Science 7 Q2 Summary of Lessons PDF

MICROSCOPE MICROSCOPY TIMELINE YEAR DISCOVERY 1000 CE unidentified inventor reading stone 1284 Italian Salvino D' Armate; first pair of wearable eyeglasses 1590 Dutch eyeglass craftsmen Zacharias Janssen and his son Hans Janssen telescope a...

MICROSCOPE MICROSCOPY TIMELINE YEAR DISCOVERY 1000 CE unidentified inventor reading stone 1284 Italian Salvino D' Armate; first pair of wearable eyeglasses 1590 Dutch eyeglass craftsmen Zacharias Janssen and his son Hans Janssen telescope and compound microscope 1665 English physicist Robert Hooke Discovered in a cork using the microscope lens the "pores" or "cells" Parts of a Microscope and their functions Eyepiece (Ocular Lens): The lens at the top of the microscope that you look through, usually with a magnification of 10x or 15x. Arm: The part of the microscope that connects the base to the head and the eyepiece tube. It is used to carry the microscope. Stage Clips: Metal clips on the stage that hold the slide in place. Coarse Adjustment Knob: A larger knob used for focusing the microscope. It moves the stage or the body tube up and down to bring the specimen into general focus. Fine Adjustment Knob: A smaller knob used for fine-tuning the focus of the specimen after using the coarse adjustment knob. It moves the stage slightly to sharpen the image. Draw Tube: The tube that connects the eyepiece to the microscope body. Revolving Nosepiece: The part that holds two or more objective lenses and can be rotated to easily change power (magnification). Objective: The lenses closest to the specimen, that are typically of varying magnifications (e.g., 4x, 10x, 40x, 100x).8 Stage: The flat platform where the slide is placed for observation. Diaphragm (Iris): A rotating disk under the stage with di_erent sized holes. It is used to vary the intensity and size of the cone of light that is projected upward into the slide. Illuminator: A light source located at the base of the microscope. Base: The bottom part of the microscope that provides stability and support. It houses the illuminator and other electrical components. PLANT AND ANIMAL CELL Scan this to use the interactive website to learn more about plant and animal cell Cell Anatomy 1. Centriole Involved in cell division; helps in the formation of spindle fibers that separate chromosomes during mitosis. 2. Cytosol/Cytoplasm The jelly-like fluid inside the cell that holds the organelles and is the site of many metabolic reactions. 3. Cytoskeleton A network of fibers that provides structural support for the cell, aids in cell movement, and helps transport materials within the cell. 4. Nuclear DNA Contains the genetic blueprint for the organism, encoding instructions for protein synthesis and cell function. 5. Golgi complex / Golgi apparatus Modifies, sorts, and packages proteins and lipids for storage or transport out of the cell. 6. Lysosome Contains digestive enzymes that break down waste materials, cellular debris, and foreign invaders like bacteria. 7. Cell membrane A semi-permeable membrane that surrounds the cell, providing protection and structure, and controlling the movement of substances in and out of the cell. 8. Mitochondrion Known as the powerhouse of the cell, mitochondria generate most of the cell's7 supply of ATP (energy) through cellular respiration. 9. Nucleolus A structure within the nucleus responsible for producing and assembling ribosome components. 10. Nucleus Contains the cell's genetic material (DNA) and controls the cell's activities by regulating gene expression; acts as the command center of the cell. 11. Peroxisome Contains enzymes that break down fatty acids and amino acids and detoxify certain chemicals, producing hydrogen peroxide as a byproduct, which is then converted to water. 12. Rough ER Studded with ribosomes and involved in protein synthesis and processing. 13. Ribosomes Small structures that are the site of protein synthesis; they can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum. 14. Smooth ER Lacks ribosomes and is involved in lipid synthesis and detoxification processes. 15. Vesicle Small membrane-bound sacs that transport and store substances Q1. What are the main structural di_erences between plant and animal cells observed under the microscope? Cell Wall is present in plant cells. Chloroplasts is present in plant cells. Vacuoles in plant cells are often large and in animal cells are usually smaller. Shape of plant cells is regular, box-like, while animal cells have a more irregular, rounded shape. Q2. Why do plant cells have a cell wall, and what is its function? The cell wall provides structural support and protection to the plant cell. It helps maintain the cell's shape and prevents it from bursting when water enters the cell. Q3. How does the shape of the cells di_er between plant and animal cells, and why? Plant cells generally have a more regular, box-like shape due to the presence of a rigid cell wall that provides structural support, while animal cells have a more irregular, rounded shape because they lack a cell wall and are only surrounded by a flexible cell membrane, allowing them to adopt various shapes and facilitating their movement and interaction with other cells. Q4. What are the similarities between plant and animal cells? Nucleus: Both plant and animal cells have a nucleus that contains their genetic material. Cell Membrane: Both types of cells have a cell membrane that controls the movement of substances in and out of the cell. Cytoplasm: Both cells contain cytoplasm, a jelly- like substance that holds the organelles and is the site of many metabolic reactions. Organelles: Both plant and animal cells have other common organelles, such as mitochondria, endoplasmic reticulum, Golgi apparatus, and ribosomes. UNICELLULAR AND MULTICELLULAR CELL MITOSIS Q1. A mosquito cell in interphase has six chromosomes. How many sister chromatids does the same cell have during metaphase? A mosquito cell that has six chromosomes in interphase will have 12 sister chromatids during metaphase: Cell phase Number of sister chromatids Interphase — Metaphase 12 During interphase, DNA replication creates two identical copies of each chromosome, called sister chromatids. The sister chromatids are joined at the centromere. During metaphase, the sister chromatids line up in the center of the cell and are ready to be separated in the next stages, anaphase and telophase. Q2. A human cell in early prophase has 46 chromosomes. How many chromosomes does one of the daughter cells have immediately after mitosis and cytokinesis? If a human cell in early prophase has 46 chromosomes, then each daughter cell will have 46 chromosomes after mitosis and cytokinesis: Mitosis - During mitosis, the cell's duplicated chromosomes are separated and distributed into two groups, each with 46 chromosomes. Cytokinesis - The cell then splits into two daughter cells, each with 46 chromosomes. The daughter cells are identical to the parent cell. This process is called mitosis and cytokinesis, and it produces two genetically identical daughter cells. MEIOSIS MEIOSIS AND GAMETE FORMATION Meiosis in Males Spermatogenesis The process by which sperm are produced in male animals occurs in the testes (male reproductive organs) a diploid cell first large immature cell The large cell then increases in size (germ cell). undergoes meiosis I The four cells change Two cells are produced, each of which in form and develop a undergoes meiosis II to tail to become male form a total of four gametes called sperm. haploid cells Meiosis in Females Oogenesis The process by which gametes are produced in female animals Notice that during cytokinesis following meiosis I, the cytoplasm divides unequally. One of the resulting cells gets nearly all of the cytoplasm. It is this cell that will ultimately give rise to an egg cell. The other cell is very small and is called a polar body. The polar bodies degenerate after oogenesis. 1. How many is the chromosome number found in a human body? The chromosome number found in a human body is 46. 2. The cell of a fruit fly has 8 chromosomes. How many chromosomes does an egg cell of a fruit fly have? The cell of a fruit fly has 8 chromosomes. An egg cell of a fruit fly has 4 chromosomes. 3. Male gametes are called sperm. 4. Female gametes are called ova. 5. True or False. The chromosomes found in body cells are paired. True. The chromosomes found in body cells are paired. 6. True or False. Meiosis maintains the number of chromosomes. False. Meiosis reduces the number of chromosomes by half. 7. True or False. The process of meiosis produces gametes. True. The process of meiosis produces gametes. 8. During meiotic (meiosis) cell division, how many daughter cells are produced? During meiotic (meiosis) cell division, 4 daughter cells are produced. 9. What are the sex chromosomes for females? The sex chromosomes for females are XX. 10. How many chromosomes does a human sperm cell contain? A human sperm cell contains 23 chromosomes. ASEXUAL REPRODUCTION Scan this QR Code to learn more about sexual reproduction LEVELS OF BIOLOGICAL AND ECOLOGICAL ORGANIZATION Ecology is the study of interrelationships among organisms and their interaction with the environment. Organisms are a_ected by both biotic (living) and abiotic (non-living) factors. A habitat is the natural home or environment of an organism. Biological organization is organizing the various levels of biological complexity, from the simplest to the most complex, using a reductionist approach, which means that complex systems are understood by breaking them down into their constituent parts. This hierarchical organization helps scientists and biologists better understand and study living organisms and their interactions. FOOD CHAIN AND FOOD WEB Scan this QR Code to learn more about food chain and food web