Sophie Lee - AHL
From KstructIB
42 TOPIC 7: CELLS
7.1 Membranes
7.1.1 3 Explain the dynamic relationship between the nucleus, rough endoplasmic reticulum (rER), Golgi apparatus and cell surface membrane.
Dynamic relationship: protein synthesis nucleus: DNA transcription to mRNA to carry genetic message into cytoplasm rough endoplasmic reticulum: contains ribosomes that translate mRNA to amino acid chain which
enters a vesicle for transport to the golgi apparatus
golgi apparatus: package and modify protein molecule for use
7.1.2 2 Describe the ways in which vesicles are used to transport materials within a cell and to the cell surface. Vesicles transport materials to and from cell surface:
phagocytosis pinocytosis exocytosis
7.1.3 2 Describe the membrane proteins and their positions within membranes. Membrane proteins:
intrinsic proteins - cytoplasm side of the cell membrane extrinsic proteins - embedded in the cell membrane; most span width of membrane, but some do not
7.1.4 2 Outline the functions of membrane proteins as antibody recognition sites, hormone binding sites, catalysts for biochemical reactions and sites of electron carriers. Membrane protein functions:
antibody recognition site - for body to identify cell as own or foreign hormone binding site - for receiving hormones message catalyst for biochemical reaction - for molecule transport electron carrier site - for electron transport chain (ACR)
7.2 Cell division - mitosis
7.2.1 2 Describe the behaviour of the chromosomes in each of the four phases of mitosis (prophase, metaphase, anaphase and telophase). Prophase: chromatin condenses into chromosomes Metaphase: chromosomes line up at cell equator Anaphase: chromatid pairs separate and go to opposite sides of cell Telophase: chromosomes unravel in newly forming nucleus
7.2.2 2 Outline the differences in mitosis and cytokinesis between animal and plant cells. Plant Animal
cell plate forms furrowing occurs
7.3 Differentiation and functional specialisation of cells
7.3.1 1 State that unicellular organisms carry out all the functions of life.
unicellular organisms - cells carry out all functions of life
7.3.2 2 State that cells in multicellular organisms differentiate to carry out specialised functions.
43
multicellular organisms - cells differentiate and specialize
7.3.3 1 Define tissue. Tissue: a collection of cells that cooperate to perform an action within an organ, eg, nerve cells
7.3.4 1 Define organ. Organ: a collection of tissues cooperating to perform a specific function for the organism, eg, heart
7.3.5 1 Define organ system. Organ System: a system of organs that cooperate in order to complete metabolic processes for the benefit of the entire organism, eg, digestive system.
7.3.6 3 Explain the hierarchial relationship between cells, tissues, organs and organ systems in multicellular organisms.
7.3.7 2 Calculate linear magnification of drawings. Magnification: length of drawing / actual length
7.3.8 1 State that cells differentiate by expression of some of their genes and not others.
cells differentiate by expression of some genes and not others
7.3.9 1 State that the pathway of differentiation is determined by the cells position relative to others and by chemical gradients.
pathway of differentiation determined by cells position relative to others by chemical gradients
Organ System Organ Tissue Cell Relationship:
cooperating cells = tissues eg, stomach lining cooperating tissues = organs eg, stomach cooperating organs = organ systems eg, digestive system
44 TOPIC 8: NUCLEIC ACIDS AND PROTEINS
8.1 DNA structure
8.1.1 2 Outline the structure or nucleosomes including histone proteins and DNA.
DNA wraps around the core of a histone molecule
8.1.2 1 State that only a small proportion of the DNA in the nucleus constitutes genes and that the majority consists of repetitive sequences (cross reference 8.3.4).
small proportion of DNA contains genes majority of DNA contains repetitive sequences
8.1.3 3 Explain the structure of DNA including the antiparallel strands, 3 - 5 linkages and hydrogen bonding between purines and pyrimidines.
8.2 DNA replication
8.2.1 1 State that DNA replication occurs in a 5 - 3 direction.
5 triphosphate can only be added to free end of 3 OH (deoxyribose) replication only occurs in a 5 - 3 direction
45
8.2.2 3 Explain the process of DNA replication in eukaryotes including the role of enzymes (helicase, DNA polymerase III, RNA primase, DNA polymerase I and DNA ligase), Okazaki fragments and deoxynucleoside triphosphates. DNA replication:
DNA unzips with help of helicase enzyme free floating nucleotides complementary base pair with exposed nucleotides DNA polymerase checks correct complementary base pairing Okazaki fragments form on lower strand b/c direction of synthesis DNA ligase seals Okazaki fragments together result: two semi-conservative DNA strands
8.2.3 1 State that in a eukaryotic chromosome, replication is initiated at many points.
replication initiated at many points in eukaryote chromosome
8.3 Transcription
8.3.1 1 State that transcription is carried out in a 5 - 3 direction.
transcription carried out in 5 - 3 direction
8.3.2 2 Outline the Lac Operon model as an example of gene expression in prokaryotes.
regulator gene codes for repressor repressor inhibits transcription of controlled gene presence of inducer inhibits binding to operator repressor-inducer complex inducer allows transcription of controlled gene
8.3.3 3 Explain the process of transcription in eukaryotes including the role of promoter region, RNA polymerase, ATP, and terminator.
promoter codes for expression of gene DNA unzips to reveal gene free floating nucleotides complementary base pair with exposed nucleotides RNA polymerase checks complementary base pairing ATP required to make RNA polymerase move terminator codon releases RNA sequence
8.3.4 1 State that eukaryotic chromosomes contain far more DNA than is needed to code for their protein products (cross reference 8.1.2).
eukaryotic chromosomes contain more DNA b/c need to code for more proteins
8.3.5 2 Outline the difference between introns and exons.
introns: excess DNA fragments inserted into a chromosome exons: excess DNA fragments removed from a chromosome
8.3.6 1 State that eukaryotic RNA needs the removal of introns to form mature mRNA and that this process is called splicing.
eukaryote DNA needs removal of introns mature mRNA splicing: removal of introns from mRNA
46
8.3.7 1 State that a small group of viruses, known as retroviruses, cause host cells to synthesise viral reverse transcriptase (cross reverence 5.3.6 and 12.1.5).
retroviruses cause host cells to synthesize viral reverse transcriptase
8.3.8 2 State that reverse transcriptase catalyses the production of single-stranded novel DNA from RNA.
RNA in retrovirus cDNA via reverse transcriptase host DNA
8.3.9 3 Explain why reverse transcriptase is a useful tool for molecular biologists. Reverse Transcriptase:
allows biologists to reconstruct DNA from RNA allows biologists to transfer genetic information from viruses into other hosts
8.4 Translation
8.4.1 2 Outline that the structure of a tRNA allows recognition by a tRNA activating enzyme that binds a specific amino acid to it using ATP for energy.
tRNA structure allows regocnition by tRNA activating enzyme tRNA activating enzyme binds specific amino acid (uses ATP)
8.4.2 2 Outline the structure of ribosomes including protein and RNA conposition, large and small subunits, two tRNA binding sites and mRNA binding sites. Ribosomes:
composed of proteins and ribosomal RNA (rRNA) 1 large protein unit 1 small rRNA unit 2 tRNA binding sites (tRNA + next amino acid added to polypeptide chain via complementary base
pairing)
8.4.3 1 State that translation consists of initiation, elongation and termination.
initiator codon - begins translation elongation - polypeptide chain grows as amino acids are added by complementary base pairing and
peptide bondage
termination - terminator codon releases polypeptide chain
8.4.4 1 State that translation occurs in a 5 - 3 direction.
translation occurs in 5 - 3 direction
8.4.5 3 Explain in detail the process of translation including GTP, ribosomes (including peptidyl transferase), polysomes, start codon and stop codons. Translation:
ribosome: made of rRNA and protein polysome: ribosome group working cooperatively to speed up translation start codon: initiates translation GTP (guanidine triphosphate) hydrolysis provides energy for peptide bondage between amino acids peptidyl transferase: catalyzes peptide bond forming between amino acids; lets tRNA exit ribosome stop codon: releases ribosome, disassembles mRNA
47
8.4.6 1 State that free ribosomes synthesise proteins for use primarily within the cell itself and that bound ribosomes synthesise proteins primarily for secretion and lysosomes.
Free ribosomes group together to form polysomes (make proteins for intracellular use) Bound ribosomes on rER (make proteins for secretion and lysosomes)
8.5 Proteins
8.5.1 3 Explain the four levels of structure of proteins, indicating their significance. Protein Structure:
primary structure: sequence of amino acids secondary structure: tight coil of amino acids tertiary structure: three-dimensional folding of amino acid coil quaternary structure: two or more tertiary proteins lock together (eg. insulin A & B)
8.5.2 2 Outline the differences between fibrous and globular proteins, with reference to two examples of each type.
Fibrous: - secondary structure only - sheet or helix
- found in ligaments, proteins, flagella
Globular: - tertiary structure
8.5.3 3 Explain the significance of polar and non-polar amino acids (cross reference 7.1.3, 1.4.1 and 1.4.2).
polar amino acid has side-group charge non-polar amino acid lacks side-group charge side-group size and charge affects folding of polypeptide
8.5.4 1 State six functions of proteins, giving a named example of each. Functions of proteins:
support - eg. keratin pores - eg. Na+ / K+ pump enzymes - eg. pepsin cell markers - eg. Rh+ genetic coding - eg. DNA polymerase receptors - eg. excitory receptors for neurotransmitters hormones - eg. FSH (follicle-stimulating hormone) regulatory - eg. lac operon
8.6 Enzymes
8.6.1 1 State that metabolic pathways consist of chains and cycles of enzyme catalysed reactions.
metabolic pathways have chains and cycles of enzyme catalyzed reactions
8.6.2 2 Describe the induced fit model. Induced fit model:
enzyme has distinct, but flexible shape when substrate enters active site, shape of site modified around it to form complex products leave enzyme reverts back to inactive, relaxed form
8.6.3 3 Explain that enzymes lower the activation energy of the chemical reactions that they catalyse.
enzymes lower activation energy of the reactions they catalyze
48
8.6.4 3 Explain the difference between competitive and non-competitive inhibition, with reference to one example of each type. Competitive inhibition:
other molecule close in shape to enzymes substrate compete for active site eg. penicillin inhibits enzyme needed to form bacterial cell wall bacteria die
Non-competitive inhibition:
molecule binds to enzyme at site other than active site causes enzyme to change shape prevent binding with substrate (normal) eg. isoleucine inhibits to threonine deaminase threonine not broken down
8.6.5 3 Explain the role of allostery with respect to feedback inhibition and the control of metabolic pathways. Allostery:
molecule that binds outside active site changes enzyme structure to increase reaction rate
Feedback inhibition:
final product binds to allosteric site on first enzyme to inhibit enzyme action
49 TOPIC 9: CELL RESPIRATION AND PHOTOSYNTHESIS
9.1 Cell respiration
9.1.1 2 Outline that oxidation involves the loss of electrons from an element whereas reduction involves gain in electrons, and that oxidation frequently involves gaining oxygen or losing hydrogen; whereas reduction frequently involves loss of oxygen or gain in hydrogen. Oxidation Reduction
electron loss electron gain gain oxygen / lose hydrogen lose oxygen / gain hydrogen
9.1.2 2 Outline what is achieved by the process of glycolysis including phosphorylation, lysis, oxidation and ATP formation. Glycolysis - oxidation
C6H12O6 (Glucose) C6 P ATP ADP P + C6 P ATP ADP 2 PGAL (phosphogluceraldehyde)
(C3) coenzyme
3 PGAP (diphosphoglyceric acid) 2 NAD 2 NADH2 2 PGA (phosphogyceric acid) 2 ADP 2 ATP 2 PYROVIC ACID (C3) 2 ADP 2 ATP TRANSITION REACTION Net gain: 4 - 2 ATP = 2 ATP 2 NADH2
9.1.3 2 Outline aerobic respiration including oxidative decarboxylation of 2-oxopropanoate (pyrovate), Krebs cycle, NADH + H+ and electron transport chain. C6H12O6 + 6O2 + ADP + P 6CO2 + 6H2O + ATP
50
9.1.4 2 Describe oxidative phosphorylation in terms of chemiosmosis including proton pumps, a proton gradient and ATP synthetase (cross reference 9.2.4). Oxidative phosphorylation:
attatchment of high-energy phosphate group to another molecule by oxidation high-energy electrons electron transfer chain protons proton pump accumulate in cristae of mitochondria proton gradient drives ATP synthesis ATP synthetase - catalyze ADP ATP
9.1.5 2 Draw the structure of a mitochondrion as seen in electronmicrographs.
9.1.6 3 Explain the relationship between the structure of the mitochondrion and its function.
51
Cristae - maximize surface area for energy production Matrix - contain enzymes that allow respiration
9.1.7 2 Describe the central role of ethanoyl (acetyl) CoA in carbohydrate and fat metabolism. Acetyl CoA (coenzyme A):
glucose pyruvic acid pyrovic acid acetyl CoA acetyl from acetyl Coa Krebs cycle metabolize fat
9.1.8 2 Outline fermentation to 2-hydroxypropanoate (lactate) and to ethanol, and the circumstances in which they occur in cells.
H O O- | || /
2 H - C - C - C 2 PYRUVIC ACID
| \\ |
H O
H O H OH O- 2 ACETALDEHYDE
| // | | / +
2 H - C - C + 2 H - C - C - C 2 LACTIC ACID
| \ | | \\ +
H H H H O 2 NAD 2 NADH
H H 2 ACETALDEHYDE
| |
2 H - C - C - OH 2 ETHANOL
| | + H H 2 NAD 2 NADH
9.2 Photosynthesis
9.2.1 2 Draw the structure of a chloroplast as seen in electronmicrographs.
9.2.2 1 State that photosynthesis consists of light-dependent and light-independent reactions.
photosynthesis consists of light-dependent and light-independent reactions
9.2.3 3 Explain the light-dependent reactions including the photoactivation of Photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of Photosystem I and reduction of NAPD+. Photosystem II Photolysis of water Electron transport Cyclic photophosphorylation Photoactivation Photosystem I NAPD+ reduction grana stroma thylakoid lamella
52
9.2.4 3 Explain photophosphorylation in terms of chemiosmosis (cross reference 9.1.4). Photophosphorylation:
attatchment of high-energy phosphate group to another molecule by photosystems high-energy electrons electron transfer chain protons proton pump accumulate in cristae of mitochondria proton gradient drives ATP synthesis ATP synthetase - catalyst to encourage ADP ATP
9.2.5 3 Explain the light-independent reactions including the rules of ribulose biphosphate (RuBP) carboxylase, reduction of glycerate 3-phosphate (GP) to triose phosphate (TP or GALP), NADPH+ = H+, ATP, regeneration of RuBP and synthesis of carbohydrate and other proteins. Light independent reaction Glucose RuBP CO2 GALP Calvin 6C Cycle ADP + Pi ATP NADPH GP
9.2.6 2 Outline the differences in carbon dioxide fixation between C3, C4, and CAM plants, noting their adaptive significance. C3 C4 CAM CO2 Retension does not retain CO2 retains CO2 retains CO2 Climate cold climates hot climates desert climates Max Photosynth 20-30 C 45 C fluctuates Calvin Cycle CO2 + RuBP 2PGA CO2 + PEP OAA night: C4 cycle
day: C3 cycle RuBP (ribulose biphosphate), PGA (phosphoglycerate), PEP (phosphoenol pyruvate), OAA
(oxaloacetic acid)
RuBP facilitates oxidation when leaf temperature increases; unsuitable for hot climates PEP - has high affinity for CO2 - binds CO2 at lower concentration increase stomatal resistance reduce water loss - expends energy to generate PEP from pyruvate (less efficient than C3 photosynthesis)
9.2.7 1 State one crop plant example for each of the following: a C3, C4, and CAM plant.
C3 plant - eg. cherry tree C4 plant - eg. coconut tree CAM plant - eg. saguaro cactus
9.2.8 2 Describe how photosynthetic pigments can be separated and identified by means of chromatography.
photosynthetic pigments can be separated / identified by chromatography
9.2.9 2 Draw the action spectrum of photosynthesis.
red and blue light
53
9.2.10 3 Explain the relationship between the action spectrum and the absorption spectra of photosynthetic pigments.
photosynthesis only requires red and blue light; green gets reflected action spectrum absorption spectra
9.2.11 3 Explain the concept of limiting factors with reference to light intensity, temperature and concentration of carbon dioxide.
temperature increase a little = increase transpiration = faster reaction temperature increase a lot = stomata close = less CO2 avaliable intense light = stomata open = more CO2 avaliable for increased photosynthesis rate = increased temperature
54 TOPIC 10: CELL RESPIRATION AND PHOTOSYNTHESIS
10.1 Meiosis
10.1.1 1 Define homologous chromosomes. Homologous chromosomes - have the same shape and contain genes for the same traints.
10.1.2 2 Describe the behaviour of the chromosomes in the phases of meiosis.
Meiosis I - homologous chromosomes separate Meiosis II - chromatids separate
10.1.3 2 Outline the process of crossing-over (cross reference 10.3.2).
corresponding segments of genetic material between chromatids of homologous chromosomes
exchange
occurs during synapsis in prophase I
10.1.4 1 Define chiasma. Chiasma (pl. chiasmata) - X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during mitosis.
10.1.5 3 Explain how meiosis results in an effectively infinite genetic variety in gametes through crossing over in Prophase I and random orientation in Metaphase I (cross reference 3.3.3).
Prophase I - homologous chromosomes, each one composed of chromatids, synapse - chromatids exchange genetic material, resulting in new combinations of genes MetaphaseI - chromosomes line up at the equator randomly daughter cells have different genetic
makeup from mother cell
10.1.6 1 Define recombination. Recombination - occurs during meiosis and fertilization; promotes genetic variety - when crossing over has taken place - when resultant cell has genetic makeup distinct from parent cell
10.1.7 1 State Mendels Second Law (Law of Independent Assortment) Law of Independent Assortment - Genes sort themselves randomly in the next generation through gametes.
10.1.8 3 Explain the relationship between Mendels Laws and meiosis.
Law of segregation - during meiosis the alleles separate from each other into gametes Law of Independent Assortment - genes sort themselves randomly through crossing over and
random orientation in meiosis
55
10.2 Dihybrid crosses
10.2.1 3 Calculate and predict the genotypic and phenotypic ratios of offspring of dihybrid crosses involving unlinked autosomal genes. Sample cross:
homo - curly black x whige straight hair (BBHH x bbhh) first filial - BbHh second filial - BbHh x BbHh
BH Bh bH bh BH BBHH BBHh BbHH BbHh Bh BBHh BBhh BbHh Bbhh bH BbHh BbHh bbHH bbHh bh BbHh Bbhh bbHh bbHhF
10.2.2 2 Identify which of the offspring in dihybrid crosses are recombinants.
recombinant offspring display recombinant trait.
10.3 Autosomal gene linkage and gene mapping
10.3.1 1 State the differences between autosomes and sex chromosomes.
Autosomes - all chromosomes except the X and Y chromosomes. Sex chromosomes - X and Y chromosomes. They carry genes that determine sex.
10.3.2 3 Explain how crossing over in Prophase I between non-sister chromatids of a homologous pair can result in an exchange of alleles.
pieces of chromosomes exchanged between chromatid pairs during crossing alleles of crossed section exchanged
10.3.3 1 Define linkage groups
Linkage group - group of genes inherited as a unit (usually on same chromosome)
10.3.4 3 Explain an example of a cross between two linked genes.
red hair & freckles stick together HhFf X HhFf = HHFF; HhFf; hhff
10.3.5 2 Identify which of the offspring in such dihybrid crosses are recombinants.
recombinant offspring display recombinant traits
10.3.6 3 Analyse cross over value (COV) data to construct gene maps of up to four genes using two- point testcross data.
10.3.7 1 Define centimorgan. Centimorgan (cM): unit to express distance on a genetic map
cM = length of an interval with a 1% probability of recombination (approx. 1 Mb DNA) Mb = megabase = 1 000 000 nitrogen bases
10.4 Statistical analysis
56
10.4.1 3 Analyse both monohybrid and dihybrid genetic crosses using the chi-squared test.
state null hypothesis find degree of freedom ( # data points - 1 ) look up chi-value on chart ( ((observed value - expected value) / expected value)) accept or reject null hypothesis
10.5 Polygenic inheritance
10.5.1 3 Define polygenic inheritance.
Polygenic inheritance - two or more genes affecting the same trait in an additive fashion - eg. height, skin color
10.5.2 3 Explain that polygenic inheritance can contribute to continuous variation, using three examples including human skin colour.
hair color skin color - black (BBBB), dark (BBBW), mulatto (BBWW), light (BWWW),
white (WWWW)
height
10.5.3 3 Explain how interaction between genes can cause modified Mendelian ratios in dihybrid crosses.
genotypic ratio same as Mendelian ratio phenotypic ratio different eg. skin color - 1:4:6:4:1 (black:dark:mulatto:light:white)
10.6 Applications of genetics to agriculture and horticulture
10.6.1 1 Define inbreeding. Inbreeding - production of offspring between closely related animals to increase the occurrence of a favored trait.
10.6.2 1 Define outbreeding. Outbreeding - breeding inbred stocks with members of other stocks to prevent the
accumulation of unwanted traits and to increase the vigor of the individual
- promotes genetic variability by creating new gene combinations
10.6.3 1 Define interspecific hybridisation. Interspecific hybridisation - crosses between different cultures, races and species used to study the inheritance of specific characteristics (eg, ripening, flesh color)
- may be used to bring in pest or disease resistance
10.6.4 1 Define polyploidy Polyploidy - condition where cells have a chromosome number 3n or higher - common in plants - can be induced artificially by environment / chemicals - can be induced naturally by nondisjunction during meiosis - polyploids have more vegetative growth (gigas features); less seed production - generally fatal in animals
57
10.6.5 1 Define F1 hybrid vigour. F1 hybrid vigor - hybrids that are larger, healthier, and grow faster than parents
10.6.6 2 Outline one example for each of the above terms.
inbreeding - eg. midieval nobility rarely wed outside the noble family outbreeding - eg. results of european exploration and expansion interspecific hybridisation - eg. crossing different corn varieties to survive Canadian weather polyploidy - eg. polyploid lettuce sells better in supermarkets F1 hybrid vigor - eg. mules are stronger than horses or donkeys
10.6.7 2 Describe a total of three examples of the use of transgenic techniques in agriculture and /or horticulture.
natural resistance gene from wild tomatoes inserted in domesticated tomatoes Bt approach - incorporation of the compound Bacillus thringiensis to plants causes them to produce
their own insecticides
inject into plants the gene in bacteria that can convert nitrogen to a form used by plants
10.6.8 3 Discuss the ethical issues arising from the use of transgenic techniques.
build transgenic animals as models of human diseases with no regards to animal suffering selecting gender of babies possibility of biological warfare
10.6.9 3 Discuss the need to maintain the biodiversity of wild plants/ancient farm breed as a reservoir of alleles which may have future value.
increased genetic pool = more chances for gene protecting animal from future disease forms
58 TOPIC 11: HUMAN REPRODUCTION
11.1 Production of gametes
11.1.1 2 Draw the structure of the testis as seen using a light microscope.
11.1.2 2 Describe the processes involved in spermatogenesis including mitosis, cell growth, the two divisions of meiosis and cell differentiation. Spermatogenesis:
cell grows mitosis - cell divides cell grows meiosis I - cell divides cell grows meiosis II - cell divides cells differentiate - 4 sperm cells
11.1.3 2 Outline the origin and the role of the hormones FSH, testosterone and LH in spermatogenesis. Hormones involved:
FSH (follicle stimulating hormone) - stimulate testes to produce sperm LH (luteinizing hormone) - stimulate sperm to mature
11.1.4 2 Draw the structure of the ovary as seen using a light microscope. Semineforous tubule
59
11.1.5 3 Explain the processes involved in oogenesis including mitosis, cell growth, the two divisions of meiosis and unequal division of cytoplasm and the degeneration of polar bodies (cross reference 7.2 and 10.1). Oogenesis:
mitosis - cell divides cell grows meiosis I - unequal division of cytoplasm egg and polar body fertilization meiosis II - unequal division of cytoplasm zygote and polar body polar bodies degenerate (die / recycle) egg keeps most of nutrients from original cytoplasm
11.1.6 1 Draw the structure of a mature sperm and egg. Sperm Egg
11.1.7 2 Outline the role of the epididymis, seminal vesicle and prostrate gland in the production of semen. Semen Production:
epididymus: store mature sperm seminal vesicle: clean tract prostrate gland: add lubricant
11.1.8 2 Compare the processes of spermatogenesis and oogenesis including the number of gametes, timing of the formation and release of gametes. Spermatogenesis: Oogenesis:
results in 4 mature sperm results in 1 mature egg + 3 polar bodies forms constantly forms one per month released in group in semen released individually into fallopian tube
11.2 Fertilization and pregnancy Acrosome Cell Body Flagella Nucleus Cell Body
60
11.2.1 2 Describe the process of fertilisation including the acrosome reaction, penetration of the egg membrane by a sperm, and the cortical reaction. Fertilization:
sperm meets egg acrosome enzymes dissolve egg membrane nuclei fuse cortical reaction causes sperm pores to close outer covering gets tougher
11.2.2 2 Describe the role of human chorionic gonadotrophin (HCG) in early pregnancy and pregnancy testing. HCG (Human Chorionic Gonadotrophin):
hormone to mantain corpus leuteum corpus leuteum secretes progesterone preserves uterine lining will find way into urine presence in urine allows test for HCG to determine pregnancy
11.2.3 2 Describe the structure and functions of the placenta including, its hormonal role (oestrogen and progesterone) in the maintenance of pregnancy. Placenta:
produce oestrogen develop breast tissue / mammary glands produce progesterone preserve uterine lining allows respiration / excretion for fetus
61 TOPIC 12: DEFENCE AGAINST INFECTIOUS DISEASE
12.1 Agents that cause infectious disease
12.1.1 1 Define pathogen. Pathogen: an agent carrying an infectious disease
12.1.2 1 State one example of an infectious disease caused by members of each of the following groups: viruses, bacteria, fungi, protozoa, flatworms, and roundworms. Viruses - cancer Bacteria - pneumonia Fungi - athletes foot Protozoa - malaria Flatworms - schistosomaisis Roundworms - elephantiasis
12.1.3 1 List six methods by which disease-causing agents are transmitted and gain entry to the body. Disease-causing agents gain entry to body via:
respiration - entry via lungs
- transmitted as airborne particles
digestion - entry via food sources
- transmitted by ingestion through lower members of food chain
contact - penetration through skin or through open wounds
- transmitted through objects the host uses
eyes - entry via eyes
- host touches disease-causing agent and rubs eyes
reproducing - entry through sexual organs
- transmitted through sexual intercourse
carrier - secondary host (eg, mosquito) becomes infected with agent and then infects primary host
12.1.4 2 Describe the cause, transmission and effects of one human bacterial disease. Disease: syphilis Cause: spirochetes bacteria Transmission: sexual intercourse Effects:
chancre latent body rash grey/white blotches on membranes tumours, insanity death
12.1.5 3 Explain the cause, transmission and social implications of AIDS. Disease: AIDS (acquired immuno-deficiency syndrome) Cause: virus binds to memory cells Transmission: sexual intercourse Implications:
fatigue; no immune system protection costly to treat
62
12.2 Types of defence
12.2.1 2 Describe the process of clotting involving, thrombokinase, prothrombin, Ca2+ ions, fibrinogen, platelets and vitamin K. Clotting:
platelets: fragments from megakaryocytes in bone marrow fibrinogen / prothrombin manufactured by liver serum forms above clot (plasma w/out fibrinogen) platelets clump at site of rupture (requires Ca2+) prothrombin activated by Ca2+ to convert to thrombin thrombokinase acts as enzyme: prothrombin thrombin thrombin acts as enzyme; sever 2 amino acid chains from each fibrinogen fibrin fibrin wind around platelet plug framework red blood cells trapped in fibrin threads clot looks red
12.2.2 2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity. Immunity:
based memory cells challenge by antigen initiates response from body memory cell which recognizes antigen gets cloned immunity
12.2.3 1 Define active immunity. Active immunity: long-term memory (ie, antigen does not mutate. eg, measles)
12.2.4 1 Define passive immunity. Passive immunity: temporary memory (ie, antigen does mutate. eg, flu)
12.2.5 1 Define natural immunity. Natural immunity: through exposure (may be mother to infant)
12.2.6 1 Define artificial immunity. Artificial immunity: acquired for less dangerous firm (ie, vaccines)
12.2.7 3 Explain the roles of B-cells, MCH proteins, helper T-cells, cytotoxic T-cells, memory cells and immunoglobulins in the antigen/antibody response.
B-cells: find virus cells and spread message MCH protein: identification of virus helper T-cells: stimulate B-cell to produce clones; activate cytotoxic T-cells cytotoxic T-cells: rupture cell membrane of virus-containing cells memory cells: mantain immunity against future attacks of antigen immunoglobulins (antibodies): stick antigens together to form a clump
12.2.8 2 Describe the production of monoclonal antibodies and one use in diagnosis and one use in treatment. Monoclonal Antibodies:
lymphocytes cloned from a single B lymphocyte that bind to a particular antigen
63
inject foreign substance extract active B lymphocytes mix with metabolically weak cancerous lymphocytes some lymphocytes fuse metabolite needed by cancer cells removed non-hybrid cells die out subdivide and grow test with antigen grow clone collect and label antibodies
12.2.9 3 Explain the need for immunisation against the bacterial infections: diphtheria, whooping cough and tetanus, and against the viral infections: measles, polio and rubella. Need for immunization:
prevent death from bacterial and viral infections bacterial: diphtheria, whooping cough, tetanus viral: measles, polio, rubella cost of treatment > cost of immunization
12.2.10 2 Outline the process of immunisation. Immunity:
encounter: macrophage digests partially virus particles
recognition: bind MHC marker onto membrane spread SOS message
mobilization: macrophage secrets interleukin when binds with helper T cell with antigen
helper T cell multiplies
helper T cell stimulates memory B cell to produce clones
attack: B-cells mature into plasma cells to release antibodies antibody-antigen complex
complement proteins attatch o cell membrane of complex; pore burst
T-cells stimulate activated killer T-cells rupture cell membrane of virus-
containing cells
cease-fire: supressor T-cells slow down rate of lymphocyte cell division memory: B and T cells remain; respond if body encounters pathogen again basis of
immunity
12.2.11 3 Discuss the benefits and danger of immunisation against bacterial and viral infection. Benefits
prevents many cases of infection
Dangers
encourages bacteria to mutate to forms not covered by immunisation
64 TOPIC 13: CLASSIFICATION AND DIVERSITY
13.1 Classification
13.1.1 2 Describe the value of classifying organisms. Value in classifying organisms:
specifies which organism is being referred to when communicating illustrate true ancestoral relationships of living things
13.1.2 2 Outline the binomial system of nomenclature. Binomial system of nomenclature:
introduced by Carolus Linnaeus in Systema Naturae based on common ancestry each organism assigned two latin names: genus and species
13.1.3 3 Discuss the definition of the term species. Species: a specific group of similarly constructed organisms that are capable of interbreeding and producing fertile offspring; organisms that share a common gene pool.
13.1.4 2 Outline the features used to classify organisms into the kingdoms: Prokaryotae, Protoctista, Fungi, Plantae, and Animalia. Prokaryotae: unicellular prokaryotic organisms (bacteria). Nutrition principally by absorption, but some are photosynthetic or chemosynthetic. Protoctista (Protista): eukaryotic unicellular organisms. Nutrition by photosynthesis, absorption, or ingestion. Fungi: eukaryotic organisms with non-cellulose cell walls, usually having haploid or multinucleated hyphal filaments: spore formation during both asexual and sexual reproduction. Nutrition principally by absorption. Plantae: eukaryotic multicellular organisms with rigid cellulose cell walls and chlorophyll a and b. Nutrition principally by photosynthesis. Starch serves as food reserve. Animalia: eukaryotic multicellular organisms without cell walls or chlorophyll. Nutrition principally ingestive, with digestion in an internal cavity. Possess nervous coorditaion.
13.1.5 1 List the seven levels in the hierarchy of taxa: kingdom, phylum, class, order, family, genus and species using an example from each of two different kingdoms. Common Name Human Corn Kingdom Animalia Plantae Phylum Chordata Angiospermophyta Class Mammalia Monocotyledoneae Order Primates Commelinales Family Hominidae Poaceae Genus Homo Zea Species sapiens mays
13.1.6 3 Design and/or apply a key for a group of up to eight organisms.
13.2 Diversity
65
13.2.1 2 Outline the wide range of metabolic activity of prokaryotes including fermentation, photosynthesis and nitrogen fixation. Metabolic activity of prokaryotes:
fermentation photosynthesis nitrogen fixation releasing CO2
13.2.2 1 State that a wide range of organisms including algae and protozoa are classified in the protoctista.
protoctista includes a wide range of organisms (includes algae and protozoa)
13.2.3 2 Describe how fungi obtain nutrients using one parasite and one saprotroph as examples. Saphrophytic fungi: mycorrhizae (symbiotic relationship with plants)
absorb water and nutrients from soil, sugars from plant saphrophytic activity increases avaliability of mineral nutrients
Parasitic fungi: Ceratocystis ulmi (Dutch elm disease)
absorb water and nutrients from xylem / phloem in elm trees; beetle carry offspring to other trees colonize and live on tree until it dies as a result of too many fungi parasites
13.2.4 2 Outline the wide range of diversity in the plant kingdom as exemplified by the structural differences between bryophytes, filicinophytes, coniferophytes and angiospermophytes. Plant Kingdom:
very diverse eg. bryophytes are true land plants (eg. moss, liverwort, hormwort) eg. filicinophytes with special water-conducting tissue (eg. club moss, fern) eg. coniferophytes bearing cones (eg. pine, fir) eg. angiospermophytes with seeds (eg. bean, flower)
13.2.5 2 Outline the wide range of diversity in the animal kingdom as exemplified by movement in earthworm, swimming in a bony fish, flying in a bird, walking in arthropods. Animal Kingdom:
very diverse eg. movement of earthworm eg. swimming of bony fish eg. flying of bird eg. walking of arthropod (eg. grasshopper)
66 TOPIC 14: NERVES, MUSCLES AND MOVEMENT
14.1 Nerves
14.1.1 2 Outline the general organization of the human nervous system including CNS (brain and spinal chord) and PNS (nerves).
14.1.2 2 Draw the structure of a motor neuron.
14.1.3 1 Define resting potential. Resting potential: voltage recorded inside a neuron when not conducting a nerve impulse
14.1.4 1 Define action potential. Acting potential: change in potential propagated along the membrane of a neuron (nerve impulse)
14.1.5 3 Explain how a nerve impulse passes along a non-myelinated neuron (axon) including the role of Na+ ions, K+ ions, ion channels, active transport and changes in membrane polarisation. Nerve impulse:
resting phase (charge -65mV) Na+ outside; K+ / large organic negatively charged proteins inside action potential: depolarization (charge increasing) sodium channels open: Na+ goes inside apex: majority of Na+ inside (charge +40mV) action potential: repolarization (charge decreasing) K+ channels open: K+ goes outside recovery (refractory) phase (charge -65mV) Na+ / K+ pump returns ions to original position
14.1.6 3 Explain the principles of synaptic transmission as exemplified by the neuromuscular junction including Ca2+ influx and release, diffusion and ginding of neurotransmitter, polarisation of the post-synaptic membrane, and subsequent removal of neurotransmitter. Synaptic transmission:
Ca2+ influx causes polarization of pre-synaptic membrane Ca2+ release stimulates contractile fibres to contract contractile fibres move neurotransmitter vesicles to pre-synaptic membrane vesicles release neurotransmitter into synaptic cleft excitory receptors pick up neurotransmitter if enough hits, post-synaptic membrane becomes polarized signal continues down dendrite if not enough hits, signal stops neurotransmitter reabsorbed by pre-synaptic membrane enzymes clean up remaining neurotransmitters
14.2 Muscles and movement Human Nervous System CNS (central nervous system)
includes brain and spinal chord
PNS (peripheral nervous system)
includes nerves, sense receptors
67
14.2.1 1 List the functions of the human skeleton. Human Skeleton:
support shape red blood cell production
14.2.2 2 Describe the roles of nerves, muscles and bones in producing movement or locomotion. Movement:
nerves send impulse Ca2+ released Ca2+ causes muscles to contract bone acts as support limb doesnt bend
14.2.3 2 Draw a diagram of the human elbow joint including cartilage, synovial fluid, tendons, ligaments, name bones and antagonistic muscles.
14.2.4 2 Outline the functions of the above named structures of the human elbow joint.
cartilage - resilience synovial fluid - lubricant tendons ligaments bones - rigidity; support antagonistic muscles - movement
form joint capsule to hold bones together
humerous triceps ligament cartilage radius biceps tendon synovial fluid ulna
68
14.2.5 2 Draw the structure of skeletal muscle as seen in electromicrographs.
14.2.6 3 Explain how skeletal muscle contracts including the role of Ca2+ ions, troponin, tropomyosin, actin, myosin, cross-bridge formation, movement and breakage, and ATP. Skeletal muscle contraction:
nerve impulse reaches neuromuscular junction acetylcholine depolarizes muscle membrane action potential action potential enters T-tubule network sacroplasmic reticulum lets Ca2+ enter from myofibrils Ca2+ bind to troponon-tropomyosin complex binding active site on actin molecules uncovered myosin heads bind to active sites on actin cross bridges form between myosin and actin myosin heads bend toward center of sacromere ATP causes myosin to release actin and reset to original position process repeats as long as Ca2+ is bound to complex
69 TOPIC 15: EXCRETION
15.1 Excretion
15.1.1 2 Outline the need for excretion in all living organisms. Need for excretion:
all living organisms produce toxins accumulation of toxins will kill organism or waste energy to maintain hence organism must excrete toxins
15.1.2 1 State that excretory products in plants include oxygen, and in animals include carbon dioxide and nitrogenous compounds. Excretory products:
plants: O2 animals: CO2 / nitrogenous compounds
15.1.3 3 Discuss the relationship between the different nitrogenous waste products and habitat in mammals, birds, amphibians and fish. decay of plant / animal tissues ammonification animal urine / feces (soil fungi / bacteria) plants / animals N2 in atmosphere ammonia (NH3) ammonium (NH4+) nitrogen loss
cultivation nitrogen fixation nitrification denitrification by soil bacteria ammonia to nitrite (NO2-) (bacteria) nitrite (NO2-) to nitrate (NO3-)
nitrate (NO3-) in soil
15.2 The Human Kidney
15.2.1 2 Draw the structure of the kidney including cortex, medulla, pelvis, ureter, and renal blood vessels.
70
15.2.2 2 Draw the structure of a glomerulus and associated nephron.
15.2.3 3 Explain the process of ultrafiltration including blood pressure, fenestrated blood capillaries, and basement membrane. Ultrafiltration:
blood pressure pushes blood through glomerulus amino acids / glucose / H2O / Na+ / Cl- reabsorbed into efferent arteriole NH2 / H2O / Na+ / Cl- descend into loop of Henle H2O / Na+ reabsorbed tubular excretion occurs in distal convoluted tube - large molecules enter for excretion collecting duct carries wastes to renal pyramid
15.2.4 3 Explain the process of selective reabsorption in the proximal convoluted tubule including the roles of microvilli, pinocytosis and active transport. Proximal Convoluted Tubule:
selective reabsorption of H2O (passive) and salt (active) microvilli expand surface area for absorption
15.2.5 3 Explain the production of hypertonic urine including the roles of the loop of Henle, medulla, collecting duct, ADH and water potential gradients (cross reference 16.2.2). Urine Production:
renal artery transports blood to kidney afferent arteriole transports blood to Bowmans Capsules glomeruli glomeruli does pressure filtration; convoluted to increase surface area proximal convoluted tubule allows selective reabsorption medulla contains all the loops of Henle (H2O reabsorption controlled by Na+ (H2O gradient) distal convoluted tubule is site of tubular excretion: large molecules enter ADH catalyzes production of amino acids to urea collecting duct carries wastes to renal pyramid (H2O reabsorbed)
15.2.6 2 Compare the composition of blood in the renal artery and renal vein, and glomerular filtrate and urine.
71 Blood composition:
renal artery: blood with wastes renal vein: blood without wastes glomerular filtrate: amino acids, glucose, Na+, Cl-, NH2, urea, nutrient excess, nitrogenous waste,
[H+], H2O
urine: wastes - urea, Na+, Cl-, NH2, H2O, large molecules
15.2.7 2 Outline the structure and action of kidney dialysis machines. to arm artery to arm vein used new dialysis solution dialysis solution Kidney dialysis machine:
blood from artery goes to dialysis chamber dialysis tubing allows nitrogenous wastes to diffuse from blood blood returns to vein fresh dialysis solution replaces used dialysis solution in dialysis chamber
72 TOPIC 16: PLANT SCIENCE A. Dicotyledonous plant structures
16.1.1 2 Draw a diagram to show the external parts of a named dicotyledonous plant including root, stem, leaf, buds, sepal, petal stamen and carpel. 16.1.2 2 Draw plan diagrams to show the distribution of tissues in the stem, root and leaf of a generalised dicotyledonous plant.
buds leaf stem roots stamen petal carpal sepal
73
16.1.3 3 Explain the relationship between the distribution of tissues of the leaf and their functions.
Tissues:
cuticle - prevent dehydration
- protect from animal bites
epidermis - hold tissues together
pallisade mesophyll - chloroplasts for photosynthesis
- produce glucose for ATP
spongy mesophyll - loosely packed for air space
bundle sheath - surround veins
phloem - transport sugar of photosynthesis to the roots
xylem - transport minerals / water up to leaves
guard cells - regulate opening / closing of stomata
stomata - release water (transpiration) and oxygen
16.1.4 2 Outline four structural adaptations of xerophytes.
Xerophytes:
desert plants
photosynthesis in stem no need broad leaf
waxy stem minimize water loss
needle-like leaves minimize water loss
long roots collect more water
C4 photosynthesis bind CO2 when stomata open
16.1.5 2 Outline two structural adaptations of hydrophytes.
Hydrophytes:
water plants
short root anchorage
wide surface area float
B. Transport in angiospermophytes
16.2.1 1 Define water potential. Water Potential: net movement of water from one region to another.
74
16.2.2 1 State that water moves down a water potential gradient. water moves down water potential gradient 16.2.3 2 Describe the process of mineral ions uptake into roots by active transport. Mineral ion uptake: root hair epidermis cortex endodermis (casparian strip) xylem 16.2.4 3 Explain how the root system provides a large surface area for mineral ion and water uptake
by means of branching, root hairs and cortex cell walls.
Root system: large surface area for mineral, ion, H2O uptake branching, root hair, cortex cell walls increase surface area 16.2.5 3 Explain the process of water uptake in roots by osmosis. Water uptake: tension draws water from root to stem to leaf low water pressure in roots water intake by osmosis 16.2.6 1 State that terrestrial plants support themselves by means of cell turgor and xylem. terrestrial plants supported by turgor pressure and xylem 16.2.7 1 Define transpiration. Transpiration: evaporation of water from leaf. 16.2.8 3 Explain how water is carried by the transpiration stream including an outline structure of xylem vessels, transpirational pull, cohesion and evaporation. Cohesion Tension Theory: H2O cohere to each other H2O adhere to sides of xylem tension from transpiration pull H2O from root to stem to leaf H2O moves through xylem cells (stacked to form pipeline) 16.2.9 3 Explain how the abiotic factors light, temperature, wind and humidity affect the rate of transpiration in a typical terrestrial mesophytic plant. Transpiration: of light: fast high temperature: fast strong wind: fast high humidity: slow 16.2.10 1 Define translocation. Translocation: transport of food in plant through phloem 16.2.11 2 Outline the role of phloem in active translocation of various biochemical.
75
Active Translocation: sucrose actively transported into phloem solute accumulation in phloem water enters water pressure fluid flow down to storage site 16.2.12 2 Describe an example of food storage in plants. eg. carrot stores starch in root 16.2.13 2 Outline gas exchange pathways in the root and leaf of a typical terrestrial mesophytic plant. Gas Exchange Pathways: Leaf: stomata regulate gas exchange: CO2 in, O2 out stomata open / close by guard cells: K+ actively transported into guard cell H2O move in turgor pressure increase cells bulge: stomata open ions / H2O pass through: stomata close Root: gases enter root hairs: diffusion
C. Germination
16.3.1 2 Draw the external and internal structures of a named dicotyledonous seed. 16.3.2 2 Describe the metabolic events of germination in a typical starchy seed. Germination of starchy seed: radicle appears (root) seedling shoot from epicotyl (hooked shape to protect delicate leaves) cotyledon degenerate in dicots above ground, stems straightens, leaves expand photosynthesis begins meristem tissue cause the plant to continue growing 16.3.3 3 Explain the conditions need for the germination of a typical seed.
76
Germination requires: Water, Oxygen, light (some) Temperature 0 45 0C
D. Plants and People
16.4.1 2 Outline the importance of plants in people in terms of food, fuel, clothing, building materials and aesthetic value. Importance of plants:
food: leaves, fruits, seeds; medicine fuel: coal, oil (fossilized plants) clothing: fiber durable fabric building material: strength support aesthetic value: beautify home; landscaping lack of plants: starvation / cold
16.4.2 1 State one example of a plant in each of the five categories above. Examples of useful plants:
food: wheat fuel: hardwoods (maple, oak) clothing: cotton building materials: oak aesthetic value: flowers (rose)
16.4.3 2 Describe the cultivation of a plant of economic importance. Wheat:
cultivated 7000 BC in Euphrates Valley (Middle East) buried with Egyptian pharaohs to help nourish in afterlife spread from Greeks & Romans to China (3000 BC) brought to North American Great Plains (1800s AD) easily handled & stored small berry with high food value keeps well 2 basic types: winter and spring (planting season) 2 varieties: soft wheat (starch source) and hard wheat (bread flour; gluten) suceptible to fungi, bacteria, virus, insects, weeds selective wheat breeding since start to create uniform fields modern day: attempt to improve characteristic (eg yield, disease resistance, bread-making quality) wheat yields can be increased by hybridization 1960-70s. fertilizer = higher yields
16.4.4 3 Discuss two techniques used in cultivation which have led to improvement in yield. Chemical Applications (eg, pesticides, fertilizers)
pest control artificially add nutrients (eg nitrogen, minerals) regulate growth Crop Rotation crop residue nutrients for next crop maintain soil fertility / productivity
