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  Vocab

  1. Allele: An allele is a variant form of a gene that is responsible for producing different traits within a population.

  2. Ancestor: An ancestor is a person, organism, or group that is related to a particular individual or organism in the past, from which it has descended.

  3. Chromosome: A chromosome is a long, coiled-up molecule of DNA found in the nucleus of cells, which carries genetic information and is responsible for passing it on from one generation to the next.

  4. Cladogram: A cladogram is a diagram that shows the evolutionary relationships between groups of organisms based on their shared characteristics.

  5. Common ancestor: A common ancestor is an organism from which two or more different species have evolved.

  6. Common descendant: A common descendant is a species that is descended from a common ancestor along with one or more other species.

  7. Descendant: A descendant is an individual or organism that is descended from a particular ancestor or group of ancestors.

  8. DNA: DNA (deoxyribonucleic acid) is a molecule that contains the genetic instructions for the development and functioning of all living organisms.

  9. Dominant: In genetics, a dominant trait is one that is expressed in an organism's phenotype even if only one copy of the gene for that trait is present.

  10. Extinct: An organism is considered extinct when there are no living members of its species left on Earth.

  11. Fossil: A fossil is the preserved remains or traces of an organism that lived in the past.

  12. Fossil record: The fossil record is the collective evidence of past life preserved in the form of fossils.

  13. Gene: A gene is a segment of DNA that carries the instructions for a specific trait, such as eye color or blood type.

  14. Limb structure: Limb structure refers to the physical arrangement and characteristics of the arms, legs, or wings of an organism.

  15. Principle of superposition: The principle of superposition is a geological concept that states that in a sequence of sedimentary rock layers, the oldest layer is at the bottom and the youngest layer is at the top.

  16. Protein: A protein is a large molecule made up of chains of amino acids that perform a variety of functions in living organisms, such as catalyzing chemical reactions and providing structural support.

  17. Recessive: In genetics, a recessive trait is one that is expressed in an organism's phenotype only if two copies of the gene for that trait are present.

  18. Transition: A transition is a type of genetic mutation in which one nucleotide is replaced by another nucleotide of the same type (purine for purine or pyrimidine for pyrimidine).

  19. Variation: Variation refers to the differences in traits or characteristics that exist among individuals within a population.

  20. Vertebrate: A vertebrate is an animal that has a backbone or vertebral column, such as a fish, bird, reptile, amphibian, or mammal.

Great Transitions

Great Transitions Questions - 2022

Answer these questions as you watch the video “Great Transitions: The Origin of Tetrapods” found in ThinkLink. This video will be found under Inv. 1, Transitions. Your answers must be thorough and in complete sentences, with correct spelling.

1. Pause the video at 5:00 minutes, then compare the embryos of the three species, make observations, and identify any patterns you see.

They all have a tail like structure, they both are in similar positions, folded, they both have vertebrae (bar the fish)

2. What evidence suggests that four–legged animals came from fish?

The evidence that they came from fish is the fact that the DNA that fish possesses is the main ancestor of tetrapods. As well as them having the same bone structure of one bone and two bone.

3. Why did Shubin and colleagues choose to look in the Canadian Arctic for transition fossils?

The climate beforehand was very different from before, as such, many animals that are now long gone are now present.

4. Describe what the environment of the Arctic might have been like 375 million years ago.

Warm, almost summer climate would accompany many long gone animals that could not adapt to the changing climate.

5. What characteristics of Tiktaalik are fish-like?

Scales, fins and gils would be the characteristics that the Tiktaalik would possess from their fish like beginnings.

6. What characteristics of Tiktaalik are tetrapod-like?

A neck, ribs, and a flat head would be the characteristics that the Tiktaalik would possess from their tetrapod beginnings.

7. Did the transition of vertebrates from water to land happen quickly? Explain.

In the grand scale of things, no, it took a long time for the fishes to adapt to land by growing arms and legs, the great transition would take a gradual process step by step.

8. Explain why the one bone/two bones/many bones/digits limb pattern is important in explaining the origin of tetrapods.

It shows a common link between evolution with the one bone and two bone pattern representing the gradual processes that would occur.

Cladogram

1. What do all the animals have in common?

Answer: All animals are multicellular, eukaryotic organisms that require energy to survive and reproduce sexually.

2. What do the alligator and bird have in common that other animals do not have?

Answer: Both alligators and birds are egg-laying, amniotic vertebrates, which means they produce amniotic eggs that can be laid on land.

3. What do humans and rabbits have in common that other animals do not have?

Answer: Both humans and rabbits are mammals, which means they are warm-blooded, have hair or fur, and produce milk to nourish their young.

4. What do the human, rabbit, bird, and alligator have in common?

Answer: All of these animals are vertebrates, which means they have a backbone or vertebral column.

5. Which characteristic does the shark share with the other animals on the cladogram?

Answer: Sharks share the characteristic of having a cartilaginous skeleton with other animals such as rays and chimaeras.

6. Which of these are most closely related? Bird and alligator, or bird and human, and how do you know?

Answer: Bird and alligator are most closely related because they share a more recent common ancestor than either does with humans. This can be seen on the cladogram, where the branch leading to the bird-alligator group is the shortest.

7. What animals on the cladogram have this same ancestor as humans and rabbits?

Answer: The animals that share the same ancestor as humans and rabbits are the primates, including apes, monkeys, and lemurs.

8. What point represents the most recent common ancestor of birds and alligators?

Answer: The point that represents the most recent common ancestor of birds and alligators is the node where their two branches converge.

9. How do you know?

Answer: We know this because cladograms are diagrams that show the evolutionary relationships between different groups of organisms based on their shared characteristics. The branch points, or nodes, represent common ancestors of different groups.

10. Is the frog an ancestor of humans? Explain.

Answer: No, the frog is not an ancestor of humans. Although humans and frogs share a common ancestor that was a tetrapod (four-limbed vertebrate), the frog is not a direct ancestor of humans. Humans and frogs are both part of the same larger group of animals called vertebrates, which also includes fish, reptiles, birds, and mammals.