Biology O level edexcel part 1
describe the common features shown by prokaryotic organisms
Biology O level edexcel part 1
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(a) CHARACTERISTICS OF LIVING ORGANISMS:1.1 understand how living organisms share the following characteristics: • they require nutrition • they respire • they excrete their waste • they respond to their surroundings • they move • they control their internal conditions • they reproduce • they grow and develop.
(b) VARIETY OF LIVING ORGANISMS:1.2 describe the common features shown by eukaryotic organisms: plants, animals, fungi and protoctists Plants: these are multicellular organisms; their cells contain chloroplasts and are able to carry out photosynthesis; their cells have cellulose cell walls; they store carbohydrates as starch or sucrose. Examples include flowering plants, such as a cereal (for example, maize), and a herbaceous legume (for example, peas or beans). Animals: these are multicellular organisms; their cells do not contain chloroplasts and are not able to carry out photosynthesis; they have no cell walls; they usually have nervous co- ordination and are able to move from one place to another; they often store carbohydrate as glycogen. Examples include mammals (for example, humans) and insects (for example, housefly and mosquito). Fungi: these are organisms that are not able to carry out photosynthesis; their body is usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei; some examples are single-celled; their cells have walls made of chitin; they feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products; this is known as saprotrophic nutrition; they may store carbohydrate as glycogen. Examples include Mucor, which has the typical fungal hyphal structure, and yeast, which is single-celled. Protoctists: these are microscopic single-celled organisms. Some, like Amoeba, that live in pond water, have features like an animal cell, while others, like Chlorella, have chloroplasts and are more like plants. A pathogenic example is Plasmodium, responsible for causing malaria.
(b) VARIETY OF LIVING ORGANISMS:1.3 describe the common features shown by prokaryotic organisms such as bacteria Bacteria: these are microscopic single-celled organisms; they have a cell wall, cell membrane, cytoplasm and plasmids; they lack a nucleus but contain a circular chromosome of DNA; some bacteria can carry out photosynthesis but most feed off other living or dead organisms. Examples include Lactobacillus bulgaricus, a rod-shaped bacterium used in the production of yoghurt from milk, and Pneumococcus, a spherical bacterium that acts as the pathogen causing pneumonia.
(b) VARIETY OF LIVING ORGANISMS:1.4 understand the term pathogen and know that pathogens may include fungi, bacteria, protoctists or viruses Viruses: these are not living organisms. They are small particles, smaller than bacteria; they are parasitic and can reproduce only inside living cells; they infect every type of living organism. They have a wide variety of shapes and sizes; they have no cellular structure but have a protein coat and contain one type of nucleic acid, either DNA or RNA. Examples include the tobacco mosaic virus that causes discolouring of the leaves of tobacco plants by preventing the formation of chloroplasts, the influenza virus that causes ‘flu’ and the HIV virus that causes AIDS.
(c) BIOLOGICAL MOLECULES:2.8 describe the structure of carbohydrates, proteins and lipids as large molecules made up from smaller basic units: starch and glycogen from simple sugars, protein from amino acids, and lipid from fatty acids and glycerol
(c) BIOLOGICAL MOLECULES:2.12 practical: investigate how enzyme activity can be affected by changes in temperature
(c) BIOLOGICAL MOLECULES:2.13 understand how enzyme function can be affected by changes in pH altering the active site
(c) BIOLOGICAL MOLECULES:2.14B practical: investigate how enzyme activity can be affected by changes in pH
(c) BIOLOGICAL MOLECULES:End Of Unit Exercise.
(d) Movement of substances into and out of cells:2.15 understand the processes of diffusion, osmosis and active transport by which substances move into and out of cells
(d) Movement of substances into and out of cells:2.16 understand how factors affect the rate of movement of substances into and out of cells, including the effects of surface area to volume ratio, distance, temperature and concentration gradient
(d) Movement of substances into and out of cells:2.17 practical: investigate diffusion and osmosis using living and non-living systems
(d) Movement of substances into and out of cells: End Of Unit Exercise.
(e)NUTRITION: Flowering plants:2.18 understand the process of photosynthesis and its importance in the conversion of light energy to chemical energy
(e)NUTRITION:Flowering plants:2.19 know the word equation and the balanced chemical symbol equation for photosynthesis
(e)NUTRITION:Flowering plants:2.20 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis
(e)NUTRITION:Flowering plants:2.21 describe the structure of the leaf and explain how it is adapted for photosynthesis
(e)NUTRITION:Flowering plants:2.22 understand that plants require mineral ions for growth, and that magnesium ions are needed for chlorophyll and nitrate ions are needed for amino acids
(e)NUTRITION:Flowering plants:2.23 practical: investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll
(e)NUTRITION: Humans:2.24 understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre
(e)NUTRITION:Humans:2.25 identify the sources and describe the functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and dietary fibre as components of the diet
(e)NUTRITION:Humans:2.26 understand how energy requirements vary with activity levels, age and pregnancy
(e)NUTRITION:Humans:2.27 describe the structure and function of the human alimentary canal, including the mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum) and pancreas
(e)NUTRITION:Humans:2.28 understand how food is moved through the gut by peristalsis
(e)NUTRITION:Humans:2.29 understand the role of digestive enzymes, including the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases
(e)NUTRITION:Humans:2.30 understand that bile is produced by the liver and stored in the gall bladder
(e)NUTRITION:Humans:2.31 understand the role of bile in neutralising stomach acid and emulsifying lipids
(e)NUTRITION:Humans:2.32 understand how the small intestine is adapted for absorption, including the structure of a villus
(e)NUTRITION:Humans:2.33B practical: investigate the energy content in a food sample
(e)NUTRITION:End Of Unit Exercise.
(f) Respiration:2.34 understand how the process of respiration produces ATP in living organisms
(f) Respiration:2.35 know that ATP provides energy for cells
(f) Respiration:2.36 describe the differences between aerobic and anaerobic respiration
(g) Gas exchange: Flowering plants:2.42B understand how the structure of the leaf is adapted for gas exchange
(g) Gas exchange: Flowering plants:2.43B describe the role of stomata in gas exchange
(g) Gas exchange: Flowering plants:2.44B understand how respiration continues during the day and night, but that the net exchange of carbon dioxide and oxygen depends on the intensity of light
(g) Gas exchange: Flowering plants:2.45B practical: investigate the effect of light on net gas exchange from a leaf, using hydrogen- carbonate indicator
(g) Gas exchange: Humans:2.46 describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes
(g) Gas exchange: Humans:2.47 understand the role of the intercostal muscles and the diaphragm in ventilation
(g) Gas exchange: Humans:2.49 understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart disease