Evolution

Question 1

What is the definition of species?

Answer 1

A group of organisms that can interbreed and produce fertile offspring.

Question 2

What is the definition of habitat?

Answer 2

The environment in which a species normally lives or the location of a living organism.

Question 3

What is the definition of population?

Answer 3

A group of organisms of the same species who live in the same area at the same time.

Question 4

What is the definition of ecosystem?

Answer 4

A community and its abiotic environment.

Question 5

What is the definition of community?

Answer 5

A group of populations living and interacting with each other in an area.

Question 6

What is the definition of ecology?

Answer 6

The study of relationships between living organisms and between organisms and their environment.

Question 7

What is the definition of evolution?

Answer 7

The cumulative change in the heritable characteristics of a population over many generations

Question 8

How do fossil records provide evidence for evolution? (4)

Answer 8

1. Fossils are the preserved remains or traces of animals, plants and other organisms from the past
2. They can either be direct (body fossils such as bones, teeth and shells) or indirect (trace fossils such as footprints)
3. They show that life on earth was once different from life found on earth today. Therefore the fossil record shows a gradual change of a species over time.
4. However, not all organisms are fossilized and there may be undiscovered organisms hidden therefore there are gaps in the fossil record.

Question 9

How does selective breeding provide evidence for evolution? (3)

Answer 9

1. Selective breeding is the process where humans breed animals or plants for particular traits
2. Individuals which show the most desirable traits are chosen to breed together, therefore the next generation will have an increased frequency of the desired trait. This process is repeated for many generations until the entire population shows the desired trait
3. Selective breeding provides evidence of evolution as targeted breeds can show significant variation in a relatively short period e.g selective breeding of plant crops and wolves

Question 10

How does comparative anatomy provide evidence for evolution (homologous and analogous structures)? (5)

Answer 10

1. Comparative anatomy of groups of animals or plants show certain structural features are basically similar/homologous
2. Homologous structures are similar structures in organisms that evolved from a common ancestor. (Same ancestor and structure, different function)
3. E.g The pentadactyl limb is a bone arrangement all present in mammals, birds, amphibians and reptiles based on a five digit limb but is used for different functions e.g flying, galloping, swimming
4. Analogous structures are similar structures having the same function, but do not share a common ancestor (same function, similar structure, different origin)
5. E.g The wings of a bat and a bird both look similar and have the same function, however their wings evolved independently in the two groups of animals

Question 11

What are vestigial structures?

Answer 11

Vestigial structures are structures that no longer serve a purpose in the organism such as the human tail bone or a whale pelvis. Evolution has reduced their size because the structures are no longer used

Question 12

What is speciation? (4)

Answer 12

1. If two populations of a species become geographically separated then they will likely experience different ecological conditions.
2. If separated for too long the two populations will adapt to the different environmental conditions and gradually diverge from one another.
3. When two populations can no longer interbreed and produce fertile, viable offspring they are considered to be separate specie
4. The degree of divergence will depend on the extent of geographical separation and the amount of time since separating occurred

Question 13

Outline two examples of evolution

Answer 13

Antibiotic resistance

1. A bacteria may contain a gene which makes it resistant to a specific antibiotic
2. Others will lack the gene and so will die if exposed to the antibiotic.
3. Over time, the non-resistant ones will all die off but the resistant ones will survive.
4. Eventually, the resistant ones will be the only ones left as a result of natural selection and so a new antibiotic must be created.

The Peppered Moth

1. There are two types of these moths, one species has a light colour while the other one is darker.
2. Before the industrial revolution, the environment was largely unpolluted and the lighter moth had a survival advantage (camouflaged by the pale lichen)
3. Following the industrial revolution, the environment became heavily polluted, conferring a survival advantage to the darker moth (lichen killed and camouflaged by soot)

Question 14

Define natural selection

Answer 14

Survival of the fittest:
Inherited Variation – There is genetic variation within a population which can be inherited
Competition – There is a struggle for survival (species tend to produce more offspring than the environment can support)
Selection – Environmental pressures lead to differential reproduction within a population
Adaptations – Individuals with beneficial traits will be more likely to survive and pass these traits on to their offspring
Evolution – Over time, there is a change in allele frequency within the population gene pool

Question 15

How is variation achieved? (3)

Answer 15

1. Mutations: New alleles are produced, hence the gene pool is enlarged
2. Meiosis: Via either crossing over (prophase I) or independent assortment (metaphase I)
3. Sexual reproduction: The combination of genetic material from two distinct sources creates new gene combinations in offspring

Question 16

What are adaptions? (5)

Answer 16

Adaptations are features of organisms that aid their survival by allowing them to be better suited to their environment
These adaptations may be classified in a number of different ways:
1. Structural: Physical differences in biological structure (e.g. neck length of a giraffe)
2. Behavioural: Differences in patterns of activity (e.g. opossums feigning death when threatened)
3. Physiological: Variations in detection and response by vital organs (e.g. homeothermy, colour perception)
4. Biochemical: Differences in molecular composition of cells and enzyme functions (e.g. blood groups, lactose tolerance)
5. Developmental: Variable changes that occur across the life span of an organism (e.g. patterns of ageing)

Question 17

What are the three domains of life?

Answer 17

o Eukaryotes - eukaryotic organisms that contain a membrane-bound nucleus, (e.g animals and plants)
o Archaea - prokaryotic cells lacking a nucleus and consist of the extremophiles, (e.g. methanogens, thermophiles)
o Eubacteria - prokaryotic cells lacking a nucleus and consist of the common pathogenic forms, naked DNA, ester lipids in membranes(e.g. E. coli, S. aureus, etc.)

Question 18

Define taxonomy

Answer 18

Taxonomy is the science involved with classifying groups of organisms on the basis of shared characteristics

Question 19

What are the advantages of having a binomial system? (4)

Answer 19

1. It allows for the identification and comparison of organisms based on recognised characteristics
2. It allows all organisms to be named according to a globally recognised scheme
3. It can show how closely related organisms are, allowing for the prediction of evolutionary links
4. It makes it easier to collect, sort and group information about organisms

Question 20

What is the human taxa?

Answer 20

Humans:
Kingdom: Animalia
Phylum: Chordata 
Class: Mammalia
Order: Primate
Family: Hominidae
Genus: Homo
Species: sapiens

Question 21

What is the white oak tree taxa?

Answer 21

White Oak tree:
Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida 
Order: Fagales
Family: Fagaceae
Genus: Quercus
Species: alba

Question 22

What is the red kangaroo taxa?

Answer 22

Red Kangaroo:
Kingdom: Animalia
Phylum: Chordata 
Class: Mammalia
Order: Diprotodontia
Family: Macropodidae
Genus: Macropus
Species: M. rufus

Question 23

Outline some plant phyla

Answer 23

Bryophyta (mosses) - furry, absorb moisture from surroundings, no vasculature, spores
Filicinophyta (ferns) - roots, leaves curled, spores
Coniferophyta (conifers) - woody, needles, female cones have seeds
Angiospermophyta (flowering plants) - roots, stem, ,seeds in fruits

Question 24

Outline some animal phyla

Answer 24

Porifera (sea sponge): no clear symmetry, attached to a surface, pores through body, no mouth or anus
Cnidaria (jellyfish): radially symmetric, tentacles, stinging cells, mouth but no anus
Platyhelminths (tapeworm): bilaterally symmetrical
flat bodies, unsegmented, mouth but no anus
Annelida (earthworm): bilaterally symmetrical, bristles often present, segmented, mouth and anus
Mollusca (slugs and snails): muscular foot and mantle
shell may be present, segmentation not visible
mouth and anus
Arthropoda (spiders and insects): bilaterally symmetric
exoskeleton, segmented, jointed appendages

Question 25

What are some Vertebrate Classes?

Answer 25

Fish - scales, gills, ectothermic
Amphibians - moist skin, external reproduction ectothermic,
Reptiles - scales, internal fertilizations, eggs, ectothermic
Birds - feathers, internal fertilization, endothermic
Mammals - hair, internal fertilization, endothermic

Question 26

What is a clade?

Answer 26

A clade is a group of organisms that have evolved from a common ancestor.

Question 27

What evidence is needed to determine cladistics of an organism? (3)

Answer 27

1. Analogous and Homologous Traits
   Homologous traits: A trait/structure that is derived from the same part of a common ancestor
   Analogous traits: Characteristics that may have the same function but they do not necessarily have the same structure and they are not derived from a common ancestor
2. Molecular Evidence
   The number of differences between comparable base sequences demonstrates the degree of evolutionary divergence
3. Structural Evidence
   A clade is a group of organisms that have evolved from a common ancestor

Question 28

What types of molecular evidence may be used?

Answer 28

1. Non-coding DNA provides the best means of comparison as mutations will occur more readily in these sequences
2. Gene sequences mutate at a slower rate, as changes to base sequence may potentially affect protein structure and function
3. Amino acid sequences may also be used for comparison, but will have the slowest rate of change due to codon degeneracy

Amino acid sequences are typically used to compare distantly related species (i.e. different taxa), while DNA or RNA base sequences are often used to compare closely related organisms (e.g. different haplogroups – such as various human ethnic groups)