steps

Question 1

Outline how monoclonal antibodies are created.

Answer 1

• Mice are immunised with an antigen
• This activates the production of B cells, which produce antibodies against the antigen
• B cells that are specific to the antigen are isolated and extracted from the mouse’s spleen
• Those B cells are then fused with myeloma cells to form hybridoma cells.
• The hybridoma that produce the desired antibody are identified and cloned
• Cloned hybridoma are immortal and are used to produce monoclonal antibodies.

Question 2

Outline the process of selective breeding.

Answer 2

1. The species’ population has heritable phenotypic variation.
2. Humans act as an artificial selection pressure selecting for organisms with desirable traits and only allowing those to breed with one another.
3. The selected trait is heritable, and so the allele frequency of the desirable trait increases over time as humans select for only those organisms to breed

Question 3

Outline the process of allopatric speciation.

Answer 3

1. A geographical barrier has isolated a population of the same species from each other, thus preventing gene flow and interbreeding between populations
2. Heritable phenotypic variation [specify the kind] exists within the population.
3. Different environmental selection pressures act on the isolated populations selecting diff advantageous phenotypes and allowing for genetic differences to accumulate.
4. Once sufficient genetic differences accumulate, reproductive isolation occurs, and the two populations cannot interbreed to form fertile viable offspring, allopatric speciation has occurred

Question 4

Outline the process of how antibiotic resistance occurs.

Answer 4

• Heritable phenotypic variation exists between bacterium in a population, with some having advantageous alleles that confer antibiotic resistance and others not.
• An antibiotic acts as an environmental selection pressure, antibiotic resistant bacteria have a selective advantage and increased chances of surviving and passing on their advantageous alleles via binary fission or bacterial conjugation while those without will die.
• Allele frequencies of those advantageous alleles increase over successive generations and an antibiotic resistant bacterial population has formed.

Question 5

Outline the steps involved in natural selection.

Answer 5

1. There is heritable phenotypic variation between members in a population.
2. A specific environmental selection pressure causes a struggle for survival, members with advantageous alleles have increased chances of surviving and reproducing.
3. These ‘fitter’ organisms thus have higher chances of passing on their advantageous alleles to their offspring, increasing those allele frequencies over successive generations.

Question 6

Outline the process of sympatric speciation in Howea Palms on Lord Howe Island.

Answer 6

1. There are differences in soil nutrients on 2 regions of lord Howe island, one region having calcareous soil while the other has volcanic soil which has more nutrients
2. The differences in soil nutrients act as selection pressures selecting for different advantageous phenotypes
3. Overtime differences accumulate and pre-zygotic isolation occurs where flowering times differ decreasing likelihood of interbreeding between populations
4. Leading to the formation of a new species that can no longer interbreed with the other to produce viable fertile offspring, sympatric speciation has occurred.

Question 7

Outline the process of the formation of different Galapagos finch species in the Galapagos islands.

Answer 7

• Each Galapagos island is separated by the ocean, a geographical barrier that limits gene flow between islands
• There is heritable phenotypic variation in beak types between the Galapagos finches.
• Each island has different food sources, which act as environmental selection pressures selecting for different advantageous phenotypes such as beak shape.
• Over time differences accumulate until finch populations cannot interbreed between islands to form fertile viable offspring.
• A new species of finch has been formed and allopatric speciation has occurred.

Question 8

how recombinant insulin is made

Answer 8

1. human insulin is composed of 2 polypeptide chains, the A & B chains are synthesised separately on separate plasmids in separate bacteria
2. The same endonuclease is used to cut the plasmid and cut out the insulin gene
3. The plasmid used has antibiotic-resistant selectable markers and another observable trait
4. Introns are removed from the insulin chain and DNA ligase is used to insert the insulin genes into the β -gal gene of the plasmids disrupting it
5. Make the bacteria more competent to transform via heat shock or electroporation
6. Plate bacteria on an agar plate containing X gal and ampicillin so that the transformed bacteria can be identified
7. Once the genes are expressed by each bacteria and the fusion proteins are produced, these fusion proteins are then purified
8. The insulin polypeptides are removed and then combined together to produce functional insulin.

Question 9

Outline the stages of transcription.

Answer 9

1. RNA polymerase attaches to promoter region
2. DNA unwinds/unzips and the 3’ to 5’ DNA strand is used as a template strand
3. RNA polymerase reads template strand and creates a complementary pre-mRNA sequence by joining free complementary RNA nucleotides.
4. The resulting pre-mRNA sequence is identical to the coding strand except uracil takes the place of thymine.

Question 10

Outline the steps of translation.

Answer 10

1. Ribosome will come along and bind to the mRNA strand which is read by a ribosome until a start codon is reached.
2. tRNA anti-codons that are complementary to mRNA codons deliver individual, specific amino acids to the ribosome.
3. Amino acids in adjacent tRNA molecules bind together via condensation polymerisation reactions, and form peptide bonds.
4. This continues until a stop codon is reached, and then the ribosome releases the polypeptide chain and translation is complete.

Question 11

Outline the process of repression in the trp operon.

Answer 11

• represssor protein producedd by reg region on operon is inactive …
• repressor binds to operator region preventing the transcription of

Question 12

Outline the process of attenuation in the trp operon.

Answer 12

• Occurs when there are high levels of bound trp in the cell otherwise repression will occur
• High levels of tryptophan bound to tRNA molecules allow the leader to be translated quickly and not pause at trp codons.
• This causes a terminator hairpin loop to form between domains 3 and 4 in the leader, which causes the mRNA attenuator to rip away from DNA which sends the RNA polymerase flying and ribosome detaches
• Prevents transcription of structural E-A genes, no tryptophan is produced

Question 13

What is the role of rRNA, tRNA, mRNA?

Answer 13

rRNA reads mRNA codons and binds specific amino acids, that were delivered by tRNA molecules, together in the correct order
- works with other proteins to make ribosomes in the cytosol [fluid; cytoplasm is entire cell contents]

tRNA delivers a specific amino acid to ribosomes after recognising complementary mRNA codons.

mRNA carries genetic information from the DNA to the ribosomes for the translation of proteins.

Question 14

How do fossils form? [steps]

Answer 14

1. An organism dies and is:
   *Rapidly buried/frozen
   *Protected from scavengers
2. Prevented from decomposition by
   *Low oxygen levels
   *Low temperatures
3. Over time, the molecules in the organism usually the hard parts are replaced by minerals from groundwater
4. sediment layers build upon each other and compact to form sedimentary rock, resulting in a fossil.
5. The fossil can take forms such as a permineralised, mould, or cast fossil. 10,000 yrs+ old

Question 15

What is the order of the fossil record?

Answer 15

• prokaryotes
• first unicellular eukaryotes
• Development of multicellularity (600 mya)
• first invertebraes
• first vertebraes (jawless fish)
• first insects
• first land plants
• first amphibians
• first reptiles
• first dinosaurs
• mammals (200 mya)
• flowering plants (125 mya)
• Humans

Question 16

Outline the cell-mediated immune response.

Answer 16

1. Antigen presenting cells display pathogenic antigens on their surface via MHC II markers to activate helper T-cells, while simultaneously they encounter a naive T-cell with matching antigens.
2. The selected T-cell is stimulated by cytokines to undergo clonal expansion and differentiate into cytotoxic T cells and memory T cells.
3. Cytotoxic T cells can recognise abnormal proteins on infected cells, destroying them by secreting chemicals to induce apoptosis.
4. Memory T cells provide long lasting immunity and remain in lymphoid tissues and can rapidly divide into helper and cytotoxic T cells if the pathogen is re-encountered for a faster adaptive immune response.

Question 17

brief outline of the humoral immune response.

Answer 17

1. Antigen presenting cells display pathogenic antigens on their cell surface to activate helper T-cells and initiate the humoral immune response.
2. Helper T release cytokines activating B cells which bind to the same antigen in secondary lymphoid tissues and express them via MHC II markers on their surface.
3. The selected Helper T-cells recognise and bind to the selected B cell and release cytokines to make the B cell undergo clonal expansion and differentiate into either plasma or B memory cells.
4. Plasma cells produce antibodies specific to the selected antigen, and are secreted into the bloodstream to defend against the pathogen.
5. Memory B cells remain in lymphoid tissues and can divide into plasma cells if reinfection occurs.

Question 18

What are the stages of DNA profiling?

Answer 18

1. Obtain DNA sample
2. Amplify DNA sample using PCR
3. Sort DNA fragments by length in a gel electrophoresis

Question 19

What occurs in the denaturation stage of PCR?

Answer 19

During the denaturation stage, the DNA is heated up to approximately 90-95 degrees Celsius to break the hydrogen bonds between complementary DNA strands, which causes the DNA to separate into single-stranded DNA.

Question 20

What occurs in the annealing stage of PCR?

Answer 20

The single-stranded DNA is cooled to approximately 50-55°C so that primers can bind to their complementary sequences in the single-stranded DNA.

Question 21

What occurs in the elongation stage of PCR?

Answer 21

During the elongation stage, DNA is heated to 72 degrees Celsius (which is the optimal temperature for Taq polymerase) so that Taq polymerase can use primers as starting points to build a complementary DNA strand from free-floating DNA nucleotides.

Question 22

Outline the process CRISPR-Cas9 uses to cut specific DNA

Answer 22

1. a bacteriophage attaches to the outside of bacterial cell and injects its VIRAL DNA into the cell (reinfection)
2. previously, a segment of the viral DNA has been stored as a spacer in the CRISPR region - the CRISPR sequence is TRANSCRIBED resulting in CRISPR RNA (crRNA)
3. tracer RNA (trcrRNA) has a complementary sequence to the repeat DNA (NOT the spacers) - role: helps hold the gRNA in place in the Cas9 enzyme
4. the specific spacer of the crRNA binds to the trcrRNA to form guide RNA (gRNA) - gRNA then binds with the Cas9 enzyme → forms a Cas9-gRNA complex
5. Cas9-gRNA complex scans DNA looking for PAM sequences and complementary bases
6. once it is found, the DNA is unzipped and Cas9 cuts/cleaves both DNA a few nucleotides away from PAM creating a double blunt end
7. the viral DNA cannot reproduce as the DNA has been disrupted

Question 23

structure of trp operon

Answer 23

regulatory gene, promoter, operator, leader, attenuator, structural genes

Question 24

design experiment

Answer 24

• hypothesis
• iv & dv
• 50+ experimental groups
• 50+ control groups
• 3 controlled variables

Question 25

hominin trends

Answer 25

• Over time, hominin dentition has generally become more parabolic
• hominin foramen magnum have generally become more centralised
• hominin sagittal crests have generally become more rounded and less pronounced
• Homo’s have larger brains relative to their body size in comparison to Australopithecus this is inferred via brain cases found from fossils
• On average Homo-sapiens have longer legs and shorter arms while Australopithecus have shorter legs and longer arms; human fossil record

Question 26

mammals

Answer 26

• 3 middle ear bones
• singular lower jaw bone
• fur/hair
• mammary glands
• variety of teeth

Question 27

primates

Answer 27

• binocular colour 3D vision
• prehensile hands and feet
• opposable digits
• sensitive touch receptors & flat nails
• a flexible skeleton with rotatable hips & shoulders

Question 28

hominoids

Answer 28

• no tail
• Broader rib cage and pelvis to help them sit upright
• Typically longer arms than legs
• Large cranium size
• Y5-shaped molar teeth

Question 29

connection to country

Answer 29

• Been here for a long time
• Very knowledgable
• Work with the environment rather than using it
• Country is their connection to culture, ancestors, plants, animals, etc

Indigenous Australians arrived in Australia around 50,000-65,000 years ago through Sahul, and once Sahul was separated into Australia and Guinea the Indigenous Australians were geographically and genetically isolated, which makes them the world’s oldest surviving civilisation to have lived in a given location and thus have a strong Connection to country.

Question 30

Explain how CRISPR-Cas9 may be used to knock out/change a gene

Answer 30

1. scientist can create synthetic sgRNA that specifically targets the OsNramp5 gene and binds that to the cas9 enzyme to form a Crispr-Cas9 complex
2. That Crispr-Cas9 complex can then search the genome for that target DNA sequence and cas9 will unwind the DNA, the guide RNA binds to the target DNA sequence and Cas9 cuts both strands of DNA
3. various methods to knock out this gene may occur, such as inserting a section to interrupt the gene, removing the gene or removing bases that make the gene non-functional. –> scientist can insert a new piece of DNA, remove, replace or add or delete single nucleotides at the site of the cut
4. The cell detects and repairs the broken strand of DNA thus a knockout of the OsNramp5 gene is complete

Question 31

PAM

Answer 31

_GG is a PAM site