Download Unit 2 Review Answers

UNIT 2 REVIEW
(Pages 154–157)
Understanding Concepts
1. (a) Many answers are possible. The characteristics of protists, fungi, and bacteria do not fit into the groups of
plants
or animals. For example, fungi have cell walls like plants but do not contain chlorophyll. Some protists move in
ways similar to animals, but many of these organisms also contain chloroplasts.
(b) Bacteria were not seen by Aristotle. Some organisms may have chlorophyll and cell walls similar to plants, but
they also lack a nuclear membrane. Other bacteria have flagella— a characteristic of animals and protists; they also
lack chlorophyll. Plant cells and animal cells have a different appearance when viewed under a microscope. If
Aristotle had been aware of this, he may have developed a different classification scheme. Both plant and animal
cells have a true nucleus. Plant cells have cell walls and chlorophyll, while animal cells have no cell walls or
chlorophyll. Some bacteria and protists would have been difficult for Aristotle to classify as plants or animals.
Bacteria have no true nuclei, but contain cell walls; some bacteria contain chlorophyll. Euglena has chloroplasts,
but no cell wall. Euglena also has a true nucleus. Fungi have cell walls and nuclei but no chlorophyll.
2. (a) Escherichia coli— Eubacteria
(b) Plasmodium— Protista
(c) Giardia lamblia— Protista
(d) adenovirus— other
(e) methanogens— Archaebacteria
(f) Bacillus anthracis— Eubacteria
(g) lichen— Protista
(h) yeast— Fungi
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3. In support of the claim that viruses are nonliving, one might argue that viruses are not cells: they have no nucleus,
cytoplasm, or cellular organelles. Viruses have no cellular respiration, so they do not exchange gases, and they do
not
feed or reproduce (outside a host cell). To refute the claim that viruses are nonliving, one might argue that viruses
contain genetic material, are capable of reproduction (when inside a host cell), and exhibit genetic variation over
time.
4. The invading virus takes over control of the host cell and directs it to expend energy making viral particles.
Normal
functioning of the host cell, including protein synthesis, stops.
5. Eubacteria contain peptidoglycan in their cell walls; Archaebacteria lack this component. Most Eubacteria
metabolize
with oxygen; most Archaebacteria live without oxygen and thrive in extreme environments (hot, salty, sulfurous).
6. Products that rely on a bacterium for part of their production include: alternate fuel sources; acetone; bioplastics;
stonewashed jeans; enzymes used in food processing (dairy products, vinegar); perfume manufacture; antibiotics and
other pharmaceuticals.
7. Comparison chart of viruses, bacteria, protists and fungi:
Feature Viruses Bacteria Protists Fungi
cell structure not a cell prokaryotic eukaryotic eukaryotic
genetic material DNA or RNA DNA loop or plasmid nucleus containing nucleus containing
chromosomes chromosomes
locomotion carried in air or flagella cilia; flagella; nonmotile
moisture pseudopods
reproduction replication via binary fission; binary fission; asexual and sexual
lytic and conjugation; conjugation; life cycles; spore
lysogenic cycles form endospores spore formation formation
nutrition supplied by host most are heterotrophs; most are heterotrophs; heterotrophs
some autotrophs some autotrophs
habitat host cell nature or host cell aquatic or moist terrestrial
environments
niche parasite producer, consumer, producer, consumer, consumer
saprophyte, or parasite or parasite
8. In Figure 1 (p. 154 of the Student Text), an amoeba is feeding. Students should draw two previous sketches in the
sequence (amoeba with pseudopod approaching food; pseudopod engulfing food particle and drawing it into the
organism). An after-sketch would show the lysis of food vacuoles after digestion is complete.
9. Bacteria are involved at every level of the food chain. Some bacteria are photosynthetic and take energy directly
from
the sun to produce oxygen and food. At the consumer and producer levels, bacteria act as saprophytes, releasing
digestive
enzymes into dead organisms and causing organic material to decay. W ithout decay, dead organisms would
accumulate
and nutrient cycles would cease to function. Bacteria play an important role in the nitrogen cycle, “fixing” this
nutrient into a usable form for producers. Arrows can also be drawn from bacteria to the deer and fox, because these
organisms take up bacteria and rely on their enzymes to digest nutrients.
10. Comparison of cilia and flagella:
Cilia Flagella
Similarities By beating, can produce cell movement
Differences – tiny (<10 ìm), hairlike, protein structures – relatively long (up to 150 mm), fine,
present on the surface of many cells, notably whiplike structures present on the
protists and some types of vertebrate epithelium surface of some cells, e.g.,
– usually occur in large groups spermatozoa, protists
– beating can create a current in fluid surrounding – occur singly or in small groups
the cell
NEL Unit
2 Review 75
sun trees
bacteria
deer
bacteria
fox
bacteria bacteria
76 Unit 2 Student Book Solutions NEL
11. Figure 3 (p. 154 of the Student Text) shows conjugation, a sexual form of reproduction. Genetic information is
exchanged; new organisms are genetically different from their parents. In binary fission, the usual form of
reproduction
in protists, one mother cell produces two genetically identical daughter cells.
12. Algae supply about 80% of the world’s oxygen. Algae are consumed as food; used in the production of
fertilizers,
consumer products and pharmaceuticals; and are instrumental in creating petroleum resources. Phytoplankton and
zooplankton occupy essential levels in aquatic food chains.
13. Answers will vary. Students may argue that most protists are unicellular eukaryotes, so do not belong in any of
the
other kingdoms. However, there are many exceptions: algae are multicellular but do not form tissues; fungilike
protists
form colonies of identical cells. Attempts to classify protists according to the following characteristics show the vast
diversity of this kingdom: size (2 :m length to 5 cm diameter); shape (amorphous— Amoeba; slipper— Euglena and
Paramecium; filamentous—algae; plasmodium— slime moulds); structure (simple— Amoeba— to complex—
Paramecium); locomotion (flagella, cilia, pseudopods, free floating, parasitic); respiration and nutrition (some
autotrophs— algae, Euglena; most are heterotrophs); habitat (fresh or salt water, animal fluids, or very damp
terrestrial
environments); and role (some essential to life on Earth, others are pathogenic).
14. Plantlike features of fungi include: eukaryotic; many cell organelles; cell walls; most are anchored in soil or other
substrate; nonmotile; reproduction can be asexual, sexual, or both.
15. The vegetative body or mycelium of a fungus may be present but unnoticed because it exists below soil level.
16. There are over 700 known yeast species and almost as many ways of using this organism. Yeasts are used
nutritionally
(as a dietary supplement), agriculturally (in a process called effective microorganisms technology), industrially (in
the production of ethanol), and medically (in gene therapy).
17. Antibiotics are administered after pathogenic bacteria have entered the body and triggered an immune system
response. They work by preventing bacteria from manufacturing proteins or constructing a normal cell wall. In each
case, normal cell processes are disrupted and bacteria that are causing the infection die. Vaccines work by
stimulating
the immune system with a structure so similar to a specific pathogen that antibodies are produced. W hen the “real”
pathogen enters the body, memory cells quickly trigger antibody production, and the antigen is neutralized before an
infection takes hold.
18. diphtheria (3); whooping cough (4); oral polio (1); measles (1); mumps (1); smallpox (5); tetanus (3); injected
polio (2)
19. Figure 5 (p. 155 of the Student Text), Old Man’s Beard, is a lichen— a symbiotic partnership of an algae and a
sac
fungus. The fungal mycelium surrounds the algal cells and provides them with essential minerals, carbon dioxide,
and
water for photosynthesis. The mycelium also lends structural support to the entire organism. The algae share the
carbohydrates
they manufacture from carbon dioxide with the fungi. Lichens are an important source of food for caribou and
other animals in the arctic tundra and boreal forests of northern Canada. Lichens are involved in plant succession: by
being able to establish themselves on rocks and in barren areas, lichen help form basic soil material. Concentrations
of
pollutants in an area can be assessed by monitoring the presence or absence of different lichens because lichens
absorb
water directly from the air.
20. smallpox (N); measles (N); anthrax (Y); E. coli food poisoning (Y); Streptococcus throat infection (Y); rabies
(N);
malaria (Y); viral throat infection (N)
21. Biotechnology is the use of living things in industrial or manufacturing applications. Traditional methods of
biotechnology
include the production of penicillin from moulds and the use of bacterial enzymes to make cheese and yogourt.
Recombinant DNA technology and viral vectoring are two new biotechnology methods that involve gene
manipulation.
22. (a) The application of chemicals (pesticides: fungicides, herbicides, insecticides) kills microorganisms in the soil
and
decreases the natural coating of microorganisms on leaf surfaces.
(b) Soil can be enriched in a more balanced way through effective microorganisms (EM ) applications and the use of
integrated pest management (IPM). EM is a cocktail of microorganisms blended in a sugar medium at low pH.
EM application improves soil structure, increases fertility, and reduces disease and the need for pesticides. IPM
uses a combination of cultural, biological, genetic, and chemical methods to control pests in parks and open areas.
Decisions are made that present the lowest health risk to humans, have a minimum impact on nontarget organisms,
have greatest effect on target species, and present the least risk to the environment and biodiversity.
23. There is a zone of antibiotic release around the mycelium of the soil fungus. In this area, no other
microorganisms
grow. This zone gives the soil fungus a competitive advantage for space, water, and food; otherwise, there would be
competition for these resources.
24. Concept map:
25. HIV is an example of a retrovirus. Lysogeny is an important part of the life cycle of this RNA virus. During the
lysogenic
cycle, the virus invades and integrates with host DNA, lying dormant for many years before resuming replication
in the lytic cycle. Many other viruses (e.g., smallpox, mumps, influenza) do not go through the process of lysogeny.
Replication occurs quickly in the lytic cycle, and symptoms appear in the host shortly after exposure to the virus.