Science 7 Q2 Reviewer PDF

**Compound microscopes** - compound microscopes are pivotal in exploring the unseen world. They magnify tiny objects, allowing us to examine cells, bacteria, and intricate structures invisible to the naked eye.  - This has revolutionized fields like medicine, biology, and materials sci...

**Compound microscopes** - compound microscopes are pivotal in exploring the unseen world. They magnify tiny objects, allowing us to examine cells, bacteria, and intricate structures invisible to the naked eye.  - This has revolutionized fields like medicine, biology, and materials science, leading to groundbreaking discoveries. - Is a device used to magnify a sample. It's commonly used in laboratory to study the specimen. - Parts can be classified as: ***Optical or Non-optical (or mechanical).*** - ***Zacharias Janssen*** is credited in making one of the earliest compound microscopes (binocular) around ***[1600.]*** **Parts of a compound microscope:** 1. ***Eyepiece (optical):*** - also called "ocular lens". - It's where you place your eye to observe the specimen / or the magnified image. (Usually 10x, or 15x.) - However, the main function of the eyepiece (or Ocular lens) is to enlarge the image, making tiny particles clearer. 2. ***Body Tube (mechanical):*** - The body tube connects the ocular lens to the objective lenses. - It ensures that the light travels correctly from the specimen, through the lenses, and finally to your eye. 3. ***Revolving nosepiece:*** - The nosepiece, or revolving turret, is the part of a microscope that holds and r-otates the objective lenses. 4. ***Stage:*** - The flat platform where you place the slides holding the specimen. 5. ***Objective lens: (optical)*** - The objective lens is a key player in a microscope's magnification game. Positioned close to the specimen, it\'s responsible for the initial magnification, creating areal image that\'s further magnified by the eyepiece.  - Most microscopes have multiple objective lenses with different magnifications, like ***[4x scanner, 10x low power objective lens, 40x high power objective lens, or 100x oil immersion objective lens.]*** - They can be changed through the revolving nosepiece. 6. ***Adjustment knob:*** - Course adjustment knob: \- A rapid control which allows for quick focusing by moving the objective lens or stage up and down. \- It is used for initial focusing. - Fine adjustment knob: \- A slow but precise control used to fine focus the image when viewing at the higher magnifications. 7. ***Arm*** -  It connects the base to the body tube and supports the headpiece and lenses. When you carry the microscope, you typically hold it by the arm. It's all about stability and structure. 8. ***Clips*** - Stage clips hold the slides in place 9. ***Mirror (optical)*** - acts as a light reflector, allowing the observer to see the specimen more clearly. 10. ***Base*** - The bottom of the microscope, used for support Illuminator **Cells** - Are the smallest and basic unit of life/all organisms. - All living things/organisms are made up of cells. - All cells came from pre-existing cells. - Not all cells look the same. - A typical cell is formed of: Plasma membrane, cytoplasm, nucleus - **Examples of cells are blood cells, bone cells, muscle cells, etc.** **Cell history:** ***[1565 -- Robert Hooke]***: a British scientist that used cork and called them cells. ***[1674 -- A. Van Leeuwenhoek:]*** studied living for the first time. ***[1831 -- Robert Brown]***: discovery and named nucleus in a cell. ***[1838-39 MJ Schleiden and Schwann]***: formulated cell theory. ***[1855 -- Rudolf Virchow]***: stated "Omnis cellula e cellula". **Cell wall:** - is rigid, tough and made of cellulose. - It protects and supports the cell. - Only PLANTS have a cell wall. **Cell membrane:** - Consists of a lipid bilayer that is semipermeable - Separates the interior of the cell from the outside world. **Cytoplasm:** - Jelly-like substance that contains organelles - Pads and supports organelles inside the cells **Nucleus:** - Ball-shaped structure and dense - Controls every cell activity The nucleus is made up of 4 parts: **Nuclear envelope -- double membrane covering which separates the n** **Nuclear pores** **Nucleoplasm** **Nucleolous** - is a double covering which separates the nucleus from the cytoplasm. **Endoplasmic reticulum: (can be smooth ER or rough ER)** - Transports materials around the cell - **Rough E.R: the site of Protein synthesis** - **Smooth E.R: the site of Lipid synthesis** **Ribosome:** - Made of RNA (ribonucleic acid) - Found in the cytoplasm - ALL cells have ribosomes **Mitochondria:** - Powerhouse of the cell - located in the cytoplasm and is bean shaped. - Supplies energy through cell respiration. - Also supplies ATP or Adenosine Triphosphate. **Vacuole:** - Large storage area, smaller in animal cells, and bigger in plant cells. **Chloroplast:** - Green structures that contain chlorophyll. - Captures sunlight for photosynthesis **Golgi body (or Golgi apparatus):** - Packages proteins for use in and out of the cell. **Cell hierarchy:** (Cells -\> Tissues -\> Organ -\> Organ system -\> Organism -\> Population -\> Community -\> Ecosystem -\> Biome -\> Biosphere) From: **Cells** **Classification of cells:** **Prokaryotic/Prokaryotes** lacks a defined nucleus. - Prokaryotes are **[SMALLER]** in size. - ***[MITOSIS is ABSENT.]*** - ***[Has a Nucleoid Region]*** (e.g: blue-green algae, bacteria, cyanobacteria and mycoplasma.) **Eukaryotic/Eukaryotes** has a defined nucleus - Eukaryotes are **[LARGER]** in size. - ***[MITOSIS is PRESENT.]*** (e.g: plants, animals, protists, humans, and fungal.) **Both Prokaryotes and Eukaryotes have the common features:** - Plasma membrane - Cytoplasm - DNA (Deoxyribonucleic acid) - Ribosomes To: **tissues**, which consists of a group of cells, - ***Connective tissue:*** the tissue that joins, supports, protects, and gives structure to other tissues and organs in the body. ***(blood, ligament, tendons, joints)*** - ***Epithelial tissue:*** protective covering over the whole body and some body surfaces. - ***Muscle tissue:*** tissue that produces, and contracts movement ***(cardiac muscle, smooth muscle, and skeletal muscle)*** - ***Nervous tissue:*** carries messages to the brain, allows us to see, and makes up brain and spine nerves. To: **organs**, which consist of a group of tissues To: **organ system**, which consists of a group of organs - THE ORGAN SYSTEM DEPEND ON EACH OTHER. IF ONE FAILS, THE SYSTEM WILL BE AFFECTED. - ***Integumentary*** - ***Nervous*** - ***Endocrine*** - ***Respiratory*** - ***Skeletal*** - ***Urinary*** - ***Reproductive*** - ***Skeletal*** - ***Muscular*** - ***Lymphatic*** - ***Digestive*** To: **organism**, where all the previous hierarchy of cells combined. - **Unicellular organisms:** only consists of ONE cell that carries all functions. (e.g: bacteria, amoeba, paramecium, protozoa, unicellular algae, and unicellular fungi.) Add-on: Most UNICELLULAR organisms are PROKARYOTES. Unicellular organisms are invisible to the naked eye. - **Multicellular organisms:** consists of MANY cells to function. (e.g: humans, animals, plants, trees) To: **population**, where the same group of organism lives in the same area. (e.g: all the white tail deer in the forest) To: **community**, where two or more different populations living in the same area. (e.g: all the populations combined in the forest \[deer, rabbits, snakes, etc.\] To: **ecosystem**, made up of both biotic and abiotic factors. **Biotic factors**: living components or the organisms (bio = life, ic = like) Ex: ***humans, plants, animals, trees, bacteria, worms, insects, etc.*** **Abiotic factors**: non-living components, or the physical and chemical conditions Ex: ***water, sunlight, temperature, soil, rocks, humidity, weather, climate, altitude, oxygen, wind, viruses etc.*** **Ecosystems on land:** terrestrial ecosystems **Ecosystems on water:** aquatic ecosystems To: **biome,** set of ecosystems sharing similar characteristics with their abiotic factors adapted to their environment. To: **biosphere**, where LIFE EXISTS, or all the hierarchy of cells combined. 3 components of biosphere: - **Lithosphere**: All the land on Earth. - **Atmosphere**: The layer of gases around the Earth. - **Hydrosphere**: All the water on Earth. Add-on: **Ecological relationships on the environment** **SYMBIOTIC RELATIONSHIPS:** (+ = benefit, 0 = unaffected, - = harmed) **-Mutualism: (+ and +)** where both or more organisms benefit from each other. Ex: **Bees and flowers** **-Commensalism: (+ and 0)** where one organism benefits and one is unaffected. Ex: **Barnacles and whales** **-Parasitism: (+ and -)** where one organism benefits and one is harmed. Ex: **Wood fungus (harms) and a tree (benefits and gets affected)** **NON-SYMBIOTIC RELATIONSHIPS:** **-Predation: (+ and -)** where a predator eats a prey for food. **-Competition: (- and -)** where one or more predators compete for the same resource for food **-Amensalism: (- and 0)** where one organism is harmed, while one is unaffected **Cell division:** - Happens when a parent cell divides into two or more cells called "daughter cells". - This is a crucial mechanism for growth, development, and repair in living organisms. **Meiosis:** - a process of cell duplication, in which one cell divides into four diverse haploid cells.