can affect enzyme structure and efficiency.
- Substrate concentration, which increases reaction rates up to a saturation point.
Inhibition types include:
- Competitive inhibition, where an inhibitor competes with the substrate for the active site.
- Non-competitive inhibition, where an inhibitor binds to a different part of the enzyme, altering its function.

Ionic Compounds

Formed through electrostatic attraction between cations and anions.
Typically composed of metals paired with nonmetals.
Exhibit high melting and boiling points due to strong ionic bonds.
Can conduct electricity when dissolved in water due to free-moving ions.

Molecular Structure

Refers to how atoms are arranged within a molecule.
Molecules can be simple (e.g., water, H2O) or complex (e.g., proteins).
Determined by atom types and inter-atomic bonds.
Geometry of molecules influenced by VSEPR theory, predicting shapes from electron pair repulsion.

Chemical Bonding

Involves two main types: ionic and covalent bonding.
Ionic Bonding: Electrons are transferred from one atom to another, producing charged ions.
Covalent Bonding: Involves sharing of electron pairs, commonly between nonmetals.
Bond strength hierarchy: triple bonds > double bonds > single bonds.

Dissociation of Ions

Occurs when ionic compounds separate into individual ions in a solvent like water.
The process involves breaking ionic bonds with polar solvent molecules.
Essential for conductivity; higher ion concentration leads to increased electrical conductivity.

Properties of Molecules

Polarity: Molecules can be polar (uneven electron sharing) or nonpolar (even sharing), impacting solubility and interactions.
Intermolecular Forces: Include hydrogen bonds, dipole-dipole interactions, and London dispersion forces, which influence melting and boiling points.
Reactivity: Depends on molecular structure and functional groups present.
Physical properties such as boiling and melting points, as well as solubility, are determined by intermolecular forces and molecular size.

Cholesterol Types

Good Cholesterol: High-Density Lipoprotein (HDL) helps remove other forms of cholesterol from the bloodstream, reducing the risk of heart disease.
Bad Cholesterol: Low-Density Lipoprotein (LDL) can lead to plaque buildup in arteries, increasing the risk of heart disease and stroke.

Effects of Fatty Acids on Cholesterol

Saturated Fatty Acids: Typically raise LDL cholesterol levels, contributing to heart disease; found in red meat, full-fat dairy, and certain oils.
Unsaturated Fatty Acids: Help lower LDL cholesterol while increasing HDL cholesterol; found in nuts, seeds, avocados, and fish oils.
Cis vs. Trans Fats: Cis fats are considered healthier (found in natural sources), while trans fats (often found in processed foods) can increase bad cholesterol levels.

Phospholipid Structure

Composed of a glycerol backbone, two fatty acid tails, and a phosphate group.
The hydrophilic (water-attracting) phosphate group and hydrophobic (water-repelling) fatty acid tails create a bilayer, forming cell membranes essential for function and integrity.

Steroid Structure

Characterized by a four-ring carbon structure.
Variability in functional groups attached to the rings determines the specific type of steroid (such as hormones like cholesterol, testosterone, and estrogen).

Definitions and Characteristics of Life

Science: A systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions regarding the universe.
Biology: The branch of science that studies living organisms, their life processes, and interactions with their environment.
Life: Distinctive characteristic of organisms that exhibit growth, reproduction, functional activity, and continual change preceding death.

Properties of Life

Living things exhibit organization, reproduction, growth and development, energy utilization, response to stimuli, regulation, and evolutionary adaptation.

Levels of Organization

Atoms: Fundamental units of matter
Molecules: Groups of atoms bonded together
Cells: Basic unit of life
Tissues: Groups of similar cells performing a specific function
Organs: Structures composed of different tissues working together
Organ Systems: Groups of organs that work together to perform complex functions
Organisms: Individual living entities
Populations: Groups of organisms of the same species in a specific area
Communities: Different populations living in a specific area
Ecosystems: Communities interacting with their environment
Biosphere: The global sum of all ecosystems

Emergent Properties

Emergent properties arise when components interact in complex ways, leading to new characteristics not present in individual parts.

Taxonomy and Domains

Taxonomy: The science of classification of organisms, establishing major categories based on similarities and differences.
Three Domains:
- Bacteria
- Archaea
- Eukarya

Taxonomic Sublevels

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Phylogeny

The study of evolutionary history and relationships among organisms.

Common Ancestry

Phylogenetic trees visually represent the evolutionary connections and divergence of species from common ancestors.

Unity of Life

All life shares genetic material (DNA), cellular structure, and biochemical processes.

The Process of Science

Basic Science: Focuses on understanding fundamental principles and knowledge; aimed at expanding knowledge.
Applied Science: Uses principles and theories from basic science to address practical problems and develop new technologies.

Reasoning in Science

Deductive Reasoning: Starts with a general statement or hypothesis and examines the possibilities to reach a specific, logical conclusion.
Inductive Reasoning: Begins with specific observations to develop broader generalizations or theories.

Flow of Information

Deductive Reasoning: General principle → Specific case → Conclusion.
Inductive Reasoning: Specific observations → Patterns → Generalizations or theories.

Scientific Method

A systematic approach involving observation, question formulation, hypothesis development, experimentation, data analysis, and conclusion drawing.

Hypothesis Qualifications

Must be testable, falsifiable, and based on existing knowledge.

Hypothesis Testing

A hypothesis cannot be definitively proven true; it can only be supported or refuted through testing.

Research Variables

Dependent Variable: The variable observed and measured.
Independent Variable: The variable manipulated or changed.
Control Variables: Constants kept the same throughout the experiment.

Reasoning in Hypothesis-Driven Research

Deductive reasoning.

Comparison of Concepts

Hypothesis: A testable prediction about the relationship between variables.
Theory: A well-substantiated explanation of an aspect of the natural world based on a body of evidence.
Scientific Law: A statement based on repeated experimental observations that describes some aspects of the universe.

Theories in Biology

Cell Theory: States that all living organisms are composed of cells, the cell is the basic unit of life, and all cells arise from preexisting cells.
Gene Theory: Proposes that traits are inherited through gene transmission.
Theory of Heredity: Explains how traits are passed from parents to offspring.
Theory of Evolution: Describes the changes in the inherited traits of a population over generations, primarily driven by natural selection.

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