Embryology & Development
What is an embryo?
An embryo is the early stage of a developing organism after fertilization from the first cell divisions until major organs and structures begin to form.
What is the Pangaea?
A massive subcontinent that united all of Earth's land mass into a giant landmass surrounded by a global ocean.
This is the overarching idea supported by the presence of homologous structures across different species.
What are homologous structures?
This is the fundamental molecule used as the genetic material by all known living organisms, demonstrating a single origin of life.
What is DNA?
True or False: Snake embryos developing and then losing hind-limb buds provides evidence that their ancestors likely had limbs.
True
Why are closely related species usually found geographically close to one another?
They share a recent common ancestor who lived in that general region before the descendant species diverged.
A structure, such as the human appendix or the pelvic bone in a whale, that is present but has no apparent function and appears to be a remnant from a past ancestor.
What is a vestigial structure?
The fact that all life uses the exact same genetic code is strong proof that we all share this.
What is a common ancestor?
What general pattern is observed when comparing the timing of shared features in related species embryos?
Related species, embryos show more homologous features in earlier developmental stages before they become specialized into their adult forms.
What major geological process helps explain why fossils of the same ancient species are found on continents that are now widely separated by oceans?Plate tectonics (continental drift). Continents that are now separate were once joined together.
Plate tectonics (continental drift). Continents that are now separate were once joined together.
The wings of a bat and the wings of a butterfly are this type of structure because they have the same function but different evolutionary origins.
What are analogous structures?
The study of these highly conserved genes, which control the development and body plan of organisms from fruit flies to vertebrates, provides evidence of a common genetic "toolkit".
What are Hox genes?
What do gill slits seen in human embryos develop into?
Ears, jaws, and throat
True or False: Species found on oceanic islands are usually identical to those found on the nearest mainland.
False; they are usually similar suggesting common ancestry but are often different to the islands due to evolution in isolation.
The presence of similar underlying structures for different functions is unlikely to have evolved independently in each species, supporting this theory.
What is the theory of evolution (by natural selection)?
The more DNA two species share, the more closely they are related. Humans share 98% of their DNA with this animal.
What is a chimpanzee?
What is atavisms?
The reappearance of ancestral traits
Why are there no large, native, land mammals in Australia other than bats and those introduced by humans?
Australia became geographically isolated from the other continents before large placental mammals evolved and split it allowing them to diversify into their ecological place instead.
This is the "blueprint" in an organism's cells that determines the structure of their body parts and explains why related organisms have similar anatomy.
What is DNA (or genetic information)?
The four letters that make up the entire genetic code, found in all living things on Earth.
What are A, T, C, and G?