lab midterm Flashcards
how do we represent which organisms are alive in a phylogenic tree
dead end branched that don’t make it to the present are extinction events. further back means that species no longer exists
why are all phylogenetic trees considered a hypothesis
because we can’t go back in time to verify the exact branching pattern
what are all organisms traced back to
an organism that lived 3.7 billion years ago. this group of prokaryotes, which forms the basal tree of life is collectively referred to as LUCA (last universal common ancestor
describe the LUCA hypothesis
Some fundamental cellular components such as DNA, ribosomes, and
plasma membranes, which are still universally shared by all life forms, were present in the
LUCA. These components are so molecularly complex that it is unlikely that they would be
so similar if they evolved independently. An example of this are ribosomes, which are
comprised of 50+ proteins and RNA molecules thousands of nucleotides long.
define taxonomy
the scientific discipline concerned with naming and classifying groups of biological organisms.
organisms. Taxonomists group organisms based on
similarities in morphology and/or molecules into taxonomic categories starting with the most
inclusive category,
(domain, kingdom, phylum, …)
what is the complete taxonomy of a human?
domain: eukarya
kingdom: animalia
phylum: chordata
class: mammalia
order: primates
family: hominidae
genus: homo
species: sapiens
what is a monophyletic clade
all members of a monophyletic clade are closer relatives to each other than they
are to all organisms outside the clade. A monophyletic clade could contain a group of closely
related genera, which taxonomists would refer to as a family, or a group of distantly related
phyla, which taxonomists would refer to as a kingdom—monophyletic clades can happen at
any taxonomic rank within the tree of life.
definition of a monophyletic clade
a group that converges on a
common ancestor prior to joining other clades.
paraphyletic bs polyphyletic groups
Paraphyletic groups exclude some descendants of the last common ancestor of the group.
Polyphyletic groups exclude some descendants as well as the common ancestor of the
group (Figure 1.
define character, give an example
an anatomical, physiological or molecular feature found in an organism
characters. For instance, all members of the mammal clade have vertebral
columns and hair. Hair is unique to mammals, but the presence of a vertebral column is also
found in other clades
for mammals, are the milk-producing mammary glands ancestral or derived? explain
derived because it’s unique to mammals
describe ancestral character
fish). Vertebral columns are found in
these other clades as well as mammals because this character evolved in an early
vertebrate ancestor, long before the emergence of these later clades. For mammals, the
vertebral column is therefore an ancestral character
all mammals have a backbone, but it
is ancestral to the formation of the mammal clade itself.
describe derived character
contrast, hair evolved in an early
mammal ancestor; therefore, all mammals, and only mammals, have hair. For mammals,
hair is therefore a derived character - all mammals have hair because it was derived in an
early ancestor within the mammal clade.
for mammals, are hinged jaws ancestral or derived? explain
ancestral because it is older than the mammal
what are shared derive characters
characters shared by only some lineages within a clade. can be used to identify less inclusive clades.
clades. For example, mammals and
reptiles (including birds) share a similar reproductive structure called the amniotic egg, and
the amniotic egg is one of the shared derived characters that helps set apart the
monophyletic clade Amniota (mammals and reptiles) within the more inclusive clade
define homologous characters
Shared characteristics that can be traced back to a common ancestor (i.e. shared due to
descent) are referred to as homologous characters.
describe convergent evolution
d convergent evolution—the characters converged on a similar morphology, often
because of similar ecological pressures
define analogous characters
Shared characters that are a result of convergent
evolution and not common ancestry are referred to as analogous characters.
are analogous characters useful for constructing phylogenies? why?
no because they can be misleading, can make lineages appear more closely related than they are
What process could cause two taxa that are not closely related to look quite similar (at least
superficially) and result in a taxonomic error?
convergent evolution. (I think)
are the wings of butterflies homologous or analogous? explain
analogous
bird wings are analogous because they are not derived from a common ancestor but evolved independently to perform the same function: flight.
are the wings of butterflies and dragonflies homologous or analogous?
homologous
what is progressivism?
It is common for students to visualize evolution as progressing through a long series of
lesser organisms only to finally reach humans, which were thought to be the pinnacle of
1-9
evolution. This view, known as progressivism, was historically quite common but is now
seen as being thoroughly obsolete
why is progressivism incorrect?
because evolution isn’t linear
Is it more accurate to say “humans descended from chimps” or “humans and chimps shared
a common ancestor”? Explain
humans and chimps share a common ancestor because chimps are not extinct and it is more scientifically accurate
are all eukaryotes equally related?
Of course, each domain is incredibly diverse, containing
(in the case of Eukarya), millions of species, all of which are comprised of cells containing
nuclei and other membrane bound organelles. This does not mean that all eukaryotes are
equally related, however; some species within Eukarya share a common ancestor recently
(millions of years ago), whereas some eukaryotes would be much more distantly related.
which one would be considered the most parsimonious tree in different phylogenetic trees
most parsimonious tree would be the one with the least number of
mutations and is thus the most likely tree or best explanation.
how does DNA store information
in the nucleotide sequence
what is a non-coding region
region of DNA is a part that does not directly code for proteins.
What is a genome? How big is your genome? How much of it is non-coding?
the entire set of DNA instructions found in a cell
23 Paris of chromosomes
about 99%
define homologous genes
genes that exist in taxa because they were inherited from a common ancestor
—genes are passed down the tree of life just as morphology is passed
down the tree; in fact, morphology is passed down because genes are. Also, you would
need to align the homologous sequences to allow direct comparisons
define conserved gene sequences. why are they so important
DNA sequences that move through evolutionary time relatively
unchanged are referred to as conserved gene sequences, and conserved sequences are
almost always linked to a critical function.
do non-doing regions diverge quickly after a speciation event
yes
what are the different shapes that bacteria can be?
Round bacteria are called cocci (coccus = singular), rod-shaped
bacteria are bacilli (bacillus = singular). Other shapes include spirilla (spirillum =
singular), which are flexible, spiral shaped cells
describe cyanobacteria
Cyanobacteria are unusual in a number of ways. Not only are they much larger than
traditional bacteria, they are all photosynthetic. Most of them grow in multicellular filaments
(a chain of cells). Cells in these filaments can be round or rectangular in shape, but are not
called cocci or bacilli.
gram positive vs gram negative bacteria
Cells that stain purple are called gram-positive bacteria and cells that stain pink are called
gram-negative bacteria. The Gram reaction is based on structural differences in the outer
covering of the cell. Most bacteria have a layer of peptidoglycan in the cell wall, outside the
plasma membrane. Peptidoglycan protects the cell from lysis in a
hypotonic environment. Gram-positive bacteria have a very thick layer of peptidoglycan.
Gram-negative bacteria have a more complex outer coating – a thin layer of peptidoglycan
is sandwiched between an inner and outer membrane.
what does the decolorizer do?
the decolorizer added in steps 6 and 7 contains alcohol, which partially dissolves the
lipids of the outer bacterial membrane. This allows the purple stain to wash out through
pores in the thin layer of peptidoglycan in the gram-negative cell wall, leaving the cell
colourless. In the gram-positive cells, the peptidoglycan layer is so thick that the purple
stain is unable to escape
what is the morphology and gram stain of e coli
morphology: baccilus
gram stain: pink
what is the morphology and gram stain of s. epidermis
morph: cocci
gram stain: purple
why is it necessary to add the counterstain
because gram-negative is hard to see under microscope until you add the counter stain
what is a bacterial colony
A bacterial colony is a visible group of bacteria that has grown from a single bacterial cell or a small group of cells on a solid nutrient surface, such as an agar plate.
When you place bacteria on the right medium and give them time, they multiply and form a cluster, which can be seen without a microscope. Each colony usually arises from one bacterium or a small group, so all the cells in the colony are genetically identical, or clones.
Colonies can have different shapes, sizes, textures, and colors, depending on the bacterial species, and scientists use these characteristics to help identify the type of bacteria.
what is mannitol salt agar
The Petri plates on display all contain mannitol salt agar, a solidified medium that contains
mannitol, nutrients, a pH indicator, and enough salt to inhibit the growth of most bacteria
eukarya vs prokaryotes
Eukaryotic organisms are usually larger and more complex than prokaryotes. Give two
additional ways that eukaryotes significantly differ from prokaryotes.
describe kingdom prosita
Historically, Kingdom Protista was used to classify a collection of very diverse, but typically
distantly related groups whose only common bond was that they didn’t fit anywhere else.
After extensive molecular studies in recent years, the relationships between them have
become clearer, and it is apparent that they deserve to be put into a variety of groups that
are as different from each other as they are from Plants, Animals, or Fungi. T
photoautotrophic vs heterotrophic and mixotrophs. which ones are the primary producers of the ecosystem
Some are photoautotrophic (using light as an energy
source to synthesize organic compounds from inorganic materials), while others are
heterotrophic (dependent on consuming organisms or organic material from the
environment) or even mixotrophs (able to use a combination of both heterotrophic and
photosynthetic nutrition). Photoautotrophs are the only organisms that can take up energy
directly from the sun and convert it into organic molecules
primary producers = photoautotrophs
what are the different relationships that organisms can have with each other
. Organisms that live on
or inside other organisms (symbiosis) can either have a negative effect on the host
(parasitic) or be beneficial (mutualism).
what are free living organisms
Free-living organisms, unlike organisms in
parasitic and mutualistic relationships, always complete their entire life cycle independent of
other organisms.
trypanosomes. what do they look like
Single-celled, internal parasites of animals. One genus, transmitted by the tse-tse fly, causes
African Sleeping Sickness. A unique feature of this group is a greatly enlarged
mitochondrion called a kinetoplast
euglena
Single-celled photosynthetic organisms that move using a flagellum. They can easily change
shape due to flexible bands of protein beneath their cell membrane. Euglena perform
photosynthesis when there is sunlight, and when there is no sun they are heterotrophs.
dinoflagellates. know what they look like
Motile photosynthetic organisms that are a very important component of marine ecosystems.
Over half of the known species are photosynthetic but many are mixotrophs
Some dinoflagellates, under certain conditions, can reproduce very rapidly. This uncontrolled
reproduction can result in what is known as a “Red Tide”. Some species can produce a
poison that paralyzes the nervous system of animals.
what is red tide and how can u get it?
when dinoflagellates, in certain conditions reproduce very rapidly
can contract this type of poisoning by ingesting filter-feeding shellfish that have accumulated the toxin from dinoflagellates
zooxanthella
are photosynthetic dinoflagellates that live in a mutualistic relationship with reef-building corals and are often what gives them colour.
They perform photosynthesis, using sunlight to produce food (sugars) and oxygen, which they share with the host.
In return, the host provides the zooxanthellae with shelter and access to carbon dioxide and nutrients, which the algae need for photosynthesis.
In coral reefs, this partnership is crucial. The energy provided by zooxanthellae helps corals build their calcium carbonate skeletons, which form the structure of coral reefs. Without them, corals would struggle to survive in nutrient-poor waters
plasmodium
cause the disease Malaria in humans and a number of other animal species. This
parasite infects the liver and red blood cells of the host and reproduces rapidly. As the
parasites burst out of the red blood cells, destroying them, the host experiences the
characteristic fever and chills of malaria
paramecium
Single-celled organisms that use many cilia for locomotion, rotating while they swim. You
can’t see the individual cilia with our compound microscopes, but you can probably see an
oral groove. The oral groove leads to a contractile vacuole. The contractile vacuole
accumulates and periodically expels water that moves into the cell by osmosis.
diatoms (know what they look like)
Free-living, unicellular organisms that have a unique glass-like cell wall made of silica.
These beautiful organisms are critical members of the marine ecosystem because they are
photoautotrophic, and so make up the base of marine food chains. Most of the oxygen we
breathe is made by Cyanobacteria, Diatoms and Dinoflagellates. Their sexual reproduction
can involve flagellated sperm.
Phaeophyta (Brown Algae
Multicellular, photosynthetic Protists. All but four of the approximately 200 species of brown
algae live in saltwater. Although they have the photopigment chlorophyll, they are generally
brownish in appearance due to the presence of brown carotenoid pigments. These large
Protists often have gas bladders that act as floats. The floats keep the leaf-like parts near
the surface of the water so they are exposed to sunlight for photosynthesis. They are
important primary producers in the ocean.
foraminifera. what do they look like
Single celled heterotrophs that produce a porous internal shell of calcium carbonate. They
are able to send thin extensions of the cytoplasm through the pores and capture small prey
by phagocytosis.
look like shells under microscope
Rhodophyta (red algae) and Chlorophyta (green algae
Two photosynthetic eukaryotic clades. Both include species large enough to be called
seaweeds, but they are not close relatives of brown algae
describe the lifecycle of plants
All
plants have a multicellular haploid (1n) gametophyte that alternates with a multicellular
diploid (2n) sporophyte. This is known as Alternation of Generations (see Figure 3.1).
The multicellular haploid gametophyte produces gametes (1n) by mitosis. After fertilization,
the diploid (2n) zygote grows to become a multicellular sporophyte, which produces haploid
(1n) spores by meiosis. For organisms that have alternation of generations, they may spend
more of their lifetime in one of the phases. The one they spend the most time in is called the
dominant generation
what are non-vascular plants
Non-vascular plants by definition lack vascular tissue. They are terrestrial and are always
small. Each plant lacks true stems, roots, or leaves. This group has flagellated sperm for
reproduction, which restricts them to wet environments because their sperm must have
water to swim in. Non-vascular plants include mosses and liverworts
what do moss and liverworts have in common
Both moss and liverwort have obvious long-lasting photosynthetic gametophyte generations
that produce eggs and sperm for sexual reproduction. Each egg is produced in an
archegonium (a small tube that makes a single egg). Sperm are produced in antheridia;
each antheridium contains thousands of sperm. These gametes are produced by mitosis.
describe the gametophytes of many liverworts
The gametophytes of many liverworts are flat, without much predictable shape. On the
gametophyte surface you can sometimes see the two types of umbrella-like structures that
bear the archegonia and antheridia. Note: the sporophyte generation is very small and short
lived
what are gemma cups
Liverworts also produce small cup-shaped structures called gemma cups. They contain small
green gemmae, each of which grows into a new haploid liverwort plant. The new haploid plant
develops without any eggs or sperm involved, so this is called asexual reproduction.
describe archegonia and antheridia in ,oos
In moss, the archegonia and antheridia are miniature structures at the tops of the gametophyte
plants. After fertilization of the moss egg, the 2n zygote develops into the sporophyte. The
moss sporophyte is a long slender stalk with a sporangium (capsule) at its tip.
what does sponargium produce
spores
what kind of cell division occurs inside the sporangium?
meosis
which is the dominant generation in mosses and liverworts?
gametophyte generation
describe seedless vascular plants
The development of vascular tissue was a major advancement in Kingdom Plantae. It
allowed the colonization of a wider range of terrestrial habitats than was possible for mosses
and liverworts, as well as a great increase in the size of terrestrial plants. There are many
phyla of seedless vascular plants. We are showing you ferns, which are in Phylum
Pteridophyte.
what do fern sporophytes produce?
Fern sporophytes produce sporangia (where spores are produced by meiosis) in clusters
on the back of the fern fronds. Each cluster is called a sorus (plural: sori). Observe the sori
on the dissecting microscope. Draw and label a fern frond with sori.
what do fern spores grow into
Fern spores grow into tiny heart-shaped photosynthetic gametophyte plants. Each plant
produces an egg in each archegonia and many flagellated sperm in each antheridia.
Observe the slides on demonstration; draw and label a gametophyte indicating an
antheridium and an archegonium. Also include a gametophyte with a young sporophyte (leaf
and root) growing out of it.
which generation is dominant in ferns
sporophyte generation
describe seed plants
Seeds can move enormous distances by wind,
water currents, or animal vectors. Seeds have the additional advantage of being able to
move through time. Seeds contain dormant plant embryos packed with stored food and a
tough outer coat that can survive much adversity. Some seeds can survive through
centuries, waiting for the right conditions to germinate and start a new population in another
place and time
what are the 2 general groups of seed plants. what are the 4 different phyla gymnosperm are divided into
There are two general groups of seed plants. Gymnosperms are plants that produce naked
seeds, and Angiosperms are flowering plants that produce seeds that are inside a fruit.
Phylum Cycadophyta top three only have few living species, only seen as fossils
Phylum Ginkgophyta
Phylum Gnetophyta
Phylum Coniferophyta – has many living species.
Phylum Angiosperms are monophyletic but morphologically diverse
what is the largest modern group of gymnosperms?
Phylum Coniferophyta (conifers) is the largest modern group of gymnosperms. This group
includes pines, cedars, firs, etc. These trees produce both male and female cones, which
are on display
what do female cones look like vs male cones
describe the life cycle of a conifer tree
locations within the cones produces haploid spores that develop into gametophyte tissue.
The gametophyte generation in gymnosperms is microscopic and does not grow into a
separate, free-living plant.
In a female cone, meiosis produces four megaspores. Three of these cells disintegrate, just
as in animals. The fourth megaspore divides (by mitosis) to produce haploid tissue, the
female gametophyte. In time, two eggs develop inside this gametophyte tissue. The
gametophyte tissue containing eggs is surrounded by sporophyte tissue. Together, this
gametophyte and the surrounding sporophyte tissue make up the ovule.
In the male cone, meiosis produces microspores, which develop into pollen grains through
mitosis. The mature pollen grains are the male gametophyte generation, with each pollen
grain containing one sperm cell. Pollen falls out of the male cone in great amounts. The
male cones later fall off the tree and disintegrate
what happens when pollen finds a female cone
When a pollen grain finds its way to a female cone, pollination occurs. The pollen grain
grows a pollen tube that delivers the sperm to the egg. After fertilization, the zygote
matures within the ovule, and the entire ovule becomes a seed. In the seed, the female
gametophyte tissue around the zygote is rich in food reserves and nourishes the zygote
when it begins to grow. By now, the female cone has grown significantly, and is the pine
cone many of us know
describe angiosperms
Phylum Angiosperm is the most complex and diverse of all the plants. They are vascular
seed plants that produce flowers and fruit. The flowers attract pollinators, which encourages
fertilization. The fruits help ensure successful seed dispersal. They may do this by acting like
parachutes (e.g. dandelions); attaching to fur (e.g. burdock) or by attracting animals that eat
the fruit and deposit the seeds (in their poop) in a different location. The dominant
generation of the angiosperm plant is a sporophyte and thus 2n.
Angiosperms are by far the largest group of land plants with more than 300,000 living
species. Their success in terms of species diversity, geographical distribution, and total
number of individuals is dependent on their reproductive organ - the flower. All angiosperms
produce flowers. Most flowers have showy petals to attract animal pollinators. However,
some flowers, such as those on the grasses, have no petals and the remaining flower parts
are typically green.
label plant
describe meoisis in angiosperms
n a flower, meiosis occurs in ovules in the ovary. Meiosis produces four megaspores, three
of which disintegrate. The remaining megaspore divides (by mitosis) to produce the female
gametophyte. The female gametophyte is a sac, called the embryo sac, which has seven
cells with eight nuclei. One of the cells with a single nucleus is the egg. Another cell in the
middle of the embryo sac contains two nuclei and are called the polar nuclei. The embryo
sac and the surrounding protective sporophyte tissue make up the ovule within the ovary.
In the anther, meiosis produces many microspores. Each develop into a pollen grain by
mitosis. The pollen grains travel via wind or insects to a flower’s stigma and pollination
occurs. Each pollen grain develops into a pollen tube which grows down the style to deliver
two sperm to the ovule in the ovary, where fertilization occurs.
what happens when spem fertilizes egg in angiosprems
One sperm fertilizes the egg, creating a new diploid (2n) structure, called the zygote. This
grows by mitosis into the embryo.
The second sperm from the pollen tube fertilizes the two polar nuclei in the middle of the
embryo sac. Together, these three nuclei form the triploid (3n) endosperm. The creation of
the embryo and the endosperm is known as double fertilization and is unique to Phylum
Anthophyta.
e. Vascular plants are organized
into two general organs:
- the root which is usually, although not always, below the ground.
- the shoot, which consists of the stem, leaves, and flowers.
what are the 3 main tissues of plants
Three main types of tissues make up the plant parts listed above: epidermis, vascular, and
ground tissue.
lable eudicot root
describe the outermost layer of eudicots
The outermost layer is called the epidermis. The cortex (made of ground tissue) is found
between the epidermis and the central vascular cylinder. The vascular cylinder contains
all of the xylem and phloem gathered in one place in the root (instead of the xylem and
phloem being divided into many small units – vascular bundles - in the stem).
Xylem stains red due to lignin strengthening its cell walls. Phloem cells are small, thin-walled
and blue/green. Phloem is actually made up of pairs of cells; one of which is much larger
than the other. The alternating large and small cells make identification of phloem much
easier.
functions of epidermis, cortex, xylem and phloem
epidermis prevents water loss. cortex stores nutrients and provides support
what is the main function of root hairs
absorb water and minerals
what are mycorrhizae and what are the function
fungal roots that absorb nutritents and transport it back to the host plan t
describe the eudicot stem
The epidermis is the outermost layer. The cortex is found between the epidermis and the
vascular bundles. A number of vascular bundles (composed of xylem and phloem) are
arranged in a ring just inside the cortex layer. This arrangement of vascular bundles is
typical of non-woody eudicot stems.
The rest of the stem is composed of ground tissue. Ground tissue between the epidermis
and vascular bundles is called cortex. Ground tissue containing no vascular bundles in the
middle of the stem is called pith.
describe the monocot stem
r. Note
the vascular bundles scattered through the ground tissue, an arrangement typical of
monocot stems.
label eudicot stem
