lecture 1

Question 1

what are the 2 ideas developed by aristotle about evolution?

Answer 1

he developed 2 ideas: either the whole body is already formed and simply gets larger, or new structures arise progressively. he inclined more towards the second option, which he called “epigenesis”

Question 2

what happens during gastrulation?

Answer 2

There is a dramatic rearrangement of cells. The endoderm and the mesoderm move inside, while the ectoderm above the notochord folds and gives rise to the neural tube.

Question 3

what gives rise to the notochord?

Answer 3

the mesoderm leads to the creation of the notochord, which is central to the body and represents the basis for the future nervous system. the ectoderm above the notochord forms the neural tube throughout neurulation, while other organs are later developed during organogenesis

Question 4

what is meant by the term “comparative anatomy”?

Answer 4

Comparative anatomy is the study of similarities and differences between different species. for example, same bone composition but different shapes and sizes for different functions

Question 5

what is allopatric speciation?

Answer 5

Allopatric speciation is caused by geographical barriers blocking 2 populations, diverging in terms of evolution and adapting to their respective environment

Question 6

what is parapatric speciation?

Answer 6

Parapatric speciation is the continuos change over time: small changes accumulate and, after a while, the new species is unable to mate with an ancestor

Question 7

what is sympatric speciation?

Answer 7

Sympatric speciation: due to being unable to mate with a previous population such as due to diploidy in animals or error of segregation of chromosomes in meiosis

Question 8

why was evolution of egg important?

Answer 8

it was important because it allowed reptiles to lay eggs on land, therefore helped organisms to expand outside of water and onto the land.
mammals, although they no longer lay eggs, still have the amniotic sac which provides protection for the embryo

Question 9

what is convergent evolution?

Answer 9

species from different lineages evolve to have similar appearances, body shapes and functions

Question 10

why did it take 1 billion years for multicellular organisms to form from single cellular organisms?

Answer 10

genetic complexity, environmental cues, genetic mutations, communication with other cells