Biology The Characteristics of Life What is Biology
Biology & The Characteristics of Life
What is Biology? Biology – the study of life Bio- means life, and -logy means the study of
Characteristics of Life
Organisman individual living thing Ex. a bacterium, tree, frog, or human
All living things share several unifying characteristics.
1. Living things are based on a universal genetic code. All living things store the complex information to live grow and reproduce in a molecule called DNA.
2. Living things are made of cells—the smallest working cells unit of living things
Unicellular and Multicellular organisms Unicellular Organism- a single cell carries out all of life’s functions Ex> bacteria Multicellular Organism- trillions of cells can be working together to carry out life functions, each having specialized functions within the organism
3. Living things grow & develop organisms absorb raw materials and process them into new tissues and structures
Single celled organisms grow larger, while multicellular organisms grow by their cells dividing over and over.
4. Living things obtain & use energy
Our ultimate energy source
Obtaining and using energy For example, leaves obtain energy from the sun, gases from the air, and water from the ground. These materials then take part in various chemical reactions within the leaves. Animals then ingest organisms like plants or other animals who have already consumed plants themselves.
Metabolism – a set of chemical reactions that occur in living organisms in order to maintain life. Our life requires matter that provides raw material, nutrients, and energy.
5. Living things respond to their environment stimulus—anything stimulus detected in an organism’s environment that causes it to react Ex. light, odor, sound, heat
Responses to stimuli Some responses are behavioral, such as a rabbit running from a predator or a plant moving its leaves to face incoming sunlight. Other examples can include a plant producing a poisonous chemical to ward off insects from eating its leaves. Plants and animals can detect changes such as light, temperature, and even gravity.
Maintaining a balance Organisms and their cells function best at certain temperatures, p. H levels, solute concentrations, etc. They must maintain these levels from becoming too high or low. Ex>Your body regulates the amount of glucose and water in it, as well as the temperature and p. H level of your blood
Homeostasisthe body’s ability to regulate its internal physiology to maintain stability in response to fluctuations in the outside environment
Homeostasis Our bodies rely on a cycle of monitoring and responding to internal conditions called a negative feedback loop, similar to the way a thermostat operates in a home. It is called a negative feedback loop because any change to the system seen as a negative causes the system to return to its original state.
Homeostasis in your body In low light environments, your pupils dilate and allow more light to pass into the eye. This is the body’s response to a stimulus, low light, to maintain constant light levels in the eye.
Thermoregulation – maintaining a stable body temperature. The hypothalamus is part of the brain that regulates many of the body’s internal states, such as temperature. It senses temperature of blood passing through it and can cause: Shivering and/or constriction of capillaries to conserve heat (warming) Perspiration (sweat evaporating and carrying heat away from the body) and /or dilation of capillaries to release heat (cooling)
Thermoregulation Warm blooded animals have a body temperature independent of the external environment. Other organisms, such as reptiles and amphibians, are cold blooded, meaning they rely on the environment to regulate their body temperature.
Warm vs. cold blooded
Warm blooded animals -convert food into energy and generate heat -must eat a lot of food to maintain a constant temperature -only a small amount of food’s energy is used for increases in body mass; most is used to maintain the constant body temperature
Warm vs. cold blooded
Cold blooded animals -much more active in warm environments and are sluggish in cold environments because muscle activity depends on chemical reactions that are temperature dependent -convert much more of their food into body mass compared to a warm-blooded animal
Osmoregulation – maintaining the balance of water and solutes (dissolved molecules and ions) in an organism.
Kidney Function
6. Living things have the ability to reproduce
Reproduction biological process by which new individual organisms are produced -every individual exists as a result of reproduction
Sexual Reproduction In sexual reproduction, offspring are produced by the fusion of two sex cells – one from each of two parents. The offspring produced inherit some genetic information from both parents. Most animals and plants and many single-celled organisms reproduce sexually.
Asexual Reproduction Asexual reproduction - reproduction that involves a single parent producing an offspring. The offspring produced are, in most cases, identical to the single cell that produced them. a simple, efficient, and effective way to produce a large number of offspring cells such as your blood cells, singlecelled organisms such as a bacteria, and even some multicellular organisms can reproduce asexually
Examples of Asexual Reproduction Bacteria reproduce by binary fission Kalanchoe plants form plantlets. Hydras reproduce by budding
Asexual reproduction
Asexual Reproduction In multicellular organisms, cell division is an example of asexual reproduction that leads to growth and also enables repair and maintaining of its body.
Comparing Sexual and Asexual Reproduction
7. Living things evolve
Evolution Over generations, groups of organisms evolve, or change over time. Evolutionary change links all forms of life to a common origin more than 3. 5 billion years ago.
Evolution Evidence of this shared history is found in all aspects of living and fossil organisms, from physical features to structures of proteins to sequences of information in DNA.
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