Characteristics of Living Organisms

• The 'M' in MRS C GREN stands for movement
• The 'N' in MRS C GREN stands for nutrition
• The 'E' in MRS C GREN stands for excretion
• The 'G' in MRS C GREN stands for growth
• The second 'R' in MRS C GREN stands for reproduction
• The first 'R' in MRS C GREN stands for respiration
• The 'S' in MRS C GREN stands for sensitivity
• The 'C' in MRS C GREN stands for control
• If something does not carry out all of the life processes in MRS C GREN, it is either dead or non-living
• Viruses are non-living particles
• Organisms must obtain food to provide energy. Energy is necessary to carry out life processes (e.g. movement, respiration and excretion)
• • Plants use sunlight, carbon dioxide and water to produce oxygen and glucose in the process of photosynthesis
• Because plants create their own food for energy, they are described as being autotrophic
• Animals consume other living organisms in order to obtain the energy they require. They break down larger complex molecules into simpler molecules through the process of digestion
• As animals obtain their food from a range of different sources, they are described as being heterotrophic
• Respiration is a chemical reaction carried out in all living organisms
• During the process of respiration, energy is released from glucose either in the presence of oxygen (aerobic respiration) or the absence of oxygen (anaerobic respiration)
• During respiration, energy is transferred in the form of ATP
• Chemical reactions that take place inside living cells are described as metabolic reactions
• Excretion is the removal of toxic materials and substances from organisms
• Metabolic reactions produce waste products, some of which may be toxic
• An example of a waste product excreted by animals is carbon dioxide from respiration
• An example of a waste product excreted by animals is water from respiration and other chemical reactions
• An example of a waste product excreted by animals is urea which contains nitrogen resulting from the breakdown of proteins
• An example of a waste product excreted by plants is oxygen from photosynthesis
• An example of a waste product excreted by plants is carbon dioxide from respiration
• An example of a waste product excreted by plants is water from respiration and other chemical reactions
• In plants, water vapour is excreted through transpiration
• In plants, carbon dioxide is excreted at night when the rate of respiration exceeds the rate of photosynthesis
• In plants, oxygen is excreted during the day when the rate of photosynthesis exceeds the rate of respiration
• • The sensitivity of an organism refers to its ability to detect and respond to stimuli in its surroundings
• • In humans, the nervous system provides a complex system of receptors, neurones and effectors which detect and respond to different stimuli using electrical impulses
• In humans, the endocrine system also allows a response to stimuli using chemical messengers, which travel in the blood, called hormones
• In animals, responding to the environment around them gives an organism the best chances of survival
• In plants, responses are controlled by chemicals and are usually much slower
• Geotropism describes a plants response to gravity which causes the roots to grow down into the soil
• • Phototropism describes a plant's response to light which causes shoots to grow towards sunlight
• Movement is an action by an organism causing a change of position or place
• The movement of an organism from place to place is called locomotion
• Living organisms control their internal environment in order to keep conditions within required limits. This is called homeostasis