Unit 5 Biology 1 HN Review

SC District Common Assessment

Natural Selection

• Describe the 4 Prerequisites for Natural Selection:

1. Overproduction of Offspring - 

Species have to have the potential to increase in number

2. Variation - 

DNA sequences have to be different between individuals in a population

• How is variation helpful for the survival of a species?

Without variation, there would be no differences in fitness among individuals, and natural selection wouldn't be able to favor traits that are beneficial for survival and reproduction

• What type of reproduction leads to the greatest genetic variation?

Sexual

3. Adaptations - 

Animals change their habits to help them survive better in their environment. Adaptations down to offspring

4. Descent with Modification - 

Species change over time, resulting in greater diversity 

Evidence for Evolution

• Anatomy

  • Homologous Structures - similar structures shared by different species with a common ancestor

  • Vestigial Structures - structures with no known current function that are conserved from an ancestor

  • Analogous Structures - structures with the same function in unrelated species that developed because they live in a similar habitat

The above image is an example of Homologous structures.

The above image is an example of Analogous structures.

The above image is an example of Vestigial structures.

• Embryology

  • If the embryos of two species have many similarities, they likely descended from a common ancestor.

• Biochemistry

  • Having similarities in DNA can indicate that two organisms evolved from a common ancestor.

• Paleontology

  • Trilobites are on the bottom and are the oldest fossils

Microevolution

• What is a species?

a group of organisms that are similar enough genetically to reproduce with each other

• Sexual vs. Asexual Reproduction

  • Which type of reproduction results in genetic variation?

    • sexual

  • Which type of reproduction results in identical offspring? 

    • asexual

• Define & describe how each of the following impacts the genetic makeup of a population:

  • Genetic Drift - Allele frequency changes randomly over time

  • Gene Flow - Migration causes genes to move in or out of a population

  • Competition (for resources like space, food, etc.) - Individuals that can get food, space, and a mate pass on their traits, while those who can’t compete never reproduce

  • Mutations - Mutations get passed on throughout generations

  • Natural selection - favoring one trait over another results in less genetic variation

• How does camouflage help an animal be more “fit” regarding natural selection?

They can blend in with their environment to hide from predators or hunt for food

• How can food type/availability lead to physical differences in populations?

The foods a population historically eats and has access to can influence their genes over generations, leading to physical adaptations, and also affect how individuals grow and develop physically within their lifetimes.

Macroevolution

• Describe the types of macroevolution and give an example:

  • Divergent evolution - Species split off from a common ancestor

  • Convergent evolution - Independent evolution of similar traits

  • Coevolution - Two or more species living in proximity change in response to one another

  • Extinction - elimination of an entire species due to its inability to adapt to  environmental changes

  • Speciation - formation of a new species from a preexisting species

Label the types of macroevolution:

A: Divergent

B: Convergent

C: Coevolution

Phylogenetic Trees (Cladograms)

Use the cladogram (left) and phylogenetic tree (right) to answer the questions below. (The cladogram and phylogenetic tree have the same information but are represented differently.)

• What is the most recent ancestor of the perch? flounder

• What derived character separates mammals from lizards? amniotic egg 

• Which organism is most closely related to birds? lizard

• Which organism is the least closely related to lobsters? mammals