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Part 2- The World of Biology Definition of biology: branch of science that studies life Examples of some things a biologist might study: 1. 2. 3. 4. 5. How living things work, interact with environment, change over time Microbiology- tiny things such as viruses and bacteria Zoology- animals Botany- plants Human biology Ways biology impacts our daily lives Health- nutrition, disease, taking care of ourselves Animals, plants, other organisms in our environment Bacteria- they’re everywhere!! Awww…our pets! Ways biology impacts human society Environmental concerns Medical improvements Gene Technology- genetic engineering, DNA testing, reproductive technologies Food/water supplies for our ever-increasing world population Living things share several characteristics, which include the following 1. 2. 3. 4. 5. 6. 7. 8. Organization and cells Genetic code Respond to stimuli Maintain homeostasis Metabolism Growth and development Reproduction As a population, change over time Organization is the high degree of order within an organism and with its interactions with its environment. All living organisms, whether made up of one cell or many cells, have some degree of organization. Definition of cell: collection of living matter enclosed by a barrier- smallest unit of an organism that can be considered alive Unicellular organisms: organisms made of only one cell (ex.- bacteria) Multicellular organisms: organisms made of many cells (ex.- plant, cow, human) Flow chart of organization in complex multicellular organisms All organisms have a genetic code. You’ve probably noticed that offspring resemble their parents in certain ways. Explaining how organisms inherit traits is one of the greatest achievements of modern biology! We now know that the directions for inheritance are carried by a molecule called DNA. With minor exceptions, the DNA genetic code determines the inherited traits of every organism on Earth! It’s an amazing little molecule!! All organisms have the ability to respond to various stimuli (singular form: stimulus) in their environment. Definition of stimulus: physical or chemical change in an organism’s internal or external environment Examples of stimuli and responses by organisms: Owl dilates pupils as light goes down Person eats when she feels hungry Dog barks when doorbell rings Plant stem and leaves grow towards light Definition of homeostasis: The process by which organisms keep their internal conditions relatively stable Examples of ways that organisms maintain homeostasis: Plant taking in and giving off water Bird maintaining constant body temperature The condition of homeostasis is constantly being threatened by changes in the environment such as shifting temperatures and changing light. If homeostasis is disrupted in a major way, what will happen to an organism? it will die Definition of metabolism: the combination of chemical reactions through which an organism builds up or breaks down materials as it carries out life processes Examples of chemical reactions that are part of the metabolisms of organisms: Photosynthesis of plants Breaking down of food by animals All living things grow, or increase in size. What causes living things to grow? Changes an organism goes through during its life cycle- involves cell division and cell specialization (turning into different kinds of cells) Although individual organisms experience many changes during their lifetimes, their basic genetic characteristics do not change. However, populations of living organisms evolve, or change over long periods of time. The ability of populations of organisms to change over time is important for survival in a changing world. It is also an important factor in explaining the great diversity of life-forms we see on Earth today.