C&C Ch. 3 Flashcards
similarities between even widely disparate types of organisms exist at
every level, from familiar, externally visible resemblances, to profound resemblances in life-cycles and the structure of the genetic material
what is the explanation for the similarities between different groups of organisms?
organisms are related through an evolutionary process of descent from common ancestors
list the various similarities between species
- biological classification
- embryonic development
- vestigial organs
- sexual reproduction
- inheritance
- genes
- mutations
- DNA sequencing
similarities between mammals and other vertebrates
basic features of their skeletons, and their digestive, circulatory, and nervous systems
similarities between mammals and insects
segmented body plans, their common need for sleep, the control of their daily rhythms of sleep and waking, and fundamental similarities in how the nerves work
systems of biological classification have long been based on
easily visible structural characteristics
describe the different levels of biological classification
domain
kingdom
phylum
class
order
family
genus
species
brief description of arthropods
phylum which includes insects, among which flies form one group (all have only one pair of wings) as well as butterflies and moths (whose members all have fine scales on their two pairs of wings)
similar species are grouped into the same
genus
what do organisms in a genus have in common?
they are united by a set of characters not shared with other genera
naming system used by biologists
genus name followed by name of the species
as you go down the hierarchy of the groups, the groups
share more and more traits that are lacking in other groups
how can we discern an inferred pattern of genealogical relationships between groups of organisms?
by directly studying the information in their genetic material
give 2 examples of instances where there are modifications of the same structure in different species
- the bones of bats’ and birds’ wings indicate that they are modified forelimbs
- the internal structure of the flippers of whales is like the feet of other mammals except for an increased number of digits
evidence that whales are modified mammals
they breath with lungs, not gills, and suckle their young
according to fossil evidence, what did the two mares of limbs of land vertebrates derive from?
the two pair of fins of the lobe-finned fishes; the earliest land vertebrate fossils had more than five digits on their limbs (like fishes and whales)
give an example of a known case in which the same basic structure was considerably modified during the course of evolution by the demands imposed by different functions
- three small bones in mammals’ ears, which transmit sound from the outside to the organ that transforms sound into nerve signals
- develop from rudiments in embryonic jaw + scull, and in reptiles enlarge during development to make parts of the head and jaw skeleton
- fossil intermediates that connect reptiles with mammals show successive modifications of these bones in the adults, finally evolving into the ear bones
how does embryonic development provide examples of similarities between different groups of organisms?
embryonic forms of different species are often extremely similar, even when the adults are very different
give an example of a similarity in embryonic development between mammals and fish
at one stage in mammalian development, structures appear that resemble the developing gill slits of fish embryos - developing blood vessels require the presence of gill slit rudiments to guide them to form in the correct places
what are vestigial organs?
organs, tissues or cells in a body which are no more functional the way they were in their ancestral form of the trait
why are vestigial organs interesting?
such cases tell us that evolution does not always create and improve structures, but sometimes reduces them
example of vestigial organs in humans
- appendix
- a greatly reduced version of a part of the digestive tract that is quite large in orangutans
compare primitive snakes with present-day snakes
- fossils of primitive snakes have been found with almost complete hindlimb, indicating that snakes evolved from lizard-like ancestors with legs
- body of a present-day snake consists of an elongated thorax, with a large number of vertebrae
example of vestigial limbs in legless animals
in the python, the change from the body to tail is marked by vertebrae with no ribs, and at this point rudimentary hindlimbs are found:
- pelvic girdle, pair of truncated thigh bones
- their development follows the normal course for other vertebrates, with expression of the same genes that normally control limb dev.
- a graft of python hindlimb tissue can even promote the formation of an extra digit in chick wings
what is a basic feature of all animal, plant, and fungal life?
their tissues are made up of essentially similar units, ce;;s
cells are the basis of the bodies of all organisms other than
viruses
define a eukaryote
all cellular non-bacterial life
how are cells organised in eukaryotes?
into the cytoplasm and the nucleus within it that contain the genetic material.
describe the cytoplasm of a cell
contains a complex set of sub cellular structures (organelles)
two of the most important organelles
mitochondria that generate cells’ energy, and chloroplasts in which photosynthesis in a green plants’ cells occurs