The Characteristics of Life-1st draft.pdf

The Characteristics of Life NTK definitions Biology: the study of life Life- an organism that shows metabolism and continuity of life Continuity of life: all living things arise from other living things of the same type* Ecology: study of living things and how they interact with their environ...

The Characteristics of Life NTK definitions Biology: the study of life Life- an organism that shows metabolism and continuity of life Continuity of life: all living things arise from other living things of the same type* Ecology: study of living things and how they interact with their environment Continuity of life describes how living organisms arise from living organisms of the same type. Other branches of biology include: microbiology: study of microorganisms (ADD IN MORE DEFINITIONS HERE FROM BIOLOGY FOLDER) 1 Life Is a state that differentiates plants, animals, and microorganisms from inorganic matter, such as rocks and water. Life includes the capacity for1. 2. 3. 4. Growth Reproduction Functional activity Continual change Due to the varied and complex nature of the organisms that we deem to be ‘alive’, a one-sentence definition of life that covers all of them is not possible. There are a certain number of features and behaviours that all living things have in common. Non-living things may have one or two of these features, but only living things have all of them. Characteristics of Life-refers to the common features shared by living organisms. **need to know 5 characteristics and be able to describe them** These include the following: 1. Organisation - Living things are composed of cells, tissues,organs and organ systems. 2. Nutrition - The way in which living things obtain and utilize food 3. Excretion -Removal of waste products of metabolism. 4. Response -The reaction of organisms to stimuli in their environment. 5. Reproduction -The production of new individuals. 2 Organisation - The ordered way in which living things are arranged structurally. All living things are made of cells. Some consist of one cell (unicellular) e.g., bacteria and amoeba, others multicellular e.g., humans. All organisms carry out their activities in cells. This gives a structured plan to improve efficiency and increase the chances of survival. (1) Molecules Organelles Cells Tissues Organs Organ Systems Organisms Populations Groups of Atoms that are chemically joined. For example, DNA, Water, Glucose Very large groups of different molecules which carry out functions. For example, nuclei, mitochondria, ribosomes, chloroplasts Basic Unit of living things. Consist of Organelles suspended in a fluid called cytosol surrounded by a cell membrane. Groups of similar cells working together to carry out a function. For example, muscles, nerves, and connective tissue in animals. Xylem, phloem, and mesophyll in plants. Groups of different tissues working together to carry out a function. For example, lungs, skin, and heart in animals. Root, stem, leaf, and flower in plants. A group of organs that work together to carry out a function. Circulatory system and Nervous system. Individual living entities ranging in complexity from unicellular examples such as bacteria and algae to complex flowering plants and mammals. Groups of individuals of the same species living together and interacting with each other and the environment. 3 Communities Ecosystems Biosphere Groups of different species interacting with each other in an ecosystem. Plants, animals, and microorganisms interacting with each other and their environment. All the parts of the earth where life exists. For example, air, water, land and underground. Nutrition - Nutrition is the way organisms obtain and use food. Food is needed as a source of materials and energy. Plants and some bacteria are autotrophic i.e., they make their own food. Animals, fungi, and most bacteria are heterotrophic i.e., they must consume food which is made by plants. Modes of Nutrition Autotrophs: Make their own food e.g plants via photosynthesis, some bacteria are chemosynthetic (energy released by chemical reactions Heterotrophs: cannot make their own food, feeds on organic matter produced by or available in other organisms e.g. humans, some bacteria, fungi (2) Excretion - Excretion is the removal of waste products of metabolism e.g., urea and carbon dioxide from the body. These waste products can become toxic to the cell if allowed to accumulate. The organism tries to maintain a constant internal environment (homeostasis). Plants have less need for excretion 4 because they make their own food and do not produce or take in as much waste (stomata used for waste gases). Advanced animals transfer waste internally from cells to blood to excretory organs e.g., lungs, skin, urinary system. The Liver breaks down toxic material. Metabolism is the sum of all the chemical reactions in an organism. There are two types of metabolism: 1. Catabolic – Reactions that involve the breakdown of large substances to smaller ones, e.g., digestion and respiration. 2. Anabolic- Reactions that involve smaller molecules being used to make larger molecules e.g., photosynthesis, synthesis of proteins and DNA, the use of illegal anabolic steroids to build up muscle and bone. Responsiveness - The reaction of organisms to stimuli in their environment. Animals use their muscles and glands to respond to stimuli such as light, temperature., pressure, and sound (5 senses). Animals tend to move to find food mainly and to avoid danger. Movement in plants is not so obvious. Plants show growth tropisms e.g., respond to light (e.g., stem bends towards light), water, gravity, chemicals, temperature, and touch. (3) Reproduction – The ability of an organism to make new organisms of the same type. There are two types of reproduction; a. Sexual Reproduction – Involves the production and fusion of gametes, one of 5 which is often referred to as male, while the other is referred to as female. It is the preferred method of reproduction in advanced organisms and leads to variation, which allows evolution. b. Asexual Reproduction – The most common in primitive organisms such as bacteria and amoebae. It only involves one parent, and it produces offspring that are identical to the parent. Some advanced organisms use both sexual and asexual reproduction. These are mainly plants, but starfish, bees and greenfly reproduce using both forms, depending on circumstances. References 6 123rf.com Wikipedia.com Sarthaks.com 7