Module 5

Question 1

What are the advantages of external fertilisation? Provide examples of organisms that externally fertilise.

Answer 1

External fertilisation is the union of male and female gametes outside of the body. It is advantageous in colonising an aquatic environment as more offspring are able to be produced in less time compared to terrestrial animals. It allows for wide dispersal of young, as fertilised eggs are carried away, which reduces competition for food and living space, and allows for rapid recovery of populations away from damaged areas. It also requires less energy and time by the parents, compared to internal fertilisation as there is no need to find a mate, and there is usually little to no parental care for young. External fertilisation occurs in the southern gastric brooding frog and staghorn coral.

Question 2

Describe the advantages and disadvantages of asexual reproduction in plants.

Answer 2

Asexual reproduction requires only one parent and gives rise to offspring that are genetically identical to each other and the parent. This can be beneficial in harsh environments where all the plants are highly specialised. However, this is also a disadvantage as lack of variation can affect survival when environmental conditions change.

Question 3

Describe the two reproductive methods of fungi.

Answer 3

Fungi reproduce by either budding or spores. Budding is the method by which a bud develops in favourable conditions, DNA is replicated, the nucleus divides with one copy moving into the daughter cell (bud), and once the bud reaches a certain size and conditions are favourable, it detaches from the parent and grows into a new individual. Fungi also reproduce by spores which are single cells that do not contain an embryo or food supply, that are produced in great numbers by fungi. These spores are easily dispersed by wind and thus assist in expanding the distribution of a species to colonise new environments.

Question 4

Describe the stages of sexual reproduction in plants.

Answer 4

Sexual reproduction in plants relies on the successful fusion of male and female gametes, which may require external agents for pollination. Pollination occurs by the male gamete inside the pollen being carried from the anther of one flower to the stigma of the same or another flower for fertilisation. The pollen tube then germinates and grows down the style carrying the sperm cell to an ovule in the ovary for fertilisation.

Question 5

Compare the advantages and disadvantages of internal fertilisation

Answer 5

Internal fertilisation is the union of male and female gametes inside the body. Internal fertilisation means that the gametes remain in a moist environment for there survival. It is beneficial to terrestrial organisms as it provides protection to the zygote from external factors such as predation or infection. The zygote, therefore, has a higher chance of survival. Offspring also have a higher chance of survival as they are usually nurtured by their parents after birth. However internal fertilisation requires time and energy from the parents as it requires finding a mate, carrying the offspring internally and nurturing the offspring once born. Internal fertilisation occurs in tortoises, which copulate then deposit eggs, birds, echidnas (monotreme), kangaroos (marsupial), humans (placental).

Question 6

Describe the two reproductive methods of protists.

Answer 6

Protists reproduce by binary fission and budding. Budding is the method by which a bud develops in favourable conditions, DNA is replicated, the nucleus divides with one copy moving into the daughter cell (bud), and once the bud reaches a certain size and conditions are favourable, it detaches from the parent and grows into a new individual. Binary fission occurs by the protist cell growing to twice its size, replicating genetic material and dividing into two new individuals.

Question 7

How do bacteria reproduce?

Answer 7

Bacteria reproduce by binary fission. During binary fission, the cell grows to twice its size, replicates its genetic material and divides forming two new individuals. E.g cyanobacteria reproduces this way.

Question 8

Name and describe the female parts of the flower.

Answer 8

Carpel

• Stigma is the sticky top surface of the flower to which pollen adheres. It may be relatively small and smooth (in insect-pollinated plants) or large and feathered (wind-pollinated plants).
• Style joins the stigma to the ovary
• Ovary is where the ovules are formed

Question 9

Name and describe the male parts of the flower.

Answer 9

Stamen

• Anther is where pollen grains are formed
• Filament is the stalk that carries the anthers. The length determines whether the anthers are contained inside the petals for insect pollination or hang outside for wind pollination.

Question 10

Describe how the knowledge of reproductive technologies can influence the reproductive capability of an organism, using a named example.

Answer 10

IVF in cows (agriculture) - This process can alter the genetic composition of a population as; a farmer can breed more offspring from a prized animal so the genes of a specific bull can be passed on in many offspring; Sperm can be imported (exported) to/from overseas to improve a bloodline of a farmer’s stock. Genes can be passed on to breed overseas (less costly than traditional copulation).

Negatives:

• reduction of genetic diversity because 1 bull may be used to ‘sire’ many offspring.
• undesirable genes spread.
• individuals that are closely related may be unintentionally crossed and this increases the chance of recessive characteristics being expressed which may be undesirable or lethal.

Positives:

• Genes that would have been eliminated in natural populations (if male is sterile), can remain part of the population.
• Sperm banks - breeders can select desired characteristics, thereby increasing the proportion of genes in a population.
• Introduce genes to another part of the world. Being used in conservation to increase the numbers of endangered species.

Question 11

Describe the phases of mitosis.

Answer 11

Prophase - nucleus is still there. chromosomes are condensing (thickening and visible)
Metaphase - chromosomes line up in the middle of the cell, nucleus disassembled.
Anaphase - chromosomes move away to opposite sides of the cell by spindle fibres that help move them.
Telophase - chromosomes at complete opposite ends and new nuclei are forming on each side to make the two new cells.
Cytokinesis - final separation into two cells by splitting the cytoplasm.

Question 12

Describe the phases of meiosis.

Answer 12

Prophase I - chromosomes condense and thicken and line up with homologous pairs, crossing over occurs.
Metaphase I - chromosomes line up in middle of cell (in pairs) nucleus disassembled.
Anaphase I - chromosomes pulled away from each other by spindle fibres.
Telophase I - Two newly formed nuclei, two new cells formed, followed by cytokinesis.
Prophase II - Chromosomes condense, spindles form.
Metaphase II - Chromosomes line up in the middle in a single file line, no pairs, nucleus disassembled.
Anaphase II - Chromatids pulled away by spindle fibres.
Telophase II - Nuclei reforming, two cells divided, therefore 4 cells form.

Question 13

Compare cross and self-pollination?

Answer 13

Self pollination is the process where pollen from a flower’s anther pollinates the same flowers stigma. Cross pollination is the process where pollen from a flower’s anther pollinates a flower’s stigma from a different plant. In most species the pollen is produced at a different time from when the stigma can receive it, so that plants are not usually pollinates by their own pollen. Flowers are usually pollinated with pollen from other plants of the same species, ensuring greater variation in the offspring. Pollination can occur by wind, birds or insects.

Question 14

Describe the process of pollination.

Answer 14

Pollination is the process by which pollen is carried from the anthers of one flower to the stigma of a flower either on another plant or the same plant. During fertilisation, the sperm cell that was transferred by the pollen tube fuses with the egg cell (ovum) inside the ovule in the female part of the flower. The fertilised ovule develops, protected within the ovary. The ovule containing an embryo is now termed a seed and the surrounding ovary grows to become a fruit.

Question 15

What is germination?

Answer 15

The development of a plant from a seed or spore after a period of dormancy.

Question 16

Angiosperm

Answer 16

flowering plant.

Question 17

Gymnosperm

Answer 17

cone-bearing plant.

Question 18

Describe a method of asexual reproduction in plants.

Answer 18

Vegetative propagation - this process involves the growth of specialised plant tissues that can grow into a new plant if it becomes separated from the parent plant. Vegetative prop can produce a rapid increase in the no. of plants growing in favourable area so that they can outcompete, or displace neighbouring species.

Question 19

fertilisation

Answer 19

The process that occurs when the haploid nucleus of the egg fuses with that of the sperm, forming a fertilised egg called a zygote.

Question 20

Describe the process of fertilisation in mammals.

Answer 20

Sperm are attracted to egg by rheotaxis (movement through a fluid) –> oviducts secrete fluid which moves down repro tract, sperm swim upstream (positive rheotaxis) –> sperm which reach oviducts are held in storage and released in small batches –> progesterone and alkaline pH allow sperm to mature so they can penetrate the egg –> mature sperm become hypermobile (tails beat strongly to penetrate the egg) –> they cross through 3 layers; follicle cells release enzymes to help the sperm penetrate; zona pellucida - the acrosome of sperm comes into contact with glycoproteins, releasing its enzymes for penetration; surface proteins on final barrier only allow one sperm to enter, enzymes released that destroy the glycoproteins in the zona pellucida and cause electrical charges preventing other sperm from entering.

Question 21

Implantation

Answer 21

The process in which a developing embryo makes contact with and attaches to the uterine wall.

Question 22

How is fertilisation in mammals ensured?

Provide animal examples.

Answer 22

Fertilisation is ensured by having a fixed breeding season where females become sexually active and males responds –> lead to copulation –> fertilisation. This occurs in Australian mammals such as the quoll, platypus and kangaroo.

Question 23

Follicle stimulating hormone (FSH)

Answer 23

Sourced from the pituitary gland and targets testes and ovaries. In a male its function is to control the production of sperm by sertoli cells in the testes, to maintain testosterone as high enough levels for sperm production. In females its function is egg maturation.

Question 24

Luteinising hormone (LH)

Answer 24

Sourced from the pituitary gland and targets testes and ovaries. In males its function is testosterone secretion. In females it assists in ovulation and luteinisation of follicle.

Question 25

Oestrogen

Answer 25

Sourced from the ovaries and targets reproductive organs - specifically endometrium of uterus. Its function is to assist in the reproductive development of the endometrium and it assists in maintaining the secondary sexual characteristics of females.

Question 26

Progesterone

Answer 26

Sourced from the ovaries and targets the endometrium of uterus. Its role is maintenance of uterus lining by suppressing uterine activity to reduce likelihood of miscarriage.

Question 27

Testosterone

Answer 27

Sourced from the testes and targets the whole body. Its role is in the reproductive development of males and maintaining secondary sexual characteristics of males.

Question 28

Describe the process of implantation in mammals

Answer 28

Day 4-7 of pregnancy - In order for successful implantation decidualisation is required; changes include thickening of endometrium, ˄ blood supply, cell adhesion molecules (integrins) produced. Day 7 - implantation begins - blastocyst burrows into endometrium (completed by day 9).

Question 29

Outline the process of DNA replication.

Answer 29

1. DNA double helix unwinds, helicase causes the DNA helix to unwind and the strands to separate.
2. DNA unzips, the two strands separate - helicase disrupts the hydrogen bonds between the complementary bases. The strands separate exposing the nucleotide bases, replication fork is created, single stranded binding proteins bind to and stabilise the single-stranded DNA.
3. Nucleotides are added against each single strand, DNA polymerase III adds DNA nucleotides by picking free nucleotide units in the nucleus and inserting them opposite their complementary base partner. (There is a leading and lagging strand - continuous and discontinuous replication)
4. Replication errors are identified and corrected - DNA polymerase I back tracks to “edit” the strand, correcting base pair errors. The strands are then sealed together by ligase. Replicated DNA molecules rewind into double helix formation and passes DNA through mitosis.

Question 30

Assess the importance of cell replication processes in the continuity of a species.

Answer 30

In mitosis it is essential that the daughter cells are genetically identical to ensure functional proteins are produced. At the individual level mitosis, ensures every single cell contains the same genetic information which is necessary for growth, repair and protein production. In meiosis, meiotic cellular division ensures genetic diversity which is essential for the survival of a species. This genetic variation is central to a species surviving changes to the environment.

Question 31

Gene

Answer 31

Smallest unit of heredity, made up of linear sequences of nucleotides that code for a cell product (polypeptide chain).

Question 32

Locus

Answer 32

Position of a gene on a chromosome

Question 33

Genome

Answer 33

Total amount of genetic material that an organism has in each of its cells.

Question 34

Alleles

Answer 34

Different forms of the same gene.

Question 35

Compare the forms in which DNA exists in eukaryotes and prokaryotes.

Answer 35

At the chemical level, the DNA of prokaryotic and eukaryotic cells is identical, they both contain the nucleotide, the basic building block of DNA. DNA also exists in organelles including mitochondria.

Prokaryote DNA:
Packaging - DNA packaged into chromosomes, Chromosome is circular and located in nucleoid, No histone proteins, Nucleoid-associated proteins cause the chromosomes to form looped structures.
Quantity - 1 main chromosome + plasmids, Nucleotide base pairs ranges from 150K to 12 million; species dependent.
Replication - Relatively simple. begins at a single point. 2,000 base pairs per second.
Content - Organised as operons, each of which can code for multiple proteins.

Eukaryote DNA:
Packaging - DNA packaged into chromosomes, Linear chromosomes, Located in the nucleus, Histone proteins cause tight coiling, dense packing.
Quantity - Multiple chromosome – species dependent, e.g humans - 23 pairs of chromosomes containing 3B base pairs.
Replication - Multiple replication origins, forks and bubbles to compensate for a slow pace, about 100 base pairs per second.
Content - Organised in genes that each code for a single polypeptide (protein).

Question 36

Describe the process of transcription.

Answer 36

1. RNA polymerase binds to a part of the DNA called the promoter and the DNA ‘unzips’. This only happens in the part of the DNA that contains the gene to be used. Only 1 strand contains the genetic info to make a protein (template/non-coding strand).
2. Transcription controlled by RNA polymerase. Non-coding strand of DNA acts as a template and RNA nucleotides are assembled, forming a complementary 1-stranded mRNA molecule. (DNA transcribed into mRNA) Base Uracil used instead of thymine. Editing/splicing then takes place.
3. mRNA moves from nucleus to cytoplasm.

Question 37

Describe the process of translation.

Answer 37

1. Ribosomes move along the mRNA molecule and attach tRNA molecules to mRNA by temporarily pairing the bases of the tRNA anticodons with their complementary triplets of bases (codons) on the mRNA.
2. Amino acids from the tail end of each tRNA are linked to one another by an enzyme to form a polypeptide chain. Each AA is then spliced off its tRNA carrier.
3. The tRNA’s move away from the mRNA, leaving the growing chain of AA’s, and move back into cytoplasm to pick up another AA and be re-used.
4. Polypeptide chain processed in the cell –> becomes a protein.
5. mRNA broken down into nucleotides, can be re-used.

Question 38

Why is mRNA important in transcription and translation?

Answer 38

mRNA is important as it carries the message contained in DNA to the cytoplasm wherein there are ribosomes. It is responsible for carrying messages needed for the production of polypeptides, as DNA cannot leave the nucleus.

Question 39

Why is tRNA important in transcription and translation?

Answer 39

tRNA is important as it brings the AA to the ribosomes to form a polypeptide chain. Its complementary nature with mRNA allows complex AA sequences to form.

Question 40

What is the function of polypeptide synthesis and why is it important? Provide an example.

Answer 40

The function of polypeptide synthesis is to create proteins essential to the structure, movement and communication between eukaryotic cells, function of organisms and regulation of body tissues and organs. Essentially, it is important as these proteins allow for cells to function and thus, the body to function. For example, Haemoglobin is an essential protein which transports O2, enzymes are proteins important for digestion.

Question 41

Describe two factors affecting phenotypic expression.

Answer 41

Genes and the environment affect phenotypic expression. Genes carry the set of instructions for all proteins necessary for growth and development, and therefore influence factors including blood type, or presence of genetic diseases such as Cystic fibrosis or Haemophilia. Gene expression, and therefore phenotype, can be influenced by the environment including the womb, diet, climate, surroundings, and disease. Diseases including Breast cancer, Schizophrenia, Hypertension are influenced by the env.

Question 42

Intron

Answer 42

A segment of a DNA or RNA molecule which does not code for proteins and interrupts the sequence of genes.

Question 43

Plasmid

Answer 43

Small circular, independent double stranded DNA molecule. Plasmids can frequently be transmitted from one bacterium to another.

Question 44

Phenotype

Answer 44

The sum of all gene products - the appearance of an organism (expression of genes)

Question 45

Gene expression

Answer 45

The translation of genes into their protein end products which determine the physical and chemical features typical of each cell type and the overall phenotype of the organism.

Question 46

Genotype

Answer 46

The set of genes in the DNA responsible for a particular phenotypic trait.

Question 47

Provide two examples of the environment affecting the phenotype of an organism.

Answer 47

During a thermosensitive period (TSP) of reptile egg incubation, gonadal tissue is responsive to temperature. This influences the gender of the offspring. At 25°C – All are born male, at 28.5°C – Yields mixed brood and at 30°C – All are born female. Another example is the effect of soil pH on hydrangea colour. Flower colour is determined by soil pH. The pH effects the availability of other ions in the soil and these ions are responsible for the colour change. At a pH<5 = acidic soil = blue flowers, at a pH ≥ 7 = neutral & alkaline soil = pink flowers.

Question 48

Provide examples of wind pollinated, bird-pollinated and insect pollinated plants.

Answer 48

Wind pollinated - Grass flowers such as lolium perenne, small.
Bird-pollinated - waratah - (telopea speciosissima), red colour.
Insect pollinated - orchids, attractive and fragrant petals.

Question 49

Provide 4 examples of vegetative propagation.

Answer 49

Some types of vegetative propagation include Rhizomes - underground stem that branches and gives rise to new shoots and roots, seen in ginger and bracken fern. Stolon/runner - above ground stem that branches and gives rise to new shoots and roots, seen in spinifex grass. Tuber - swollen underground stems with buds that easily frown into new plants, e.g sweet potatoes, dahlias. Apomixis - In apomictic flowers, viable seed is produced without fertilisation of the ova by pollen. The seeds produced in this way give rise to individuals that are genetically identical to their parents, seen in kangaroo grass (Themeda triandra), lemon and orange trees (citrus) and dandelions.

Question 50

Structure and function of proteins - structural

Answer 50

Support - Fibrous and stringy to maintain shape of cells.
Tubulin is a structural protein responsible for forming the cytoskeleton, maintaining the shape of cells.

Movement - Found alongside other proteins and microfilaments allowing for contraction.
In muscles the contractile protein actin acts alongside myosin to allow the muscle to contract.

Question 51

What are the genetic consequences of meiosis?

Answer 51

• 1 cell undergoes 2 meiotic divisions to generate 4 haploid cells
• The genes in each haploid cell are a new combination of the parental genes
• The new combination results from both crossing over and random segregation, allowing the individual alleles of maternally and paternally derived chromosomes to assort independently.

Question 52

What are the genetic consequences of fertilisation?

Answer 52

• 2 haploid gametes fuse to form a diploid zygote
• The genes in the zygote are a combination of the genes contributed by the parents; 50% maternal and 50% paternal (excluding crossing over)

Question 53

What are the genetic consequences of mutations?

Answer 53

• Mutations contribute to genetic variation in an individual and thus, genetic variability within a population.

Question 54

What is an Autosomal dominant pattern of inheritance?

Answer 54

Gene on chromosomes other than sex chromosomes; either sex can be affected. Affected individuals must carry at least one dominant allele. Unaffected parents will not produce affected offspring.

Question 55

What is an Autosomal recessive pattern of inheritance?

Answer 55

Gene on chromosomes other than sex chromosomes and either sex can be affected. Affected individuals must be homozygous recessive. 2 affected parents will have affected offspring. Unaffected parents can produce affected offspring.

Question 56

What is an X-linked dominant pattern of inheritance?

Answer 56

Does not skip gens. Affected males transmit the trait to all their daughters, but not their sons.

Question 57

What is an X-linked recessive pattern of inheritance?

Answer 57

More common in males than females. Affected females pass the trait to all their sons. Affected sons may be produced by normal parents.

Question 58

Heterozygous

Answer 58

Chromosomes have different alleles of the same gene e.g stem length

Question 59

Homozygous

Answer 59

Chromosomes have same alleles, e.g both dominant or both recessive.

Question 60

Variation

Answer 60

Differences in individuals, e.g height

Question 61

Variability

Answer 61

Different forms of a gene within a pop. Total of all alleles present in the gene pool of a pop. (e.g coat colour of Australian kelpie dog)

Question 62

Complete dominance

Answer 62

The phenotype of heterozygotes cannot be distinguished from homozygous dominants.

Question 63

Incomplete dominance

Answer 63

The phenotype of heterozygotes appears as a blend of the phenotypes of either type of homozygote.
(e.g pink snapdragons from red and white)

Question 64

Codominance

Answer 64

The phenotype of heterozygotes involves both alleles being expressed, with neither dominant over the other.
(e.g roan cattle)

Question 65

Compare continuous and discontinuous variation.

Answer 65

Height in humans shows continuous variation with a smoothly graded range of heights from short to tall, the result of many genes coding for the height. Single-gene inheritance in Mendel’s garden peas shows discontinuous variation; only 2 alleles for height; short or tall.

Question 66

Explain sex linkage and give an example.

Answer 66

Sex linkage occurs when genes on the X and Y chromosomes code for characteristics other than gender determination. If a gene occurs on the X chromosome, females will have 2 alleles whereas males will only have 1 allele, therefore recessive disorders occur more frequently in males. Haemophilia is an X-linked disorder - a male who inherits 1 mutant allele will suffer the condition as he has no dominant allele to mask the affected allele. A female with 2 recessive alleles will have a lethal form of the condition.

Question 67

Explain what an SNP is.

Answer 67

An SNP, a single nucleotide polymorphism is an error in DNA where one nucleotide is replaced by another. It usually arises during DNA replication where an incorrect nucleotide is inserted.

Question 68

Describe three applications of SNP data.

Answer 68

Some applications of identifying SNP markers, or haplotypes include:
It allows for the recognition of diseases
It allows for the establishment of family lineage by determining the genetic relatedness of individuals
Allows for the study of evolutionary relatedness.

Question 69

What are the limitations of SNP data.

Answer 69

It is only reliable as long as the regions selected are fairly evenly distributed throughout the genome.
Selection of markers is important as genetic markers that are closer together give more accurate data.
If there is crossing over during meiosis, the SNPs on a chromosome might not all be inherited together.

Question 70

Describe the Sanger method of DNA sequencing.

Answer 70

1. Isolate the DNA from the cells
2. Double-stranded DNA is separated into single strands by heating.
3. A primer binds to the start of the single strand of DNA, using it as a template to build the complementary strand of DNA using free nucleotides.
4. Chain terminating nucleotides in the reaction mixture. After they attach to their complementary base they prevent further nucleotides from attaching.
5. Each terminating nucleotide is labelled with a different fluorescent dye and will randomly combine with the complementary base on the strands of the DNA template, resulting in different lengths.
6. These strands are placed into a tiny capillary tube containing gel. Electric current pulls the strands through the gel, shorter strands move quicker.
7. Strands passed through laser beam –> glow.
8. A computer analyses colours and displays chromatogram of the sequence of bases in the original DNA sample.

Question 71

Describe the Polymerase Chain reaction technique of DNA sequencing.

Answer 71

Technique used to exponentially amplify large no.s of copies of a specific sequence of DNA.
Primer - short nucleic acid sequence provides a starting point for DNA synthesis.
DNA polymerase - enzyme responsible for making new copies of DNA.
A PCR machine used variations in temp to control the replication process via 3 steps;
1. Denaturation - DNA sample heated to separate it into 2 single strands (95°C for 1 min)
2. Annealing - primers attach to the 3’ ends of the target sequence (50°C for 1 min)
3. Elongation - heat-tolerant DNA polymerase binds to primer and copies the strand of DNA (22°C for 2 min). 30 cycles can give approx 1B copies of DNA.

Question 72

Describe the Gel electrophoresis technique of DNA sequencing.

Answer 72

Technique used to separate mixtures of DNA based on molecular size.

1. DNA extracted.
2. PCR isolation and amplification of DNA
3. DNA added to the gel wells.
4. Electric current applied to gel.
5. DNA bands separated by size (after a period of hrs)
6. DNA bands stained.

Question 73

How can PCR be used for DNA profiling?

Answer 73

It can be used to generate a DNA profile of parents concerned that they may be both carrying a recessive allele for a genetic disease, e.g CF. The process requires the sequence of the gene to be known so that specific primers (2) can be developed to target the genes associated with the disease. Once gene is amplified using PCR, it is analysed via gel electrophoresis to determine if the mutation is present.

Question 74

What is an Short Tandem repeat?

Answer 74

An STR is section of DNA unique to each individual, non-coding DNA that are repeated many times over. The no. of repeats at any given location in the non-coding regions of DNA carrier between individuals and gives rise to the different DNA profiles. Each individual has 2 alleles for each STR (1 from each parent) - the length of a large no. of STR’s can be used as a basis for identification.

Question 75

How does karyotyping work?

Answer 75

A karyotype is the no. and visual appearance of the chromosomes in the cell nuclei of an organism/species.
It requires dividing wbc’s from patient -> chromosomes are stained, counted, sorted in homologous chromosomes and analysed, under light micro at magnification of 1000-1500x. Used to detect abnormalities in whole chromosome no.s or structural issues.

Question 76

What is population genetics?

Answer 76

The study of genetic variation within a population, including changes in the frequency of genes and alleles within a population and among populations overtime.

Question 77

Provide examples and explain how population genetics data has been used in conservation management.

Answer 77

An example of this can be seen in the modern koala population. The control region of mitochondrial DNA in koalas was analysed to determine the different lineages and genetic diversity in koalas in Eastern Australia. It was found that the southern lineage of Koalas demonstrates the lowest genetic diversity compared to lineages from other regions. Scientists then use this information to determine future and current strategies for conservation. Population genetics can also be used to identify the regions where slized ivory has been poached, to then enable low enforcement efforts to focus time and budget on reducing poaching in those regions.

Question 78

Provide an example of population genetics being used to determine the inheritance of a disease or disorder.

Answer 78

An example of this is newborn screening tests.
They test for the SNPs associated with phenylketonuria, congenital hypothyroidism, cystic fibrosis, galactosaemia and many more congenital diseases, as most of these conditions are genetic. The data collected provide the potential for large-scale genomic analysis of newborns. Such screenings have a significant impact on individuals, through early detection and improved treatment options. They also assist in generating data about the occurrence of specific genetic conditions in a population.

Question 79

Polymorphism

Answer 79

Genetic difference.

Question 80

Monogenic

Answer 80

(of a disease) that results from a mutation in a single gene in all cells of the body.

Question 81

Compare the multiregional hypothesis and replacement hypothesis (Out of Africa theory)

Answer 81

Multiregional hypothesis

• relies mostly on fossil evidence
• suggests that all human populations can be traced back to when homo erectus first left Africa, about 2 million years ago
• suggests that there was Gene flow between neighbouring populations and that once they dispersed into other portions of the world, they slowly evolved into modern humans

Out of Africa Theory

• suggests that archaic Homo sapiens left Africa
• proposes that a second migration Out Of Africa happened about 100 000 years ago and that modern Humans of African origin conquered archaic groups and replaced them by integrating with and out-competing them.

Question 82

Which of the two theories, multiregional hypothesis or Out of Africa theory, does genetic evidence support?

Answer 82

Out of Africa theory - Genetic studies have shown that if the MRE were correct, common populations would contain ancient alleles scattered in different regions of the world. Research was done to investigate this and it was found that, among modern humans, most of the variation in mtDNA sequences occurs in African populations. The mtDNA of Europeans, Asians and the indigenous peoples of Australia, the Americas and Pacific Islands represent just a subset of total human mtDNA diversity.

Question 83

Outline the use of DNA fingerprinting as an investigation tool.

Answer 83

DNA fingerprinting is used to identify and compare individuals by characteristics in their DNA. The process involves isolating the DNA to be profiled which can come from a variety of cells such as saliva, blood or cheek cells. The Polymerase chain reaction is used to amplify the amount of the DNA sequence under study. Gel electrophoresis is then used to separate the segments based on their length, smaller fragments will move further in the gel. This then provides a DNA profile.

Question 84

Structure and function of proteins - Regulating metabolic functioning

Answer 84

Enzymes
Protein molecules involved in all biochemical aspects of cellular metabolism.
The enzyme amylase found in saliva helps change starches into sugars.

Hormones
Chemical messenger molecules secreted by endocrine glands.
The antidiuretic hormone (ADH) helps regulate the concentration of water in the body.

Question 85

Structure and function of proteins - Cell communication

Answer 85

Biological recognition
Occurs between chemical messengers and their target cells.
Antibodies recognise foreign invaders by the different proteins on the surfaces of their cells.

Signalling
Some proteins act as chemical messengers between cells, they communicate messages to a cell about the env around it and trigger responses.
The antibodies bind with these antigens to signal to other defence cells in the body that the invading antigens need to be destroyed.

Question 86

Structure and function of proteins - Sensory protein

Answer 86

Response to stimuli
These proteins change their shape or biochemical activity in response to stimuli.
Opsins are proteins in the retina (innermost layer) of the eye, they detect light.

Question 87

Structure and function of proteins - Storage and transport

Answer 87

Storage
Store chemicals for use by the organism.
Ferritin stores iron.

Transport
Some proteins bind to and carry or store chemicals in the body, they bind easily with the chemical and also release it when and where it is needed.
Haemoglobin has an affinity for O2, particularly where it is present in ∧ conc. It loses its affinity for O2 its conc is ∨.