Essay on Neil: Blood and Appropriate Information

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AQA IGCSE Biology : Biology for You : Mapping Doc Yr 10 TA

AQA IGCSE Biology specification | Page numbers in Biology for You | The page numbers shown in the right-hand column refer to the Biology for You Students’ Book (ISBN 978-1-4085-0920-3).In addition there are many printable Help & Extension Sheets in the Kerboodle Book (ISBN 978-1-4085-0917-3). | Red italic numbers indicate support within the Kerboodle Book | 1 Cell activity | | 1.1 Cell structure | a) 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 most energy is released in respiration ribosomes, which is where protein synthesis occurs.Most human cells are like most other animal cells. | 6-9,8-9 | | b) * In addition to the above, plant cells often have: chloroplasts, which absorb light energy to make food * a permanent vacuole filled with cell sap.Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell | 7,9,9 | | c)A bacterial cell consists of cytoplasm and a membrane surrounded by a cell wall; the genes are not in a distinct nucleus; some of the genes are located in circular structures called plasmids. | 139 | | d)Yeast is a single-celled organism. Yeast cells have a nucleus, cytoplasm and a membrane surrounded by a cell wall. | 73,215,351 | | e)Cells may be specialised to carry out a particular function.Candidates should be able, when provided with appropriate information, to relate the structure of different types of cell to their function in a tissue, an organ, or the whole organism. | 10,13,10 | 1.2 The movement of substances into and out of cells | a)Diffusion is the spreading of the particles of any substance in solution, or particles of a gas, resulting in a net movement from a region where they are of a higher concentration to a region with a lower concentration. The greater the difference in concentration, the faster the rate of diffusion. | 17,17 | | b)Dissolved substances can move into and out of cells by diffusion. | 17 | | c)Oxygen required for respiration passes through cell membranes by diffusion. | 17,70 | | d)Osmosis is the diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules. | 18 | | e)Differences in the concentrations of the solutions inside and outside a cell cause water to move into or out of the cell by osmosis.Candidates should be familiar with the terms isotonic, hypotonic, hypertonic, turgor and plasmolysis | 18-21,18-20 | | f)Substances are sometimes absorbed against a concentration gradient. This requires the use of energy from respiration. The process is called active transport. | 23 | | g)Active transport enables plants to absorb ions from very dilute solutions, eg by root hair cells. Similarly, sugar may be absorbed from low concentrations in the intestine and from low concentrations in the kidney tubules. | 23 | | h)A single-celled organism has a relatively large surface area to volume ratio. All the necessary exchanges occur via its surface membrane.The size and complexity of an organism increase the difficulty of exchanging materials | 11-12 | | i)In multicellular organisms many organ systems are specialised for exchanging materials. The effectiveness of an exchange surface is increased by: having a large surface area that is thin, to provide a short diffusion path (in animals) having an efficient blood supply (in animals, for gaseous exchange) being ventilated.Candidates should be able to explain how the small intestine and lungs in mammals, and the roots and leaves in plants, are adapted for exchanging materials. | 13-14,58,70,190,20458,70,190,204 | | j)Gas and solute exchange surfaces in humans and