Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. Grade 7 – Science Revision – Q2 “ Model Answer” Lesson 1: Cell Structure and Functions + Levels of Cellular Organization Section 1: Define: 1. Cell: The smallest structural and functional unit of all living organisms. 2. Organism: is any living thing that carries out its own life processes. 3. Unicellular: Organisms made up of just one cell. 4. Multicellular: Organisms made up of more than one cell. 5. Cell membrane: a protective layer that covers a cell’s surface and controls materials moving into and out of the cell. 6. Cytoplasm: is the region inside the cell that includes the fluid and all the organelles. 7. Nucleus: membrane-bound organelle that contains DNA. 8. Ribosome: They are organelles without cell membranes which are important to produce proteins. 9. Prokaryote: are single-celled organisms that do not have a nucleus or membrane-bound organelles. 10. Eukaryote: are organisms made up of cells that contain DNA in a nucleus, membrane-bound organelles, and ribosomes. 11. Flagella: hair like structures (tail) that help the cell move. 12. Cytoskeleton: network of protein filaments that give shape and support to cells. 13. Tissue: Made of cells that work together to perform a specific function. 14. Organ: Made of different types of tissues 15. Organ system: made of different organs. Section 2 : Draw and label a prokaryotic cell: Page 1 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. Section 3: Short answers: 1) 1) 2) 3) 4) 1) 2) State the cell theory? All organisms are made up of one or more cells. The cell is the basic unit of all organisms. All cells come from existing cells. What are the 5 common features of all cells? Cytoplasm 3) Ribosomes. Cytoskeleton 5) Cell membrane 4) DNA Section 4: Match: Scientist Robert Hooke Contributions Schwann He concluded that all animals are made up of cells. Virchow He stated that all cells come from pre-existing cells. Anton van Leeuwenhoek The first scientist who observed living cells. Schleiden He concluded that all plant tissue are made up of cells. The first scientist to observe cells and name them. Lesson 2 : The Chemistry of life. Section 1: Define: 1. Atom: The smallest unit of an element that maintains the properties of that element 2. Element: a substance that cannot be broken down into a simpler substance. 3. Compound: is a substance made up of atoms of two or more elements joined by chemical bonds. 4. Simple carbohydrates: are made of one or a few sugars linked together. 5. Complex carbohydrates: _contain many sugar molecules linked together. 6. Hydrophilic: Substances that attract water. 7. Hydrophobic: Substances that repel water. Page 2 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. Section 2 : Label the following: 2) Ribose sugar 1) Phosphate 3) Nitrogen base Hydrophilic phosphate head Phospholipid Hydrophobic lipid tail Section 3 : Complete the table: Macromolecule: Lipids Subunit: Fat molecules Function: 1- Insulate organs. 2. Form our cell membrane. 3. Store energy Carbohydrate Glucose Food types: Vegetables, bread, pasta & chocolate Examples: 1- Oil 2- Wax 3- Phospholipid Main source of energy Proteins Amino Acid 1- Build and repair body structures. 2- Proteins called enzymes speed up chemical reactions Nucleic acids Nucleotide Carries our genetic information that cells need to make other molecules. Fish, meat and chicken Simple and complex DNA & RNA Page 3 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. Lesson 3: Homeostasis & Cellular Respiration. Section 1: Define: 1. Homeostasis: is the maintenance of a constant internal state in a changing environment. 2. Photosynthesis: is a process by which the plants store the energy from the sun into sugar. 3. Cellular respiration: is a process by which Plants & animals use oxygen to produce energy from food. 4. Semi permeable: allow only certain particles to move into or out of the cell. 5. Diffusion: is the movement of molecules from high concentrations to low concentrations. 6. Osmosis: is the diffusion of water through a semi-permeable membrane. 7. Facilitated diffusion: is the movement molecule in and out of cells through protein channels. 8. Passive transport: Is the movement of particles with a concentration gradient and uses no energy. 9. Active transport: Is the movement of particles against a concentration gradient and requires energy 10. Hypertonic solution: Low levels of water and high concentration of salt 11. Hypotonic solution: Low concentration of salt and high levels of water 12. Endocytosis: is a process by which a cell uses energy to surround a particle to bring it into the cell. 13. Exocytosis: is a process by which particles are released from the cell using energy. Section 2: Compare: Cellular Respiration Photosynthesis Location: Reactant: Mitochondria Glucose and water Product: Energy: (Stored/produced) Carbon dioxide and water Is produced from food Chloroplast Carbon dioxide and water Glucose and water Is stored in food. Page 4 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. What happens to Cells if placed in: Hypertonic solution Isotonic solution Hypotonic solution The cell will lose water and shrink Nothing The cell will take in water, swell and burst. Section 3 : Label the following: The reactants are: Carbon dioxide and water The products are: Glucose and water Lesson 4 : Bacteria & Viruses. Section 1: Define: 1. Microorganism: an organism which is too small to be seen by the naked human eye. 2. Pathogen: Bacteria, virus, or other microorganism that can cause disease. 3. Host: a living thing a microorganism uses as food or shelter. 4. Microbial infection: Infection is the invasion of body tissues by a microorganism (pathogen), usually causing disease. 5. Bacteria: Unicellular prokaryotic cell with no nucleus. 6. Virus: Are Non- Living as they do not possess any of the characteristics of living organisms 7. Binary fission: the asexual reproduction of bacteria, where the cell divides into 2 identical daughter cells. Page 5 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. 8. Lytic cycle: The viral cycle where the virus takes over the cell, reproduces new viruses, and destroys the cell 9. Lysogenic cycle: the viral cycle in which the viral DNA integrates into the cell’s DNA and becomes part of the host. 10. Provirus: When the viral DNA becomes a part of the host. 11. Bacteriophage: A virus that attacks bacteria. Section 2: Complete the table: Cocci bacteria: Spirillum bacteria: Bacillus bacteria: Bacterial shape Sphere shaped bacteria Spiral shaped bacteria Rod shaped bacteria Draw Section 3: Draw & Label A bacteriophage and then label the bacteria: A: Pilli B: Ribosomes C: DNA D: Flagella E: Cell wall B. Draw & Label the lytic cycle of a virus: F: Cell membrane Page 6 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. Section 4: Short Answers: 1) How does the body fight off infection? a. By a rise in TEMPERATURE. b. Production of ANTIBODIES by white blood cells. 2) What are the methods of prophylaxis against infection? a. Vaccination, b. Disinfection, c. General & personal hygiene. 3) Modes of disease transmission? 1- Air (Coughing and sneezing). 2- Direct contact (blood, saliva or semen). 3- Contaminated food, and water. 4- Contact with infected creatures (vector), 4) Is the virus living or non-living? Why? - They do not possess any of the characteristics of living organisms (except when found inside a host they Reproduce). Lesson 5 : Mitosis & cell cycle. Section 1: Define: 1. Chromatin: DNA is found in a mass of loose strands 2. Chromatid: When the chromatin coils around the protein. 3. Chromosome: 2 sister chromatids attached by a centromere. 4. Centromere: The structure that holds the 2 sister chromatids together. 5. Interphase: is the stage in the cell cycle during which the cell is not dividing. 6. Mitosis: the part of the cell cycle during which the nucleus divides. 7. Cytokinesis: is the division of the parent cell’s cytoplasm to form 2 new cells. Section 2: State the phase: Cytokinesis Anaphase 1. What phase are daughter cells in as a result of mitosis? 2. During what phase of mitosis do centromeres divide and the chromosomes move toward their Page 7 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. respective poles? Prophase 3. What is the phase where chromatin condenses to form chromosomes? Centromere Chromatid 4. What is the name of the structure that connects the two chromatids? 5. In a chromosome pair connected by a centromere, what is each individual chromosome called? Cytokinesis 6. When do cytoplasms divide ? Prophase I 7. When do crossing over occur ? Metaphase 8. Which phase of mitosis is the last phase that chromatids are together? Interphase 9. Which phase of the cell cycle is characterized by a non-dividing cell? Interphase 10. The period of cell growth and development between mitotic divisions? The diagram below shows size cells in various phases of the cell cycle. Note the cells are not arranged in the order in which the cell cycle occurs. ____________________1. Which cell is in metaphase? C ____________________2. Which cell is in the first phase of M phase (mitosis)? A ____________________3. In cell A, what structure is labeled X? Centriole ____________________4. List the diagrams in order from first to last in the cell cycle. DACEB ____________________5. Which cell is in anaphase? E Lesson 6: Meiosis Page 8 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. Section 1: Define: 1. Haploid: Cells with 1 set of chromosomes. 2. Diploid: Cells with 2 sets of chromosomes. 3. Sex chromosome: One chromosome pair which control the development of sexual characteristics. 4. Meiosis: the type of cell division that produces haploid sex cells such as sperm or egg cells. 5. Crossing over: The exchange of genetic material between the homologous chromosomes 6. Homologous chromosome: chromosomes are found in pairs of homologous chromosomes, which have the same structure and size and carry the same genes but different versions. 7. Fertilization: When sperm and ova join to form a zygote. B. State the phase: 1. Metaphase I : 2. Interphase : DNA replication occurs 3. Telophase II : daughter cells divide forming 4 haploid cells 4. Anaphase II : sister chromatids separate 5. Metaphase I : spindle fibers attach to centromeres of tetrads 6. Telophase I : two daughter cells are created 7. Metaphase I : chromosomes move to opposite poles 8. Metaphase I : homologous pairs separate. 9. Metaphase II : chromosomes line up in the middle of the cell. : centromere splits. 10. Anaphase II tetrads line up at the equator Section 2: Compare: Page 9 of 10 “Upon my honor I have neither given nor received aid with this work” Our mission is to empower our students to utilize their potentials in a diverse and challenging world. We provide outstanding education for the mind, spirit and body using state-of-the-art methodologies while fostering intercultural awareness, and lifelong learning. What happens in the cell? Anaphase I The homologous chromosomes separate from their partners and move to opposite ends. Anaphase II The sister chromatids separate from their partners and move to opposite ends. Centromere intact Centromere splits . Draw What happens in the cell? Draw Metaphase I The homologous chromosome pairs line up in the middle of the cell. Metaphase II The chromosomes line up in the middle of the cell. Section 3: Fill in the diagram 1. 2. 3. 4. 5. 6. 7. 8. Anaphase I Anaphase II Prophase I Metaphase I Metaphase II Telophase I Prophase II Telophase II & cytokinesis. Good-luck Page 10 of 10 “Upon my honor I have neither given nor received aid with this work”