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← Unit 1: Tissues, Organs & Systems of Living Things

SNC2D · Unit 1 test review

Tissues, Organs & Systems of Living Things: Test Review

Everything for the Unit 1 test on one page: the key facts from all 9 lessons, the mistakes that cost the most marks, and a practice test that points you back to the lessons you need.

Key facts

Plant and Animal Cells and the Microscope

  • Cell theory: all living things are made of cells, the cell is the basic unit of life, and cells come only from existing cells.
  • Of the two, only plant cells have a cell wall, chloroplasts and a large central vacuole; animal cells have small vacuoles, and lysosomes are found mainly in animal cells.
  • Mitochondria release energy by cellular respiration; chloroplasts capture light energy by photosynthesis; ribosomes make proteins.
  • Total magnification = ocular × objective, for example 10× × 40× = 400×.
  • Field of view at high power = field of view at low power × (low magnification ÷ high magnification).
  • Estimated cell size = field of view diameter ÷ number of cells that fit across it; 1 mm = 1000 µm.

The Cell Cycle and Mitosis

  • The cell cycle: interphase (growth and DNA copying), then mitosis (prophase, metaphase, anaphase, telophase), then cytokinesis.
  • Prophase: chromosomes condense and the nuclear membrane breaks down. Metaphase: chromosomes line up at the equator. Anaphase: sister chromatids are pulled apart. Telophase: two nuclei re-form.
  • Mitosis makes two daughter cells genetically identical to the parent with the same chromosome number (46 in most human body cells).
  • Cells divide for growth, repair and replacement, and to keep a high surface-area-to-volume ratio.
  • Plant cells form a cell plate during cytokinesis; animal cells form a cleavage furrow.
  • Time in a stage = (cells in that stage ÷ total cells) × total cycle time.

Cancer: When Cell Division Goes Wrong

  • Cancer is a group of many diseases in which cells divide uncontrollably, caused by mutations in genes that control the cell cycle.
  • Normal cells obey checkpoints, contact inhibition and programmed cell death; cancer cells escape these controls.
  • Benign tumours stay in one place; malignant tumours invade nearby tissue and can metastasize through blood or lymph.
  • Mitotic index = (cells in mitosis ÷ total cells) × 100%; it is usually higher in tumour tissue.
  • Major risk factors include tobacco smoke, UV radiation, HPV, radon, asbestos and alcohol.
  • Treatments: surgery, radiation, chemotherapy, immunotherapy and targeted drugs; screening finds cancer early.

Cell Specialization, Differentiation and Stem Cells

  • Differentiation: a cell becomes specialized by using only the instructions it needs for one job; its structure then fits its function.
  • Stem cells are unspecialized cells that can self-renew and differentiate into specialized cells.
  • Embryonic stem cells and iPSCs are pluripotent (can become almost any cell type); adult stem cells are more limited.
  • Meristematic cells at root and shoot tips (and in the cambium) let plants grow throughout their lives.
  • Regeneration is the regrowth of lost parts; it is extensive in planarians, salamanders and many plants but limited in humans.
  • McCulloch and Till (Toronto, early 1960s) gave the first clear evidence of stem cells.

From Cells to Systems in Animals

  • Levels of organization: cell → tissue → organ → organ system → organism.
  • A tissue is a group of similar cells doing one job; an organ is made of two or more tissue types.
  • The four animal tissue types are epithelial, connective, muscle and nervous.
  • Muscle tissue comes in three kinds: skeletal (voluntary), smooth (involuntary, in hollow organs) and cardiac (involuntary, heart only).
  • Blood, bone, cartilage, tendons and fat are all connective tissues.
  • Organ systems depend on each other: for example, the respiratory system brings in oxygen and the circulatory system delivers it to cells.

The Digestive System

  • Mechanical digestion (chewing, churning, emulsifying) increases surface area; chemical digestion uses enzymes to break molecules into smaller ones.
  • Starch digestion begins in the mouth (amylase), protein digestion in the stomach (pepsin), and most digestion is completed in the small intestine.
  • Bile from the liver emulsifies fat; it is not an enzyme.
  • Villi and microvilli give the small intestine a huge surface area for absorption; nutrients pass into capillaries in each villus.
  • The large intestine absorbs much of the remaining water and forms feces.
  • Surface area of a cube = 6 × side²; cutting food into smaller pieces increases total surface area.

The Circulatory and Respiratory Systems

  • The heart has four chambers; the right side pumps blood to the lungs and the left side pumps it to the body (double circulation).
  • Arteries carry blood away from the heart, veins carry it back, and capillaries (walls one cell thick) are where materials are exchanged.
  • Red blood cells carry oxygen bound to hemoglobin; white blood cells fight infection; platelets help clotting; plasma carries dissolved materials.
  • Air path: nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.
  • Diffusion moves particles from higher to lower concentration; oxygen diffuses from alveoli into capillaries and carbon dioxide diffuses out.
  • Cardiac output = heart rate × stroke volume.

Plant Tissues, Organs and Systems

  • Plant tissues: dermal (protection), ground (photosynthesis, storage), vascular (transport) and meristematic (new cells).
  • The root system anchors the plant and absorbs water and minerals; the shoot system (stems, leaves, flowers) photosynthesizes, supports and reproduces.
  • Xylem carries water and minerals upward from the roots; phloem carries sugars from the leaves to wherever they are needed, up or down.
  • Leaf layers: cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, veins, lower epidermis with stomata and guard cells.
  • Transpiration is water loss from leaves through the stomata; it pulls water up the xylem.
  • Stomatal density = number of stomata ÷ field-of-view area, where area = π × radius².

Medical Imaging, Public Health and Ethics

  • X-rays and CT use ionizing radiation; dense tissue such as bone absorbs X-rays. CT builds cross-section slices from many X-ray images.
  • MRI uses a strong magnet and radio waves acting on hydrogen nuclei; it shows soft tissue in great detail with no ionizing radiation.
  • Ultrasound times echoes of high-frequency sound: depth = speed × time ÷ 2, with sound travelling about 1540 m/s in soft tissue.
  • Public health strategies include cancer screening, vaccines (HPV, MMR) and education programs.
  • Community immunity protects people who cannot be vaccinated; measles needs about 95% of people to be immune.
  • Transplants, cloning and stem cells raise ethical questions; a balanced analysis weighs benefits, risks and values.

Where marks get lost

  • Adding the ocular and objective magnifications. They multiply: 10× and 40× give 400×, not 50×. (Plant and Animal Cells and the Microscope)
  • Thinking the field of view gets bigger at higher power. You see a smaller area in more detail, so the diameter shrinks. (Plant and Animal Cells and the Microscope)
  • Saying plant cells have no mitochondria because they have chloroplasts. Plant cells have both: chloroplasts make sugar, and mitochondria release energy from it. (Plant and Animal Cells and the Microscope)
  • Saying every cell has a nucleus. Mature red blood cells in mammals push theirs out, which leaves more room for hemoglobin. (Plant and Animal Cells and the Microscope)
  • Using the coarse adjustment knob at high power. It can drive the objective into the slide and crack it; use only the fine knob above low power. (Plant and Animal Cells and the Microscope)
  • Calling interphase a resting stage. The cell is busy growing, doing its job and copying its DNA. (The Cell Cycle and Mitosis)
  • Mixing up metaphase and anaphase. Metaphase: one line at the middle (M for middle). Anaphase: chromatids moving apart (A for away). (The Cell Cycle and Mitosis)
  • Thinking mitosis halves the chromosome number. Mitosis keeps it the same; the DNA was copied first, so each daughter cell gets a full set. (The Cell Cycle and Mitosis)
  • Saying plant cells pinch in two like animal cells. The rigid wall cannot pinch, so a cell plate forms across the middle instead. (The Cell Cycle and Mitosis)
  • Using the number of cells in a stage directly as a time. You need the fraction of cells in that stage multiplied by the total cycle time. (The Cell Cycle and Mitosis)
  • Saying every tumour is cancer. Benign tumours do not invade or spread; only malignant tumours are cancer. (Cancer: When Cell Division Goes Wrong)
  • Thinking cancer cells are invaders from outside the body. They are the body's own cells whose DNA has changed so they no longer obey controls. (Cancer: When Cell Division Goes Wrong)
  • Saying cancer is caused by a single mutation. Usually several mutations build up over time, which is why risk rises with age. (Cancer: When Cell Division Goes Wrong)
  • Confusing screening with diagnosis. Screening tests healthy people for early signs; a positive screening result leads to further tests to confirm. (Cancer: When Cell Division Goes Wrong)
  • Assuming a vaccine cannot prevent cancer. The HPV vaccine prevents infection by the virus types that cause most cervical cancers. (Cancer: When Cell Division Goes Wrong)
  • Saying specialized cells have different DNA. Almost all body cells carry the same DNA; they differ in which instructions they use. (Mature red blood cells are an exception: they have no nucleus at all.) (Cell Specialization, Differentiation and Stem Cells)
  • Thinking all stem cells can become any cell type. Adult stem cells are usually limited to the cell types of their own tissue. (Cell Specialization, Differentiation and Stem Cells)
  • Assuming every stem cell use is a proven treatment. Blood stem cell transplants are established; most other uses are still experimental. (Cell Specialization, Differentiation and Stem Cells)
  • Saying plants grow everywhere at once. New cells come mainly from meristems at the root and shoot tips and in the cambium. (Cell Specialization, Differentiation and Stem Cells)
  • Presenting an ethical issue as one-sided. A strong answer states the benefits, the risks and the values behind the different positions. (Cell Specialization, Differentiation and Stem Cells)
  • Calling blood an organ or saying it is not a tissue. Blood is a connective tissue: cells suspended in a liquid matrix (plasma). (From Cells to Systems in Animals)
  • Thinking an organ is made of one kind of tissue. By definition an organ contains two or more tissue types working together. (From Cells to Systems in Animals)
  • Mixing up tissue and organ system. Cardiac muscle is a tissue; the heart is an organ; the circulatory system is an organ system. (From Cells to Systems in Animals)
  • Saying smooth muscle is found in the arms and legs. Muscles attached to bones are skeletal; smooth muscle lines hollow organs and blood vessels. (From Cells to Systems in Animals)
  • Describing systems in isolation. Most questions about organ systems are really asking how two or more of them depend on each other. (From Cells to Systems in Animals)
  • Saying the stomach absorbs most nutrients. It churns food and starts protein digestion; nearly all nutrient absorption happens through the villi of the small intestine. (The Digestive System)
  • Calling bile an enzyme. It emulsifies fat (mechanical); lipase is the enzyme that breaks fat molecules apart. (The Digestive System)
  • Listing the liver or pancreas as places food passes through. They deliver secretions into the small intestine through ducts. (The Digestive System)
  • Saying chewing turns starch into sugar. Chewing only makes pieces smaller; amylase in saliva does the chemical change. (The Digestive System)
  • Thinking the large intestine does most of the digestion. By the time material reaches it, digestion and nutrient absorption are mostly finished; it mainly absorbs water. (The Digestive System)
  • Saying arteries always carry oxygen-rich blood. Arteries carry blood away from the heart; the pulmonary arteries carry oxygen-poor blood to the lungs. (The Circulatory and Respiratory Systems)
  • Thinking blood in veins is actually blue. Oxygen-poor blood is dark red; veins only look bluish through the skin, and diagrams colour them blue as a code. (The Circulatory and Respiratory Systems)
  • Saying we breathe in oxygen and breathe out only carbon dioxide. Exhaled air is still mostly nitrogen and contains a good deal of oxygen; it just has less oxygen and more carbon dioxide than inhaled air. (The Circulatory and Respiratory Systems)
  • Describing gas exchange as being pushed or pumped. Oxygen and carbon dioxide cross the alveolus and capillary walls by diffusion, down their concentration differences. (The Circulatory and Respiratory Systems)
  • Saying the lungs inflate themselves. Breathing is driven by the diaphragm and rib muscles changing the size of the chest; air flows in because the pressure inside drops. (The Circulatory and Respiratory Systems)
  • Mixing up xylem and phloem. Xylem carries water up (think: xylem is the water pipe); phloem carries food (sugar) both ways. (Plant Tissues, Organs and Systems)
  • Saying phloem only flows down. Sugar moves from where it is made or stored to where it is needed, which can be up to a fruit or a growing tip. (Plant Tissues, Organs and Systems)
  • Thinking plants take in water through their leaves. Almost all water is absorbed by the roots, mainly through root hairs; leaves lose water by transpiration. (Plant Tissues, Organs and Systems)
  • Saying stomata are only for water loss. Their main purpose is letting carbon dioxide in for photosynthesis; water loss is the unavoidable cost. (Plant Tissues, Organs and Systems)
  • Forgetting the circle area when finding stomatal density. Divide the count by the area (π × radius²), not by the diameter. (Plant Tissues, Organs and Systems)
  • Saying MRI uses X-rays. MRI uses a strong magnet and radio waves; CT is the one built from X-rays. (Medical Imaging, Public Health and Ethics)
  • Thinking ultrasound is a sound you can hear. Its frequency is far above the range of human hearing. (Medical Imaging, Public Health and Ethics)
  • Forgetting to halve the distance in an ultrasound echo calculation. The pulse travels to the boundary and back. (Medical Imaging, Public Health and Ethics)
  • Assuming every imaging method is risk-free, or that all are dangerous. X-ray and CT carry a small radiation risk; MRI and ultrasound do not, but each has other limits. (Medical Imaging, Public Health and Ethics)
  • Writing a one-sided answer to an ethics question. Strong answers present benefits, risks and the values behind each position before taking a side. (Medical Imaging, Public Health and Ethics)

Practice test

27 questions from across the unit. Each one shows the lesson it comes from.

  1. Plant and Animal Cells and the Microscope
    1
    Which structure is found in plant cells but not in animal cells?
  2. Plant and Animal Cells and the Microscope
    2
    Match each organelle to its main job.
    Mitochondrion
    Chloroplast
    Ribosome
    Lysosome
    Nucleus
  3. Plant and Animal Cells and the Microscope
    3
    Name the stacked membrane sacs inside a chloroplast where chlorophyll captures light energy.
  4. The Cell Cycle and Mitosis
    4
    Put the stages of the cell cycle in order, starting with interphase.
    1. 1Telophase
    2. 2Anaphase
    3. 3Cytokinesis
    4. 4Interphase
    5. 5Prophase
    6. 6Metaphase
  5. The Cell Cycle and Mitosis
    5
    A cube-shaped cell has sides 4 µm long. What is its surface-area-to-volume ratio (surface area ÷ volume, in units of 1/µm)?
  6. The Cell Cycle and Mitosis
    6
    Why is interphase the stage seen most often in a root tip slide?
  7. Cancer: When Cell Division Goes Wrong
    7
    Which feature best distinguishes a malignant tumour from a benign one?
  8. Cancer: When Cell Division Goes Wrong
    8
    What is the term for the spread of cancer cells through the blood or lymph to form new tumours in other parts of the body?
  9. Cancer: When Cell Division Goes Wrong
    9
    Chemotherapy causes hair loss mainly because:
  10. Cell Specialization, Differentiation and Stem Cells
    10
    Which type of cell can become almost any cell type in the body?
  11. Cell Specialization, Differentiation and Stem Cells
    11
    Which example is regeneration?
  12. Cell Specialization, Differentiation and Stem Cells
    12
    Why are induced pluripotent stem cells (iPSCs) seen as a possible way around one ethical concern?
  13. From Cells to Systems in Animals
    13
    Put these levels of organization in order from smallest to largest.
    1. 1Human
    2. 2Circulatory system
    3. 3Heart
    4. 4Cardiac muscle cell
    5. 5Cardiac muscle tissue
  14. From Cells to Systems in Animals
    14
    Which of the four tissue types covers body surfaces and lines organs?
  15. From Cells to Systems in Animals
    15
    Which statement about blood is correct?
  16. The Digestive System
    16
    Put these organs in the order food passes through them.
    1. 1Large intestine
    2. 2Small intestine
    3. 3Rectum
    4. 4Mouth
    5. 5Esophagus
    6. 6Stomach
  17. The Digestive System
    17
    Which is an example of chemical digestion?
  18. The Digestive System
    18
    In celiac disease the villi are damaged. What is the most direct result?
  19. The Circulatory and Respiratory Systems
    19
    Put the parts of the respiratory system in the order air passes through them when you breathe in.
    1. 1Bronchi
    2. 2Alveoli
    3. 3Bronchioles
    4. 4Nasal cavity
    5. 5Pharynx
    6. 6Larynx
    7. 7Trachea
  20. The Circulatory and Respiratory Systems
    20
    Match each part of the blood to its job.
    Red blood cells
    White blood cells
    Platelets
    Plasma
  21. The Circulatory and Respiratory Systems
    21
    Why does the left ventricle have a thicker muscular wall than the right ventricle?
  22. Plant Tissues, Organs and Systems
    22
    Which tissue carries sugar from the leaves to the roots?
  23. Plant Tissues, Organs and Systems
    23
    Put the steps in the path of water through a plant in order.
    1. 1Water evaporates from a mesophyll cell into an air space
    2. 2Water reaches a vein in the leaf
    3. 3Water vapour diffuses out through a stomate
    4. 4Water enters a root hair cell from the soil
    5. 5Water enters the xylem in the root
    6. 6Water travels up the xylem in the stem
  24. Plant Tissues, Organs and Systems
    24
    Why are most chloroplasts found in the palisade mesophyll?
  25. Medical Imaging, Public Health and Ethics
    25
    Match each situation to the most suitable imaging technology.
    Checking the growth of a fetus
    A suspected broken arm
    A detailed look at a torn knee ligament
    Fast cross-section images of a head injury in an emergency
  26. Medical Imaging, Public Health and Ethics
    26
    A school has 800 students. To stop measles from spreading, about 95% need to be immune. What is the greatest number of students who could be non-immune while still meeting that target?
    students
  27. Medical Imaging, Public Health and Ethics
    27
    Why is ultrasound, rather than CT, used to check a fetus during pregnancy?

Endless drill

Fresh numbers every time, for the calculation questions in this unit.

Endless drillnew numbers every time

Generating a problem…

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