3.1.10 SPECIES AND TAXONOMY

Q: Despite the fact that comparisons of DNA sequences can give more data about evolutionary relationships than amino acid sequences in proteins, it may be preferable to analyse protein structures. Suggest one practical reason why this may be the case. (1 MARK)

Protein is easier to isolate/extract from cells/tissues; [1 mark]

What is the binomial naming system?

genus, then species, genus is capitalized. Genus e.g. homo + species e.g. sapien = homo sapien

What is courtship behaviour?

increases the chance of successful mating & production of fertile offspring because: - Recognition of the same species - Stimulate the release of gametes - Recognise the opposite sex / geneder - Indicate sexual maturity - Established a pri bond to raise young - Synchronise mating → maximum probability that sperm will fertilise ovum Eg cricket song, 'dance' of birds of paradise

What is a species?

the largest group of similar organisms WITH similar features capable of interbreeding and producing fertile offspring.

Q: The three domains system is one mechanism of classifying organisms. The domains are shown in Figure 1 below: State two differences that would be seen between the cells of the bacteria and archaea kingdoms, and the cells of the eukarya kingdom. (2 MARKS)

- Bacteria and archaea cells are much smaller than cells of the eukarya; [1 mark] - Bacteria and archaea cells have no membrane-bound organelles / nucleus / endoplasmic reticulum / golgi / mitochondria / chloroplasts, while cells of the eukarya do; - Bacteria and archaea have a circular chromosome and eukarya have linear chromosomes; [1 mark] - Bacteria and archaea have smaller ribosomes than the eukarya; [1 mark]

Describe natural classification.

- Based on evolutionary relationships between organisms and their ancestors - Classifies species into groups using shared features derived from their ancestors - Arranges the group into a hierarchy, in which the groups are contained within larger composite groups with no overlap - Based on homologous characteristics; similar evolutionary origins regardless of their functions in the adult of a species - Eg the wing of a bird, the arm of a human, the front leg of a horse all have the same basic structure and all evolved from a common ancestor and are therefore homologous

Q: Describe one similarity and one difference between a phylogenetic system and a simple hierarchy. (2 MARKS)

- Both involve large groups that are divided into smaller groups (with no overlap); - A phylogenetic system is based on evolutionary history OR simple hierarchical system is based on shared characteristics;

Q: The red panda is native to South East Asia. These are two populations that are separated by a deep river gorge. These populations are very different from each other in appearance. How could scientists show that the two populations are the same species? (2 MARKS)

- Breed together red pandas from different areas - If fertile offspring, then still same species

Q: There are 18 different species of penguin, living almost exclusively in the Southern hemisphere. They feed on fish, squid, krill and other sea animals. A group of scientists wanted to find how closely related a group of different species of penguin (surviving and extinct) were and used the method of DNA hybridisation. This is a process where a single strand of DNA is taken from each species and mixed with the opposite strand from another species. Time is allowed to form a hybrid, double stranded DNA molecule by complementary base pairing. Table 1 shows the results of the scientists' investigation. Explain why, in Table 1, two members of P. antarcticus (chinstrap penguin) did not have 100% DNA hybridisation. Do not include sources of measurement error in your answer. (2 MARKS)

- Different members of the same species will have different alleles / versions of a gene; - Different genders / males and females may have different sex chromosomes / males have a shorter sex chromosome / males have XY karyotype but females have XX;

Q: The scientists analysed the amino acid sequences of the blood protein samples that were taken from the different specimens. Explain how these sequences could provide evidence to determine if specimen A and specimen B are different species. (2 MARKS)

- Different species will have different amino acid sequences OR more closely related organisms will have more similar amino acid sequences; [1 mark] - Amino acid sequences are the result of the alleles OR the amino acid sequences are a result of the DNA / DNA base sequences; [1 mark]

Q: The biologists analysed the amino acid sequences of the blood protein samples from two species of hummingbird. Explain how these sequences could provide evidence as to whether they are different species. (2 MARKS)

- Different species would have different amino acid sequences - Amino acid sequence is the result of DNA/alleles//base sequence

Describe artificial classification.

- Divides organisms according to differences that are useful at the time - Eg colour, size, number of legs - Analogous characteristics; same function but not the same evolutionary instincts

Q: Taxonomists use specific principles when classifying organisms into different groups. Explain what these are. (3 MARKS)

- Dividing large groups into smaller groups (with no overlap); - The members of a group have features in common based on their DNA /fossils /anatomy /embryology/homologous structures; - The groups reflect their evolutionary history;

Q: Songbirds use elaborate songs to attract a mate. This is a type of courtship behaviour. Explain one way in which courtship behaviour makes organisms more likely to mate successfully. (2 marks)

- E.g. courtship behaviour is species specific (1 mark). - This reduces the probability of animals mating with different species and producing infertile offspring (1 mark).

Q: During courtship, males of two species of fruitfly vibrate their wings. This produces a sound. Explain how this sound helps to ensure that the female mates only with a male of the same species. (2 MARKS)

- Female recognises own species sound - Responds to that sound only/courtship sequence continues

Q: Describe what Figure 1 below represents. Explain your answer. (3 MARKS)

- Figure 1 represents a hierarchy/ hierarchical system; [1 mark] - As there are small groups contained within a larger group; [1 mark] - With no overlap; [1 mark] - It is not a phylogenetic system as there are no details of evolutionary origin/relationships; [1 mark]

Q: Give one reason why DNA analysis has been useful in the field of taxonomy. (1 MARK)

- Gene/allele sequences can be compared (to establish relatedness/distinct species); - It can give more detail than observable/phenotypic differences (between organisms) OR it is useful when two species are very physically similar; [1 mark] - It can establish evolutionary history; [1 mark] - Can allow comparison with an extinct species to be made (provided their DNA is still intact); [1 mark]

Q: There are 18 different species of penguin, living almost exclusively in the Southern hemisphere. They feed on fish, squid, krill and other sea animals. A group of scientists wanted to find how closely related a group of different species of penguin (surviving and extinct) were and used the method of DNA hybridisation. This is a process where a single strand of DNA is taken from each species and mixed with the opposite strand from another species. Time is allowed to form a hybrid, double stranded DNA molecule by complementary base pairing. Table 1 shows the results of the scientists' investigation. The scientists measured the temperatures at which each sample of hybrid DNA separated into single strands. Explain how the information obtained could be used to find the percentage of hybridisation. (3 MARKS)

- If there is greater DNA hybridisation then there must be more hydrogen bonding formed between the bases; [1 mark] - (...which requires) more energy / a higher temperature to break; [1 mark] - If two species are more closely related, DNA sequences will be more alike / they will form more/a greater percentage of complementary base pairing; [1 mark]

Q: The proteins of different species can be compared using immunological techniques. The protein albumin obtained from a human was injected into a rabbit. The rabbit produced antibodies against the human albumin. These antibodies were extracted from the rabbit and then added to samples of albumin obtained from four different animal species. The amount of precipitate produced in each sample was then measured. The results are shown in the table. What do the results suggest about the evolutionary relationship between humans and other species? (2 MARKS)

- Most closely related to chimpanzee - Least closely related to trout

Q: The offspring produced from breeding a horse with a donkey is known as a mule. The body cells of a horse contain 64 chromosomes while the body cells of a donkey contain 62 chromosomes. Predict whether mules are fertile or infertile. Explain your answer. (3 MARKS)

- Mules will be infertile; [1 mark] - Their body cells will have 63 chromosomes OR their body cells will have an odd/uneven number of chromosomes; [1 mark] - As a result, the chromosomes cannot pair / are not homologous OR the chromosome number cannot be halved OR meiosis cannot occur / haploid cells are not produced;

Q: Before protein analysis and DNA sequencing became available as techniques for establishing evolutionary relationships, state two kinds of observation that taxonomists could make to distinguish between two species. (2 MARKS)

- Physical features (appearance, colour, size); [1 mark] - Behavioural differences (habitat, feeding patterns, migration, diet, courtship behaviour, etc.); [1 mark]

What is a hierarchy?

- Smaller groups placed within larger groups - No overlap between each group

Q: There are over 200 species of catfish. All catfish evolved from a common ancestor. The diaphragm shows how some species of catfish are classified. This diagram is based on the evolutionary links between these species. 1. Which species of catfish is most closely related to Synodontis membranacea? (1 MARK) 2. Which species of catfish is most distantly related to Synodontis membranacea? (1 MARK) 3. How many different genera are shown in this diagram? (1 MARK)

- Synodontis batensoda - Mochokus niloticus - 5

Q: DNA comparisons between extinct and living species can be made in order to establish evolutionary relationships. Suggest one reason why DNA analysis of extinct species can be challenging. (1 MARK)

- The DNA must be preserved/intact / DNA can break down easily / DNA is fragile / ancient DNA can have gaps in it; [1 mark] - It is easy for a sample from an extinct species to become contaminated with modern - DNA / DNA from living organisms; [1 mark] - DNA is only preserved in tissues e.g. bones, hair, teeth / not preserved in petrified/stone fossils; [1 mark]

Q: The red panda has 36 chromosomes per somatic cell whereas the giant panda has 42 chromosomes. Offspring born when these two species mate are infertile. Suggest why.

- The offspring will have a diploid number of 39 / (78÷2) SO the chromosomes cannot pair; [1 mark] - The chromosomes are not homologous / meiosis cannot occur / haploid cells cannot be made; [1 mark]

Q: Comparisons of DNA sequences are more accurate than the amino acid sequences in proteins. Explain why. (1 MARK)

- There are 3 DNA bases for every one amino acid OR the triplet code is degenerate / base mutations may not affect amino acid sequence/protein structure; [1 mark]

Q: Ailuropoda melanoleuca, the giant panda, and Ailurus fulgens, the red panda, are both native to China. The following evolutionary evidence suggests that these two panda species are closely related. - They live in similar environments; - They both digest bamboo as a primary source of food; - They both have a pseudo-thumb (a sixth digit) used to grip and shred food such as bamboo. Table 1 shows the differences between a comparable sequence of mitochondrial DNA of four different mammals. A group of students concluded that the raccoon is most closely related to the black bear. Use Table 1 to evaluate this conclusion. (2 MARKS)

- There is only one base difference between the raccoon and black bear; [1 mark] - The DNA sequence being compared is very short SO it may not be representative / there may be larger differences elsewhere in the DNA / in nuclear DNA; [1 mark]

EQ: Scientists have discovered five new species, A, B, C, D and E, of Chinese giant salamander. In their natural habitat all of these species are in danger of extinction. Large populations of species B are kept in captive breeding farms.The Chinese government has taken action to conserve salamanders by releasing individual salamanders from the breeding farms into rivers. Figure 3 shows how species A-E may have evolved. Explain what Figure 3 shows about the evolutionary relationships between species B and the other four species. (2 MARKS)

1. Species B most closely related to species C as they share a more/most recent common ancestor; 2. Species B more related to species D and E than to species A as they share a more recent ancestor; OR Species B least related to species A as they share a more/most distant common ancestor/diverged a long time ago/before the other species;

EQ: Male fireflies emit flashes of light as part of their courtship behaviour to attract females of the same species. Different species of firefly emit flashes lasting different lengths of time. Scientists studied three different species of firefly living in the same community. They recorded the length of the flashes of 1000 males from each species. Figure 5 shows the results they obtained. Fireflies that have a flash length between 0.7 and 0.8 seconds are less likely to pass their alleles on to the next generation. Suggest why. (2 MARKS)

1. These males are more likely to accidentally mate/form hybrids with females of a different species; 2. Hybrids are inviable/sterile/non-fertile (so alleles can't be passed on);

EQ: Figure box 5 represents the phylogenetic classification of four different species of fruit fly 1. Figure 5 shows a hierarchy. Explain how. (2 MARKS) 2. Name the taxon to which Drosophilidae belongs. (1 MARK)

1. - (It shows) smaller groups within larger groups / larger groups containing smaller groups; - With no overlap (between groups); 2. Family;

Q: Explain what is meant by a phylogenetic group. (1 MARK)

(Grouped according to) evolutionary links/history/relationships / common ancestry

Q: Explain how genome sequencing can be used to deduce evolutionary relationships between organisms, such as the giant panda and red panda. (3 MARKS)

- (Determining the) sequence / order of bases in DNA OR mRNA; - Comparing multiple regions of the genome allows for more representative data SO conclusions can be drawn; - The greater the differences between gene sequences, the less closely related the species are; - Which allows silent mutations to be examined / changes in DNA where the same amino acid is still coded for / there is no phenotypic variation;

Q: Scientists studied the amino acid sequence of cytochrome c in five different animals. The number of differences in the amino acid sequence were recorded and compared with human cytochrome c. Table 1 below shows their results. An assistant who looked at the results in Table 1 suggested that dogs were more closely related to ducks than to any of the other animals. Is this conclusion credible? Justify your answer. (3 MARKS)

- (The amino acid sequences of cytochrome c has been) compared with humans cytochrome c/ not compared with each other's cytochrome c; [1 mark] - DNA is degenerate OR more than one triplet codes for an amino acid; [1 mark] - (The amino acid) differences may be at different positions OR different amino acids may be affected - OR the data does not show where the differences are (in the amino acid sequence); [1 mark]

Q: The diagrams show two systems of classification of mammals. Figure 2 shows a simple hierarchy. Figure 3 shows a phylogenetic system. By reference to Figures 2 and 3, explain how a phylogenetic system differs from a simple hierarchy. (3 MARKS)

- (phylogenetic) based on evolutionary history; - shows ancestry of groups / points of divergence / example, - e.g. reptiles and birds separated after mammals / reptiles - and birds more closely related than mammals; - (hierarchical) based on shared characteristics (seen today);

Q: There are 18 different species of penguin, living almost exclusively in the Southern hemisphere. They feed on fish, squid, krill and other sea animals. A group of scientists wanted to find how closely related a group of different species of penguin (surviving and extinct) were and used the method of DNA hybridisation. This is a process where a single strand of DNA is taken from each species and mixed with the opposite strand from another species. Time is allowed to form a hybrid, double stranded DNA molecule by complementary base pairing. Table 1 shows the results of the scientists' investigation. Explain what the data in Table 1 shows about the evolutionary relationships between the different species of penguin. (2 MARKS)

- A. patagonicus and A. forsteri are most closely related because they have the highest percentage DNA hybridisation; [1 mark] - P. antracticus and P. adeliae are very closely related because they have a very high percentage DNA hybridisation; [1 mark] - A. forsteri and P. adeliae are furthest-related / in different genera / largest difference between DNA sequences; [1 mark]

Describe the phylogenetic classification system

- Arranges species into groups based on their evolutionary origins (common ancestors) and relationships - Family tree = hierarchy - Hierarchy = Smaller groups placed within larger groups No overlap between each group - Each group = taxon - Taxon: level in hierarchy

Ways to determine similarities between he DNA of different organisms: DNA hybridisation

- When DNA is heated, double strands separate into two complementary single strands. When cooled, complementary single strands recombine to reform double strand - This can be used to compare the DNA of two species by - DNA from two species extracted, purified, cut into short pieces - DNA from one of the species is labelled by attaching a radioactive or fluorescent marker to it. It is then mixed with unlabelled DNA from the other species - The mixture of both sets of DNA is heated to separate their strands - The mixture is cooled to allow the strands to combine with other strands that have a complementary sequence of bases - Some of the double strands that reform will be made up of one strand from each species. This is called hybridisation and the new strands are called hybrid strands. These can be identified because they are 50 percent labelled - These hybrid strands are separated out and the temperature is increased in stages - At each temperature stage the degree to which the two strands are still linked together is measured - If the two species are closely related they will share many complementary nucleotide bases - There will therefore be more hydrogen bonds linking them together in the hybrid strand - The greater the number of hydrogen bonds, the stronger the hybrid strand will be - The stronger the hybrid strand, the higher the temperature needed to separate it into its two single strands - The higher the temperature at which the hybrid strand splits, the more closely the two species are related - The lower the temperature at which it splits, the more distantly the species are related.

Q: On Christmas Eve 1987, the last female Spix's Macaw, Cyanopsitta spixii, was removed from the wild in Brazil. The last remaining male bird continued to live in the wild for a further six years. This male bird, having lost its partner, mated with a Blue-winged Macaw, Propyrrhura maracana. Explain why eggs produced by this mating did not hatch. (2 MARKS)

- different species/ different genus - genetically incompatible/ (may have) different number of chromosomes / physical / - behavioural , reason for reproductive incompatibility e.g. eggs remain unfertilised / different incubation patterns

Offspring from 2 different species mating may be ________ because they will have an odd number of chromosomes so cant perform meiosis to produce (haploid) _______ (gametes)

- infertile - sex cells

Q: The system used by scientists for classifying living things has developed from the original classification system proposed by Carl Linnaeus around 250 years ago. Complete the following paragraph by using the most appropriate term(s). The system of classifying organisms according to their observable features or genetic characteristics is called ___________. Organisms are classified into large groups which are then subdivided into increasingly smaller groups. A system such as this is called a __________. The term that describes the evolutionary relationship between organisms is _______. (3 MARKS)

- taxonomy / taxonomic - Hierarchy - phylogeny / phylogenetic

EQ: Male fireflies emit flashes of light as part of their courtship behaviour to attract females of the same species. Different species of firefly emit flashes lasting different lengths of time. Scientists studied three different species of firefly living in the same community. They recorded the length of the flashes of 1000 males from each species. Figure 5 shows the results they obtained. Describe the results shown in Figure 5. (2 MARKS)

1. (Most common/modal) flash length longest in P.hemipterus/shortest in P. pyralis; 2. P. castus has largest spread of data/flash lengths; 3. Overlap in data between P. pyralis and P.castus/no overlap in the data beween P. hemipterus and any other species; 4. Data normally distributed for all the species;

EQ: To reduce the damage caused by insect pests, some farmers spray their fields of crop plants with pesticide. Many of these pesticides have been shown to cause environmental damage. Bt plants have been genetically modified to produce a toxin that kills insect pests. The use of Bt crop plants has led to a reduction in the use of pesticides. Scientists have found that some species of insect pest have become resistant to the toxin produced by the Bt crop plants. Figure 6 shows information about the use of Bt crops and the number of species of insect pest resistant to the Bt toxin in one country. 1. Can you conclude that the insect pest resistant to Bt toxin found in the years 2002 to 2005 was the same insect species? Explain your answer. (1 MARK) 2. One farmer stated that the increase in the use of Bt crop plants had caused a mutation in one of the insect species and that this mutation had spread to other species of insect. Was he correct? Explain your answer. (4 MARKS) 3. There was a time lag between the introduction of Bt crops and the appearance of the first insect species that was resistant to the Bt toxin. Explain why there was a time lag. (3 MARKS)

1. (No - no mark); Graph/bar chart only shows number of species, not the name of the species; 2. - Mutations are spontaneous/random; - Only the rate of mutation is affected by environment; - Different species do not interbreed/do not produce fertile offspring; - So mutation/gene/allele cannot be passed from one species to another; 3. - Initially one/few insects with favourable mutation/allele; - Individuals with (favourable) mutation/allele will have more offspring; - Takes many generations for (favourable) mutation/allele to become the most common allele (of this gene);

Q: A zedonk is the offspring produced from breeding a mountain zebra with a donkey. • The body cells of a mountain zebra contain 32 chromosomes. • The body cells of a donkey contain 62 chromosomes. Use this information to suggest why zedonks are usually infertile. (2 MARKS)

1. (Zedonk has) 47 / odd / uneven number of chromosomes; 2. Chromosomes cannot pair / are not homologous / chromosome number cannot be halved / meiosis cannot occur / sex cells / haploid cells are not produced;

EQ: Drosophila box fruit flies display courtship behaviour. One of the stages of courtship is singing by males. Normally a male will produce a 'sine song', in which continual noise is made, and a 'pulse song', in which there is continual noise with some louder peaks. Scientists showed fruit flies a visual stimulus that made them sing. They made recordings of these songs. Figure 6 shows the recordings of the songs of three flies over the same time period. 1. D. erecta and D. willistoni are closely related species but different species. Describe evidence from Figure 6 that supports this statement. (2 MARKS) 2. The scientists repeated their experiments, using female fruit flies as the visual stimulus. When a male and female D. willistoni were together, their songs led to mating. When two female D.willistoni were together, their songs did not lead to any attempt to mate. Use information from Figure 6 to suggest why the two females did not attempt to mate. (2 MARKS)

1. - Sine song is (very) similar / same length (for both, so closely related). - (But) have different peaks / pulses (in pulse song); 2. - (Three) peaks (in pulse song) occur at the same time (since both female) / songs identical / male peaks are different; - (Therefore) no male (song) to stimulate / cause mating; OR Nothing to stimulate / cause mating;

EQ: Scientists investigated the effect of hunting on the genetic diversity of otters. Otters are animals that were killed in very large numbers for their fur in the past. The scientists obtained DNA from otters alive today and otters that were alive before hunting started. For each sample of DNA, they recorded the number of base pairs in alleles of the same gene. Mutations change the numbers of base pairs over time. Figure 6 shows the scientists' results. 1. The scientists obtained DNA from otters that were alive before hunting started. Suggest one source of this DNA. (1 MARK) 2. What can you conclude about the effect of hunting on genetic diversity in otters? Use data from Figure 6 to support your answer. (2 MARKS)

1. Bone/skin/preserved remains / museums; 2. - (Hunting) reduced population size(s), so (much) only few alleles left; - Otters today from one/few surviving population(s); - Inbreeding;

EQ: There is genetic diversity within HPV. Give two ways doctors could use base sequences to compare different types of HPV.

1. Compare (base sequences of) DNA; 2. Look for mutations/named mutations (that change the base sequence); 3. Compare (base sequences of) (m)RNA;

EQ: Figure 5 shows two dogs, a Chihuahua and a Great Dane. All dogs are members of the same species. A species may be defined as a group of organisms capable of interbreeding and producing fertile offspring. Suggest the difficulty with using this definition.Use information from Figure 5 to support your answer. (2 MARKS)

1. Considerable variation within a species; 2. Interbreeding may not be possible;

One hierarchy comprises the taxa:

1. Domain (drunken) 2. Kingdom (kangaroos) 3. Phylum (punch) 4. Class (children) 5. Order (on) 6. Family (family) 7. Genus (game) 8. Species (shows) Dominant, kinky, people, can, often, find, good, sex. Eg humans: eukarya, animalia, chordata, mammalia, primates, hominidae, homo, sapiens

Q: The RuBisCo gene is found in all plants. When a new species of plant is being classified, this gene is often compared with the gene in other species to determine evolutionary relatedness. 1. Explain why the RuBisCo gene is useful for determining relationships between plant species. (1 mark) 2. Evolutionary relationships could also be determined by comparing the RuBisCo protein itself. Describe one way in which proteins from two different organisms could be used to determine evolutionary relationships. (2 marks)

1. It is present in all plants so any two species of plant can be compared by looking at RuBisCo (1 mark). 2. - Any one from, e.g. by comparing the amino acid sequence (1 mark). - The more similar the amino acid sequences the more closely related the species are (1 mark). - By using immunological comparison (1 mark). - If two proteins are bound by the same antibody they must be similar and the two species must be closely related (1 mark).

Q: Cytochrome C is a protein found in living organisms. The structure of cytochrome C varies between different organisms. However, closely related organisms have similar cytochrome C. Fig. 5.1 shows a possible evolutionary tree for vertebrates. Common ancestors are indicated by the number 1 and various letters. State the letter of the common ancestor that has cytochrome C which will be: 1. most similar in structure to common ancestor 1 2. least similar in structure to common ancestor 1 (2 MARKS)

1. J 2. T

EQ: Haemoglobins are chemically similar molecules found in many different species. Differences in the primary structure of haemoglobin molecules can provide evidence of phylogenetic (evolutionary) relationships between species. Explain how. (5 MARKS)

1. Mutations change base / nucleotide (sequence); 2. (Causing) change in amino acid sequence; 3. Mutations build up over time; 4. More mutations / more differences (in amino acid / base / nucleotide sequence / primary structure) between distantly related species; OR Few(er) mutations / differences (in amino acid / base / nucleotide sequence / primary structure) in closely related species; 5. Distantly related species have earlier common ancestor; OR Closely related species have recent common ancestor;

EQ: Table 1 shows the taxons and the names of the taxons used to classify one species of otter. They are not in the correct order. 1. Put letters from Table 1 into the boxes in the correct order. Some boxes have been completed for you. (1 MARK) 2. Give the scientific name of this otter. (1 MARK)

1. PKNJ; 2. Lutra lutra

EQ: DNA taken from Photinus pyralis and Photinus castus was hybridised and then reheated. The hybrid strands separated at 80 °C. DNA from Photinus pyralis and Phosphaenus hemipterus was also hybridised and then reheated. The hybrid strands separated at 75 °C. Use these results to conclude which two species are most likely to share the most recent common ancestor. Two species sharing the most recent common ancestor are ..... Explain how you reached this conclusion. (3 MARKS)

1. Photinus pyralis and Photinus castus; And any two from: 2. Idea of more complementary base pairing between closely related/correctly named species; 3. More hydrogen bonds forming; 4. More heat/energy needed to break (the hybridised) strands apart;

EQ: Some populations of animals that have never been hunted show very low levels of genetic diversity. Other than hunting, suggest two reasons why populations might show very low levels of genetic diversity. (2 MARKS)

1. Population might have been very small/genetic bottleneck; 2. Population might have started with small number of individuals / by one pregnant female / founder effect; 3. Inbreeding;

What is the advantage of the binomial naming system of organisms?

Advantage - universal; no confusion as many organisms have more than one common name

Immunology and genome sequencing help to clarify evolutionary relationships between organisms, Phologenetics:

Gene Sequencing: - Compare the order of base sequence of whole genome of different species (ATCG's) - Higher % match = more closely related - Humans and chimps = 96% related Immunology: - DNA → mRNA → sequence of amino acids in polypeptide → proteins - Tertiary structure of protein tells us about sequence of DNA - If same antibodies bind to a species' antigen then it is closely related