Download Unit 1 Review Answers

Unit 1: Diversity of Living Things
Review
(Page 124-131)
Knowledge
1. (d)
2. (a)
3. (c)
4. (b)
5. (d)
6. (c)
7. (c)
8. (d)
9. (b)
10. (a)
11. (a)
12. (b)
13. True.
14. False. Botanists and taxonomists rely on classification systems in their daily work.
15. False. Taxonomists today use different methods for classifying organisms..
16. True.
17. True.
18. False. Viruses are small, nonliving particles.
19. True.
20. False. Protists are by far the most diverse kingdom of eukaryotes.
21. False. Not all fungi are helpful to other organisms. Fungi are responsible for some animal and
plant diseases.
22. True.
23. True.
24. False. Unlike plants and fungi, animal cells do not have cell walls.
25. Species can also change or evolve across great distances.
26. Plants are considered autotrophs because they produce their own nutrients.
27. In chemistry, elements are carefully arranged in the periodic table into families.
28. Carl Linnaeus introduced a consistent way of grouping species according to their morphological
(or physical) similarities.
29. The main difference between the traditional classification system and modern biological
classification is that the traditional system groups species primarily by observed morphological
characteristics while the modern system is based on phylogeny, which is the evolutionary
relatedness of species.
30. The six kingdoms of life are Eubacteria, Archaea, Protists, Fungi, Plants, and Animals.
31. Evidence suggests a strong evolutionary connection between birds and dinosaurs and crocodiles.
32. Natural antibiotics are produced by bacteria or fungi.
33. An obligate aerobe is an organism that cannot survive without oxygen.
34. Viruses and living things both reproduce.
35. Viruses become active only when they have entered and taken control of a living cell.
36. The Animal, Plant, Fungi, Eubacteria, and Archaea kingdoms are all based on evolutionary
kinship. The Protist Kingdom is not.
37. A haploid cell contains half the usual complement of chromosomes. A diploid cell contains two
copies of each chromosome.
38. Fungi and plants are both sessile multicellular eukaryotes, and many species of both fungi and
plants grow in the ground.
39. Lichen are symbiotic combinations of fungi and photosynthetic cyanobacteria, or green algae.
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-6
40. Habitat destruction, invasive species, pollution, and climate change are all current threats to the
world’s plants.
41. Land plants must be able to take in small amounts of carbon dioxide gas from the atmosphere in
order to perform photosynthesis.
42. The bodies of animals with radial symmetry are regularly arranged around a central axis. The
bodies of animals with bilateral symmetry have left and right sides that are mirror images of each
other.
43. Sponges are the simplest invertebrates.
Understanding
44. The first step for scientists is to choose a fundamental unit. In the case of living things, this unit is
the species.
45. Answers will vary. Many reptilian creatures have very similar, if not the same, characteristics as
their ancient ancestors. This may be because they were, and continue to be, adaptable to different
climates.
46. (a) Humans inherit unique combinations of genetic information from our parents.
(b) Answers will vary. Students may answer that they look like one or both of their parents, or
that they possess a certain skill or ability that one or both of their parents also possess.
47. (a) A heterotroph is an organism that obtains energy-rich nutrients by consuming living or dead
organisms.
(b) Answers will vary. Humans are heterotrophs. In order to obtain energy-rich nutrients they
must consume animals and/or plants.
48. Botanists are scientists who specialize in the study of plants. Their days are probably filled with
researching and observing many different plant life forms. They must benefit greatly from the use
of taxonomy and, specifically, phylogenetic trees that include many or all species of plants.
49. New species can arise from hybridization, by which two different species crossbreed to create a
new species. Also, species change over time and distance through evolutionary change.
50. Answers will vary. Students’ phylogenetic trees should clearly and correctly demonstrate the
closer relationship between two of the three species by drawing each of their branches coming off
from the same main branch. The third, less related species’ branch should be below the meeting
point of the other two. Students’ diagrams should be similar to the following:
51. Answers will vary. Students’ pairs of phylogenetic trees should show a consistent relationship
between clades of animals on one and family members on the other. For instance, the order
Carnivora branches out to different carnivores just as a grandfather branches out to his children
and grandchildren. Students’ diagrams should be similar to the following:
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-7
52. Answers will vary. Darwin’s theory should be well represented and student’s phylogenetic trees
should clearly illustrate the lineage of all organisms working back to one common ancestor.
Students’ diagrams should be similar to the following:
53. Fungi are heterotrophic, while plants are autotrophic and photosynthetic. Plant cells have
chloroplasts and walls composed of cellulose, while fungi cells have no chloroplasts and walls
composed of chitin. A fungus consumes organisms for nutrients whereas a plant does not.
54. Answers under “EXAMPLE” column will vary.
KINGDOM
EXAMPLE
Eubacteria
Salmonella
Archaea
Methanogens
Protists
Green Algae
Fungi
Mushrooms
Plants
Ferns
Animals
Humans
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-8
55. (a) Characteristics common to birds and dinosaurs are skeletal structure, feathers, and hard-shell
egg-laying. Characteristics shared by birds and crocodiles include four-chambered hearts, skeletal
structure, and the tendency to care for their young.
(b) Because dinosaurs and crocodiles both share many characteristics with birds, they also share
many characteristics with each other, suggesting that they are closely related.
56. Prokaryotes inhabit every imaginable place on Earth. They live inside and on the surface of other
organisms, in water and soil, deep within Earth, in boiling hot springs, and even in ice. More than
100 trillion bacteria live within each of our bodies, outnumbering all other human cells. In fact,
prokaryotes outnumber all other living things. Their sheer numbers and ability to live anywhere,
then, make them the most dominant life forms.
57. (a) Because of their sheer numbers and the fact that they live virtually everywhere on Earth,
prokaryotes are important to us. They cause many diseases, play key roles in ecosystems, and
have many commercial uses.
(b) Answers will vary. Sample answer: Photosynthetic bacteria are the major producers in
marine ecosystems and are therefore major producers of atmospheric oxygen. Bacteria are also
essential in the production of foods such as cheeses, yogurt, and chocolate.
58. (a) Answers will vary. Under certain conditions, some prokaryotic organisms, such as algae, can
experience a sudden rapid increase in numbers. This results in an algal bloom that reduces oxygen
content in the water and can be damaging to the entire aquatic ecosystem. In addition, many
prokaryotes live as infectious agents in other living things. Bacteria that cause disease have a
negative impact on the organisms they infect. If the disease is widespread causing a large die-off
of a particular group of organisms, this could upset the food web within an entire ecosystem and
have more far reaching negative impacts.
(b) Answers will vary. Infectious bacteria are pathogens and are responsible for millions of
human deaths each year. Bacteria also infect livestock and crops and therefore also threaten our
food sources.
59. Antibiotics are substances that kill micro-organisms. Antibiotics are immensely important to
humans as they are used to kill bacteria where they are not wanted.
60. Though viruses are small and nonliving, they have the ability to enter and take control of healthy
cells. These infected cells eventually make copies of the virus. Viruses are responsible for
diseases ranging from the common cold to HIV-AIDS, rabies, and cholera.
61. Although many viruses are harmful, they are important in ecosystems. By causing disease, they
control the populations of other organisms.
62. Answers will vary. All cancers involve uncontrolled cell division that is caused by mutations in
the cell’s DNA. When viruses infect host cells, they sometimes create changes in the host’s DNA
that can lead to cancer. The Hepatitis C virus, for example, has been shown to be a major
contributor to liver cancer.
63. Answers will vary. Protists are valuable to humans in various ways. Nori, the seaweed wrap used
to make sushi, is the common name for several species of Porphyra, which is a multicellular
protist. Photosynthetic protists are the primary producers in aquatic food webs.
64. The Animal, Plant, Fungi, Eubacteria, and Archaea Kingdoms are all based on evolutionary
kinship. The Protist Kingdom is not. Instead, this kingdom has traditionally been a “catch-all” for
any species that did not fit into the other major kingdoms of life. As a result, most of the major
taxa of protists are very distantly related to each other.
65. (a) Unlike plants, fungi are not photosynthetic and they do not produce their own food. Their
cells are unlike plant cells and they have entirely different methods of reproducing.
(b) Like animals, fungi are heterotrophs and must consume other organisms to survive.
66. Answers will vary. Truffles grow underground and are very difficult to find. Trained pigs and
dogs, with their keen sense of smell, are used to find these rare and valuable gourmet fungi.
67. Some fungi, such as puffballs, produce reproductive cells, called spores, within a soft, enclosed
structure. The top splits open when it is mature, and the slightest contact—such as being hit by a
raindrop—causes millions of spores to puff out into the air.
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-9
68. (a) Answers will vary. St. Augustine grasses (known by some as crab grasses) thrive in the very
hot, dry climate of the Southwestern United States.
(b) Answers will vary. This plant is probably able to succeed in this climate by adapting to very
low-moisture needs as well as by adapting a tolerance for high heat.
(c) Answers will vary. Because this plant thrives in a low-moisture, high-heat climate, it would
probably not do well in cooler or damper environments because it is so specifically adapted to the
one type of environment..
69. (a) The first requirement for life on land was the ability to prevent water loss.
(b) Plants developed a flexible, waxy cuticle on their outer surfaces that effectively prevents
water loss.
70. (a) The most widespread threat to plants today is climate change, which has the potential to affect
plants living everywhere on Earth.
(b) This threat has worsened as human actions have caused much more rapid and severe climate
change. Consequences include vast forest fires, severe droughts, unprecedented flooding, and
record heat in many locations across the globe. Any and all of these can be very detrimental to
plant life.
71. Answers will vary. Instead of its round or cylindrical shape, a jellyfish with bilateral symmetry
would have sides that were mirror images of each other, similar to a fish or an eel.
72. (a) Answers will vary. Corn earworms are significant pests in Ontario, where they have the
potential to impact corn production significantly.
(b) Answers will vary. Mosquitoes spread the deadly disease malaria across Earth’s warm and
tropical climates.
(c) Answers will vary. Silk is a very valuable fibre produced by caterpillars of the silkworm
moth.
73. The development of an amniotic egg was a key development that enabled some of the vertebrates
to conquer land. Mammals, including humans, retain amniotic membranes around the developing
fetus.
74. (a) Answers will vary. Sample answer: One way in which the supplies of marine foods have
been affected is by overharvesting.
(b) Answers will vary. Sample answer: A potential solution is for fisheries to become more
sustainable by changing their harvesting and farming methods.
Analysis and Application
75. Individual variability is very different from evolutionary change. Individual variability is
represented in an entire species of organisms in the present. In other words, it is how members of
the species appear differently right now. Evolutionary change, on the other hand, happens over a
long period of time, even within one, multiple-generation family of humans. These are the
changes that occur, for various reasons, over great distances with time.
76. (a) Sample answer: An example of evolutionary change over time is a giraffe species that, over
thousands of years, becomes gradually taller to accommodate for the higher and higher branches
of taller growing, evolving trees (which also an example of evolutionary change over time). An
example of evolutionary change over distance is a species of squirrel whose members have a
much thicker coat of fur in the colder climate of Northern Canada than do those living in the
much warmer Southeastern United States.
(b) Sample answer: An overlap may occur by which evolutionary change over time and distance
happens for the same reason. An example of this could also be the species of giraffe mentioned in
part (a). If the same species exists in a region of the world where the trees are not growing taller
over thousands of years, that region’s giraffes would have had no reason to grow taller. Therefore,
their cousins who did grow taller did so via evolutionary change over time and distance.
77. (a) Answers will vary. Sample answer: Clear-cutting for logging can create even-aged tree
populations that exhibit almost no structural diversity and, therefore, very little biodiversity.
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-10
78.
79.
80.
81.
(b) Answers will vary. Sample answer:Humans are affected in many ways by forests that
experience a decline in biodiversity. Fewer species of wildlife might mean fewer species of big
game for food supplies. Even-aged trees will also mean much longer wait times between
harvesting for building, fuel, etc.
(a) Answers will vary. Sample answer: A world without classification systems would be quite
chaotic. Our knowledge of species would be greatly affected as our understanding of the
relationships between species is key to our full understanding of any one species.
(b) Answers will vary. Sample answer: Without an Internet classification system Internet
searches would be virtually impossible
(a) Answers will vary. Students’ answers should show knowledge of the characteristics of the
taxon they choose (gills on fish, for instance).
(b) Answers will vary. Students should demonstrate the ability to include or not include species
based on whether or not they qualify under the criteria they set.
Answers will vary. Students should intelligently discuss which of the two jobs they would rather
have, list real duties and responsibilities, and explain why they would choose one over the other.
(a) This phylogenetic tree is incorrect as it is drawn because it shows the bird and the bat as
closely related and the fox and the crocodile as closely related.
(b) Students should redraw the branches to show the fox and the bat as more closely related to
each other than to the other two and the same for the bird and the crocodile. Students’ diagrams
should be similar to the following:
(c) These species are more closely related because birds and crocodiles share many more
characteristics with each other than with either of the other two, and the same is true of the bat
and fox.
82. (a) Carl Linnaeus described only two kingdoms of living things: Plants and Animals. Carl
Woese, working with the modern six-kingdom view, grouped all organisms into three domains.
(b) Woese did, in fact, compliment Linnaeus’ theories by taking what had been done some twohundred plus years before and refining it.
83. Students’ diagrams should be similar to the following:
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-11
84. Answers will vary. Students’ answers should be, above all, creative. There is really no wrong
answer here. Students should show some knowledge of dinosaur characteristics in their
“redefined” species. Students should also intelligently prove the relationship utilizing
classification diagrams.
85. (a) Sample answer: The infectious bacteria (pathogen) that causes tuberculosis is just as
damaging and deadly as photosynthetic bacteria are helpful and essential. Tuberculosis makes
humans very sick and can be deadly. Photosynthetic bacteria, on the other hand, are the major
producers of marine ecosystems and are, therefore, major producers of atmospheric oxygen.
(b) Answers will vary. Students’ responses should intelligently make the case for why they feel
one of the two has the biggest impact on human life.
86. Antibiotics kill bacteria and other micro-organisms. They are important because many of the
bacteria they target cause disease.
87. Perhaps the biggest difference between bacteria and viruses lies in the fact that bacteria are living
organisms and viruses are not. Though this is a major difference, they are similar in that they both
have the potential to make humans very sick. And, although this is something that they both have
the ability to do, they are also both very beneficial to us in other, more positive, ways.
88. Answers will vary. Vaccination programs have vastly reduced human suffering and saved many
lives. Thanks to a now widely used smallpox vaccine, for example, the last recorded case of
smallpox was in 1977.
89. (a) Answers will vary. Students’ answers should show a clear understanding of the wide variance
among organisms in the Protist Kingdom.
(b) Answers will vary. Students’ hypotheses should be intellectually presented and should utilize
taxonomic and phylogenetic tools.
90. (a) Fungi are sessile, multicellular eukaryotes that grow mostly in the ground. Unlike plants, they
do not produce their own food. The bodies of most fungi are mesh-like, composed of branching
filaments called mycelium.
(b) Answers will vary. Sample answer: Fungi are relatively unfamiliar to many people because
they often live underground or within other organisms. Many of their symbiotic relationships
require this type of environment. For example, they help and are helped by the underground roots
of many plants.
91. (a) A symbiotic relationship between two organisms is one in which each organism provides
something the other needs. They “co-exist.”
(b) Leaf-cutter ants live in tropical rain forests in large colonies where they cut and gather pieces
of leaves to feed an underground fungus. They grow and tend to their underground fungus
gardens and feed almost exclusively on them.
(c) Students’ answers must intelligently report on an actual symbiotic relationship they have with
another organism. For example, they might cite an apple tree in their yard that they prune, water,
and protect for the purposes of eating the fruit that it, in turn, provides them.
92. (a) Answers will vary. Students’ answers should focus on two very different climates (the desert
and the arctic, for example). They should demonstrate knowledge of the plants they discuss and of
what makes each plant suitable for its environment.
(b) Answers will vary. Students should name two different organisms that exist in these two
vastly different and extreme climates and show how they depend on the plants.
93. Answers will vary. Students’ responses should show knowledge of the ocean and its
unsuitableness for plant life. In their hypotheses, they might propose that the salty waters, the tidal
currents, or the lack of soil is the culprit for the virtual absence of aquatic plant life.
94. Answers will vary. In most seed plants, the entire male gametophyte is carried from one plant to
another by the wind or by animals. Seed plants are therefore not restricted to reproduction over
short distances in wet conditions, and so they have become the dominant land plants on Earth.
95. (a) Answers will vary. Sample answer: Humans use other animals for a variety of purposes.
Perhaps the two most common purposes are companionship (e.g., pet dogs and cats) and
transportation (e.g., horses, and camels).
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-12
(b) Answers will vary. Sample answer: Both of these uses are very important to humans across
the globe. In some cases it is habit or tradition, as in pets. And, in other cases it is out of necessity,
as in transportation. Transportation usage can be replaced by mechanical or machine equipment.
In these cases, though, economics and technology play a large role as less developed countries
have fewer bicycles and cars on which to rely.
96. (a) Answers will vary. Students’ answers should include three different species along with
accurate descriptions of characteristics.
(b) Answers will vary. Using these characteristics, the second part of the question should be
answered creatively and intelligently to show how the three different sets of characteristics might
have been combined into one common ancestor. For example, the common ancestor of a giraffe, a
snake, and an owl might have had an elongated neck, scaly skin, and nocturnal vision, just as the
dinosaurs had both bird-like and crocodile-like characteristics.
97. (a) Answers will vary. Students’ responses should include two vertebrates that live in or can
survive in extreme climates. For example, they might discuss the penguin and the polar bear.
(b) Answers will vary. Sample answer: In both of these cases, part of their ability to thrive in
extreme cold is their ability to maintain warm body temperatures. Heavy fur on the polar bear and
layers of fat on both animals help with this, as do other characteristics.
Evaluation
98. Answers will vary. Students’ reports should include detailed findings on the ecosystem or habitat
they visited. They should be thoughtful in their suggestions and recommend real and possible
solutions to the wildlife commission.
99. Answers will vary. Students’ arguments should include real characteristics in common (such as
both are eukaryotic, both are multicellular, etc.) as well as other commonalities that show
creativity in their thinking (for instance, both are often the subject of paintings, both are integral
to the playing of many popular outdoor sports, etc.).
100. (a) Answers will vary. Students’ family trees should be as detailed as possible and show the
correct branching of generations.
(b) Answers will vary. Students’ responses should intelligently and accurately speak to the
relatedness of their family tree with the phylogenetic trees from Chapter 1.
101. Answers will vary. Students can be very creative here, They should, however, create a unique set
of organisms that is unlike any of those in the six existing kingdoms. They might point out that
their organisms, no matter how different, should be placed into the Protista Kingdom, as that is
the kingdom in which, traditionally, those organisms that do not belong elsewhere are placed.
102. Answers will vary. Students’ answers should show a real knowledge of both bird and either
mammal or amphibian characteristics. While creative, their answers should also not be too much
of a departure from reality. For instance, they might suggest that their new, adapted bird group
contains creatures that have feathers and can fly, but that also give birth to live offspring and
breastfeed their young.
103. (a) Answers will vary. Students’ responses should point out that these living viruses might
behave a lot more like infectious bacteria.
(b) Answers will vary. Sample answer: As living organisms, viruses would not need to find and
take over host cells. Without this need to cause damage, viruses might have a much easier time
infiltrating, infecting, and killing.
104. Answers will vary. Students’ answers should discuss the dangers and diseases that result from
drinking unpurified water. Their pamphlets should also include a plan to make drinking water safe
for tourists to drink.
105. Answers will vary. Students’ answers should paint a real picture of what an ecosystem would
eventually look like if there were no potential for any decomposition. In such an ecosystem, there
would potentially be piles and piles of broken, yet fully composed trees, branches, and other plant
parts. Also, there would certainly be piles and piles of dead, yet fully composed, animals.
106. Answers will vary. Students’ lessons should be as engaging as they are educational. They should
discuss the many different varieties of plants, the great importance of plants, and the great
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-13
107.
108.
109.
110.
111.
112.
113.
114.
115.
116.
117.
118.
119.
120.
numbers of symbiotic relationships humans enjoy with plants, not the least of which is the critical
oxygen/carbon dioxide exchange.
Answers will vary. Students’ answers should focus on the great differences between sponges and
humans. The list of these differences should be great. The common characteristics, on the other
hand, are very few. It is not a stretch to imagine these two organisms separated into two different
kingdoms. Students should, however, be careful not to place sponges in with the Plant Kingdom,
as they are clearly not plants. Including them within the Protista Kingdom or assigning them into
an entirely new kingdom might be the only two real choices.
Answers will vary. Students’ reports should include several of the animals and plants that inhabit
the area on which they choose to report. Their classification systems (one for Plants and one for
Animals) should be completed accurately based on the species discussed. Taxonomy and
phylogeny should be used correctly and appropriately.
Answers will vary. Students’ classification tables should include the many different types and
genres of books which they noted from their trip to the library or bookstore. They should
accurately assign the sub-types of books under the general categories and those below the
subtypes accordingly as well. The tables should be completed neatly and should use a similar
system to those used in Chapter 1.
Answers will vary. Students’ responses should be accurate representations of what, in fact, might
very well happen in a world without vaccines. They should cite the different nature of today’s
world from years ago before vaccines. Today, they might point out, vaccines are even more
important as diseases have many more opportunities to spread across great distances in drastically
less time. Diseases that wiped out towns and villages hundreds of years ago might well wipe out
countries and continents today if it weren’t for vaccines.
Answers will vary. Students’ arguments should cite the many characteristics unique to humans.
There should be valid reasoning and explanation for the new designation as well as reasons why it
makes more sense for taxonomists to do so.
Answers will vary. Students’ reports should describe what life on Earth would be like without
land plants. They should detail the effects that this would have on humans and animals and how
we would be able to survive.
Answers will vary. Students’ reports should intelligently discuss an animal species native to
Canada and living nowhere else on Earth. They should demonstrate knowledge of the species, the
ecosystem, and the reasons why this particular species depends on this particular ecosystem.
Answers will vary. Students’ answers should show knowledge of the characteristics of the
dinosaurs they choose. They should also make realistic phylogenetic connections to the modern
species with which they align their three dinosaur species.
Answers will vary.Students’ reports should discuss the many accomplishments of Louis Pasteur in
detail. His contributions to microbiology and medicine were among the most significant of all
time. This should be revealed in their reports.
Answers will vary. Students’ responses should discuss how systems of biological classification
have changed over time as new scientific discoveries have been made. They should also describe
how these changes in classification affect our understanding of biodiversity.
Answers will vary. Students’ responses should provide details about how tuberculosis is spread,
diagnosed, and treated. They should also be able to discuss prevention methods used.
Answers will vary. Students’ reports should be very factual and full of valuable information on
the virus of their choosing. They should report in detail about the characteristics of the virus as
well as its treatments, if any. Their recommendations for controlling the virus should be
thoughtful and realistic.
Answers will vary. Students’ summaries should discuss the ways that scientists are using
Physarum polycephalum to study network construction.
Answers will vary. Students’ reports should include well-researched information on flowering
plants. They should discuss the characteristics common to flowering plants as well as the special
symbiotic relationships flowering plants may have with other organisms that other types of plants
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-14
do not. Finally, they should pinpoint what they think to be the characteristic or characteristics that
flowering plants have to give them such an edge in numbers over non-flowering plants.
121. Answers will vary. Students’ responses should describe reasons why scientists believe that more
than half of all major fisheries are unsustainable. Many different kinds of fish (including wild
caught tuna and salmon, wild and farmed shrimp, north Atlantic cod stocks, and many of the
world’s large shark species) are at risk today. This, of course, results in a cycle whereby fewer
fish create a higher demand for fish, which results in heavier fishing and farming, resulting in
even fewer fish, and so on.
122. Answers will vary. Students should give an example of biomimicry, describe what inspired it, and
how it is used in our society.
123. Answers will vary. Students’ responses should discuss how fungi affect the forestry industry.
They should also be sure to include ways that these fungi might be affected by climate change.
Copyright © 2011 Nelson Education Ltd.
Unit 1: Diversity of Living Things
U1-15