Year 9 Science Independent Learning Revision - AQA GCSE Biology PDF

# Year 9 Science Independent Learning Revision | Homework | Set | Due wb | Task | |---|---|---|---| | 1 | 18th Nov | 25th Nov | Choose one of the activities and revise Cell Structure. | | 2 | 25th Nov | 2nd Dec | Choose one of the activities and revise Cell division, Stem cells and Microscopy. | |...

# Year 9 Science Independent Learning Revision | Homework | Set | Due wb | Task | |---|---|---|---| | 1 | 18th Nov | 25th Nov | Choose one of the activities and revise Cell Structure. | | 2 | 25th Nov | 2nd Dec | Choose one of the activities and revise Cell division, Stem cells and Microscopy. | | 3 | 2nd Dec | 9th Dec | Choose one of the activities and revise Atoms, elements and compounds. | | 4 | 9th Dec | 16th Dec | Choose one of the activities and revise Scientific models of the atom and the Plum Pudding model. | | 5 | 16th Dec | 7th Jan | Choose one of the activities and revise Energy stores and changes. | You can use quiz questions to make mind maps, flash cards or just make question and answer cards. Use the knowledge organiser and checklist to make Cornell notes or to look for answers. Please also remember to check Seneca Learning for revision tasks to complete for the assessments. # AP1 Year 9 AQA GCSE Science (BIOLOGY) ## Topic 1: Cell Biology ### 4.1.1 Cell Structure #### 4.1.1.1 Eukaryotes and Prokaryotes Plant and animal cells (eukaryotic cells) have a cell membrane, cytoplasm and genetic material enclosed in a nucleus. Bacterial cells (prokaryotic cells) are much smaller in comparison. They have cytoplasm and a cell membrane surrounded by a cell wall. The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids. Students should be able to: * Demonstrate an understanding of the scale and size of cells and be able to make order of magnitude calculations, including the use of standard form. * Use prefixes centi, milli, micro and nano. #### 4.1.1.2 Animal and Plant Cells Most animal cells have the following parts: * a nucleus, which controls the activities of the cell * cytoplasm, in which most of the chemical reactions take place * a cell membrane, which controls the passage of substances into and out of the cell * mitochondria, which is where aerobic respiration takes place * ribosomes, which are where protein synthesis occurs. In addition to the parts found in animal cells, plant cells often have: * chloroplasts, which absorb light to make food by photosynthesis * a permanent vacuole filled with cell sap. Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell. Students should be able to: * Explain how the main sub-cellular structures, including the nucleus, cell membranes, mitochondria, chloroplasts in plant cells and plasmids in bacterial cells are related to their functions. * Use estimations and explain what they should be used to judge the relative size or area of subcellular structures. * Recognise, draw and interpret images of cells. **REQUIRED PRACTICAL - Microscopy. AT 1 & 7** #### 4.1.1.3 Cell Specialisation Cells may be specialised to carry out a particular function: * Animals: sperm cells, nerve cells and muscle cells * Plants: root hair cells, xylem and phloem cells Students should be able to, when provided with appropriate information: * Explain how the structure of different types of cell relate to their function in a tissue, an organ or organ system, or the whole organism. #### 4.1.1.4 Cell Differentiation As an organism develops, cells differentiate to form different types of cells. * Most types of animal cell differentiate at an early stage. * Many types of plant cells retain the ability to differentiate throughout life. In mature animals, cell division is mainly restricted to repair and replacement. As a cell differentiates it acquires different sub-cellular structures to enable it to carry out a certain function. It has become a specialised cell. Students should be able to: * Explain the importance of cell differentiation. #### 4.1.1.5 Microscopy An electron microscope has much higher magnification and resolving power than a light microscope. This means that it can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures. Students should be able to: * Understand how microscopy techniques have developed over time. * Explain how electron microscopy has increased understanding of sub-cellular structures. Limited to the differences in magnification and resolution. * Carry out calculations involving magnification, real size and image size using the formula: $magnification = \frac{size\ of\ image}{size\ of\ real\ object}$ * Express answers in standard form if appropriate. * Use prefixes centi, milli, micro and nano. ### 4.1.2 Cell Division #### 4.1.2.1 Chromosomes The nucleus of a cell contains chromosomes made of DNA molecules. Each chromosome carries a large number of genes. In body cells the chromosomes are normally found in pairs. #### 4.1.2.2 Mitosis and the Cell Cycle Cells divide in a series of stages called the cell cycle. Students should be able to describe the stages of the cell cycle, including mitosis. During the cell cycle the genetic material is doubled and then divided into two identical cells. Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome. In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides. Finally, the cytoplasm and cell membranes divide to form two identical cells. Cell division by mitosis is important in the growth and development of multicellular organisms. Students should: * Understand the three overall stages of the cell cycle but do not need to know the different phases of the mitosis stage. * Be able to recognise and describe situations in given contexts where mitosis is occurring. #### 4.1.2.3 Stem Cells A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation. Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells. Stem cells from adult bone marrow can form many types of cells including blood cells. Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant. **Treatment with stem cells may be able to help conditions such as diabetes and paralysis.** In therapeutic cloning an embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient's body so they may be used for medical treatment. The use of stem cells has potential risks such as transfer of viral infection, and some people have ethical or religious objections. Stem cells from meristems in plants can be used to produce clones of plants quickly and economically. * Rare species can be cloned to protect from extinction. * Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers. Students should be able to: * Describe the function of stem cells in embryos, in adult animals and in the meristems in plants. * Evaluate the practical risks and benefits, as well as social and ethical issues, of the use of stem cells in medical research and treatments.