Chapter 5. Evolution And Biodiversity

Question 1

Clade

Answer 1

A group of species that have/had evolved from a common ancestor, including all the species alive and extinct.

Question 2

Cladistics

Answer 2

Construction of cladograms and identification of clades.

Question 3

Molecular (evolutionary clock)

Answer 3

A method to calculate the time of divergence of different species absed on the number of differences in their DNA base sequences and an estimated rate of mutations.

Question 4

Analogous structures

Answer 4

Structures which appear to be similar and have the same functions, but are foundamentally (structurally) different. They are results of convergent evolution and are developed from different ancestors to adapt to similar conditions.

Question 5

Homologous structures

Answer 5

Structures that appear to be superficial and have different functions but are structurally similar. They are results of adaptive radiation (i.e. the structures developed from a common ancestor of different individuals become progressively different as the individuals live and adapt to different environments). Ex) pentadactyle limbs in birds, reptiles, amphibians, and mammals.

Question 6

Morphology

Answer 6

Form and structure: often used in traditional classification but is highly subjective.

Question 7

Cladograms

Answer 7

Tree diagrams illustrating the sequence of divergence of different species from a common ancestor IN A CLADE.

Question 8

Primates

Answer 8

Mammals adapted to climb trees.

Question 9

Evolution

Answer 9

Cumulative changes in the heritable characteristics of a POPULATION.

Question 10

Artificial selection

Answer 10

The process of REPEATEDLY selecting and breeding organism with traits that are the most suited to human uses.

Question 11

Vestigial organs

Answer 11

Reduced structures that serve no function.

Question 12

Speciation

Answer 12

Development of a new species from existing species.

Question 13

Sympatric speciation

Answer 13

Development of a new species from existing species relying on factors including preference of different foods, mates, and biochemical changes. To investigate sympatric speciation, individuals which may not breed in the wild will do so in labs (e.g. stickleback and cichlid fish studies).

Question 14

Allopatric speciation

Answer 14

Development of a new species from existing species due to physical barriers which separate populations.

Question 15

Melanistic

Answer 15

Dark varieties of typically light-coloured animals and insects.

Question 16

Explain industrial melanism with a named example

Answer 16

Example: Peppered moth

1. Peppered moths with pale-coloured wings are camoufalged well against trees with pale-coloured lichens.
2. Industrial pollution causes blackening of tree branches (sulphure dioxide kills lichens, soot from coal burning blakens tree branches).
3. Moths with pale-coloured wings are no longer camouflaged against dark tree branches, and become targets of predators (e.g. birds) during daytime.
4. Instead, the melanistic moths are camouflaged well and are less likely to be hunted.
5. Over time, the melanistic moths replace the moths with pale-coloured wings.

Question 17

Natural selection

Answer 17

Natural selection refers to the preservation of favourable variations and the rejection of injurious variations among organisms of a population in their struggle of existence.

Question 18

Adaptations

Answer 18

Characteristics which make an organism suited to its environment and ecological niche. Examples include, water storage tissue in cactus infrequent rainfall; thick coat of musk ox low temperatures in northerly habitats; birds’ beak length and width diet and method of feeding

Question 19

Acquired characteristics

Answer 19

Characteristics are ones that develop during a lifetime and are inheritable (since they are not controlled by genes). Examples include: scars and hairstyles.

Question 20

Explain briefly why does natural selection cause evolution

Answer 20

Natural selection refers to … (definition). There is often a change in the environment which exerts selection pressure upon the population. The pressure increases the frequency of the characteristics that make individuals better adapted and decreases the frequencies of other characteristics (only true if these characteristics are inheritable). Those being selected for natural selection have a selective and reproductive advantage, which means these fittest individuals will survive and breed (survival of the fittest). Over time, the entire population will be replaced by individuals with the favoured trait.

Question 21

Outline the three sources of variations

Answer 21

1. Mutation: original source of variations, where new alleles are produced (enlarges the gene pool) due to viral infections and/or errors in DNA replication. It is the only source of variation for organisms that reproduce asexually.
2. Meiosis: alleles in a diploid cell are rearranged to form new combinations by crossing over and random assortment.
3. Sexual reproduction: the combination of gametes from different individuals. This allows mutations formed in different individuals to be brought together.

Question 22

Outline Charles Darwin’s observations

Answer 22

1. Offspring tend to resemble their parents.
2. All offspring have the potential to reproduce.
3. More offspring are reproduced than the environment can support.
4. Despite 3, the population sizes often remain constant.

Question 23

Outline Charles Darwin’s conclusions from his observations

Answer 23

1. Most offspring do not survive to breed.
2. Only the fittest ones survive.
3. Overtime and under the right circumstances, mutations give rise to new species.

Question 24

Explain how the development of antibiotic resistance in bacteria demonstrate natural selection can lead to evolution.

Answer 24

1. 【Definition of antibiotics】: Antibiotics is a type of medicine used to control bacterial infections by blocking the metabolism of prokaryotic cells.
2. The use of antibiotics exerts a selection pressure among bacteria in a population.
3. There are variations among bacteria in the population. For example, some bacteria have antibiotic resistance
4. 1） from mutations
5. 2）received from bacteria of other populations by exchanging genetic information by pili.
6. These variations are inheritable.
7. Those possessing antibiotic resistance genes have selective and reproductive advantages and so are selected for, those without are selected against.
8. Overtime, the desirable trait (one makes bacteria adapted i.e. resistance) is preserved. The entire population is replaced by bacteria with resistance.
9. The development of antibiotic resistance shows how evolution can take place by the survival of the fittest.
10. Example: MRSA bacteria

Question 25

Explain how the binomial nomenclature is used.

Answer 25

1. Universal name that can be used by scientists from different countries instead of many varied local names.
2. Promotes international cooperation and collaboration.
3. Informative and follows natural classification: gives information abou the genus and species of the organism.
4. Agreed on congresses.

Question 26

Taxonomy

Answer 26

The classification of organisms using hierarchies of taxa.

Question 27

State the order of the taxa that is used to classify eukaryotes (Hint: DON’T KILL PARENTS GET OTHERWISE FAMILY GETS SEPARATED)

Answer 27

1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species

Question 28

State the names of the three domains and their members

Answer 28

1. Eubacteria: bacteria
2. Archaea: archaeans
3. Eukaryota: eukaryotes

Question 29

Distinguish the members of the three domains

Answer 29

1. DNA associated with histone: N/With proteins similar to histone/Y
2. Presence of Intron:N/Some/Y
3. Presence and material of cell wall: Y(made of peptidoglycan)/Y(not made of peptidoglycan)/N(made of cellulose)
4. Cell membrane with glycerol-estor lipids, unbranched side chains: Y(d-form of glycerol)/Y(l-form of glycerol)/Y(d-form of glycerol)

Question 30

Homo sapien

Answer 30

Eukaryota
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
sapein (注意小写)

Question 31

Phoenix dactylifera

Answer 31

Eukaryota
Plantae
Angiospermophyta (枣子=fruit)
Monocotyledoneae
Palmales
Arecaceae
Phoenix
dactylifera

Question 32

Reclassification

Answer 32

1. Reclassification of the three domains based on ribosomal RNA sequencing: new domain archaea
2. Reclassification of great apes based on mitochondrial DNA sequencing: those (e.g. chimpanzees and gorilla) that were incorrectly placed under Pongidae are moved to Hominidae

Question 33

Natural Classification: WHY?

Answer 33

1. Identification of specimens becomes easier: following dichotomous keys/assigning specimens down the taxon hierarchies
2. Predictions of characteristics shared by species within a group (clade)

Question 34

Reclassification of the figwort family

Answer 34

1. Analysis of base sequences of 3 chloroplast genes.
2. More than half of the species were being transferred from the figwort family to: plantain family, lopseed.
3. New families were created: pocketbook flower, Linderniaceae.
4. Two families were merged with the figwort family: butterfly bush (buddleja), myoporum.
5. The classification was based on morphology: although structures appear to be similar, they were only results of convergent evolution.