biology 1-4

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chapter summaries of the science junior cert higher level course

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1. Living things Biology is the study of living things (organisms)Living things have seven characteristics. Nutrition Respiration Excretion Growth Reproduction Movement Response Three main differences between animals and plants: Animals move from place to place but plants do not. Animals take in food but plants make their own food. Animal cells do not have a cell wall but plant cells do have a cell wall. Invertebrates are animals that do not have backbones. Vertebrates are animals that have a backbone. Living things can be identified and named using keys.

2. Cells and the microscope The main parts in animal cells are: The cell membrane The nucleus Cytoplasm Plant cells have the three features listed above but also have a cell wall. Cell division is the basis for the growth of an organism. Organisms are arranged into: cells tissues organs systems A microscope is used to view small objects in detail. Eyepiece lens: enlarges the image of the object Focus knobs: allow a clear, sharp image to be seen Nosepiece; rotates so that different lenses can be used Objective lens: located on the nosepiece, it enlarges the image of the object Stage: the slide is placed on the stage for viewing MIrror; used to shine a light source through the slide The total magnification is calculated by multiplying the power of the eyepiece lens by the power of the objective lens being used.

3.Food Food is needed for energy, growth, repair and to prevent diseases. A balanced diet consists of the right amounts of carbohydrates (including fibre), fats, proteins and vitamins, minerals and water. The main functions of the major food constituents are: Carbohydrates give energy Fibre helps to move food through the intestines Fat stores energy and insulates Proteins make and repair body parts Vitamin C keeps skin and gums healthy; vitamin D helps to form strong bones Minerals such as iron form red blood cells; calcium forms healthy bones Water allows cells to function properly A food pyramid suggests the daily number of servings of each of the five food groups. Fats have twice the energy value of carbohydrates or proteins. Starch is tested using iodine solution. Reducing sugars are tested using Benedict's solution. Fats are tested using brown paper. Proteins are tested using the Biuret solution (sodium hydroxide and copper sulfate).

4.Digestion and enzymes Digestion is the breaking down of food. Physical digestion is the breakdown of food by mechanical means Chemical digestion is the breakdown of food by enzymes. The functions of the main parts of the digestive system are: The mouth carries out physical digestion and chemical digestion The oesophagus moves food to the stomach The stomach has acid which softens the food and kills bacteria The liver makes bile which breaks down fats The pancreas makes enzymes which digest food The fist part of the small intestine completes the breakdown The second part of the small intestine allows the food to be absorbed from the intestine into the bloodstream The large intestine takes water back into the bloodstream The functions of the four types of teeth are as follows; Incisors cut and slice food Canines grip and tear food Premolars chew, crush and grind food Molars also chew, crush and grind food Enzymes are proteins which speed up chemical reactions in the body without the enzymes being used up. The substance produced by an enzyme is called the product The substance the enzyme acts on is called the substrate The enzyme amylase acts on starch to produce a simple or reducing sugar called maltose

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