Characteristics of Living Thing Grade 7th – Chapter 1 By the end of this topic you should be able to • comprehend the common features of living thing as the basic differences living thing, non living thing and once living • identify the vital functions characteristic of all living thing Characteristics of Living Thing Mnemonic MRS GREN-A • M: Movement • R: Respiration • S: Sensitivity • G: Growth • R: Reproduction • E: Excretion • N: Nutrition • A: Adaptation Movement • Movement: An action by an organism or part of an organism causing a change of position or place. Movement in Plants vs in Animals Movement Plant Animal Only the body parts move. Entire body of the organism moves from one place to another. Movement Movement and Locomotion Part movement in plants is as a result of growth as a response to various stimuli. It is a reaction to the external/ environmental stimuli and it may involve part of the organism or the entire organism Respiration • Respiration: The chemical reactions in cells that break down nutrient molecules and release energy for metabolism. • Respiration is the burning of food (glucose) to release energy 2 Type of Respiration • Aerobic Respiration • An-erobic Respiration • Aerobic respiration uses oxygen to release energy from food • An-aerobic respiration does not use oxygen to release energy from food Aerobic Respiration • The oxygen needed for aerobic respiration comes from the environment • Aerobic respiration produces carbon dioxide, which is removed when we breathe out. This exchange of gases is called gaseous exchange • There are different organs for this: 1. Human =>? 2. Fish =>? 3. Frog =>? Sensitivity • Sensitivity: The ability to detect or sense stimuli in the internal or external environment and to make appropriate responses • Organisms can identify stimuli in their surroundings and respond to them. Sensitivity Growth and Development • Growth: A permanent increase in size and dry mass by an increase in cell number or cell size or both Reproduction • Reproduction: The processes that make more of the same type of organism • All living organisms eventually die. • They avoid becoming extinct by producing copies of themselves. • Offspring have the same characteristics as parents. Sexual vs Asexual Excretion • Excretion: Removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials, and substances in excess of requirements • Example of substances: • Carbon dioxide • Water (Sweat or Vapour) • Urine These are not excretion • Egestion => the removal of undigested food from the body. Since this food has not taken part in any chemical reaction, it is not considered as part of excretion. • Secretion => the release of useful substances produced by cells or glands into or out of the body. E.g. tears are secreted under the eyelid. Tears are not a harmful substance, and not a waste product. Nutrition • Nutrition: Taking in of materials for energy, growth and development. • Plants require light, carbon dioxide, water and ions; • Animals need organic compounds and ions and usually need water Adaptation • Adaptation: adjustment of organisms to their environment in order to improve their chances at survival in that environment.
