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IB Biology SL Core Curriculum Revision Notes

Updated on April 16, 2014

Cells

Eukaryotic Cell
Eukaryotic Cell | Source
Prokaryotic Cell
Prokaryotic Cell | Source

Topic 2 - Cells

- Cell Theory

  • Living organisms are composed of cells
  • Cells are the smallest unit of life
  • Cells come from pre-existing cells
  • Evidence
    • Cells can survive on their own.
    • Cells only formed by cell division.
  • Unicellular organisms carry out all functions of life.
    • Metabolism
    • Response
    • Homeostasis
    • Growth
    • Reproduction
    • Nutrition
    • Respiration
  • Size (1000nm=1 μm, 1000 μm = 1mm)
    • Molecule = 1nm
    • Membranes = 10nm
    • Viruses = 100nm
    • Bacteria = 1 μm
    • Organelles = 10 μm
    • Cells = 100 μm
  • Magnification = size of image / size of specimen
  • Surface area to volume ration importance
    • Rate of material exchange
    • Rate of usage/production
    • Survival

- Multicellular organism

  • Show emergent properties, as the whole organism is more than the sum of its parts – complex interaction between cells. Cells differentiate to carry out specialized functions by expressing some genes but not others.

- Stem Cells

  • Have the capacity to divide, yet also may differentiate along different pathways – Blood Transfusions.
    • 1. Placenta/Umbilical Cord used as source of stem cells
    • 2. Red blood cells are removed and the remaining fluid is tested.
    • 3. “Cord” Blood can be used to treat leukemia (Bone marrow transplant)
    • 4. The blood is transfused when needed.

- Prokaryote Cells

  • Cell wall – protection & shape
  • Plasma membrane – entry/exit of substances, active transport.
  • Cytoplasm – enzymes, which catalase metabolism reactions
  • Pili – used to pull cells together
  • Flagellum – movement
  • Ribosomes – produce proteins
  • Nucleoid – Naked DNA region – genetic information

- Eukaryotic Cells

  • Mitochondria – aerobic respiration
  • Golgi apparatus processes proteins
  • Lysosome – digestive enzymes
  • Plasma membrane – controls exit/entry
  • Ribosomes – makes proteins for cytoplasm
  • Rough endoplasmic reticulum – Proteins for Secretion
  • Microvilli – pulls cells together

- Differences Between Animal and Plant Cells

  • Animal
    • Only plasma membrane
    • No chloroplasts
    • No vacuole
    • Round shape
  • Plants
    • Cell Wall + membrane
    • Always chloroplasts
    • Always vacuole
    • Fixed square shape

- Membranes

  • Glycoproteins
  • Cholesterol
  • Integral proteins
  • Phospholipid Bilayer
    • Hydrophobic hydrocarbon tails
    • Hydrophilic hydrocarbon heads
  • Peripheral proteins

- Function of membrane proteins

  • Hormone binding sites
  • Active & passive transport
  • Cell adhesion with glycoproteins
  • Enzymes to catalase reactions
  • Cell to Cell Communication

- Diffusion

  • The passive movement of particles from a region of high concentration to a region of low concentration. Simple – without help channels – gas exchange. Facilitated – with channels

- Osmosis

  • The passive movement of water molecules (solute) across a partially permeable membrane from a region of lower concentration to a region of high concentration.

- Active transport & Pump proteins

  • 1. Particles enter from side with lower concentration.
  • 2. Particles bind to specific sites
  • 3. ATP used to change pump shape
  • 4. Particle released, pump back to normal.

- Vesicle Transport

  • 1. Proteins made by Ribosomes & go to RER.
  • 2. Vesicles bud of the RER & carry the proteins to the Golgi Apparatus
  • 3. Golgi A. modifies the proteins.
  • 4. Vesicles of the Golgi A, carry proteins to membranes.
  • Exocytosis
    • 1. Vesicles fuse with membranes
    • 2. Contents released
    • 3. Vesicle flattens out
  • Endocytosis
    • 1. Membrane pulled inwards
    • 2. Particle enclosed in vesicles
    • 3. Vesicles in cytoplasm
    • 4. Particle digested.

- Cell Division

  • G1 – Growth, DNA, Transcription, Protein synthesis
  • S phase – DNA in nucleus Is replicated
  • G2 – preparation for division
  • Mitosis – produces 2 genetically identical nuclei
    • Early Prophase
      • Chromosomes become short and fat by supercoiling
      • Spindle microtubules grow
    • Late Prophase
      • Each chromosome two identical chromatids held by a centromere
      • Spindle microtubules extend from pole to equator
    • Metaphase
      • No nuclear membrane
      • Spindle microtubules attach to centromeres
    • Anaphase
      • Chromatids have become chromosomes
      • Spindle microtubules pull.
    • Early Telophase
      • Nuclear membrane forms
      • Spindle microtubules break down
    • Late Telophase
      • Uncoiling
      • Cytokinesis (Cell Division)

Chemicals of Life

A water molecule.
A water molecule. | Source
Structure of DNA
Structure of DNA | Source

Topic 3 - Chemicals of life

- Chemicals of Life

  • Most Frequently occurring elements
    • Carbon
    • Hydrogen
    • Oxygen
    • Nitrogen
    • Sulfur
    • Calcium
    • Phosphorus
    • Iron, Sodium

- Water polarity & hydrogen bonding

  • 2xHydrogen + 0xygen

- Properties of Water

  • Cohesive – hydrogen bonds – transport medium
  • Solvent – polarity - transport medium
  • Thermal
    • Heat Capacity
    • Boiling point
    • Cooling evaporation

- Organic

  • Compounds containing Carbon that are found in living organisms (except hydro carbonates, carbonates, oxides of carbon)
  • The rest = organic
  • Ribose, Glucose, Amino acids, fatty acids

- Sugars

  • Monosaccharide – glucose, galactose, fructose
  • Disaccharides – maltose, lactose, sucrose
  • Polysaccharides – starch, glycogen, cellulose

- Condensation – two amino acids to form a dipeptide + water

- Hydrolysis – polypeptide + water = dipeptide or amino acids

- Lipids

  • Energy Storage
  • Heat insulation
  • Buoyancy

- DNA Structure

  • Bases – Complementary Base Pairing (A+T, G+C)
    • Adenine
    • Cytosine
    • Guanine
    • Thymine
  • Hydrogen bonds
  • Deoxyribose
  • Double Helix

- DNA Replication

  • 1. DNA double helix is unwound & separated into strands by breaking the hydrogen bonds with Helicase.
  • 2. The single strands out as templates for new strands. Free nucleotides are present in large numbers around the replication fork. Hydrogen bonds are formed. New strand is form with Polymerase (DNA)
  • 3. Two double helix reforms – identical due to complementary base pairing.

- Transcription

  • DNA – Double Helix, Deoxyribose, A,C,G,T
  • RNA – Single Strand, Ribose, A,C,G,U (Uracil)
  • 1. DNA double helix uncoils. 2 Strands separates.
  • 2. Free RNA nucleotides assembles wings 1 of the 2 strands
  • 3. The RNA link up and form a strand of RNA
  • 4. The mRNA separates from DNA
  • 5. The DNA double helix reforms.

- Translation (of genetic code for amino acids)

  • 1. Messenger RNA binds to the small subunit of the ribosome. The mRNA contains a series of codons each codes for an amino acids.
  • 2. Transfer RNA molecules are present in large numbers. Each tRNA has a triplet of bases called an anticodon which also codes for the corresponding Amino Acid it carriers.
  • 3. tRNA binds to the ribosome 2 at once. Complementary codon, anti codon pairing. Complementary Base Pairing as in Replication & Transcription.
  • 4. The 2 amino acids carried by the tRNA are boned by a peptide link. A dipeptide is formed on the right. The tRNA left detaches. The ribosome moves along to the next. Repeated until a polypeptide is formed.

Genetics & Enzymes

Source
Source
Steps of Meiosis
Steps of Meiosis | Source

Topic 4 - Enzymes & Genetics

- Enzymes = Globular proteins, which act a catalysts of chemical reactions.

  • Active Site – a region on the surface of an enzyme to which substrate binds and which catalyzes a chemical reaction involving the substrates.
  • Enzyme-Substrate specificity – lock & key model
  • Effect of Temp.
  • Effect of PH
  • Effect of Substrate concentration
  • Denaturation – a structural change in a protein that results in the loss of its biological properties – Ph & Temp.
  • Lactose --------(lactose)------à glucose + galactose
    • Lactose intolerance
    • Ice cream production
    • Faster creation of Yoghurt/Cheese due to bacterial fermentation

- Cell Respiration = the controlled release of energy from organic compounds in the cells to form ATP.

  • Glucose ------------Pyruvate + Small amount of ATP
  • Anaerobic cell respiration
    • Pyruvate -------humans------lactate
    • Pyruvate -------yeast-------ethanol, CO2
  • Aerobic cell respiration
    • Pyruvate -------mitochondria----C02, H20,Large Amount of ATP
  • Photosynthesis
    • Light energy – chemical energy
    • Sunlight is composed of a range of different wavelengths (colours)
    • Chlorophyll is the main photosynthetic pigment
    • Green Light is not absorbed
    • Red & Blue absorbed more than green
    • Light is used to produce ATP
      • Photolysis = splitting of water molecule to form 02 + H2
    • ATP + H2 used to fix C02 to make organic molecule
    • Photosynthesis measured by
      • Production of Oxygen
      • Uptake of C02
      • Increase in Biomass

- Genetics

  • Gene = a heritable factor that controls a specific characteristic
  • Allele = one specific form of a gene, differing from other alleles by one or a few bases only.
  • Genome = the whole genetic information of an organism.
  • Gene mutation – a change to the base sequence of a gene (Sickle Cell Anemia)
  • Gene locus = the position of a gene on a chromosome.

- Meiosis – reduction division of a diploid nucleus to a haploid nucleus.

  • Homologous chromosomes = the same genes as each other but the same alleles of those genes.
  • Prophase 1
    • Chromosomes pair up
    • Nuclear membrane breaks down
    • Spindle microtubules break down
  • Metaphase 1
    • Spindle microtubules attach to different chromosomes.
  • Anaphase
    • Chromosomes pulled a part
    • Cell membrane will soon break
  • Prophase 2
    • 2 haploid cells are formed
    • New spindle microtubules grow
  • Anaphase 2
    • Centromeres have divided making separate chromosomes
  • Telophase
    • 4 haploid cells with half as many chromosomes as the parent cells.
  • Down Syndrome or Trisomy 2
    • Non-Disjunction = non-separation of the chromosomes in anaphase

- Karyotyping – chromosomes are arranged by pairs according to size and structure. Pre-natal karyotyping – villus sampling & amniocentesis

  • Genotype – the alleles of an organism
  • Phenotype – the characteristics of an organism
  • Dominant allele – has the same effect on the phenotype regardless if hetero or homozygous.
  • Recessive allele - has effects only on the phenotype on a homozygous state.
  • Co - dominant allele – pairs of alleles that both affect the phenotype when present in a heterozygous state.
  • Carrier – an organism that has one copy of a recessive allele that causes a genetic disease.
  • Test Cross – testing a suspected heterozygote by crossing it with a known homozygous recessive.
  • Multiple allele cells also exist.
  • Sex chromosomes control offspring
  • Sex linkage – the association of a characteristic with gender because the gene controlling the characteristic is located on a sex chromosome. (Blindness & Hemophilia)

- PCR – Polymerase Chain Reaction

  • DNA is copied many times
  • Carried out at high temps.

- Gel electrophoresis – fragments of DNA move in an electric field and are separated by size. Used in DNA profiling to detect paternity and in forensic investigations.

Classification

Source

Topic 5 - ecology & evolution

- Ecology & Evolution

  • Species = a group of organisms that can interbreed and produce fertile offspring.
  • Habitat = the environment in which species live
  • Population = a group of organism of the same species living in the same area.
  • Community = a group of populations living and interacting with each other.
  • Ecosystem = a community and its abiotic environment.
  • Autotroph = an organism that synthesizes its organic molecules from simple inorganic matter.
  • Heterotroph = an organism that obtains organic molecules from other organisms.
  • Saprotroph = an organism that lives in or on a non-living organic matter secreting enzymes and absorbing products
  • Consumer = an organism that ingests other organic matter, living or recently killed.
  • Detritivore = an organism that ingests non-living organic matter.
  • The Carbon Cycle

- Populations

  • Population change = (natality + immigration) – (mortality + emigration.

- Evolution (For all the believers)

  • The cumulative change in the heritable characteristics of a population.
    • Fossil Records
    • Selective Breeding
    • Homologous Structure
  • A population tends to produce more offspring than the environment can support.
  • Overpopulation leads to a struggle for survival
  • Members of one species show a variation
  • Sexual reproduction promotes variation
  • Natural selection leads to evolution – adaptation.

- Classification – Binomial system of nomenclature

  • Genus – Family – Order – Class – Phylum – Kingdom
  • Plants
    • Bryophytes
    • Filicinophytes
    • Coniferophytes
    • Angiosperophytes
  • Animals
    • Porifera
    • Platyhelminthes
    • Mollusca
    • Cnidaria
    • Annelid
    • Anthropods

Systems

Respiratory (Ventilation) system
Respiratory (Ventilation) system | Source
Digestive System
Digestive System | Source
Biological breakdown of the Heart muscle
Biological breakdown of the Heart muscle | Source

Topic 6 - Human Health

- Human Health

  • Large molecules are digested, and then broken down into smaller ones.
  • Enzymes are used to speed up the digestive process.
  • Amylase from the Salivary glands digests Starch in the mouth to make maltose at a ph of 7
  • Pepsin from the wall of the stomach digests proteins to make small polypeptides in the stomach at a ph of 1.5
  • Lipase from the pancreas digests fat into fatty acids and glycerol in the intestines at a ph of 7.

- Digestive System

  • Mouth
  • Esophagus
  • Stomach
  • Pancreas
  • Gall bladder
  • Liver
  • Large & small intestines (with Villi)
  • Anus
  • Absorption – food molecules absorbed by Villi
  • Assimilation – food molecule become part of tissue

- Transport System (blood)

  • Heart
    • Vena Cava superior
    • Vena Cava inferior
    • Aorta
    • Pulmonary arteries
    • Pulmonary veins
    • Right & left atrium
    • Right & left ventricle
    • Semi-lunar valves
    • Atrio-ventricular valves.
    • Coronary arteries supply heart muscle with oxygen and nutrients.
    • Heart beats by myogenic contraction, i.e. without nerve stimulation, through a pacemaker controlled by the medulla and epinephrine/adrenaline.
  • Arteries
    • Thick outer layer of collagen & elastic fibers to avoid leaks.
    • Thick layers of elastic muscle fibers to help pump blood along.
    • Narrow lumen to help maintain high pressure.
    • Think wall to resist high pressures
  • Veins
    • Thin layers because blood does not pulse in veins
    • Thin walls allow the vein to be pressed by muscle to move the blood along.
    • Thin layer of elastic fibers/collage = little danger of bursting.
    • Wide lumen to accommodate slow blood flow.
  • Capillaries
    • One cell layer walls so diffusion distance is small
    • Pores for plasma leakage to form tissue fluid
    • Very narrow lumen so capillaries are small
    • Large surface area
  • Blood
    • Plasma transporting nutrients, C02, hormones, antibodies, urea, heat.
    • Erythrocytes (red blood cells) transporting oxygen
    • Leukocytes (white blood cells) – Lymphocytes or Phagocytes.
    • Platelets
  • Pathogen
    • An organism or virus that causes a disease
    • Antibodies block specific metabolic pathways found in bacteria
    • Viruses reproduce using the host cells metabolic pathways, which are affected by antibiotic.
    • Skin forms a physical barrier and is slightly acidic
    • Mucus, lysosome enzymes kill many bacteria.
    • Phagocytes ingest pathogens by endocytosis
  • Antibodies = proteins that bind to specific antigens.
  • Antigen = a foreign substance that stimulates the production of antibodies.

- Antibody production

  • 1. Antibodies made my lymphocytes
  • 2. Variety of antibodies on lymphocyte surface
  • 3. When a pathogen enters the body its antigen binds to the antibodies in the plasma membrane of one type of lymphocyte
  • 4. When antigens bind to the antibodies the lymphocytes becomes active and divides to produce clones by mitosis.
  • 5. The clones of the cells start to produce large quantities of the same antibody – the antibody needed to defend the body against the pathogen.
  • HIV - reduction in the number of active lymphocytes and a loss of the ability to produce antibodies.

- Gas Exchange

  • Ventilation – the process of bringing fresh air to the alveoli and removing stale air
  • Gas exchange – the process of swapping one gas for another
  • Cell respiration – release of energy in ATP form for use inside the cell.

- Alveoli

  • Huge overall surface area for gas exchange
  • Single layer of very thin cells – diffusion distance very short.
  • Capillaries with low oxygen and more C02 concentrations
  • Moist allows the gases to dissolve, prevent them sticking together.

- Ventilation System

  • Trachea
  • Lungs
  • Bronchus
  • Bronchioles
  • Alveoli
  • Intercostal Muscles & Ribcage
  • Diaphragm
  • Inhaling & Exhaling

- Nerves, Hormones, Homeostasis

  • Nervous system = Central NS + peripheral nerves
  • Neurons
    • Sensory = from receptors to CNS
    • Relay = within the CNS
    • Motor = from CNS to effector
  • Nerve Cell
    • Dendrites
    • Cell body
    • Nucleus
    • Myelin sheaths
    • Nodes of Ranvier
    • Axon (nerve fiber)
    • Motor end plates
  • Resting potential = an electrical potential across the plasma membrane of a cell that is not conducting an impulse.
  • Active Potential (depolarization and repolarization) = the reversal and restoration of the electrical potential across the plasma membrane of a cells as an electrical impulse passes along it.
  • Nerve impulse
    • 1. Due to the diffusion of Sodium ions between regions with an action potential, the resting potential is reduced. If the potential rise above the threshold level, voltage gated channels open.
    • 2. Sodium channels then open and sodium ions diffse down the concentration gradient. The membrane potential is reduced and more sodium channels open. The positively charged sodium ions cause the development of a net positive charge and the potential is reversed. = Depolarization.
    • 3. Potassium channels open. A net negative charge is caused. The potential across the membrane is restored. = Repolarization.
    • 4. Sodium ions are transported out of the neuron. Potassium ions are transported into the neuron. – the resting potential is restored. The neuron is ready to conduct another nerve impulse.
  • Synaptic transmission
    • 1. Nerve impulse reaches end of the pre-synaptic neuron.
    • 2. Calcium diffuses in through calcium channels.
    • 3. Vesicles release neuro-transmitters.
    • 4. Neuro- transmitters diffuse across the synaptic cleft and bind to receptors.
    • 5. Sodium ions enther the post-synaptic neuron and cause depolarization.
    • 6. The nerve impulse setting of along the post-synaptic neuron.
    • 7. Calcium is pumped out and the vesicles reabsorb the neurotransmitters.
  • Homeostasis = maintaining the internal environment between limits.
    • Blood ph
    • C02 concentration
    • Blood glucose
    • Body temp.
    • Water balance
    • Controlled by negative feedback.
  • Endocrine system – glands releasing hormones transported by blood.
    • Pituitary gland
    • Thyroid gland
    • Adrenal gland
    • Pancreas
    • Testis / ovaries
  • Control of Body Temp.
    • Overheating
      • Wider skin arterioles, more blood in skin.
      • Relaxed skeletal muscles.
      • Sweat
      • Cooling
        • Narrow skin arterioles, less blood in skin.
        • Shivering of skeletal muscles.
        • No sweat.
  • Control of Blood Glucose
    • High Levels
      • Beta cells in the pancreatic islets make insulin
      • Insulin stimulates the liver and muscles cells to make glucose into glycogen. Others use glucose in cell respiration instead of fat.
      • Low Levels
        • Alpha cells in the pancreatic islets make glycogen.
        • Glycogen stimulates liver cells to make glycogen into glucose.
  • Diabetes
    • Type1
      • Usually during childhood
      • Beta cells produce insufficient insulin
      • Insulin injections
      • Diet insufficient
      • Type II
        • Usually after childhood
        • Cells become insensitive to insulin
        • Rarely insulin injections
        • Low carb diets to control.

- Reproduction

  • Male
    • Penis
    • Urethra
    • Foreskin
    • Testis
    • Scrotum
    • Epididymis
    • Prostate Gland
    • Seminal Vesicles
    • Bladder
    • Sperm Duct
    • Erectile Tissue
  • Female
    • Cervix
    • Vagina
    • Anus
    • Urethra
    • Bladder
    • Uterus
    • Ovary
    • Oviduct

- The menstrual cycle

  • FSH
  • LH
  • Estrogen
  • Progesterone
  • Ovulation
  • Corpus Luteum
  • Menstruation


- Testosterone

  • Pre natal development of male genitals
  • Development of secondary sexual characteristics
  • Maintenance of sex drive.

- In-Vitro fertilization

  • Drug is injected once a day for 3 weeks to stop the normal menstrual cycle.
  • Large doses of FSH are injected once a day for 10-12 days to stimulate the ovaries to develop follicles
  • HCG hormone is injected 36 hours before egg collection to loosen the egg in the follicles to make them mature.
  • The man gives semen and only the healthiest sperms are taken.
  • The eggs are extracted from the follicles using a device instead through the walls of the vagina.
  • Each egg is mixed with sperm in a shallow dish. The dishes are kept in an incubator.
  • Dishes are checked
  • 2-3 embryos are selected & place into the uterus.
  • Pregnancy test in the 8th week

Scan/Check-up in the 9th week

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