Unit B Final Exam Study Guide - Science 8 Notes

Unit B: Unit Final

Section 1: Cells and Systems

Key Concept: Relationships

Related Concepts: Form and Function
  • Form and Function:
    • Form: The shape and structure of an object, body part, or organ.
    • Function: What that object, body part, or organ does.
    • Example 1: Eye
      • Function: Detects light and enables vision.
      • Form: Curved shape to focus light; specialized cells in the retina detect light.
    • Example 2: Dolphin's Tail
      • Function: Propels the dolphin through the water.
      • Form: Flattened shape and strong muscles for efficient swimming.

1.1 Characteristics of Living Things

  • All living things share seven common characteristics:
    • Made of Cells:
      • Cells are the basic unit of life, performing all essential processes.
      • Microscopic: Single-celled organisms are not visible to the naked eye.
      • Multicellular organisms consist of millions to trillions of cells.
    • Need Energy:
      • All living organisms require energy to perform actions.
      • Plants obtain energy from sunlight through photosynthesis.
      • Animals get energy by consuming food or other organisms.
      • Nutrients (e.g., carbohydrates) provide energy and building materials for growth, development, and reproduction.
    • Respond to the Environment:
      • Organisms must react to stimuli in their environment to survive.
      • A stimulus is something that provokes a response in an organism.
    • Grow and Develop:
      • Organisms grow and develop throughout their lives.
      • Even if physical growth stops, cellular repair and regeneration continue.
    • Reproduction:
      • Reproduction is vital for species survival but not necessary for the life of an individual organism.
    • Adaptations:
      • Adaptations are characteristics that allow organisms to survive in their environments.
      • Behavioral: Actions taken to survive.
      • Structural: Physical features that aid survival.
    • Produce Waste:
      • Living things create waste products due to metabolic processes that need to be eliminated.

1.2 Structure & Function

  • Organisms share characteristics and must perform specific functions to stay alive.
  • Structures: Parts that carry out specific jobs.
  • Different organisms may have distinct structures that allow them to fulfill similar functions.
  • Examples:
    • Movement:
      • Dolphins: Swim using their tail and fins.
      • Trees: Don't move but have roots that anchor them and grow tall to reach sunlight.
      • Beetles: Use legs for movement and can fly.
      • Tigers: Rely on their strong legs to run quickly.
    • Food Gathering:
      • Dolphins: Use echolocation to find and catch fish.
      • Trees: Use sunlight to create food through photosynthesis.
      • Beetles: Consume organic material with their mouthparts.
      • Tigers: Hunt and eat other animals for food.
    • Breathing:
      • Dolphins: Breathe through a blowhole on their heads.
      • Trees: Take air in through tiny holes called stomata on their leaves.
      • Beetles: Respire using small tubes within their bodies.
      • Tigers: Breathe using lungs, similar to humans.

1.3 Organs & Organ Systems

  • Organ: Tissues working together to perform a function (e.g., heart pumping blood, lungs exchanging gases).
  • Organ System: A group of organs collaborating to execute a more complex task.
  • Examples of Organ Systems:
    • Circulatory System:
      • Components: Heart, arteries, veins, capillaries, and blood.
      • Function: Transports oxygen, nutrients, and waste throughout the body; defends against disease.
    • Respiratory System:
      • Components: Nose, mouth, trachea, diaphragm, bronchi, lungs, and alveoli.
      • Function: Transports oxygen to the blood and removes carbon dioxide from the body.
    • Digestive System:
      • Components: Salivary glands, mouth, esophagus, stomach, liver, pancreas, gallbladder, small intestine, and large intestine.
      • Function: Processes food to extract energy and nutrients.
    • Nervous System:
      • Components: Brain, spinal cord, nerves, and sensory organs.
      • Function: Coordinates and controls the actions of all organs and organ systems; detects, processes, and responds to changes in both the external and internal environments.
    • Excretory System:
      • Components: Kidneys, bladder, lungs, skin, and liver.
      • Function: Removes chemical and gaseous wastes from the blood.
    • Muscular System:
      • Components: Muscles, tendons, and organs that contain muscle tissue (e.g., heart and stomach).
      • Function: Facilitates movement.
    • Integumentary System:
      • Components: Skin and associated structures.
      • Function: Provides protection to internal organs from the external environment; sensory functions (detecting pain, pressure, and temperature).

Section 2: Cells and Systems

2.1 Microscopes

  • Compound Microscope: A microscope that has two or more lenses; the most common type used in laboratories.
  • Microscope History:
    • Antonie van Leeuwenhoek:
      • First person to discover microorganisms.
      • Examined blood samples, pond water, and plaque from his teeth using a microscope he invented.
      • Observed tiny organisms he called "animalcules."
    • Robert Hooke:
      • Used a microscope to look at tiny pieces of cork.
      • Discovered small holes that resembled honeycombs.
      • Described these holes as "little rooms" or boxes, which he termed “cells” (from the Latin word "cellular").
  • Types of Microscopes:
    • Scanning Electron Microscope (SEM): Scans the surface of a specimen bit by bit.
    • Transmission Electron Microscope (TEM): Looks at the inside of a whole sample.
  • Parts of a Microscope:
    • Slide: A flat piece of glass where the specimen is placed for viewing.
    • Stage: The platform that holds the slide in place.
    • Stage Clips: Clips that secure the slide onto the stage.
    • Eyepiece: The lens through which you look to view the specimen.
    • Nose Piece: Holds the objective lenses and allows you to switch between them.
    • Objective Lenses: Lenses with different magnifications used to view the specimen.
    • Light Source: Provides illumination to make the specimen visible.
    • Diaphragm: Regulates the amount of light that reaches the slide.
    • Coarse Adjustment Knob: Used to make large adjustments to focus the microscope.
    • Fine Adjustment Knob: Used for fine-tuning the focus after using the coarse adjustment.
    • Arm: The part of the microscope that connects the head to the base and provides support for carrying.
    • Total Magnification: Multiply the magnification of the eyepiece by the magnification of the objective lens being used.
    • Adjustment Tips:
      • Start with the coarse adjustment knob when focusing at lower magnifications.
      • Once the specimen is in focus, switch to the fine adjustment knob for clarity.
      • The stage should be just below the nosepiece when beginning to view a specimen to allow space to insert the slide.

2.2 The Cell is the Basic Unit of Life

  • Cells are the basic unit of life because they control all the functions carried out by living organisms.
  • Cell Theory States:
    • All living things are made of one or more cells.
    • The cell is the basic unit of life.
    • All cells come from pre-existing cells.
  • Organelles and Their Functions:
    • Nucleus: The control center of the cell that contains genetic material.
    • Mitochondria: The powerhouse of the cell, where cellular respiration occurs, turning sugar into ATP (adenosine triphosphate), the energy currency of the cell.
    • Cell Membrane: A semi-permeable barrier that controls what enters and exits the cell.
    • Vacuoles: Storage units within the cell. Plant cells generally have one large vacuole, while animal cells have multiple smaller vacuoles.
    • Cytoplasm: The gel-like fluid that fills the inside with the cell, containing nutrients and facilitating chemical reactions.
    • Cell Wall: A rigid structure that provides support and protection to plant cells, found outside the cell membrane (in plant cells).
    • Chloroplasts: Organelles found in plant cells that conduct photosynthesis, converting sunlight into energy.

2.3 Single and Multicellular Organisms

  • Unicellular Organisms: Organisms made up of only one cell.
    • Examples: Mycoplasma, amoeba, and paramecium.
  • Multicellular Organisms: Organisms made up of multiple cells.
    • Examples: Humans, trees, and animals.
  • Advantages of Multicellular Organisms:
    • Longer lifespan.
    • Ability to inhabit diverse environments.
    • Can perform various functions.
    • Can grow larger.
  • Disadvantages of Multicellular Organisms:
    • Slower reproduction compared to unicellular counterparts.
    • Require more energy for survival.
  • Unicellular Organisms Specialized Structures:
    • Pseudopods: Temporary projections that help in movement and feeding.
    • Cilia: Short hair-like structures that enable movement and transport of materials.

2.4 Osmosis and Diffusion

  • Osmosis and diffusion are essential processes allowing cell exchanges.
  • Every cell brings in nutrients, and every cell eliminates waste.
  • The structure that facilitates this exchange is called the cell membrane.
  • The cell membrane is a selectively permeable barrier that controls what enters and exits.
  • Diffusion: The movement of particles from an area of higher concentration to an area of lower concentration until equilibrium is reached.
  • Osmosis: A specific type of diffusion that refers to the movement of water through a semipermeable membrane.
    • If the concentration of water is higher inside the cell than outside, water moves out of the cell.
    • If the concentration of water is lower inside the cell than outside, water moves into the cell.
    • Water will move through a membrane to equalize concentrations on both sides.

2.5 Cells Combine to Form Tissues and Organs

  • Various cell types combine to form tissues, which then build organs.
  • Cell Type and Examples:
    • Connective Tissue: Supports and binds other tissues (e.g., blood, bone).
    • Epithelial Tissue: Covers surfaces and lines cavities (e.g., skin).
    • Nervous Tissue: Transmits signals (e.g., neurons).
    • Muscle Tissue: Enables movement (e.g., skeletal, cardiac, and smooth muscle).
  • Plant Tissue Types:
    • Ground Tissue: Responsible for photosynthesis, storage, and support.
    • Dermal Tissue: Protective outer covering of the plant.
    • Vascular Tissue: Transports water and nutrients throughout the plant.
  • Advantages of Specialized Cells:
    • Specialized cells provide efficiency in performing specific functions, enhancing the organism’s ability to respond to its environment and maintain homeostasis. However, specialization may reduce cellular versatility, as highly specialized cells may rely more on other cells to perform functions they cannot.
  • Cells Working Together:
    • Cells that work together form tissues.
    • Tissues that work together form organs.

Section 3 & 4: Cells and Systems

3.1 The Digestive System

  • Function: The digestive system is used to break down food to provide energy for your body's cells and building materials for various life functions (growth, reproduction, repair, and maintenance).
  • 3 Types of Nutrients:
    • Carbohydrates: Provide energy.
    • Proteins: Essential for growth and repair of tissues.
    • Lipids (fats): Store energy and support cell structure.
  • Digestion:
    • Mechanical Digestion: The physical breaking down of food (e.g., using your teeth).
    • Chemical Digestion: The breakdown of food using enzymes (e.g., enzymes in saliva breaking down carbohydrates into simple sugars).
  • Structures:
    • Mouth:
      • Chewing food with teeth, gums, and tongue.
      • Saliva contains enzymes that begin carbohydrate breakdown, turning food into a bolus.
    • Esophagus:
      • The bolus travels down via involuntary muscle contractions (peristalsis).
      • The epiglottis prevents food from entering the trachea.
    • Stomach:
      • Mixes food with gastric juice (mucus, hydrochloric acid, digestive enzymes).
      • Churns food to create a liquid called chyme.
    • Small Intestine:
      • Chyme is released from the stomach.
      • The pancreas releases enzymes for glucose breakdown.
      • The liver produces bile stored in the gallbladder, aiding in fat digestion.
      • Villi in the small intestine increase nutrient absorption.
    • Pancreas:
      • Produces enzymes that digest sugars and other nutrients.
    • Large Intestine:
      • Absorbs excess water.
      • Undigested food becomes feces, which is prepared for excretion.

3.2 The Respiratory System

  • Function: The respiratory system is responsible for gas exchange, bringing oxygen into the body and removing carbon dioxide.
  • Inhalation: The process of taking air into the lungs.
  • Exhalation: The process of breathing out carbon dioxide.
  • Diaphragm: A muscle that assists in breathing by contracting and relaxing to change lung volume.
  • Structures:
    • Mouth / Nose: Entry point for oxygen.
    • Trachea: Tube that transports air to and from the lungs; made of cartilage to keep it open.
    • Bronchi: Split from the trachea; one bronchus leads to each lung.
    • Bronchioles: Smaller branches of the bronchi that carry air to the alveoli.
    • Alveoli: Tiny air sacs surrounded by capillaries where gas exchange occurs (oxygen absorbed, carbon dioxide released).
    • Bloodstream: Transports oxygen to cells and carries carbon dioxide back to the lungs.

3.3 The Circulatory System

  • Function: The circulatory system is the body's transportation network, moving nutrients, oxygen, and waste products.
  • Heart:
    • The major organ that pumps blood; consists of a right and left pump.
    • The left side receives oxygenated blood from the lungs and pumps it throughout the body.
    • The right side receives deoxygenated blood from the body and sends it to the lungs for oxygenation.
  • Blood Flow Process:
    • Deoxygenated blood from the body returns to the heart.
    • Blood enters the right atrium and flows into the right ventricle.
    • The right ventricle pumps blood to the lungs to be oxygenated.
    • Oxygenated blood returns to the left atrium, flows into the left ventricle.
    • The left ventricle pumps oxygenated blood to the body via the aorta.
  • Blood Vessels:
    • Arteries: Thick-walled vessels carrying blood away from the heart; contain more muscle for pressure.
    • Veins: Slightly thinner vessels with valves to prevent backflow, carrying blood back to the heart.
    • Capillaries: Very thin (one cell thick) vessels facilitating gas and nutrient exchange.
  • Parts of Blood:
    • Red Blood Cells: Carry oxygen from the lungs to the body and return carbon dioxide.
    • White Blood Cells: Part of the immune system; help fight infections.
    • Platelets: Involved in blood clotting.
    • Plasma: The liquid component of blood that carries cells, nutrients, and waste.

3.4 The Excretory System

  • Function: The excretory system removes waste products from the body and regulates water and electrolyte balance.
  • Types of Waste in the Body:
    • Metabolic waste (e.g., urea).
    • Unused substances (e.g., excess salts).
  • Urine Formation:
    • Blood enters the kidney via the renal artery, which splits into smaller arterioles to reach the nephrons.
    • Nephrons filter the blood, collect waste, and funnel it into larger ducts leading to the renal pelvis.
    • Filtered blood exits through the renal vein; collected waste flows into the ureters, leading to the bladder.
  • Role of the Liver: Converts toxic ammonia into urea, which is then excreted in urine.
  • Kidneys: Organs that filter blood to remove waste and excess substances.
  • Nephrons: Functional units in the kidneys that filter blood, collect waste, and create urine.
  • Ureters: Tubes that transport urine from the kidneys to the bladder.
  • Bladder: A muscle sac that stores urine until excretion.
  • Urethra: The tube through which urine is expelled from the body.
  • Questions to Explore:
    • How can urine reveal diseases?
      • Urinalysis can indicate kidney function, diabetes, liver problems, and other health issues by assessing substances present in the urine.
    • How does the integumentary system help with waste removal?
      • The skin eliminates waste products through perspiration, which contains salts and urea.
    • What is dialysis? How does it work and why would you need it?
      • Dialysis is a medical procedure that artificially removes waste products and excess fluid from the blood when kidneys are unable to perform this function, often due to kidney failure.

3.5 The Nervous System

  • Function: Coordinates and controls the actions of all body organs and systems.
  • Neurons:
    • Specialized cells in the nervous system.
    • Dendrites: Receive stimuli and transmit signals to the cell body.
    • Soma (cell body): Contains the nucleus and organelles.
    • Axon: Relays signals to other neurons or muscles.
  • Types of Neurons:
    • Sensory Neurons: Carry information from sensory receptors to the central nervous system (CNS).
    • Motor Neurons: Carry information from the CNS to muscles and organs to trigger responses.
    • Interneurons: Connect sensory and motor neurons and facilitate communication within the CNS.
  • Divisions:
    • Somatic Nervous System: Controls voluntary movements and reflexes.
    • Autonomic Nervous System: Regulates involuntary control over internal organs (sympathetic and parasympathetic divisions).
    • Central Nervous System (CNS): Comprises the brain and spinal cord; processes information and coordinates responses.
    • Peripheral Nervous System (PNS): Connects the CNS to the rest of the body; consists of sensory and motor neurons.
    • Reflex: An automatic response to a stimulus, processed quickly with minimal involvement of the brain (e.g., pulling hand away from a hot surface).

4.1 Developing a Theory of Disease

  • Vaccines: Biological preparations that provide immunity against specific diseases by stimulating the body’s immune response.
  • Louis Pasteur: A pioneer in microbiology; developed vaccines and discovered that microorganisms cause disease.
  • Dealing with Germs: Importance of hygiene, sanitation, and vaccinations in preventing the spread of infectious diseases.

4.2 Factors that Affect the Functioning of Body Systems

  • Factors that Affect Your Health: Diet, exercise, genetics, environment, stress, lifestyle choices such as smoking and alcohol use.
  • Factors that Affect the Respiratory System:
    • Asthma: A chronic condition that causes difficulty in breathing due to airway inflammation.
    • Smoking: Damages lung tissue and reduces lung function.
    • Emphysema: A progressive disease that destroys lung tissue and decreases airflow.
    • Bronchitis: Inflammation of the bronchial tubes, often caused by smoking or infections.
  • Factors that Affect the Circulatory System:
    • Atherosclerosis: Buildup of plaque in arteries, leading to restricted blood flow.
    • Anemia: A condition marked by a deficiency of red blood cells or hemoglobin, leading to fatigue and weakness.
  • Factors that Affect the Digestive System:
    • Ulcers: Sores in the stomach lining due to acid, often caused by stress, infections, or certain medications.