Classification, Evolution, Speciation, and Cladistics - TEST

Question 1

What information can be deduced from the sequence of nodes in a cladogram?

Answer 1

The probable sequence of divergence among the species in the clade.

Question 2

Which cell is a polyploid zygote produced by fusion of one haploid and one diploid gamete?

Answer 2

One with six chromosomes.

Question 3

Explain how cladistics can be used to investigate evolutionary relationships.

Answer 3

• Shows evolutionary relationships through a common ancestor
• Uses DNA / shared anatomical traits

Question 4

Outline the criteria that should be used to assess wether a group of organisms is a species.

Answer 4

• Organisms can potentially interbreed to produce fertile offspring
• Same traits / chromosome number

Question 5

Describe the changes that occur in gene pools during speciation.

Answer 5

Gene pool: all genes in a population
- pool splits during speciation due to reproductive isolation
- Allele frequencies change
- Changes natural selection and causes mutations to occur

Question 6

Which cladogram shows the most likely phylogenic relationship between the four species, based on the data provided?

Answer 6

Species 2
Species 3
Species 4
Species 1

Question 7

Explain how natural selection can lead to speciation.

Answer 7

• Speciation: formation of a new species from one population
• Natural selection caused by selection pressures in the environment (requires variation within a species)
• Individuals with the best variations survive to reproduce
• Offspring with better adapted traits causes genetic divergence to increase
• Leads to reproductive isolation and then speciation

Question 8

The cladogram shows the relationships of five species I to V. Which species is / are most closely related to IV?

Answer 8

II and III

Question 9

Explain how polyploidy occurs and - using a NAMED example - how polyploidy can lead to speciation.

Answer 9

Polyploidy: having more than 2 sets of homologous chromosomes
- Triploid = 3 sets // Tetraploid = 4 sets
- Nondisjunction
- Allium (plant) - 2n normal // 4n polyploidy
- Causes immediate speciation as polyploids cannot produce offspring with diploids

Question 10

What evidence from the graph indicates that disruptive selection is occurring?

Answer 10

An intermediate beak size is less common.

Question 11

List TWO types of evidence used to determine which species belong in the same clade.

Answer 11

1 - DNA sequences in a gene
2 - Amino acid sequences in a protein

Question 12

List TWO causes of variation within a gene pool.

Answer 12

1 - Meiosis
2 - Mutation

Question 13

Outline the use of analogous and homologous traits in natural classification.

Answer 13

Analogous: NO common ancestor
- Caused by convergent evolution
Homologous: Similar structures (due to common ancestor) but different functions
- Caused by divergent evolution

Question 14

Outline how reproductive isolation can occur in an animal population.

Answer 14

• Polyploidy
• Temporal: members reproducing at different times
• Behavioral: difference in courtship behaviors
• Geographic: Population being separated by river / mountain

Question 15

Starting from the concept of gene pool, explain briefly how populations of early vertebrates could have evolved into different groups.

Answer 15

• Gene pool: all genes in a species
• Gene pools split if populations do not interbreed
• Caused by temporal / behavioral / geographic isolation
• Migration to different areas

Question 16

What is required for natural selection to occur?

Answer 16

Advantageous characteristics and genetic variation ONLY.

Question 17

Which of the adaptations of flowers would be most successful for the survival of a species?

Answer 17

Specific odors for better insect pollination.

Question 18

What causes variation within a population?

Answer 18

Fertilization and mutation.

Question 19

Explain how evolution may happen in response to an environmental change.

Answer 19

Evolution: cumulative change in population over time
- Evolution by natural selection
ex:
- Trees were darkened by soot
- Caused competition between light / dark peppered moths
- Darker moths (best adapted) could camouflage more and therefore passed on their genes
- Increased black moth population

Question 20

Outline how fossil records can provide evidence for evolution.

Answer 20

• Comparing fossils and living organisms shows change in characteristics
• Showing evolutionary change has occurred
  EX: reptiles follow amphibians

Question 21

A dichotomous key can be used to distinguish four types of plant. Which of the plants could be a bryophyte?

Answer 21

Plant A.

Question 22

Which is a characteristic of both byrophyta and filicinophyta?

Answer 22

Release of spores.

Question 23

Ana animal shows radial symmetry, has only one opening leading to digestive cavity and is soft without a skeleton. To which phylum does this animal belong?

Answer 23

Cnidaria.