Download chapter 2 answers

CHAPTER 2 ANSWERS
CYU 2.1 p. 42
1. A tissue is a group of cells that are similar in shape and function. Tissues can be organized into larger
structures called organs. Many organs are composed of different types of tissues. Organ systems are groups
of organs that have a related function. Students’ examples will vary (e.g., muscle tissue—heart and
circulatory system). See Table 1: Levels of Cell Organization in the Human Body for possible examples.
2. The correct order is molecule, cell, tissue, organ, organ system. Students’ examples will vary (e.g., protein,
nerve, nerve tissue, spinal cord, nervous system).
3. Students’ answers will vary. One example is provided below.
Levels of cell
Hockey organization
organization
cell
player
tissue
team
organ
league
organ system
BC Minor Hockey
Association
CYU 2.2 p. 47
1. Diatoms are called plantlike protests because they have chlorophyll, which is a green pigment found in
plants.
2.
Characteristic
Euglena
Plants
chloroplasts
✓
✓
cell wall
pellicle
✓
Golgi apparatus
✓
✓
mitochondria
✓
flagellum
(movement)
eyespot
✓
✓
no
✓
no
no
✓
3. A paramecium draws microbes into the oral groove; cilia create a current. An amoeba slowly engulfs food
particles by extending its pseudopodia. Both organisms dissolve food in vacuoles.
4. Bacteria are considered to be more primitive than other cells because they do not have a nuclear
membrane, mitochondria, or ribosomes.
5. Micro-organisms cause many diseases.
6. Euglena, paramecia, and amoebae live in fresh water. The concentration of solutes inside each organism
is greater than this concentration of solutes in the water. Therefore, water moves into the organism by
osmosis. Contractile vacuoles are needed to expel the excess water that enters the organism.
7.
single cell
CYU 2.3 p. 50K YOUR UNDERSTANDING—SUGGESTED ANSWERS
1. (a) Small cells are more efficient at transporting messages because the nucleus is closer to the cell
membrane.
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(b) Small cells are more efficient at exchanging nutrients and waste materials because they have more
surface area per unit volume.
2. Highly active cells require a greater proportion of nutrients and produce more wastes than less active cells.
Therefore, they tend to be small because this gives them a greater proportion of cell membrane to cell size
for moving materials in and out.
3. The advantage of a highly folded cell membrane is that it gives a cell a much greater surface area to
volume ratio.
CYU 2.4 p. 53
1. Flexible cell walls allow a plant to bend. In a high wind or under a load of snow, the plant will bend rather
than break.
2. Plant cells would no longer stay attached to each other if the pectin were digested. Multicellular plants
would topple like building blocks.
3. Cells of the trachea have cilia that are similar to the cilia of paramecia. White blood cells move by
amoeboid motion. Sperm cells have a flagellum that is similar to the flagellum of euglena.
CYU 2.5 p. 56
1. Some types of invaders are living things, such as bacteria, fungi, and parasitic worms. Other types are
viruses.
2. Viruses have only one characteristic of living things—they can reproduce. They can only reproduce inside
living host cells, however. A virus is not a cell. A virus contains no nucleus, cytoplasm, organelles, or cell
membrane. A virus is only active when it invades a living cell.
3. A disease can be defined as a condition that interferes with the well-being of an organism. (Encourage
students to use their own wording for their definition.)
4. White blood cells produce antibodies that attach themselves to invading organisms. White blood cells also
engulf antigens that are the markers on the surface of invaders.
CYU 2.6 p.59
1. Sperm from one species cannot be used to fertilize an egg from another species. If fertilization does take
place, the zygote will probably not develop.
2. Pieces of genetic information from one animal may be inserted into the genetic information of another
animal.
Chapter 2 Review p. 62
1. Students can use BLM 0.0-6 Three-Column Table to complete question 1.
2. (e) 3. (b) 4. (a) 5. (e)
6. Unicellular organisms are often called micro-organisms because they are so small that they cannot be
seen with the unaided eye. They can only be seen with the help of a microscope.
7. (a) Three harmful effects of unicellular organisms:
• Some protists and bacteria cause diseases such as malaria and conditions such as pneumonia, strep
throat, and athlete’s foot.
• Some bacteria spoil food.
• Some bacteria and protists contaminate drinking water.
(b) Three ways in which unicellular organisms are useful:
• Fungi can be used for making food (e.g., yeast for bread, wine, and beer).
• Bacteria can be used for making food (e.g., buttermilk, cottage cheese, and yogurt).
• Unicellular organisms help the body (e.g., production of vitamin K in the intestines).
8. (a) The volume of cell A is 6 μm x 6 μm x 6 μm = 216 μm3
The volume of cell B is 3 μm x 3 μm x 3 μm = 27 μm3.
(b)
The surface area of cell A is (6 μm x 6 μm) x 6 sides = 216 μm2
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The surface area of cell B is (3 μm x 3 μm) x 6 sides = 54 μm2
The ratio of surface area to volume for cell A is 216 μm2/216 μm3 = 1 μm2/1 μm3
The ratio of surface area to volume for cell B is 54 μm2/27 μm3 = 2 μm2/1 μm3
(d) The smaller cell should be better at absorbing nutrients and removing waste because it has a 2:1 ratio of
surface area to volume. It has twice as much surface area as the larger cell, for the same amount of volume.
9. Tissues, organs, and organ systems are required in large Multicellular organisms because individual cells
depend on diffusion to obtain nutrients and get rid of wastes. An individual cell that is surrounded by layers of
other cells would not be able to obtain nutrients by diffusion directly from the source or get rid of wastes
directly to the outside. It needs some way to have nutrients delivered to it. Specialized cells, tissues, and
organs fulfill these special functions. An individual cell in a large multicellular organism must also have a way
to communicate with the external environment, so that it can respond appropriately. Specialization of cells,
tissues, and organs allows this communication to take place.
10. Cell specialization means that a cell is designed to perform only one main function and does not have to
use any energy for other functions, as in a unicellular organism. Specialization allows a cell to develop the
specialized structures or take on a particular shape required to do a job well. A cell that is required to do
multiple jobs must have a shape and structures that permit diversity and versatility.
11. Viruses are only active once they invade a living cell. The genetic information from a virus directs the host
cell to begin producing virus particles. Once the virus particles are produced, the cell ruptures. This releases
a new batch of viruses that can attack other cells, which will, in turn, produce more viruses. Living cells
become virus factories.
12. An antibody produced against the influenza virus will not lock onto a common cold virus. Each antibody
has a specific shape to lock onto the marker molecules of a specific invader, so it can only lock onto this
invader.
13. Since all multicellular organisms start off as a single cell, and all cells in an organism have the same
DNA, the cell must duplicate itself. Duplication or replication of DNA occurs during cell division.
14. If stomach acids burn the lining of the esophagus, you can infer that the cells lining the esophagus are not
protected by a layer of mucus, like the cells lining the stomach are.
15. Students’ diagrams will vary. They should resemble Figure 8 on page 84 of the student book.
(c)
16. Ideal conditions for the growth of the fungus that causes
athlete’s foot are warmth and moisture—the conditions found
between the toes when wearing athletic shoes.
17. (a) The large circular cell is most suitable for an egg cell. It has
the greatest amount of cytoplasm to store the nutrients that are
required for many cell divisions. The Golgi apparatus stores the
nutrients.
(b) The cell with the flagellum is most suitable for movement. This
cell is also streamlined in shape. (The mitochondria, or
energytransforming organelles, should be next to the flagellum. In
other words, the energy providers should be located next to the
structure that uses the energy.)
(c) The flat cell with the greatest surface area provides maximum
coverage and is most suitable for covering an organ.
18. The biggest advantage of being a multicellular organism is having specialized cells and/or tissues to
perform specific functions. If a cell or tissue has only one function, it is more efficient than if it had to perform
several functions.
19. Students have likely read or heard about early historical accounts of illnesses, diseases, and death being
attributed to witchcraft, demons or evil spirits, or “the gods.” For some religious people, sickness and death
were viewed as punishment for sin or wrongdoing. For people who believed in the spirit world, illness and
death were caused by evil spirits. When witchcraft was popular, illness and disease were believed to be
inflicted on someone as revenge for wrongdoing—real or perceived. So the approach to treating diseases
and illnesses was to offer sacrifices to appease the spirits, to pray to the gods, or to identify and eliminate the
witch or wizard who was inflicting the punishment on an individual. The acceptance of the germ theory led to
changes in health practices (e.g., pasteurization of foods, immunization, sterile surgical procedures) and the
total elimination of some diseases. Some students may mention an idea promoted by a small group of
scientists—that disease-causing agents (specifically the SARS virus) came to Earth from other parts of the
universe on a meteorite.
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20. Students will likely argue that flu vaccines should be mandatory for some groups. For example, hospital
workers could transmit influenza from inside the hospital to people outside the hospital, or from outside the
hospital to people inside the hospital with other serious medical problems, which would become more serious
if they contracted influenza. The Public Health Agency of Canada recommends that “immunization programs
should focus on those at high risk for influenza-related complications, those capable of transmitting influenza
to individuals at high risk for complications, and those who provide essential community services. These
groups remain the priority for influenza vaccination programs.” People at high risk of influenza-related
complications include
– adults and children with chronic cardiac or pulmonary disorders
– people of any age who are residents of nursing homes and other chronic-care facilities
– adults and children with chronic conditions, such as diabetes mellitus, metabolic diseases, cancer,
immunodeficiency, and immunosuppression
– people over the age of 65
– adults and children with any condition that can compromise respiratory function or the handling of
respiratory secretions or that can increase the risk of aspiration
– healthy children who are 6 to 23 months old
– children and adolescents (6 months to 18 years old) with conditions treated for long periods with
acetylsalicylic acid (aspirin)
– people at high risk of influenza complications who embark on travel to destinations where influenza is likely
to be circulating People who are potentially capable of transmitting influenza to those at high risk include
– health-care and other service providers
– people who provide services within closed or relatively closed settings
– people who provide regular child care to children who are 0 to 23 months old
– people who provide essential community services
– people in direct contact with avian influenza-infected poultry during culling operations
21. “Bacteria can affect people directly and indirectly.” For example, some bacteria cause human diseases,
such as pneumonia, strep throat, or tetanus. These bacteria get into the tissues and organs, and cause
serious health problems for the individual. Other bacteria, such as the salmonella species of bacteria, can
cause food to spoil. As these bacteria break down the food, they produce toxins as waste products. Eating
such spoiled food can seriously affect the digestive system, with symptoms such as vomiting or diarrhea. It is
not the bacteria themselves, but rather their waste products that cause the problems.
22. Letters that argue for the federal government’s support of research into genetic engineering are likely to
mention the benefits in areas such as agriculture (e.g., better quality crops, increased crop yields, diseasefree and insect-resistant plants), medicine (cheaper and more efficient drug production), and scientific
progress. Letters that argue against the federal government’s support for research into genetic engineering
are likely to mention the risks to humans and the environment (health risks to humans, GE species released
into the wild and out-competing wild species) or moral reasons (no one other than “God” or “the Creator”
should be allowed to create a new species of organism). This activity provides a good opportunity to discuss
the importance of using sound scientific evidence, rather than personal opinions or pseudoscience, when
making decisions about science and technology.
23. Students’ answers will vary. Some students may change their opinion on the benefits or risks of genetic
engineering after completing Explore an Issue. The change could go either way. Students who previously had
a negative opinion about genetic engineering may develop a positive opinion after analyzing and evaluating
the available evidence. Conversely, students who previously had a positive opinion may develop a negative
opinion. Information that would be likely to change students’ opinions would be information that shows how
the technology could affect them personally (positively or negatively), or personal testimonies about positive
or negative experiences with genetic engineering.
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