4.2.2 Classification and evolution Flashcards
(72 cards)
1
Q
What is the main purpose of biological classification?
A
- Identify new species
- Study evolutionary relationships
- Understand shared traits and adaptions
- Share research globally
2
Q
What is a species?
A
A species is a group of organisms that are able to breed to produce fertile offspring.
3
Q
List the 8 taxonomic ranks from broadest to most specific.
A
- Domain
- Kingdom
- Phlylum
- Class
- Order
- Family
- Genus
- Species
4
Q
Name the three domains in which all organisms are classified.
A
- Bacteria (prokaryotes)
- Archaea (prokaryotes, but genetically distinct)
- Eukarya (all eukaryotes)
5
Q
Which four kingdoms are part of the domain Eukarya?
A
- Plantae
- Animalia
- Protoctista
- Fungi
6
Q
What is the binomial naming system?
A
A two-part Latin naming system for species:
- First part: Genus (capitalised)
- Second part: species (lowercase)
Typed in italics or underlined if handwritten
For example, Homo sapiens
7
Q
List the five kingdoms of life in the traditional classification system.
A
- Plantae
- Animalia
- Prokaryotae
- Protoctista
- Fungi
8
Q
What type of cell does each kingdom have?
A
- Prokaryotic - Prokaryotae
- Eukaryotic - Protoctista, Fungi, Plantae, Animalia
9
Q
What cellular organisation does each kingdom have?
A
- Multicellular - Plantae, Animalia, Fungi
- Unicellular - Prokaryotae, Fungi, Protoctista
10
Q
Do the kingdoms have cell walls?
If yes, what are they made of?
A
Plantae - Yes, cellulose
Animalia - No
Prokaryotae - Yes, peptidoglycan (murein)
Protoctista - Variable
Fungi - Yes, chitin
11
Q
How do the five kingdoms obtain nutrition?
A
- Plantae: Autotrophic (photosynthesis)
- Animalia: Heterotrophic
- Fungi: Saprophytic (absorb nutrients from dead matter)
- Prokaryotae, Protoctista: Autotrophic, Heterotrophic, or parasitic
12
Q
What form of energy storage is used in each kingdom?
A
- Plantae: Starch (amylose & amylopectin)
- Animalia, Fungi, Prokaryotae: Glycogen
- Protoctista: Variable
13
Q
How do fungi reproduce?
A
Production and dispersal of spores
14
Q
What key change did the three domain system introduce?
A
It splits Prokaryotae into two separate domains:
- Bacteria - Eubacteria (kingdom)
- Archaea - Archaebacteria (kingdom)
The three domain system proposes six kingdoms instead of five.
15
Q
What are some features of domain Bacteria?
A
- Contains the kingdom Eubacteria only, found in all environments.
- Prokaryotic unicellular organisms.
- Have peptidogylcan (murein) in their cell walls.
- Unique RNA polymerase enzyme.
16
Q
What are some features of the Domain Archae?
A
- Contains the kingdom Archaebacteria only, typically found in extreme environments.
- Prokaryotic unicellular organisms.
- Have histones so gene and protein synthesis is more similar to Eukarya than Bacteria.
- No peptidogylcan in their cell walls.
- Different cell membranes that contain fatty acids bound to glycerol by ether linkages.
- Have a more complex form of RNA polymerase than Bacteria.
17
Q
What is the main feature of Domain Eukarya making it different to other?
A
All have nuceli and membrane-bound organelles.
18
Q
What is phylogeny?
A
The study of the evolutionary history and relationships among species.
19
Q
What is phylogenetic classification based on?
A
It is based on evolutionary relationships between organisms and their ancestors, grouping species by common ancestry.
20
Q
Give two advantages of phylogenetic classification.
A
- Forms a continuous evolutionary tree without forcing organisms into fixed groups.
- No overlap between groups
21
Q
What does a phylogenetic tree show?
A
A diagram that maps evolutionary relationships.
- Branching points = common ancestors
- Proximity = closeness of relation
- Length of branches = evolutionary distance
22
Q
What is artificial classification based on?
A
It groups organisms based on observable traits, like size, shape, or colour.
Not evolutionary history.
For example, sharks (fish) and dolphins (mammals) both have dorsal fins.
23
Q
List four types of evidence used in modern classification.
A
- Molecular comparisons - between DNA and amino acids in proteins, e.g. cytochrome C
- Developmental studies - comparisons of embryonic similaries and differences
- Anatomic examinations - Comparisons of similarities in species’ physical characteristics, e.g. from fossils.
- Behavioural analysis - comparisons of behaviour of species.
24
Q
Who proposed the theory of evolution by natural selection?
A
Charles Darwin and Alfred Russel Wallace independently proposed it.
25
What does **natural selection** suggest?
Organisms **best suited** to their environment are more likely to survive, reproduce and pass on their **advantageous characteristics** to their offspring.
26
What is the key evidence from the **fossil record** that supports evolution?
* Simple bacteria and algae fossils are found in the **oldest** rocks, progressing to more **complex vertebrates** in newer rocks.
* Plant fossils appear before those of animals that feed on these plants, indicating a natural order of evolution.
(organisms evolved gradually in response to environmental changes - like new food sources).
27
Why is the fossil record incomplete?
* Many organisms decompose before they can fossilise.
* Fossilisation is **uncommon**, and requires specific conditions for an organism to be preserved.
* Over time, many fossils have been lost due to erosion or **geological processes**.
* Many organisms have not yet been discovered.
* Certain organisms, especially those with **soft bodies**, are less likely to fossilise, leading to gaps in the record.
28
What is comparative biochemistry?
Comparing molecules (e.g., DNA, proteins) to study evolutionary relationships.
29
What are some useful molecules to study evolutionary links?
* **Cytochrome C** - highly conserved protein, involved in cellular respiration.
* **rRNA** - integral to protein synthesis so it changes slowly
* Nuclear, mitochondria or chloroplast **DNA** - closely related species will have similar DNA sequences
* **mRNA** - complementary to DNA sequences
* Sequence of **amino acids** - closely related species will have similar aa sequences, determined by mRNA & DNA.
30
What is **divergent** evolution?
When two or more species evolve from a **common ancestor** but become increasingly **different** over time.
31
What is **convergent** evolution?
When **unrelated species** evolve **similar traits** because they live in **similar environments** or face similar **selection pressures** - not because of shared ancestry.
32
What is **variation**?
Variation is the differences observed among individuals within any given population.
33
What are the two types of causes of variation?
Genetic and Environmental
34
Name four genetic causes of variation.
* **Mutations** - changes to DNA sequence, that may be passed on
* **Meiosis** - new combination of alleles in gametes (crossing over & independent assortment of homologous chromosomes)
* **Random fertilisation**
* **Random mating**
35
What is environmental variation?
Variation caused by the environment in which an organism lives.
36
Give examples of environmental factors that cause variation.
Light intensity, nutrient and food availability, temperature, rainfall, soil pH
37
How do genetic and environmental factors interact in variation?
Genetic makeup determines potential for variation, while environment influences actual expression.
For example, human height.
38
What are **polygenes**?
* These are **different genes** at **different loci** that **all** contribute to a particular aspect of phenotype.
* Their individual effects on a phenotype are too small to observe, but they can act together to produce **observable variation**.
* This combined effect of multiple genes is common in **continuous variation**.
39
Describe **continuous** variation.
* Individuals in a population vary within a range - there are no distinct categories.
* Caused by combined effect of **polygenes** and the **environment**.
* Information displayed using a **histogram** or line graph with a curve.
* For example, human height, milk yield, mass, no. of leaves
40
Describe **discontinuous** variation.
* There are two or more **distinct categories** - each individual falls into only one of these categories, there are no intermediates.
* Caused by **single genes** with little to no environmental influence.
* Information displayed using a **bar graph**
* For example, blood group, colour of plant, antibiotic resistance
41
What is **intra**specific variation?
Variation **within** a species.
42
What is **inter**specific variation?
Variation **between** species.
43
What does the **mean** represent in variation studies?
It shows the average value of a trait in a sample.
44
What is **standard deviation**?
A measure of how much individual values **deviate** from the mean.
The spread of data from the mean.
45
What does a small and large standard deviation indicate?
Small: Values are **closely** clustered around the mean (low variability)
Large: Values are **widely** spread around the mean = more variation (high variability).
46
What is the purpose of the **Student’s t-test**?
To determine if there is a significant difference between the mean values of a particular variable across two populations.
47
What is the null hypothesis in a t-test?
There is no significant difference between the means of the two groups.
48
What happens if the t-value > critical value?
**Reject** the null hypothesis → There is a significant difference between the means.
48
What do you compare the t-value to in unpaired t-test?
A critical value from the t-distribution table based on:
* Degrees of freedom: df = n₁ + n₂ − 2
* Significance level (commonly p = **0.05**)
49
What happens if the t-value < critical value?
Accept the null hypothesis → Any difference is likely due to chance.
50
What does a **positive correlation** mean?
As one variable increases, the other also increases.
51
What does a **negative correlation** mean?
As one variable increases, the other decreases.
52
What does **Spearman’s rank correlation coefficient** measure?
The strength and direction of a relationship between two sets of data.
53
What does a Spearman’s ρ value of +1 mean?
A perfect positive correlation — as one variable increases, the other does too.
54
What does a Spearman’s ρ value of -1 mean?
A perfect negative correlation — as one variable increases, the other decreases.
55
What does a Spearman’s ρ value of 0 mean?
No correlation between the two variables.
56
How do you interpret Spearman’s rank correlation coefficient (rs) compared to the critical value?
* If ρ > critical value → **Reject** the null hypothesis → Significant correlation exists.
* If ρ ≤ critical value → **Accept** the null hypothesis → No significant correlation.
57
What are **adaptations**?
Inherited characteristics that enhance an organism's ability to survive and reproduce in it specific environment.
58
Describe the three categories of adaptations.
* **Anatomical** - physical structure, both internal and external
* **Behavioral** - activities & responses
* **Physiological** - internal biological function
59
Examples of anatomical adaptations?
* Fur, feathers, scales for protection
* Camouflage to blend in
* **Mimicry** to imitate dangerous species
* Teeth adapted to diet
60
Examples of behavioural adaptations?
* Defensive responses (e.g., opossums playing dead)
* Courtship displays (e.g., scorpion dances)
* Seasonal actions (migration, hibernation)
61
Examples of physiological adaptations?
* Some bacteria produce **antibiotics**, killing other species of bacteria in the area, less competition.
* Brown bears hibernate, lowering metabolic rate, conserving energy (also a behavioural adaptation)
62
Why do organisms from different taxonomic groups show similar features?
**Convergent Evolution** - unrelated organisms (from different evolutionary lineages) evolve similar traits.
This happens because they face **similar environmental pressures** and natural selection favours similar solutions to survival challenges.
63
What are selection pressures?
Environmental factors that affect an organism's survival and reproduction.
64
Give examples of selection pressures.
* Predation
* Competition for resources
* Climate change
* Disease
65
What is genetic diversity?
The total number of different alleles in a population, leading to variation in traits.
66
Describe the process of natural selection.
1. There is **variation** in characteristics within a species.
2. More genetic variation emerges within a population due to **random mutations**.
3. Individuals with alleles that code for traits that are **advantageous** for survival are **more likely** to survive & reproduce.
4. These advantageous alleles are **passed down** to offspring.
5. Over time, these beneficial alleles become more common in the population.
67
What does natural selection lead to over time?
Populations becoming more adapted to their environment.
68
What is an example of natural selection that can be observed currently?
* Antiobiotic Resistance in bacteria, such as MRSA.
* Pesticide-resistant insects
69
How does antibiotic resistance evolve in bacteria?
1. Some bacteria develop **random mutations** that provide resistance to antibiotics.
2. When **antibiotics** are used, only the resistant bacteria survive, while the others die off.
3. The resistant bacteria reproduce, passing on resistant alleles to their offspring.
4. Over time, the proportion of resistant alleles increases, leading to mostly resistant bacteria.
70
How do insects become resistant to pesticides?
1. Some insects randomly develop a mutation providing resistance to a pesticide, so they survive while the majority die.
2. The resistant individuals reproduce, passing on their resistance alleles to their offspring.
3. The **frequency** of resistance alleles increases over generations, increasing the population's overall resistance to the pesticide.
4. Eventually, the pest population evolves to a point where the pesticide is no longer effective.
71
Why is antibiotic resistance a problem for the human population?
It makes infections harder to treat, increases costs, and raises mortality rates.
