Biology Test Review

Characteristics of life

1. Composed of Cells – Cells → Tissues → Organs → Organ Systems

1. Adapt and Respond to Stimuli

2. Use Energy

3. Reproduce

4. Grow

Principles of Cell Theory

1. All living things are made of cells

2. The cell is the simplest unit that can carry out all life processes

3. All cells come from pre-existing cells

4. Living things depend upon the total activity of all their cells

Plant vs Animal Cells

Plant Cells

• Have a cell wall

• Have chloroplasts and chlorophyll

• One large central vacuole

• Store energy as starch or oils

Animal Cells

• Small vacuoles

• Store energy as glycogen or fats

• Have centrioles

Cell Membrane (Plant & Animal)

• Protective barrier, controls entry/exit

• Made of lipid bilayer, allows diffusion

Cytoplasm (Plant & Animal)

• Jelly-like, suspends organelles

• Contains nutrients, allows material movement

Nucleus (Plant & Animal)

• Control center: growth, activities, reproduction

• Surrounded by nuclear envelope with pores

• Contains DNA and nucleolus

• DNA forms: Chromatin (uncoiled), Chromosomes (condensed for division)

Vacuole (Plant & Animal)

• Stores water, nutrients, waste

• Plant: one large central vacuole (firmness)

• Animal: small vacuoles

Vesicles (Plant & Animal)

• Small sacs for transport and storage

Mitochondria (Plant & Animal)

• “Powerhouse” of cell

• Converts sugar → energy for cell

Lysosomes (Animal Only)

• Digestive enzymes: break down waste, bacteria, old organelles

Ribosomes (Plant & Animal)

• Protein synthesis

• Found in cytoplasm or on rough ER

Endoplasmic Reticulum (ER)

• Rough ER: ribosomes, makes & transports proteins

• Smooth ER: no ribosomes, produces fats/oils

Golgi Apparatus (Plant & Animal)

• Modifies, sorts, packages proteins for cell or export

Cytoskeleton (Plant & Animal)

• Protein filaments for shape & organelle movement

Plant-Only Parts

• Cell Wall: rigid, supports/protects

• Chloroplasts: chlorophyll, photosynthesis (CO₂ + H₂O → sugar + O₂)

Animal-Only Parts

• Cilia & Flagella: movement (cilia: short/numerous, flagella: long/few)

• Centrioles: microtubules, critical for cell division

Magnification

Formula:

Total Magnification = Ocular Lens × Objective Lens

• Ocular lens = 10×

• Low: 4× → 40×

• Medium: 10× → 100×

• High: 40× → 400×

• Eyepiece (Ocular Lens):

• Lens you look through; 10× magnification

• Objective Lenses:

• Main magnifying lenses (4× low, 10× medium, 40× high)

• Revolving Nosepiece:

• Holds objectives; rotates to change magnification

• Stage:

• Flat platform that holds the slide

• Stage Clips:

• Secure the slide on the stage

• Diaphragm:

• Controls how much light passes through the specimen

• Condenser Lens:

• Focuses light onto the specimen

• Lamp / Light Source:

• Provides light

• Coarse Adjustment Knob:

• Large focus movements (LOW power only)

• Fine Adjustment Knob:

• Small, precise focus (medium & high power)

• Arm:

• Supports upper parts; used to carry microscope

• Base:

• Bottom support; keeps microscope stable

• Tube:

• Keeps eyepiece and objectives at correct distance

What is the Cell Cycle?

The cell cycle is the series of stages a cell goes through to grow, copy its DNA, and divide into two new cells.

Why Do Cells Divide?

1. Growth – more cells make tissues and organisms bigger

2. Healing & Repair – replace damaged or dead cells (cuts, bruises)

Reproduction – create new cells

Main Parts of the Cell Cycle

There are 4 main sections. Most of the time is spent in interphase.

1⃣ G1 Phase (Growth Phase)

• Cell grows

• Performs normal functions

• Makes proteins and organelles

• ~50% of the cycle

2⃣ S Phase (DNA Replication)

• DNA is copied

• Each chromosome is duplicated

• ~33% of the cycle

3⃣ G2 Phase (Second Growth Phase)

• Cell grows more

• Prepares for division

• Checks DNA for errors

• ~12% of the cycle

➡ Interphase = G1 + S + G2

4⃣ M Phase (Cell Division)

• Includes mitosis and cytokinesis

• DNA and organelles are divided evenly

• Produces 2 identical daughter cells

• ~5% of the cycle

Apoptosis

• Programmed cell death

• Happens when a cell is damaged or no longer needed

• Prevents damaged cells from becoming harmful (ex: cancer)

DNA Terminology

Chromatin

• Uncondensed / uncoiled DNA

• Thread-like appearance

• Found when the cell is not dividing (interphase)

Chromosome

• Condensed / tightly coiled DNA

• Visible during cell division

• Often appears X-shaped

Chromatid

• One half of a duplicated chromosome

Sister Chromatids

• Two identical chromatids

Joined together at a centromere

Stages of Mitosis

(Remember: I Party Mainly At The Club)

1⃣ Prophase (Condensation)

• Chromatin condenses into chromosomes

• Nuclear membrane dissolves so chromatids can separate

• Centrioles migrate to poles

• Spindle fibers form and attach to centromeres

• Sometimes divided into early and late prophase

2⃣ Metaphase (Line Up)

• Chromosomes line up at the equatorial plate (middle of cell)

• Sister chromatids face opposite directions

• Centrioles reach poles

• Spindle fibers ensure proper alignment

3⃣ Anaphase (Separation)

• Sister chromatids separate at centromere → now called single-stranded chromosomes

• Pulled to opposite poles by spindle fibers

4⃣ Telophase (Daughter Cell Formation)

• New nuclei form around separated chromosomes

• Spindle fibers disappear

• Cytokinesis occurs:

  • Animal cells: cell pinches in half

  • Plant cells: new cell wall

• Result: 2 identical daughter cells

Cells return to G1 phase of interphase

Why is Mitosis Needed?

• To produce 2 identical daughter cells with the same number of chromosomes as the original cell.

• Ensures each new cell has a complete copy of DNA and enough organelles to function.

• Needed for:

  • Growth – making more cells for tissues and organisms

  • Healing & Repair – replacing damaged or dead cells

  • Reproduction – creating new cells

1. What is Cancer?

• Group of diseases where cells grow and divide out of control.

• Occurs when DNA controlling the cell cycle is mutated.

At least one checkpoint fails, so cells don’t stop dividing.

Causes of Cancer

• Mutations in DNA controlling cell division

• Carcinogens: tobacco, UV & X-ray radiation, some viruses (HPV)

• Hereditary factors: increase risk but not guarantee

• Random mutations

3. Tumours

• Mass of abnormal cells that don’t perform normal functions.

• Types:

  1. Benign: harmless, don’t spread, can crowd nearby cells.

Malignant: cancerous, invade tissues, can metastasize (spread to other parts).

6. Treatments of Cancer

1. Surgery

   • Removes cancer tissue physically

   • Pros: may remove entire tumour

   • Cons: may not work if spread, near vital organs

2. Radiation Therapy

   • Focused radiation damages DNA of cancer cells

   • Pros: effective at stopping division

   • Cons: can harm healthy cells, side effects, possible secondary cancer

3. Chemotherapy

   • Drugs stop division or kill cancer cells

   • Pros: works if cancer has spread

   • Cons: toxic to healthy cells (hair loss, nausea, fatigue)

Newer Treatments:

• Personalized Medicine: genetic info used to target treatment

• Biophotonics: uses light to detect & treat cancer precisely

• Oncolytic Virotherapy: viruses designed to attack cancer cells

Cytosponge: capsule collects esophagus cells for early detection

What are Stem Cells?

• Undifferentiated cells (no specific job yet)

• Rare and valuable for growth and repair

 Purpose of Stem Cells

• Replace or regenerate damaged tissues

• Grow new cells for organs and body parts

• Used in medicine for: cancer, Parkinson’s, Alzheimer’s, strokes, heart disease, diabetes, arthritis

3. Where Stem Cells Are Found

1. Umbilical cord blood – safe, after birth, discarded cord

2. Adult tissues – bone marrow, liver, fat; limited differentiation

3. Embryos – harvested around day 5 after conception; can become any cell type

Plant stem cells: called meristematic cells, found in roots and shoots, continuously make new cells

 Importance of Stem Cells

• Basis for cellular differentiation → specialized cells like muscle, nerve, blood, bone, skin

• Critical for regeneration (e.g., liver, skin, fingertip in humans)

Potential for organ regeneration could change healthcare, economy, and politics

Stem Cells in Plants

• Called meristematic cells

• Found in roots and shoots

• Continuously produce new cells for growth and repair

Stem Cell Controversy

• Early stem cell research used embryonic stem cells, often taken from unused embryos from IVF treatments

• Ethical concerns arose because obtaining these cells destroys the embryo

• In 2006, scientists developed induced pluripotent stem cells where adult cells are reprogrammed to behave like embryonic stem cells, reducing ethical concerns

Levels of Organization of an Organism

1. Cell – Basic unit of life; carries out all life processes

2. Tissue – Group of similar cells working together for a specific function

3. Organ – Structure made of different tissues working together to perform a job

4. Organ System – Group of organs working together to carry out a major function

5. Organism – Entire living thing; all organ systems working together

4 Types of Animal Tissues

1. Epithelial Tissue

• Function: Covers body surfaces, lines organs & cavities, protects, absorbs, and secretes

• Characteristics: Cells tightly packed, forms continuous sheets, has a free surface

2. Connective Tissue

• Function: Supports, protects, binds other tissues, stores fat, transports substances (blood)

• Characteristics: Few cells, lots of extracellular matrix (fibers & fluid)

3. Muscle Tissue

• Function: Produces movement of body or internal organs

• Characteristics: Long cells (fibers), can contract, types: skeletal, smooth, cardiac

4. Nervous Tissue

• Function: Transmits electrical signals, coordinates body functions, responds to stimuli

• Characteristics: Made of neurons (nerve cells) + supporting cells (glial cells)

1. Integumentary System

1. (Skin, hair, nails, sweat glands)

• Protects body

• Regulates temperature

• Prevents water loss

• Sensory reception

2. Digestive System

2. (Mouth, esophagus, stomach, intestines, liver, pancreas)

• Breaks down food

• Eliminates waste

• Liver produces bile; pancreas produces enzymes and insulin

• Small intestine absorbs nutrients

3. Circulatory / Cardiovascular System

3. (Heart, blood vessels, blood)

• Transports oxygen, nutrients, hormones

• Removes wastes

• Regulates body temperature

• Heart pumps blood; arteries carry oxygenated blood; veins carry deoxygenated blood

4. Respiratory System

4. (Nose, trachea, lungs, diaphragm)

• Gas exchange (O₂ in, CO₂ out)

• Maintains blood pH

• Lungs contain alveoli; diaphragm helps breathing

5. Muscular System

5. (Skeletal muscles, tendons)

• Movement, posture, heat production

• Works with skeletal system; skeletal muscles contract to move body parts

• Skeletal System

• (Bones, cartilage, ligaments, joints) – Supports & protects organs, produces blood cells, stores minerals, allows movement

• Excretory / Urinary System

• (Kidneys, ureters, bladder, urethra) – Removes wastes, regulates water & salt balance

• Nervous System

• (Brain, spinal cord, nerves) – Controls body functions, responds to stimuli, coordinates other systems

• Endocrine System

• (Glands: thyroid, adrenal, pituitary, pancreas) – Produces hormones regulating growth, metabolism, reproduction, homeostasis

• Reproductive System

• (Ovaries, testes, uterus, penis, vagina) – Produces gametes, supports offspring development

• Immune / Lymphatic System

• Lymph nodes, spleen, thymus, lymph vessels) – Protects from infection, transports lymph, removes toxins/pathogens

key differences between the organ systems of a human, frog and earthworm.

• Humans

  • Most complex organ systems

  • Circulatory: 4-chambered heart

  • Respiratory: lungs only

  • Digestive: stomach, liver, pancreas

  • Excretory: kidneys filter blood

• Frogs

  • Similar systems to humans but simpler

  • Circulatory: 3-chambered heart

  • Respiratory: lungs and skin

  • Digestive: shorter digestive tract

  • Excretory: waste exits via cloaca

• Earthworms

  • Simplest organ systems

  • Circulatory: closed system with aortic arches

  • Respiratory: diffusion through skin

  • Digestive: long, segmented tube

  • Excretory: nephridia in each segment for waste removal

Homeostasis:

The process by which the body maintains a stable internal environment (temperature, water balance, pH, etc.) despite changes outside the body.

Interdependence of organ systems:

Organ systems rely on each other to function properly; one system failing can affect others.

Importance of homeostasis:

• Keeps cells and tissues working efficiently

• Prevents illness or death

• Allows the organism to survive in changing environments

Examples of interdependence:

• Respiratory & Circulatory: The lungs bring in oxygen, which the blood carries to all cells; the circulatory system also carries carbon dioxide back to the lungs for removal.

• Digestive & Circulatory: The digestive system breaks down food into nutrients, which the circulatory system delivers to cells for energy and growth.

1. X-Ray

• How it works: High-energy radiation passes through body; absorbed by dense materials like bones.

• Medical info: Shows broken bones, lung/heart problems, detects some cancers.

• Pros/Cons: Quick, painless, non-invasive / Radiation can harm DNA.

2. Fluoroscopy

• How it works: Continuous X-ray beam; contrast dye may be used.

• Medical info: Real-time organ movement; blood vessels (angiograms).

• Pros/Cons: See organs in motion / Radiation exposure; dye can cause reactions.

3. Ultrasound

• How it works: Sound waves reflect off organs → images on screen.

• Medical info: Fetus development, soft tissues, heart, guiding biopsies.

• Pros/Cons: Safe, no radiation, real-time / Cannot see through bone or gas

4. CT Scan

• How it works: Multiple X-rays from different angles → computer creates 3D image.

• Medical info: Bones, soft tissues, blood vessels; detects bleeding, cancer, injuries.

• Pros/Cons: Quick, detailed / Radiation exposure.

5. MRI

• How it works: Magnets + radio waves interact with hydrogen atoms → detailed images.

• Medical info: Brain, heart, liver, soft tissue, inside bones; detects cancer & diseases.

• Pros/Cons: Very detailed, no radiation / Expensive, can feel confined.

6. Nuclear Medicine

• How it works: Radioisotopes absorbed by tissues → camera detects radiation → image.

• Medical info: Organ function, cancer detection, blood circulation.

• Pros/Cons: Functional info, can treat some cancers / Radiation exposure.

7. PET Scan

• How it works: Radioisotopes emit positrons; often combined with CT for detailed view.

• Medical info: Detects cancer, heart disease, brain disorders.

  • Pros/Cons: Shows function and structure / Expensive, radiation exposure.

1. Immunization

• Definition: Process of making a person immune to a disease.

• Purpose: Helps prevent infection and spread of diseases in the community

2. Vaccine

• Definition: Substance that stimulates the immune system to produce immunity.

• Types:

  • Live attenuated: Weakened germ

  • Inactivated: Killed germ

  • Subunit: Part of the germ

  • Toxoid: Immunity to a toxin produced by the germ

3. Why yearly vaccines?

• Some diseases (like influenza) mutate each year.

• Immunity can wane over time, so yearly shots keep protection up to date.

4. Examples of Routine Vaccines in Ontario:

• MMR (measles, mumps, rubella), HPV, polio, tetanus, whooping cough, meningitis

5. Public Health Units

• Protect community health and prevent disease spread.

• Roles: Vaccinations, health education, screening programs, outbreak control.

6. Health Education & Screening

• Examples: HIV awareness, nutrition programs, mammograms, Pap tests, colorectal screening.

• Benefits: Early detection, disease prevention, better health outcomes.

7. Pandemic Response Example (COVID-19)

• Measures: Borders closed, business closures, PPE, testing, social distancing, hand washing.

• Purpose: Slow disease spread, prevent healthcare overload, reduce deaths.

8. Other Public Health Tips

• Healthy diet, exercise, avoid smoking, UV protection, vaccines, participate in screening programs.