Bat wings, a human hand, and a whale flipper are all structures. Explain WHY? Butterfly wings and bat wings are examples of structures.

The mouths of horseflies and mosquitoes are examples of structures.

A structure is one that does not currently have a function in the organism. Give an example.

Comparing structures of embryos is an example of .

If embryos share a common structure, what does that say about their evolutionary relationship?

How would the protein sequence of two closely related species compared to the protein sequences of two unrelated species? Give an example of each here.

Answers:

blank: Homologous

why?: They all have similar structures passed on from a common ancestor. Although they all have different functions now, they still all have the same basic pattern of bones.

blank: Analogous

why?: Butterflies and bats are both unrelated organisms but they both have similar structures. However, unlike homologous structures, analogous structures do the same job (help the organism fly) but are structured entirely differently because they evolved in the two species independently and did not share a common ancestor.

blank: Homologous

why?: (see question 1 ^)

blank: Vestigial

example: An example of a vestigial structure is a human's tail bone.

why?: Over time humans evolved and our tail bones shrank as we adapted. While we still have one, it serves no purpose in our lives today.

blank: Embryology

why?: Embryology is the branch of science and medicine that is focused on the development and study of embryos. Scientists in this field study the prenatal development of gametes, fertilization, and development of embryos and fetuses.

They share a common ancestor

why?: Embryos of many different species can show evidence of sharing a common ancestor based on the similarities and structures of them all. Similar structures during development support common ancestry. For example, all vertebrae embryos develop gill slits and tails but not all develop into those structures. Over time as organisms evolved their structures changed with them.

If the protein sequence of two species is closely related the two species are most likely similar, but the protein sequences of two unrelated species are not similar meaning these two species are very different. By comparing the positions of amino acids on protein chains you can determine how similar the species are. The less different the positions are, the more alike and related they are.

why?: For example, humans and chimpanzees only have one position on the amino acid chain where they are different but if you compare humans and moths there are 31 different positions.

I included some extra information in this for you so you hopefully can learn something too! I hope this helps and if you have any questions on what I put or anything else, let me know. :)

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.