Biology 198 Exam 6 Questions With 100% Correct Answers
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Course
Biology 198
Institution
Biology 198
Biology 198 Exam 6 Questions With 100% Correct Answers
1) Examine the symbiotic interaction of algae and fungi, and understand the role of lichens.
1: the fungus provides the algae or cyanobacteria with carbon dioxide , minerals , and water , it also provides the algae with "housing" , protection...
Biology 198 Exam 6 Questions With 100%
Correct Answers
1) Examine the symbiotic interaction of algae and fungi, and understand the role of lichens.
1: the fungus provides the algae or cyanobacteria with carbon dioxide , minerals , and water , it also
provides the algae with "housing" , protection of its photosynthetic organelles- the algae or
cyanobacteria provides the fungus with energy through photosynthesis^ this symbiosis forms lichens-
pioneer organisms that can settle on rock and secrete acids to form soil environments suitable to
other plant species (primary succession)
2: Lichens are formed as a result of mutualistic interaction between a fungus and a photosynthetic
microbe such as a green algae or a cyanobacterium. Lichens are well organized and have definite
structures. Lichens are photosynthetic and often can also fix nitrogen. Lichens are formed through a
mutualistic reaction because both partners benefit from each other. The fungus supplies the green
algae or the cyanobacterium with carbon dioxide, minerals, and water. The fungus also protects its
partner's photosynthetic mechanisms and provides "housing" for the green algae or cyanobacterium.
The green alga or cyanobacterium, in return, provides the fungus with food that it makes through
photosynthesis. Lichens typically colonize habitats that are too hostile for most organisms. They often
live on bare rocks, for example. As they grow, they secrete acids that break down the rocks and form
soil, which in turn benefits other organisms (recall primary succession from our ecology module). The
soil that is formed enriches the habitat and eventually leads to colonization of the area by plants and
other organisms.
1) Learn some characteristics of algae, and understand the role of algae
1: - not all algae are marine organisms , commercially they provide us agar and carageenan from their
cell walls- their polysaccharides are used for solidifying agents for baking and dairy products- red
algae : red pigment , predominantly marine- green algae : fresh water or marine , unicellular , non-
motile , green pigment
2: All algae are eukaryotic protistans. There are red and green algae. Nearly all red algae are marine
organisms. Some red algae are commercially important because we get polysaccharides such as agar
and carrageenan from their cell walls. These polysaccharides are used as solidifying and emulsion
agents in many baked goods, dairy products (such as ice cream), and cosmetics. Seaweed is red algae.
Most green algae live in freshwater. Some live in colonies (Volvox) and some as single-celled
individuals (Chlamydomonas).
1) Understand the evidence supporting the hypothesis that land plants and aquatic green algae
evolved from a common ancestor.
1: Green algae exhibit similar features to land plants: Charophytes (one of the two groups of green
algae) are the closest living relatives to land plants and resemble them in their morphology (form and
structure) and reproductive strategies. Cell walls are both made of cellulose Chloroplasts contain
chlorophylls a and b. They both use chlorophylls a and b as well as carotene in a particular ratio.
Cellulose-synthesizing proteinsStructure of the flagellated spermGamete producing structures
2: aquatic green algae and land plants share several similar traits that imply a common ancestor : -
chlorophyll a & b - cell wall- cellulose based cell walls-chloroplasts
1) Describe the environmental challenges against living on land, and the adaptations that plants have
which allow them to live on land despite the barriers.
1: Three main problems:1. Obtaining resources: plants faced desiccation (drying-out) because water
supplies are not as plentiful on land as they are in aquatic environments. They adapted by developing
roots to absorb water from soil and having waxy cuticles to prevent evaporation from their leaves.
The stomata in the leaves allows for gas exchange. 2. Internal Transportation and Support: Vascular
tissues (xylem and phloem) transports water and nutrients from one part of a plant to another part.
, Plants faced greater gravitational pull on land than in water because water provides buoyancy. They
adapted by having cell walls with lignin that gives plants structural rigidity so that they can withstand
the pull of gravity. 3. Reproduction: the alternation of generations is when a multicellular diploid
stage alternates with a multicellular haploid stage. A prominent trend among land plants is the
change in relative sizes and independence of the gametophyte and sporophyte generations. Plants
are classified on the presence or absences of various structures associated with transport tissue,
seeds, flowers, and fruits which reflects the adaptations of the different stages of the alternation of
generations life cycle. The development of various adaptations that protect the gametes and zygote
from drying out, e.g. gametes=pollen, ovary and zygote=seed.
2: major adaptation show a changing environment from marine to terrestrial : 1) obtaining resources -
plants faced desiccation on land (drying out) , as water supply wasn't as constant as in their marine
environments so they developed roots that were able to absorb water , cuticles to prevent
evaporation from the leaves , and controllable stomata2) internal transportation and support -
vascular tissues formed (xylem & phloem) , transporting water and nutrients to other parts of plant ,
they also combat gravitational pull by forming lignin in their cell walls 3) reproduction - alternation of
generation between haploid (gametophyte) and diploid (sporophyte) stages , structures are formed
as adaptation for stage processes : tissue , seeds , flowers , and fruits which protect either zygote or
each reproductive part and avoid desiccation
1) Describe the benefits for early plants as they evolved to live on land.
1: - abundant sunlight- carbon dioxide is more available- evolution- no predators- no competition
2: Sunlight is abundant. Carbon dioxide is more readily available in the air than in water. Land plants
evolved before land animals, so for a while they did not have any predators.
1) Describe the four main categories of plants that are displayed in the studio and provide an example
of each.
1: Nonvascular, seedless plants (bryophytes)- plants that do not produce seeds, and they have no
vascular tissues. Bryophytes are nonvascular. They are usually fairly small. If they were large and tall,
it would not be possible for them to transport water and nutrients from one organ to another.
Examples: mosses, liverworts, and hornwortsVascular, seedless plants- these plants have vascular
tissues, but do not produce seeds. Examples: ferns and horsetailsVascular, flowering, seed plants
(angiosperms) plants that have vascular tissues, flowers, and after flowering, they had seeds as well.
Most plants we see are angiosperms. These can include obvious ones such as roses, petunias, and
daffodils. Grasses are also angiosperms, although you cannot see their flowers sometimes because
they are very small. Oak trees, cottonwood, and other trees also produce inconspicuous flowers.
Vascular, non-flowering, seed plants (gymnosperms)- plants that have vascular tissues and produce
seeds, but they do not flower. Examples: conifers, pine trees, and cycads.
2: 1) non-vascular , seedless : aka bryophytes , they do not produce seeds and are generally smaller in
size (ex : mosses , liverworts , hornworts) 2) vascular , seedless : plants that have vascular tissue but
do not produce seeds , small-medium size (ex : ferns , horsetails) 3) vascular , non-flowering ,
seeding : aka gymnosperms , they have vascular tissue and produce seeds but they do not flower (ex :
conifers , pine trees , cycads) 4) vascular , flowering , seeding : aka angiosperms , have vascular tissues
and they flower , after flowering they produce seeds , majority of modern plants are angiosperms (ex :
daffodils , roses , grass , oak trees)
1) Understand the main differences in the life cycles of bryophytes, seedless vascular plants and
vascular plants.
1: - bryophytes and seedless vascular plants live in the dominant stage of gametophyte -
gymnosperms and angiosperms live in the dominant stage of sporophyte
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