Topic 4.3 - Genetic Diversity, Adaptation and Taxonomy

Question 1

Define Species

Answer 1

Group of similar organisms able to reproduce to give fertile offspring

Question 2

Describe how the binomial naming system work

Answer 2

Each species is given a Latin name that has 2 parts

1. Genus
   
   • Has capital letter
2. Species
   
   • Lower case letter

• Names are written in italics or they’re underlined if handwritten e.g. Homo sapiens

Question 3

Why is the binomial naming system used?

Answer 3

Avoids confusion of using common names

Question 4

Name 3 difficulties of defining species

Answer 4

• Species are not fixed forever
• Can change and evolve over time into new species
• Many species are extinct and most left no fossils
• Some species are sterile

Question 5

What is phylogeny?

Answer 5

Study of evolutionary history of groups of organisms

Question 6

What is this known as?

Answer 6

Phylogenetic tree

Question 7

What does each following branch points represent?

Answer 7

Another common ancestor from which a different group diverged

Question 8

What is taxonomy?

Answer 8

Science of classification

Question 9

Why is taxonomy used?

Answer 9

Makes it easier to identify and study organisms

Question 10

How many taxa are there?

Answer 10

8 taxas

Question 11

How are the taxa arranged?

Answer 11

In a hierarchy: largest groups at top & smallest at bottom

Question 12

Organisms only belong to __ group at each level in hierarchy - no overlap

Answer 12

1

Question 13

Name all the taxa (from largest to smallest)

Answer 13

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

(Taxa Mnemonic: Dear King Philip Came Over For Good Soup)

Question 14

As you move down hierarchy…

Answer 14

there are more groups but fewer organism in each group & organisms in each group become more closely related

Question 15

What can be used to help classify species?

Answer 15

Courtship Behaviour

Question 16

Courtship behaviour is carried out by organism to…

Answer 16

attract a mate of the right species

Question 17

Describe how courtship behaviour can be used to help classify species

Answer 17

1. Courtship behaviour = species specific
2. Only members of same species will do/respond to it
3. ∵ of this specificity - courtship behaviours can be used to classify organisms

Question 18

Why do organisms carry out courtship behaviour? Name 2 reasons

Answer 18

• Allows same species to recognise each other
• Prevents interbreeding and making reproduction more successful

Question 19

More closely related species are = the more _____ their courtship behaviour is

Answer 19

similar

Question 20

Name 3 advances in techniques that can help clarify evolutionary relationships

Answer 20

1. Genome Sequencing
2. Comparing Amino Acid Sequence
3. Immunological Comparisons

Question 21

Describe how genome sequencing can help clarify evolutionary relationships

Answer 21

1. Advances in genome sequencing = entire base sequence of organism’s DNA can be determined
2. DNA base sequence can be compared to DNA base sequence of other organisms = to see how closely related they are
3. Closely related species = higher percentage of similarity in their DNA base order

Question 22

Describe how comparing amino acid sequence can help clarify evolutionary relationships

Answer 22

1. Sequence of amino acids in protein is coded by base sequence in DNA
2. Related organisms have similar DNA sequences and so similar amino acid sequences in their proteins

(e.g. Cytochrome C = protein found in many species → more similar amino acid sequence of cytochrome C in 2 different species = mores closely related spices are likely to be)

Question 23

Describe how immunological comparisons can help clarify evolutionary relationships

Answer 23

1. Mix together antibody and proteins
2. Similar proteins will also bind to same antibodies & form precipitate
3. More precipitate = more similarities in protein/DNA between the species (more evolutionarily close)
   
   • Similar species have a similar immune response to a protein

e.g. If antibodies to a human version of a protein are added to isolated samples from other species, any protein that’s like human version will be recognised by that antibody

Question 24

Explain how courtship behaviour increases the probability of successful mating (4)

Answer 24

• Indication of fertility
• Recognises same species
• Attracts mate
• Stimulates release of gametes

Question 25

Explain how a phylogenetic system differs from a simple hierarchy (3)

Answer 25

* Phylogenetic system is based on evolutionary history * Shows ancestry of groups/points of divergence * Hierarchical system is based on shared characteristics (seen today)

Question 26

What is meant by a hierarchy?

Answer 26

* Groups within groups * No overlap between groups

Question 27

What is meant by a phylogenetic group?

Answer 27

(grouped according to) common ancestry

Question 28

Describe the process of DNA hybridisation

Answer 28

* Heat DNA from 2 different species * To break hydrogen bonds and separate strands * Mix and cool strands to allow h-bonds to reform * Complementary bases joined together by h-bonding * Non-complementary bases that cannot pair join together

Question 29

DNA hybridisation When two species share a recent common ancestor/are closely related, what are results like (i.e. the hybrid DNA strands)?

Answer 29

* More complementary base pairing * More hydrogen bonds forming * More heat/energy needed to break (the hybridised) strands apart

Question 30

DNA hybridisation What are hybrid strands where two species are distantly related like & what is needed to separate the two strands?

Answer 30

Few bases are paired up Lower temperature is sufficient to separate the two strands

Question 31

Name the 3 domains

Answer 31

Eukarya, Bacteria & Archaea

Question 32

Name the 5 kingdoms

Answer 32

* Prokaryotae * Protoctista * Fungi * Plantae * Animalia

Question 33

What is meant by species diversity?

Answer 33

Number of species in a community

Question 34

What is genetic diversity?

Answer 34

The total number of different alleles in the population

Question 35

What is a population?

Answer 35

A population is defined as a group of individuals of the same species that live in the same place and are able to breed with one another. A species consists of more than one population.

Question 36

Why is genetic diversity within a population important?

Answer 36

The greater the number of alleles in a population the greater the genetic diversity and therefore the greater the chance that population would survive a change in their habitat

Question 37

What is meant by the term niche?

Answer 37

The niche of a species is its role within the environment. Species which share the same niche compete with each other.

Question 38

What is a selection pressure?

Answer 38

A change or factor within a population's environment that may cause them to adapt. E.g. a change in weather, a new predator, a change in food sources or a disease.

Question 39

Explain the process of evolution via the theory of natural selection

Answer 39

- When a population is genetically diverse, it means that there is also variation of phenotypes within the population. - An environmental change may occur which causes a selection pressure - Some individuals may possess advantageous alleles which gives them a selective advantage which makes it more likely they will survive and reproduce. - The advantageous alleles are passed on to their offspring - Overtime, the frequency of alleles in a population changes and this leads to evolution.

Question 40

Name the three types of selection.

Answer 40

Directional selection, stabilizing selection, disruptive selection

Question 41

Explain how directional selection occurs

Answer 41

Directional selection occurs when the environmental conditions change and the phenotype best suited to the new conditions are more likely to survive. As a result these individuals will breed and produce offspring. Overtime the mean of the population will move to one extreme.

Question 42

Explain how stabilizing selection occurs.

Answer 42

In stabilising selection, the phenotypes with successful characteristics are preserved and those of greater diversity are reduced. This selection doesn't occur due to changes in the environment. If the environment stays he same then the individuals closest to the mean are favored. Overall, the genetic variation in the population decreases.

Question 43

Explain how disruptive selection occurs

Answer 43

Disruptive selection occurs when selection pressures favour both extremes of the mean. This causes a decrease in the mean phenotype. Disruptive selection can lead to speciation if the extremes of the mean become so different they are no longer able to breed.

Question 44

What are some ways that organisms may be adapted to their environment?

Answer 44

Anatomical adaptations are internal and external physical adaptations - e.g. camoflaged fur, or desert-dwelling organisms have a longer loop of Henle to increase water reabsroption. Behavioural adaptations are changes in behaviour which improve an organisms chance of survival e.g. mating calls Physiolological adaptations are processes inside an organism's body that increase its chance of survival - e.g. resistance to a disease or increased regulation of blood flow through the skin.