2.1- Suggested Answers
1. The cell is the simplest unit of life. All life forms are made of cells. All cells come from other cells.
2. My cells are eukaryotic. Human cells are eukaryotic because they contain a nucleus and membranebound organelles.
3. The most obvious difference is that eukaryotic cells have membrane-bound organelles and nucleus.
4. DNA in the nucleus contains codes to create proteins that perform functions for the cell. DNA also
controls cell activities.
5. You need oxygen to burn sugar for energy. During exercise, mitochondria in muscle cells work harder
to produce energy and need more oxygen to turn sugar into energy. The demand for more oxygen
makes you breathe harder and faster.
6. If a plant cell does not contain chloroplasts, it may be a cell that does not carry out photosynthesis.
7. The function of the cell wall is to provide structure and protection for the cell.
8. Plant cells need mitochondria to release energy from the sugar that they make.
2.3 - Suggested Answers
1. Three reasons for cell division are growth, reproduction, and repair.
2. The surface will not stay bacteria-free forever, because if a single bacterium is left alive, it can
reproduce to a large number in a fairly short period of time.
3. Asexual reproduction involves only one parent. Sexual reproduction involves two. In asexual
reproduction, offspring and parent are identical. In sexual reproduction, offspring and parent are not
identical. Asexual reproduction does not involve cells joining together, whereas sexual reproduction
does.
4. The two processes responsible for moving chemicals into, throughout, and out of cells are osmosis
and diffusion.
5. Cells divide instead of just getting bigger, because if cells become too large, osmosis and diffusion
are no longer efficient for transporting materials in and out.
6. Cell division creates new cells that replace those in the wounded area to close and heal the wound.
2.5- Suggested Answers
1. Replication of the DNA occurs during the stage of interphase.
2. The cell needs one complete copy of the DNA for each of the daughter cells that will form.
3. Chromosomes are condensed during mitosis, which makes them more visible.
4. Some cells can appear to be between phases because mitosis is a smoothly fl owing process. Each
phase flows into the next, with no clear breaks between stages.
5. (a) A new cell wall begins to form during cytokinesis.
(b) The membrane of the nucleus dissolves during metaphase.
(c) Daughter chromosomes begin to separate during anaphase.
(d) The cell begins to pinch together during cytokinesis.
(e) Chromosomes are visible in two distinct regions of the cell during telophase.
(f) The cell grows and copies its DNA during interphase.
6. Phase Events
interphase : growth, receive information about replication, replication of organelles, DNA replication
mitosis: daughter chromosomes line up and separate, form two new nuclei
cytokinesis: cell splits into two daughter cells
7. Cells are never resting. They are constantly performing a specifi c cell function, growing, monitoring
outside information, replicating DNA, and replicating organelles.
2.7
1. Cancer cells grow unchecked. They do not respond to signals to stop undergoing mitosis.
2. (a) Some cancers run in families and are inherited or partly inherited. This means that DNA passed
from one generation to the next may contain information that makes the person more susceptible to
cancer.
(b) Cancer cannot be transmitted from one person to another because cancer is caused by a mistake in
DNA.
3. (a) A carcinogen is a factor that increases the risk of cancer, such as smoking, UV sunlight, or certain
foods.
(b) Some examples of carcinogens that may be present in everyday life are smoke, UV rays in sunlight,
cleaning chemicals, viruses such as HPV, food additives, and pollution.
4. Cancer is sometimes easy to overlook because there are few symptoms in the early stages.
5. Five diagnostic techniques used to detect cancer are CT scans, ultrasound, endoscopy, MRI, and
mammogram.
6. Three conventional methods of treating cancer are surgery, chemotherapy, and radiation. Surgery
cuts out the tumour. Chemotherapy uses drugs to kill cancer cells and reduce the size of the tumour.
Radiation also kills cells and reduces the size of a tumour.
7. Appearance of cancer cells in the blood show that the cancer exists somewhere in the body. Cancer
cells in the blood may also indicate that these cells have broken off from the original tumour and have
travelled to other sites in the body. Tumours may be forming at secondary sites.
8. Lifestyle choices that help reduce the risk of cancer are avoiding tanning, maintaining a healthy
weight, eating a better overall diet that includes “super foods,” increasing exercise, and quitting smoking.
9. Some cancer screening tests are Pap smear, mole screening, and breast and testicle exam.
10. There is a risk of cancer recurring because neither the patient nor doctor know if all cancerous cells
have been removed from the body. If any still exist, they can grow and start new tumours.
2.9- Suggested Answers
1. Complex organisms have organs and organ systems that perform very different, specialized
functions. Different functions require specialized cell types.
2. Four activities my body must do to stay alive are breathe, eat, eliminate waste, and stay warm.
3. Red blood cells are smooth, fl at, round, and concave (pinched in) in the middle to pass easily through
blood vessels. Muscle cells are organized in fi bres that, when activated by a nerve signal, suddenly
contract and pull together, causing the attached bone to move.
4. Because every cell came from one fertilized egg cell, the original zygote had all of the instructions
(DNA) for forming all of the different types of cells in the body. Every cell has exactly the same DNA.
5. Plant cells specialize in different ways in some cases. For example, plants do not have blood, so they
do not have blood cells. Plants do transport water, so they have special cells for water transport.
Animals do not photosynthesize, so they do not have cells with chloroplasts like plants do. Similarly, only
plants have guard cells to prevent water loss in leaves.
6. With only one cell, single-celled organisms cannot specialize.
3.1 Suggested Answers
1. Concept map should include all levels in the hierarchy of organization within an animal, such as
organism level: mouse; organ system level: nervous system; organ level: brain; tissue level: nerve
tissue; cellular level: nerve cell.
2. (a) The brain is an organ that is part of only one organ system—the nervous system.
(b) The lungs play a role in more than one organ system—the respiratory system and the circulatory
system.
3. An organ system is made up of many organs that work together. Each organ is made up of a complex
arrangement of tissues, which are made up of highly specialized cells. An organ system is more
complex than a highly specialized cell because it is made up of organs, tissues, and cells, and can
contain many types of highly specialized cells.
4. The main functions all living things must perform are: get rid of wastes (urinary and digestive
systems), respond to the environment (nervous and musculoskeletal system), transport materials within
the organism (circulatory system), obtain materials from outside (digestive and respiratory systems), and
reproduce (reproductive system).
5. The well-known organ systems of most animals are very efficient, so different animals tend to have
the same systems that are modified for their own needs.
6. Single-celled organisms only have one cell, so cells cannot specialize for different tasks.
3.2 Suggested Answers
1. Cellular differentiation means stem cells can grow into specialized cells, such as liver cells or heart
cells.
2. Embryonic cells come from an embryo in the earliest stage of cell division and have the potential to
become any kind of cell. Tissue stem cells are limited in what they can become.
3. Stem cells collected from cord blood are considered tissue stem cells because they can only
differentiate into various kinds of blood cells, and not any type of cell.
4. Embryonic stem cells, which can specialize into any type of cell, have the potential to re-grow and
replace any damaged or diseased cells, tissues, or organs so they can be placed inside the body.
5. In a bone marrow transplant, diseased white blood cells are removed and existing bone marrow cells
must be killed. A donor supplies new healthy bone marrow cells that are injected into the patient’s
bloodstream. The transplanted cells are taken up in the bone marrow and begin to produce healthy new
blood cells.
6. Regeneration allows the animal to replace damaged or diseased body parts.
7. In mammals, tissues can regenerate, but not organs or limbs. In less complex animals, entire limbs
can regenerate.
3.3 Suggested Answers
1. The main parts and functions of the digestive system are: mouth: mechanically break down food into
small pieces, start chemical digestion; esophagus: bring food to stomach; stomach: use enzymes to
digest, use nerves to sense fullness; small intestine: further digest, pass nutrients to bloodstream; large
intestine: re-absorb water, get rid of waste.
2. Digestion is necessary because food must be broken down into molecules to be able to diffuse
through the walls of the intestine into the bloodstream and ultimately diffuse into cells.
3. Substances added to the food in the digestive tract are saliva, stomach acid, enzymes, bile, and
mucus.
4. Muscle tissue contracts to push food through the digestive system.
5. One disease of the digestive system is colitis. Colitis results when epithelial tissue in the colon
becomes inflamed due to infection and stops the colon from working properly.
3.4 Suggested Answers
1. The function of the circulatory system is to transport substances to different parts of the body.
2. Four substances carried by the circulatory system are blood, oxygen, nutrients, and carbon dioxide.
3. The circulatory system obtains nutrients from the small intestine in the digestive system and
transports it throughout the body to cells.
4. In an angiogram, a fluorescent dye is injected so blockages show up in X-ray images. An ordinary Xray does not include the dye.
5. (a) The artery has thick walls to withstand the high pressure of arterial blood fl ow.
(b) A capillary’s small diameter allows more efficient exchange of oxygen and nutrients for carbon
dioxide and wastes.
(c) A vein has thin walls because blood fl owing through it is under low pressure.
6.
Blood connective tissue
Blood vessels epithelial tissue, smooth muscle tissue, connective tissue
Heart cardiac muscle tissue, nerve tissue, epithelial tissue, connective tissue
7. (a) Circle graph should show: 45 % red blood cells, 55 % plasma, <1 % white blood cells, <1 %
platelets
(b) I had to figure out the correct fraction or angle measure for each wedge of the chart.
8. Cardiac muscle goes through rhythmic contractions even without nerve input. Smooth muscle cells,
such as those in the digestive tract, contract only with nerve input.
9. Coronary artery disease is a buildup of plaque in arteries that supply the heart with blood. If blockage
becomes severe, a heart attack can result. Blood clot disorders occur when blood clots too easily so it
blocks blood vessels, or when blood does not clot easily and excess bleeding occurs.
3.6 Suggested Answers
1. The main organs of the respiratory system are the nasal cavity, mouth, trachea, bronchi, lungs,
bronchioles, and alveoli.
2. The role of epithelial tissue in the trachea and bronchi is to secrete mucus to filter out foreign material.
3. The circulatory system carries oxygen and carbon dioxide that are exchanged by the respiratory
system.
4. Breathing is the intake and output of air. Gas exchange involves the diffusion of oxygen into the blood
and carbon dioxide out of the blood.
5. (a) An X-ray can show TB. However, pneumonia and other conditions can look like TB in an X-ray.
(b) To confirm TB, stomach and lung secretions must be examined.
6. Both fish and humans exchange oxygen and carbon dioxide. The fish takes in oxygenated water,
whereas the human takes in air. Humans breathe air in and out. Gas exchange occurs as water flows
over a fish's gills.
3.7 Suggested Answers
1. Living donors are able to donate an organ or tissue, and remain alive. Most needed organs and
tissues cannot be taken from a living donor, so deceased donors are much more common.
2. The list of living donor organs is shorter because it is harder to get living people to go through the risk
and trouble of being a donor than a person who is no longer alive and has no risk.
3. Before any transplants can occur, the donor and the recipient must be carefully screened to ensure as
close a match as possible. In a liver transplant, doctors remove a liver lobe and place it in the recipient.
The lobe has the ability to regenerate, so both the donor and recipient end up with a fully functioning
organ. Most organ transplants require the recipient to take anti-rejection medication, sometimes for the
rest of their lives, so that their bodies do not reject the donated organ.
4. Two risks for transplant patients are rejection and susceptibility to infection. Rejection is combated by
the administration of anti-rejection drugs. However, these drugs can reduce overall immunity and make
a patient susceptible to infection.
5. Xenotransplantation is the transplanting of animal parts to humans. It is controversial because it
clashes with some religious and ethical beliefs. Xenotransplantation may introduce new diseases into
the human population.
6. Positions will vary. Students should support their position with solid reasoning and meaningful
evidence.
3.8 Suggested Answers
1. The main functions of the musculoskeletal system are movement, support, and protection.
2. A ligament exists in joints between bones to prevent scraping or damage to bones. A tendon connects
a muscle to a bone, so the muscular contraction can move the bone.
3. Skeletal muscle is voluntary because it does not move on its own like cardiac muscle or smooth
muscle in the intestines.
4. Diagram should show front calf muscle straightening the leg and rear calf muscle pulling the calf up.
This diagram should be similar to Figure 5 on page 100.
5. Loss of calcium can cause a decrease in bone density. In senior citizens, the bone density has been
decreasing for a long time, so bones are weaker, more brittle, and easier to break.
6. The leg muscles would have a lot of fast twitch muscle fibres to allow us to run fast.
3.10 Suggested Answers
1. The functions of the nervous system include responding to the environment; controlling automatic
functions such as heartbeat and breathing; controlling voluntary movement; sensing (sight, hearing,
touch, taste, smell), thinking, and perceiving the surrounding environment.
2. Diagram should show cell body, nucleus, axon with myelin sheath, and the spiny nerve endings
(dendrites, not named in the text).
3. The series of events that occur when swinging a baseball bat at an approaching baseball are: eyes
receive input of ball coming and signal to brain that ball is coming; brain sends signal to spinal cord to
swing; spinal cord sends signal to arm and trunk nerves to swing; muscles in arms and trunk receive
signal and contract; batter swings.
4. Three examples of the nervous system coordinating activities are nerve impulses that increase
breathing and heartbeat rate when exercise takes place, and the nerve impulses that control digestion
and appetite for the digestive system.
5. The function of sensory receptors is to tell the body what is happening in the outer world. For
example, sensory receptors in the eye allow people to see. Hearing receptors in the inner ear allow
people to hear.
6. A CT scan or MRI scan can be used to pinpoint brain and spinal cord injuries. The advantage of this
technology is that any injuries to the brain or spinal cord can be viewed without operating on the patient.
The exact location and nature of the injury can be determined with minimum risk to the patient.
7. The hearing loss following Jila’s accident may be a result of damage to the sensory receptor cells in
Jila’s ear.
3.11 Suggested Answers
1. The circulatory and digestive systems interact to deliver food to body cells. The circulatory and
respiratory systems interact to deliver oxygen to and remove carbon dioxide from cells. The nervous and
musculoskeletal systems interact to coordinate movement.
2. (a) The circulatory system interacts with most other systems.
(b) The circulatory must bring food and oxygen to and remove wastes from all cells, so it interacts with
all systems. This is advantageous because one system can supply necessary material to all other
systems. The systems could not function without these materials.
3. Two systems that amphibians use for gas exchange are the skin (integumentary) and respiratory
systems.
4. A tape worm can live without a digestive system because its food is already digested for it by its host.
5. Webbed feet show that the integumentary system can interact with the musculoskeletal system to
produce efficient locomotion through water.
6. (a) Skin cells contain nerves to detect temperature, pain, and other feelings.
(b) Nerve impulses cause the musculoskeletal system to make the body move.
(c) The nervous system regulates breathing, both involuntary and voluntary.
(d) When the bladder is full, a message is sent to the nervous system telling the body to get rid of its
urine.
4.1 Suggested Answers
1. The flowering plant body has two main body systems, the root system and the shoot system. Each
system is made up of different plant parts. The root system is made up of one or more plant parts called
the root. The shoot system is made up of plant parts called the stem, the leaves, and the fl owers. There
are three main types of plant tissue, which are also referred to as systems: the dermal tissue system,
the vascular tissue system, and the ground tissue system.
2. (a) Two differences between plants and animals are that plants perform photosynthesis to make their
own food, and have structures (roots) to anchor them in one place.
(b) Because plants can make their own food, they do not need musculoskeletal systems or digestive
systems to find and process food. Instead, they need root systems to obtain water and minerals, and
elements of the shoot system, like leaves, to collect sunlight and perform photosynthesis to create food.
3. Dermal tissue is tissue that forms the outer surface of plant parts. Vascular tissue is specialized for
the transportation of water, minerals, and nutrients throughout the plant. Ground tissue makes up all
other structures within a plant.
4. The leaf is the part of the plant where most photosynthesis takes place. Chloroplasts in the leaf
perform photosynthesis. The stem is the part of the plant that transports materials from the roots to the
leaves and flowers, and contains significant amounts of vascular tissue. The stem is an important
structural support for the plant. In addition to these standard functions, some plants’ stems and leaves
have special adaptations that allow them other functions, like protection or reproduction.
5. The root usually grows below the ground and absorbs from the soil most of the water and minerals
the plant needs. The stem typically grows above the ground and transports water and minerals from the
roots to parts like leaves and flowers.
6. (a) The primary function of a flower is reproduction. A flower has male parts that create pollen, and
female parts that create ovules. The spreading of pollen, by wind, insect, or other means, is called
pollination. Pollination enables plants to create seeds and reproduce.
(b) Grasses are wind pollinated. They have small drab flowers and lots of pollen, which is spread by the
wind. Other plants, such as roses or tulips, are pollinated by insects, bats, or birds, and have large,
colourful, fragrant flowers to attract these animals.
7. Food can be stored in roots (like sweet potatoes, carrots, or beets), in leaves (like in lettuce, onions,
or herbs), or in stems (like sugarcane).
4.2 Suggested Answers
1. Cell division is responsible for plant growth, repair, and reproduction.
2. The main function of the dermal tissue system is to cover the outside surface of the plant. Dermal
tissue is often specialized to perform unique functions. In woody plants, periderm tissue forms bark on
stems and large roots. Epidermal leaf cells produce a layer of wax that waterproofs the leaf’s surface.
Dermal tissue on roots absorbs water and minerals from the surrounding soil. The vascular tissue
system transports water, minerals, and other chemicals within the plant. The ground tissue system also
has varied functions; important functions include manufacturing nutrients through photosynthesis and
structural support.
3. Xylem is made up of elongated cells that transport water and minerals upward from the roots to the
leaves. When fully formed, they are hollow tubes with rigid walls. They do not contain a cytoplasm,
nucleus, or other organelles, and are no longer living tissue. Phloem is also made up of elongated cells,
and their function is to transport substances, such as sugars and hormones, both up and down within
the plant. Unlike xylem, phloem is comprised of living cells while mature and functioning.
4. Some epidermal root cells are specialized to form long extensions called root hairs, which enable
them to absorb water and minerals from the soil by increasing surface area. Some epidermal cells have
hair-like structures containing chemical irritants that defend the plant by dissuading animals from
touching it.
5. It is important for plant leaves to be waterproof because water is necessary for photosynthesis. A
plant needs to keep water in and prevent water loss through evaporation. For this reason, plants in dry
climates will have a thicker cuticle than those in wet climates.
6. Water and minerals always move upward through the xylem because water and minerals are
absorbed from the ground by the roots and must move to the rest of the plant, which is above the roots.
4.4 Suggested Answers
1. (a) Sample answer: I find it somewhat confusing. Animals and plants perform a lot of the same
processes, such as gas exchange and obtaining nutrients, but they do it in different ways. Also, the
hierarchical organization is different.
(b) Sample answer: My classmates generally feel the same way I do.
2. Two types of ground tissue, the palisade layer and the spongy mesophyll layer, inside the leaf are
responsible for photosynthesis. Stomata are openings in the surface of the leaf that are controlled by
guard cells to let in the carbon dioxide necessary for photosynthesis. Water is absorbed from the soil by
vascular tissue called root hairs, and is transported up to the leaf by vascular tissue called xylem.
3. The spongy mesophyll layer is in the middle of the leaf and is more loosely arranged to allow gases to
move around.
4. (a) The cuticle and guard cells both ensure that the leaf does not lose too much water.
(b) While the cuticle never allows water or gases to enter or exit the leaf, the guard cells control the
opening and closing of stomata to allow gas exchange at the proper times.
5. Cells in the palisade layer are closely packed to absorb the most sunlight possible. Cells in the
spongy mesophyll layer are more loosely packed to allow the movement of gases required for and
produced by photosynthesis.
6. The leaves in Figure 1 are broad and thin, which gives them a greater surface area than a thick,
narrow leaf. A greater surface area enables them to absorb more sunlight for photosynthesis.
7. Guard cells control the opening and closing of stomata. When there is a good supply of water in the
plant, guard cells swell with water, causing the stomata to open. When there is less water in the plant,
water exits the cells and the cells collapse to close the stomata, which prevents water from evaporating.
4.6 Suggested Answers
1. Plant growth is limited to meristem areas. Once meristems have grown and cells have differentiated,
no more cell division occurs. In animal cells, cell division can take place in many tissues throughout life.
Also, animals tend to grow to a maximum size. Plants, on the other hand, will keep on growing if
conditions allow.
2. The two main types of meristem are apical and lateral meristems. Apical meristems are located at the
tips of roots and shoots. They enable the roots and shoots to grow longer. Lateral meristems are located
as a hollow cylinder, like a pipe, that runs the full length of the roots and shoots. They enable roots and
shoots to grow wider.
3. Apical meristem cells divide and the roots and branches grow longer, pushing their way upward or
into the soil.
4. The inner lateral meristem produces new phloem along its outer edge. It produces new xylem along
its inner edge.
5. Vascular tissue in non-woody plant comes from apical meristems.
6. Advantages to the plant of producing woody tissue are that the plant can grow to large size and has
an effi cient water transport with xylem. The bark also provides protection, and the hard tissues provide
strong support.
7. The cells in a callus are undifferentiated, just like embryonic stem cells. Calluses are able to
differentiate into specialized cells.