Grade 7 Science

• Microscope


  A tool that can help you see tiny objects and living organisms
• Major parts of a microscope

  • Magnifying
  • Illuminating
  • Mechanical
• Magnifying parts


  • Where the specimen in focus appears larger
  • Ocular (eyepiece) - a lens attached to a draw tube
  • Objective lenses - primary optical lenses ranging from 4x to 100x magnification, typically including 3 lenses: high power, low power, and oil immersion
• Illuminating parts


  • Supply and regulate light towards the focused specimen
  • Mirror - reflects light from an external source up through the bottom of the stage
  • Diaphragm - controls amount of light reaching the specimen, located above the condenser and below the stage
  • Stage condenser - collects and focuses light from the illuminator onto the specimen, located under the stage often with an iris diaphragm
• Mechanical parts


  • Used to support and adjust other parts
  • Body tube - separates the objective and eyepiece, maintains alignment
  • Coarse adjustment knob - moves the tube up and down
  • Fine adjustment knob - brings specimen into sharp focus under low power, used for all focusing with high power
  • Arm - curved part that supports the body tube, used for transporting
  • Inclination joint - connects the arm to the base, allows inclining the microscope
  • Stage clips - hold the glass slide in place
  • Stage - flat surface where the mounted slide is placed
  • Base - provides support for the microscope
• A microscope is a portable and very powerful tool in the field of biology that allows us to capture images of living things to its tiniest cell and provides us with essential data about the existence of things with life
• The direction of the stage knob when turned

  Is always opposite to the direction of the specimen under the microscope
• Magnification


  The ability to enlarge an image of the object's apparent size but not changing the actual physical size
• The specimen's magnification can be computed as multiplying the magnification of the inscription in the eyepiece to the magnification inscription of the objective
• Biology


  The branch of science which deals with the study of life of all the organisms on earth
• Biological levels of organization

  • Cells
  • Tissues
  • Organs
  • Organ systems
  • Organism
  • Population
  • Community
  • Ecosystem
  • Biosphere
• Cells are the basic unit of life
• Plant cells


  • Have a rigid cell wall made of cellulose molecules
• Animal cells


  • Have flexible cell membranes
• Tissue


  A group of cells performing a similar function
• Organ


  A group of tissues performing a similar function
• Organ system


  A group of organs performing a similar function
• Organism


  An individual living thing that is made up of one or more organ systems
• Population


  A group of organisms of one type that live in the same area
• Community


  A population that lives together in a defined area, consisting of all the different species within that area
• Ecosystem


  Composed of a community, its non-living surroundings and physical components of the environment
• Biosphere


  The part of the earth that contains all ecosystems
• A microscope enables us to see small things because of its ability to magnify
• The first person to observe cells as microscopic structures was the British scientist Robert Hooke
• Cell


  Tiny rooms or compartments that make up living organisms
• Cells are made up of tiny organs called organelles that perform specific functions
• Basic structures of cells


  • Cell membrane
  • Nucleus
  • Cytoplasm
• Cell membrane


  Encapsulates the contents of the cell, acts as a gatekeeper to protect the cell from the outside environment, and controls what materials can go in and out of the cell
• Nucleus


  Houses DNA, the hereditary material that carries genetic instructions, and various proteins including the nucleolus; considered the brain of the cell that directs all its activities
• Cytoplasm


  The jelly-like fluid between the cell membrane and the nucleus where all the organelles are located
• Organelles


  • Mitochondria
  • Ribosomes
  • Endoplasmic reticulum (smooth and rough)
  • Golgi apparatus
  • Lysosomes
  • Vacuoles
• Mitochondria


  The powerhouse of the cell where ATP (the energy of the cell) is produced
• Ribosomes


  Tiny organelles that contain RNA and specific proteins, directly involved in the manufacture of proteins
• Endoplasmic reticulum (ER)


  Smooth ER lacks ribosomes and is involved in the synthesis of lipids, while rough ER has ribosomes and is involved in the manufacture and transportation of proteins
• Golgi apparatus


  Responsible for transporting, modifying, and packaging proteins and lipids into vesicles for delivery to targeted destinations
• Lysosomes


  Contain chemicals that digest waste and worn out or damaged cell parts, acting as the waste disposal system of the cell
• Sexual reproduction


  Combining genetic material from two parents
• Vacuoles


  Membrane-bound spaces inside the cell that store various molecules including enzymes, waste products, water, and food material
• Asexual reproduction


  Produces offspring genetically identical to one parent only
• Sexual reproduction occurs when a new individual is formed by the union of two sex cells or gametes