10) Classification and Evolution

Question 1

What is a species?

Answer 1

A group of similar organisms that can interbreed to produce fertile offspring.

Question 2

What is the order of taxonomic hierarchy?

Answer 2

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species.

Question 3

What is binomial nomenclature?

Answer 3

A two-part naming system (Genus + species) in Latin, e.g., Homo sapiens. Genus is capitalized; both parts are italicized.

Question 4

List the five kingdoms and a key feature of each.

Answer 4

Prokaryotae: Unicellular, no nucleus (e.g., bacteria).

Protoctista: Mainly unicellular, has a nucleus (e.g., amoeba).

Fungi: Chitin cell wall, (e.g., yeast).

Plantae: Cellulose cell wall, autotrophic (e.g., oak tree).

Animalia: No cell wall, heterotrophic (e.g., humans).

Question 5

What are the three domains and what are they based on?

Answer 5

A higher classification level based on differences in rRNA and cell structure.

Archaea: Prokaryotes in extreme environments.

Bacteria: “True” bacteria (Eubacteria).

Eukarya: All organisms with a nucleus (Protoctista, Fungi, Plantae, Animalia).

Question 6

What is phylogeny?

Answer 6

The study of the evolutionary history and relationships between organisms.

Question 7

What is a phylogenetic tree?

Answer 7

A diagram showing evolutionary relationships. Closer branches = closer relationship. Nodes represent common ancestors.

Question 8

How do fossils provide evidence?

Answer 8

The fossil record shows a sequence from simple to complex organisms in rock strata, indicating gradual change over time.

Question 9

What is a homologous structure?

Answer 9

Structures with the same evolutionary origin but different functions (e.g., pentadactyl limb in vertebrates). Evidence for divergent evolution.

Question 10

How does comparative biochemistry provide evidence?

Answer 10

Closely related species have more similar DNA and protein sequences (e.g., cytochrome c). Molecular clocks use the rate of neutral mutations to estimate time since divergence.

Question 11

What is embryology evidence?

Answer 11

Similar early stages of development in different species suggest common ancestry (e.g., all vertebrates have gill slits as embryos).

Question 12

What is the difference between interspecific and intraspecific variation?

Answer 12

Interspecific: Variation between different species. I

Intraspecific: Variation within a single species.

Question 13

What causes variation?

Answer 13

Genetic: Alleles, mutation, meiosis, sexual reproduction.

Environmental: Diet, climate, accidents (e.g., scars).

Most characteristics are a combination of both.

Question 14

What does standard deviation measure?

Answer 14

The spread of data around the mean. A larger SD means data is more spread out (greater variation).

Question 15

What is the rule for a normal distribution?

Answer 15

68% of values lie within ±1 SD of the mean. 95% within ±2 SD.

Question 16

What is the purpose of the t-test?

Answer 16

To compare the means of two sets of data to see if they are significantly different.

Question 17

How do you interpret the result?

Answer 17

Calculate t-value and degrees of freedom (df). Compare to critical value at p=0.05. If t > critical value, reject the null hypothesis (the difference is significant).

Question 18

What does Spearman’s rank measure?

Answer 18

The strength and direction of a relationship (correlation) between two variables.

Question 19

What do the values mean?

Answer 19

+1: Perfect positive correlation.

-1: Perfect negative correlation.

0: No correlation.
Compare calculated value (ρ) to critical value at p=0.05 to determine significance.

Question 20

What are the three types of adaptation?

Answer 20

Anatomical: Physical features (e.g., thick fur, sharp teeth).

Behavioural: Ways an organism acts (e.g., migration, tool use).

Physiological: Internal processes (e.g., venom production, temperature regulation).

Question 21

What is convergent evolution?

Answer 21

Unrelated species evolve similar traits (analogous structures) due to adapting to similar environments/selections pressures (e.g., shark and dolphin fins, marsupial and placental moles).

Question 22

What is divergent evolution?

Answer 22

Related species evolve different traits (homologous structures) from a common ancestor due to adapting to different environments (e.g., pentadactyl limb).

Question 23

Outline the process of natural selection.

Answer 23

Variation exists in a population due to mutations/meiosis.

A selection pressure (e.g., predation, competition) exists.

Individuals with advantageous alleles are better adapted and more likely to survive and reproduce.

These individuals pass on the advantageous alleles.

Over time, the frequency of the advantageous allele increases in the population.

Question 24

How did antibiotic resistance (e.g., MRSA) evolve?

Answer 24

Mutation provided resistance. Antibiotic acted as a selection pressure, killing non-resistant bacteria. Resistant bacteria survived and reproduced, passing on the resistance allele.

Question 25

What happened to peppered moths?

Answer 25

Selection pressure: Bird predation. Pale moths were camouflaged on clean trees. Soot from pollution darkened trees. Dark moths then had the selective advantage, so their allele frequency increased.

Question 26

What is the difference between Bacteria and Archaea

Answer 26

Archaea and bacteria have several important differences. For example, archaea have cell walls without peptidoglycan, while bacterial cell walls contain peptidoglycan. Archaea also show a closer evolutionary relationship to eukaryotes than to bacteria.

Question 27

What are the 5 evidence for evolutions

Answer 27

anatomy molecular biology biogeography fossils direct observation

Question 28

What is used to determine the age of the rocks?

Answer 28

To establish the age of a rock or a fossil, researchers use some type of clock to determine the date it was formed. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events.

Question 29

What are the principles of Darwin's theory of evolution by natural selection?

Answer 29

individual organisms within a particular species show a wide range of variation for a characteristic individuals with characteristics most suited to the environment are more likely to survive to breed successfully the characteristics that have enabled these individuals to survive are then passed on to the next generation

Question 30

What are the main genetic causes of variation within a species (intraspecific variation)?

Answer 30

Genetic variation is caused by differences in the DNA sequence (genotype). The main causes are: Alleles: Different versions of the same gene exist (e.g., alleles for blood group A, B, or O). Individuals inherit different combinations from their parents. Mutation: A random, permanent change in the DNA base sequence. This creates new alleles and is the original source of all genetic variation. Meiosis: Homologous chromosomes exchange genetic material during Prophase I, creating new combinations of alleles on chromosomes. The random lining up of homologous pairs during Metaphase I leads to gametes with many different combinations of maternal and paternal chromosomes. Sexual Reproduction: Combines genetic material from two parents, creating a unique combination of alleles in the offspring that differs from both parents. Random Fertilisation: The fusion of a randomly selected male gamete with a randomly selected female gamete, further increasing genetic variation.

Question 31

What are the main environmental causes of variation, and how do they interact with genetics?

Answer 31

Environmental variation is caused by differences in an organism's surroundings and experiences. The main causes are: Climate & Weather: Access to sunlight, temperature, and rainfall (e.g., a well-watered plant vs. a drought-stressed plant). Diet & Nutrition: Quality and quantity of food available (e.g., human height can be stunted by poor nutrition despite genetic potential). Lifestyle & Accidents: Physical experiences like scars, injuries, or muscle development from exercise. Social Factors: For humans and some animals, cultural influences and learned behaviors. Chemical Factors: Soil pH for plants (e.g., hydrangea flower color is blue in acidic soil and pink in alkaline soil). Key Point: Environmental variation affects the phenotype but not the genotype. It is not heritable (e.g., a scar cannot be passed to offspring). Most characteristics (e.g., height, intelligence, skin colour) are a result of a complex interaction between genetic predisposition and environmental factors

Question 32

What are the point of Twin Studies?

Answer 32

The use of twins can improve the statistical power of a genetic study by reducing the amount of genetic and/or environmental variability; the extent to which different assumptions matter may depend on which trait is being studied.

Question 33

What are Analogous structures?

Answer 33

Analogous structures are features of different species that are similar in function but not necessarily in structure and which do not derive from a common ancestral feature (compare to homologous structures) and which evolved in response to a similar environmental challenge.

Question 34

How do analogous structures show convergent evolution?

Answer 34

Analogous structures are said to be the result of convergent evolution because though they perform similar function but are different in their structural details and origin e.g. wing of insects birds and bats like unrelated organisms.

Question 35

What is the Founder Effect?

Answer 35

A founder effect occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have: a reduction in genetic variability from the original population.

Question 36

Why is there limitation in the fossil record for studying evolution?

Answer 36

There are gaps in the fossil record because many early forms of life were soft-bodied. The soft parts of organisms do not form fossils well. This means there is little information about what these organisms looked like. Any traces of fossils that there may have been were likely destroyed by geological activity. This is why scientists cannot be certain about how life began.

Question 37

What does the study of Sheep Blowflies (Lucilia cuprina) demonstrate about evolution?

Answer 37

It is a classic example of rapid evolution by natural selection and the concept of pre-adaptation. Selection Pressure: The pesticide diazinon was used in the 1950s to control blowflies that cause "flystrike" in sheep. Process: A random mutation provided resistance to diazinon in some flies. These resistant individuals survived, reproduced, and passed the resistance allele to their offspring. Within six years, the population evolved high resistance. Key Finding (Pre-adaptation): Scientists found that pre-existing resistance alleles for a similar pesticide (malathion) were already present in the population decades before diazinon was used. This pre-adaptation allowed resistance to evolve extremely quickly when the new selection pressure was applied. Conclusion: Evolution can occur very rapidly when selection pressure is strong, especially if genetic variation for resistance already exists.

Question 38

How is a new species formed?

Answer 38

A new species forms through speciation, which requires reproductive isolation. The most common path is allopatric speciation: Isolation: A population is split by a geographical barrier (e.g., a mountain range or river). Divergence: The separated groups evolve independently due to different selection pressures and mutations. Incompatibility: Genetic differences accumulate until the groups can no longer interbreed to produce fertile offspring (the definition of a species). This creates a new, reproductively isolated species.

Question 39

How is a new genus formed?

Answer 39

A genus is a group of closely related species. A new genus is formed after multiple speciation events and significant divergent evolution over a very long time. As species within a genus continue to evolve and accumulate differences, some become so genetically and morphologically distinct from their original group that they are reclassified into a new genus. In short: New species form by splitting. New genera form from the accumulated divergence of multiple species from a common ancestor.

Question 40

What is interspecific variation?

Answer 40

Interspecific variation refers to the differences in characteristics that exist between different species. Cause: It is caused by species having different gene pools. Each species has a unique set of genes and alleles, leading to distinct phenotypes. Scale: The differences are usually large and discontinuous (e.g., the presence of feathers vs. fur, number of legs, type of nutrition). Why it matters: These differences are fundamental for classification and allow us to distinguish one species from another.