Biology Exam

Parts of RNA nucleotides

• RNA Sugar: Ribose

• RNA Bases: A, U, C, G

Parts of DNA nucleotides

• DNA Sugar: Deoxyribose

• DNA Bases: A, T, C, G

Describe features of Macromolecules

• Large complex structures

• Polymers made up of monomers

• Essential for life (carbohydrates, lipids, proteins, nucleic acids)

Monomers

Simple building blocks of polymers (e.g., amino acids, monosaccharides)

Polymers

Large molecules formed by the joining of monomers (e.g., proteins, polysaccharides)

Functions of Macromolecules

• Carbohydrates: energy storage and structural support

• Lipids: energy storage, insulation, and cell membrane structure

• Proteins: enzymes, structural components, and transport

• Nucleic Acids: store and transmit genetic information

Lipids

• Hydrophobic molecules including fats, oils, and waxes

• Made of hydrocarbon chains and rings

Examples of Lipids

• Triglycerides (fats and oils)

• Phospholipids (cell membranes)

• Steroids (hormones)

Proteins

• Polymers made of amino acids

• Amino acids linked by peptide bonds

Protein is a polymer or a chain of sub units

a) what is the sub unit of a polymer

b) what kind of bond links these sub units together

a) The sub unit of a polymer is called a monomer.

b) The sub units called monomers are linked together with peptide bonds.

Sugars

• Carbohydrates including monosaccharides (glucose, fructose) and disaccharides (sucrose, lactose)

• Used for energy storage and structural components

Nucleic Acids

• Polymers made of nucleotides (DNA and RNA)

• Store and transmit genetic information

How to Identify a Compound as Ionic or Covalent

Ionic: Metal + Non-metal (transfer of electrons) → e.g., NaCl

Covalent: Two non-metals (sharing of electron) → e.g., H2O

Use examples of ionic, covalent, and polar covalent bonds to help explain how they are different

Ionic Bond: Complete transfer of electrons (NaCl: Na gives electron to Cl)

Covalent Bond: Sharing electrons equally, Nonpolar (H2 molecule

Polar Covalent Bond: Unequal sharing of electrons, results in partial charges (H2O)

Describe examples of different Chemical Reactions

• Synthesis: A + B → AB

• Decomposition: AB → A + B

• Single Replacement: A + BC → AC + B

• Double Replacement: AB + CD → AD + CB

Give Examples of Chemical Reactions

• Dehydration Synthesis: monomers join to form polymers by removing water

• Hydrolysis: polymers break down into monomers by adding water

• Neutralization: acid + base → salt + water

• Redox: transfer of electrons

Describe how an Enzyme works

• Enzymes lower activation energy

• Substrate binds to active site

  • Lock and key or induced fit

• Enzyme remains unchanged, product is released

How is an enzyme shape important to the enzyme-substrate complex

The shape of an enzyme is critical because it determines the specificity of the enzyme for its substrate. The active site's shape must precisely match the shape of the substrate to form the enzyme-substrate complex, allowing the reaction to occur efficiently.

What is a functional group? State 2 characteristics of a functional group that make it important to biological systems

A functional group is a specific group of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Key characteristics include:

1. Conferring specific properties: Functional groups dictate the molecule's polarity, acidity, basicity, and ability to form hydrogen bonds.
2. Participating in chemical reactions: Functional groups are often the sites of chemical reactions, allowing molecules to interact with each other.

Identify the different Functional Groups

• Hydroxyl (-OH)

• Carboxyl (-COOH)

• Amino (-NH2)

• Phosphate (-PO4)

• Methyl (-CH3)

Identify the functional group involved in the condensation reaction that forms the long chains of glucose molecules that form starch?

The condensation reaction that forms long chains of glucose molecules to create starch involves the hydroxyl (-OH) functional group. The hydroxyl group on one glucose molecule reacts with a hydroxyl group on another glucose molecule, resulting in the release of water and the formation of a glycosidic bond.

Functions of Functional Groups

• Hydroxyl: polar, forms hydrogen bonds

• Carboxyl: acidic

• Amino: basic

• Phosphate: energy transfer (ATP)

• Methyl: gene expression

Difference of Hydrophobic and Hydrophilic

HydroPHILIC = likes water

HydroPHOBIC = repels water

Provide an example of both Hydrophilic and Hydrophobic

Hydrophilic: Sugar

Hydrophobic: Oil (Lipids)

Difference between Hypertonic, Hypotonic and Isotonic

Hypertonic = water moves out of the cell

Hypotonic = water moves into the cell

Isotonic = no net change → remains the same

Difference between Anabolic and Catabolic

Anabolic = build molecules (requires energy)

Catabolic = break molecules (releases energy)

Difference Between Deoxyribose (DNA) and Ribose (RNA)

DNA → no OH (hydroxyl group) on 2' carbon

RNA → has OH (hydroxyl group) on 2' carbon

Difference between Purine and Pyrimidine

Purines = A, G (adenine, guanine) → two rings

Pyrimidines = C, T, U (cytosine, thymine, uracil) → one ring

Difference between 3’ and 5’ ends of DNA

3’ end: has a hydroxyl (-OH) group on the 3' carbon of deoxyribose

5’ end: has a phosphate group attached to the 5' carbon of deoxyribose

Difference between Leading and Lagging Strand

Leading = continuous replication

Lagging = replicated in Okazaki Fragments

Difference between Nonsense and Missense Mutations

Nonsense = Stop codon appears early

Missense = Wrong Amino Acid inserted

Difference between Substitution, Insertion, Deletion and Frameshift Mutations

Substitution = Base swap

Insertion = add base(s)

Deletion = remove base(s)

Frameshift = caused by insertion and/or deletion, alters reading frame

Difference between Introns and Exons

Introns = non-coding regions (removed during splicing)

Exons = Coding regions (expressed)

Difference between mRNA, tRNA and rRNA

• mRNA = messenger RNA: carries genetic code from DNA to ribosome

• tRNA = transfer RNA: brings amino acids to the ribosome

• rRNA = ribosomal RNA: forms part of the ribosome

Difference between -70mV and +30mV

-70mV = resting membrane potential

+30mV = Peak Action Potential (depolarization)

Difference between Autonomic and Somatic Nervous Systems

Autonomic = involuntary nervous system (e.g., heart rate, digestion)

Somatic = Voluntary nervous system (e.g., muscle movement)

Difference between Insulin and Glucagon

Insulin = lowers blood glucose levels

Glucagon = Raises blood glucose levels

Nucleus

Contains DNA; control center of the cell

Ribosome

Site of protein synthesis

ER (rough vs smooth)

Rough ER = Protein processing and synthesis

Smooth ER = Lipid processing and synthesis

Golgi Apparatus

Modifies, sorts, and packages proteins for secretion or transport

Mitochondria

Site of cellular respiration; produces ATP

Chloroplast

Site of photosynthesis in plant cells

Lysosome

Contains digestive enzymes for breaking down cellular waste

Vacuole

Storage of water, nutrients, and waste

Plasma membrane

Selective barrier controlling entry and exit of substances

Transport Types: Passive vs Active

• Passive: Diffusion, osmosis, facilitated diffusion (no energy required)

• Active: Requires ATP → pumps, endocytosis, and exocytosis

Fluid Mosaic Model

• Phospholipid bilayer with embedded proteins

• Cholesterol = maintains fluidity

• Carbohydrates = cell identification tags

Protein Structure

• Primary: Amino acid sequence

• Secondary: Alpha-helix, Beta-sheet (local folding patterns)

• Tertiary: 3D folding (overall shape)

• Quaternary: multiple polypeptide chains

Mitochondria and Chloroplast Function

Mitochondria: inner membrane (ETC), matrix (Krebs cycle)

Chloroplast: thylakoid (light reactions), stroma (Calvin cycle)

Cellular respiration stages

• Glycolysis

• Krebs Cycle (Citric Acid Cycle)

• Electron Transport Chain (ETC)

Products at each stage of Cellular Respiration

• Glycolysis → 2 ATP, 2 NADH, 2 pyruvate

• Krebs Cycle → 2 ATP, NADH, FADH2, CO2

• ETC → 32-34 ATP, H2O

What is the purpose of glycolysis?

The purpose of glycolysis is to break down glucose into pyruvate, producing a small amount of ATP and NADH. This process occurs in the cytoplasm and does not require oxygen.

How is NAD+ important to glycolysis?

NAD+ is crucial in glycolysis as it acts as an electron acceptor, becoming NADH. This reduction is essential for energy transfer during the pathway and helps in ATP production.

How is ATP important to start glycolysis

ATP is important to start glycolysis because two ATP molecules are initially used to phosphorylate glucose, which is necessary to destabilize the molecule and allow the subsequent reactions to occur. This initial investment of energy is required for glycolysis to proceed and generate a net gain of ATP.

Locations of cellular respiration

• Glycolysis → Cytoplasm

• Krebs Cycle → Mitochondrial Matrix

• ETC → Inner Mitochondrial Membrane

Describe how the Electron Transport Chain (ETC) works

• Uses NADH/FADH2 to pump H+ ions across inner mitochondrial membrane

• H+ gradient drives ATP synthase to produce ATP

• Final electron acceptor = O2, forming H2O

What are the 4 steps of aerobic cellular respiration?

The four steps of aerobic cellular respiration are:

1. Glycolysis occurs in the cytoplasm.
2. Pyruvate oxidation occurs in the mitochondrial matrix.
3. The Krebs cycle also occurs in the mitochondrial matrix.
4. The electron transport chain which occurs across the inner mitochondrial membrane.

Which one of those steps act on glucose

Glycolysis acts on glucose.

Which of the 4 happen in the mitochondria

Pyruvate oxidation, and the Krebs cycle and the electron transport chain all happen in the mitochondria

Where is pyruvate produced?

Pyruvate is produced in the cytoplasm during glycolysis.

How is NADH formed during glycolysis

NADH is formed during glycolysis when NAD+ accepts high-energy electrons and a proton from glucose, reducing it to NADH. This occurs during the oxidation of glyceraldehyde-3-phosphate.

Where in the mitochondrion does kerbs cycle take place?

The Krebs cycle takes place in the mitochondrial matrix.

Acetylene Co-A is produced by the translation reaction. What happens to each part?

Acetylene Co-A is a molecule involved in several biochemical pathways, most notably the Krebs cycle (also known as the citric acid cycle or tricarboxylic acid cycle). It does not undergo a translation reaction. Acetyl-CoA is formed through the breakdown of glucose, fatty acids, and amino acids, and it serves as a central molecule in metabolism.

• Acetyl Group: This group enters the Krebs cycle, where it is completely oxidized to carbon dioxide (CO2) and water (H2O), generating energy in the form of ATP, NADH, and FADH2.
• Coenzyme A (CoA): Coenzyme A is recycled back to participate in the next step of Acetyl-CoA formation or other biochemical reactions.

What is meant by the term decarbonxylation

The term decarboxylation refers to a chemical reaction that involves the removal of a carboxyl group (-COOH) from a molecule and releases carbon dioxide (CO_2). This process is crucial in various metabolic pathways, such as the Krebs cycle, where decarboxylation steps help in the oxidation of organic molecules to generate energy.

List key product of the Krebs cycle

Key products of the Krebs cycle include:

1. ATP (Adenosine Triphosphate): Provides energy for cellular functions.
2. NADH (Nicotinamide Adenine Dinucleotide): Carries electrons to the electron transport chain.
3. FADH2 (Flavin Adenine Dinucleotide): Also carries electrons to the electron transport chain.
4. CO2 (Carbon Dioxide): Released as a waste product.

What are the roles of NADH and FADH2 in the mitochondrion

NADH and FADH2 are electron carriers. The roles are:

• NADH (Nicotinamide Adenine Dinucleotide):
  • Role: NADH carries high-energy electrons from glycolysis and the Krebs cycle to the electron transport chain (ETC).
  • Function: It donates electrons to the first protein complex in the ETC, which then passes them along the chain, ultimately contributing to the production of ATP.
• FADH2 (Flavin Adenine Dinucleotide):
  • Role: FADH2 also carries high-energy electrons to the electron transport chain, but it enters the chain at a later point than NADH
  • Function: It donates electrons to a protein complex in the ETC at a lower energy level compared to NADH, resulting in a slightly smaller contribution to ATP production.

What is chemiomosis? Where does it take place

• Where is the high concentration of hydrogen ins located in the mitochondrion

• How did the hydrogen ions get there

• Chemiosmosis: Chemiosmosis is the movement of ions across a semipermeable membrane, down their electrochemical gradient. More specifically, it relates to the creation of ATP by the movement of hydrogen ions (H^+) across a membrane during cellular respiration or photosynthesis.
• Location: Chemiosmosis takes place in:
  • Mitochondria (inner mitochondrial membrane during cellular respiration)
  • Chloroplasts (thylakoid membrane during photosynthesis)

High concentration of hydrogen ions (H^+) in the intermembrane space between the inner and outer mitochondrial membranes.

The hydrogen ions (H^+) are pumped from the mitochondrial matrix into the intermembrane space by the electron transport chain (ETC).

List the products of the photo reaction in photosynthesis. Which products participate in synthesis reactions

• what is the product of the Calvin cycle

• Light Reaction Products: Oxygen (O_2), ATP, and NADPH
  • Participate Products: Among these products, ATP and NADPH participate in the synthesis reactions of the Calvin cycle.
• Calvin Cycle Product: The product of the Calvin cycle is glucose (C6H{12}O_6).

Make a chart listing the major macromolecules, an example for each, and a list of the functional groups that are characteristics of each macromolecule

Macromolecule	Example	Functional Groups
Carbohydrates	Starch, Glucose	Hydroxyl (-OH), Carbonyl (C=O)
Lipids	Triglycerides	Methyl (-CH3), Carboxyl (-COOH) (in fatty acids)
Proteins	Enzymes, Antibodies	Amino (-NH2), Carboxyl (-COOH), R-groups (various functional groups)
Nucleic Acids	DNA, RNA	Phosphate (-PO4), Hydroxyl (-OH)

Where does the light dependant reactions take place

The light-dependent reactions of photosynthesis take place in the thylakoid membrane within the chloroplasts.

What is photolysis and why is it important for photosynthesis

Photolysis is the splitting of water molecules (H2O) into hydrogen ions (H^+), electrons, and oxygen (O2) using light energy.

Importance:

• Electron Source: Provides electrons to replace those lost by chlorophyll in Photosystem II (PSII).
• Proton Gradient: Releases hydrogen ions (H^+) into the thylakoid lumen, contributing to the proton gradient used for ATP synthesis.
• Oxygen Production: Generates oxygen as a byproduct.

Make diagram of the celll showing membrane, nucleus, cytoskeleton and at least one mitochondrion. Use one colour to show the path of one molecule of glucose into the cell, through glycolysis and into the mitochondrion for respiration. Use a second colour to show where energy is used to drive cellular respiration. Use a third to show where energy is stored by cellular respiration

Makes a diagram of a mitochondrion and chloroplast. Indicate which reaction take place on membrane and which reaction take place dissolved in solution. Indicate how the following molecules move between two organelles: glucose, CO2, O2, H2O

Give examples of each of these reactions:

• hydrolysis

• Condensation

• Neutralization

• Hydrolysis: Sucrose + H_2O → Glucose + Fructose
  • Condensation: Glucose + Glucose → Maltose + H_2O
  • Neutralization: HCl + NaOH → NaCl + H_2O

Give an example of an oxidation reduction reaction. Identify which reactant is more electronegative than the other

An example of an oxidation-reduction reaction is cellular respiration:

C6H{12}O6 + 6O2 → 6CO2 + 6H2O

In this reaction:

• Electronegativity:
  • Oxygen (O_2) is more electronegative than carbon (C)

Use structural formulas to draw one polar molecule and one non-polar molecule. Explain how the bonding electrons contribute to the polar and non-polar nature of the molecules

Water (H_2O) is polar

Methane (CH_4) is non-polar

Reasons:

• Polar Molecule (H_2O):

  • The oxygen atom in water is more electronegative than the hydrogen atoms. This means that oxygen attracts the bonding electrons more strongly, creating a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms.

• Non-Polar Molecule (CH_4):

  • Methane consists of one carbon atom bonded to four hydrogen atoms. Carbon and hydrogen have relatively similar electronegativities, so the bonding electrons are shared almost equally.

Describe the role of the skin in maintaining homeostasis in the body

The skin plays a crucial role in maintaining homeostasis in the body through several mechanisms:

• Thermoregulation: The skin helps regulate body temperature through sweating and adjusting blood flow.
• Protection: The skin acts as a barrier against pathogens, UV radiation, and physical damage.
• Sensation: Sensory receptors in the skin detect temperature, pain, and pressure, allowing the body to respond to the external environment.
• Excretion: The skin excretes small amounts of waste products through sweat.

Draw the shape of a nephron found in human kidney tissue. Label the four major sections of the nephron

I am unable to generate charts or diagrams in this format.

On the diagram drawn, show wher the following processes occur

• glomerular filtration

• Glucose leaves the filtrate

• Water leaves the nephron

• Salt ions removed from the nephron

• Urea diffuses out of the nephron

I am unable to generate charts or diagrams in this format.

Draw a negative feedback loop that illustrates how beta cells regulate glucose blood sugar levels

I am unable to generate charts or diagrams in this format.

Make a diagram of a neuron and label it

I am unable to generate charts or diagrams in this format.

Referring to the diagram, show where each of these ions is concentrated for a neuron at rest:

• Na+

• K+

• Cl-

• And other ions

I am unable to generate charts or diagrams in this format.

A neuron at rest shows the ions concentrated:

• Na+: concentrated outside the Axon
• K+: concentrated inside the Axon
• Cl-: concentrated outside the Axon

The phospholipid layer bilateral is not very permeable to ions. How can ions diffuse into or out of a nerve cell

Ions cannot freely diffuse through the phospholipid bilayer because it is hydrophobic. Therefore, ions can diffuse in and out of a nerve cell only with the help of ion channels that facilitate to transport.

Explain what is meant by resting potential

Resting potential refers to the electrical potential difference across the plasma membrane of a neuron when the neuron is not actively transmitting signals. This potential is typically around -70mV

Describe the role of the Na+/Ka+ pump in restoring resting potential of a nerve cell membrane following a nerve impulse

The Na+/K+ pump helps maintain the resting potential by actively transporting sodium ions (Na+) out of the cell and potassium ions (K+) into the cell against their concentration gradients. This helps restore the ion balance needed for nerve impulse transmission.

Compare the way steroid and non-steroid hormones affect cellular activity

Steroid hormones (e.g., estrogen, testosterone) typically enter the cell and bind to intracellular receptors, forming a complex that directly influences gene expression.

Non-steroid hormones (e.g., insulin, epinephrine) usually bind to receptors on the cell surface, triggering intracellular signaling cascades that amplify the signal and alter cell activity through secondary messengers.

Identify the organs that produce sex hormones in males and females. List the hormones produced by each structure

• Males:
  • Testes: Produce testosterone.
• Females:
  • Ovaries: Produce estrogen and progesterone.

How does the body restore and maintain a normal homeostatic state after exposure to extreme environmental temperatures

After exposure to extreme environmental temperatures, the body restores and maintains a normal homeostatic state through various mechanisms:

• In response to Heat:
  • Vasodilation: Increases blood to the skin to dissipate heat.
  • Sweating: Evaporation cools the skin.
• In response to Cold:
  • Vasoconstriction: Reduces blood flow to the skin to conserve heat.
  • Shivering: Muscle activity generates heat.
  • Hormonal Regulation: Thyroid hormones increase metabolic rate to produce more heat.

Create a chart that compares and contrasts the similarities and differences in the structure of DNA and RNA

I am unable to generate charts or diagrams in this format. However here is the information you requested:

Feature	DNA	RNA
Sugar	Deoxyribose	Ribose
Bases	Adenine (A), Thymine (T), Cytosine (C), Guanine (G)	Adenine (A), Uracil (U), Cytosine (C), Guanine (G)
Structure	Double helix	Single-stranded
Location	Nucleus	Nucleus and Cytoplasm
Primary Function	Stores genetic information	Transmits genetic information and protein synthesis

What is the base sequence of the DNA strand that is complementary with the sequence ACG TTG CTA

The base sequence of the DNA strand that is complementary to the sequence ACG TTG CTA is TGC AAC GAT.

Molecules and enzymes involved in DNA replication

• Primer

• DNA ligase

• DNA polymerase

• Okazaki fragments

• Helicase

State functions and state whether it’s involved in leading strand, lagging strand synthesis, or both.

*Primer: short strand of RNA or DNA that serves as a starting point for DNA synthesis.
*DNA ligase: enzyme that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond
*DNA polymerase: enzyme that synthesizes DNA molecules from deoxyribonucleotides, the building blocks of DNA.
*Okazaki fragments: short fragments of DNA that are synthesized on the lagging strand during DNA replication
*Helicase: Helicases are enzymes that bind to nucleic acids and unwind the DNA double helix, which is essential for processes like DNA replication and transcription.

Here are the roles:

• Primer: involved in both leading and lagging strands
  • Function: Provides a starting point for DNA polymerase to begin synthesis.
• DNA ligase: involved in lagging strand
  • Function: Joins Okazaki fragments.
• DNA polymerase: involved in both leading and lagging strands
  • Function: Synthesizes new DNA strands by adding nucleotides to the 3' end of a primer or existing DNA strand.
• Okazaki fragments: involved in lagging strand
  • Function: Short DNA fragments synthesized discontinuously.
• Helicase: involved in both leading and lagging strands
  • Function: Unwinds the DNA double helix at the replication fork, separating the two strands to allow DNA polymerase to access the template strands.

List the similarities and differences between the roles of the endocrine system and the nervous system

I am unable to generate charts or diagrams in this format. However here is the information you requested:

Feature	Endocrine System	Nervous System
Signaling Method	Hormones secreted into the bloodstream	Electrical and chemical signals transmitted through neurons
Speed of Response	Slow; effects may take minutes to days to manifest	Fast; responses occur within milliseconds
Duration of Effect	Long-lasting; effects can persist for hours to weeks	Short-lived; effects are transient
Target Specificity	Hormones can affect multiple target cells throughout the body	Specific; targets specific muscles, glands, or other neurons
Regulatory Control	Regulates long-term processes (e.g., growth, reproduction)	Controls rapid responses and coordination of body functions.

Describe how female sex hormones prepare the reproductive system for a possible pregnancy during a normal menstrual cycle

During a normal menstrual cycle, female sex hormones orchestrate a series of events to prepare the reproductive system for a possible pregnancy:

• Follicular Phase:
  • Estrogen levels rise, stimulating the thickening of the endometrial lining.
  • Increased estrogen levels prompt the hypothalamus to release gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
• Ovulation:
  • A surge in LH triggers ovulation, the release of a mature egg from the ovary.
• Luteal Phase:
  • After ovulation, the ruptured follicle becomes the corpus luteum, which secretes progesterone and estrogen.
  • Progesterone maintains the thickened endometrial lining, making it receptive to implantation.
  • If fertilization does not occur, the corpus luteum degenerates, leading to a drop in hormone levels and menstruation.

Which of the following substances are not normally found in urine?

A) Sodium

B) Water

C) Glucose

D) Urea

E) Uric acid

C) Glucose is normally reabsorbed in the kidneys and is not found in significant amounts in the urine of healthy individuals. The other substances are normally present in urine.

Identify the 5 different nucleotides. Which one is only found in RNA?

The 5 nucleotides are:

• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Thymine (T)
• Uracil (U)

Uracil is only found in RNA.

Label each component of a DNA nucleotide

I am unable to generate charts or diagrams in this format. However here is the information you requested:

A DNA nucleotide includes:

• Deoxyribose Sugar: A five-carbon sugar molecule.
• Phosphate Group: Attached to the 5' carbon of the deoxyribose sugar.
• Nitrogenous Base: Attached to the 1' carbon of the deoxyribose sugar. The nitrogenous base can be adenine (A), guanine (G), cytos