SCIENCE GATEWAY Biological Systems and Life Processes REVIEW AND PRACTICE BIOLOGY

What does it mean to be alive? Life What does it mean to be alive?

Biological Systems Homeostasis

ENERGY/MATTER TRANSFORMATIONS RESPIRATION AND PHOTOSYNTHESIS

RESPIRATION Process by which plants and animals obtain energy from foods Organisms break down food into smaller molecules, which combine with oxygen Energy stored in sugars (glucose) is released as ATP

RESPIRATION Process occurs in two phases: Glycolosis: breakdown of glucose into pyruvic acid Occurs in cytoplasm in eukaryotes Oxidation of pyruvic acid to carbon dioxide and water Occurs in mitochondria

RESPIRATION After the breakdown of glucose, waste products, such as CO2 and water, leave through cell membrane

RESPIRATION Chemical reactions produce the nucleotide, ATP ATP stores energy Energy is released from ATP when needed ATP is used for all the energy-consuming activities of the cell

RESPIRATION

OVERALL REACTION Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy Glucose Oxygen Carbon Dioxide Water Similar to combustion reaction (burning)

PHOTOSYNTHESIS 6CO2 + 6H2O + energy → C6H12O6 + 6O2 Uses CO2 and water Releases oxygen as waste Process of producing food in plants Chloroplasts (cells) use energy from the sun to produce glucose

PHOTOSYNTHESIS Light Reaction Chlorophyll traps the energy available in sunlight ATP is produced ATP stores energy for cell processes Water is split into hydrogen and oxygen Some oxygen is used in respiration A great deal of oxygen is released to the environment

Dark Reaction CO2 and other chemicals combine to form glucose, using energy from ATP Some of the glucose produced is used in respiration Some glucose is used for growth Excess glucose is stored in roots, stems and leaves of plants

RELATIONSHIP BETWEEN PHOTOSYNTHESIS AND RESPIRATION ALL plants and animals carry on respiration Uses oxygen Releases water and CO2 Photosynthesis Plants with chlorophyll carry on photosynthesis Produces oxygen Uses water and CO2

LIFE FUNCTIONS

BASIC LIFE FUNCTIONS All living organisms need to perform certain functions to remain alive Living organisms contain systems designed to carry out these essential functions

BASIC LIFE FUNCTIONS Six basic functions: D Digestion R Respiration R Reproduction R Response E Excretion G Growth

BASIC LIFE FUNCTIONS DIGESTION The process of changing food into a usable form to provide energy

BASIC LIFE FUNCTIONS RESPIRATION The process of using food Breaking down stored food and combining it with oxygen to provide energy The exchange of gases to produce food and energy

BASIC LIFE FUNCTIONS REPRODUCTION The process by which new organisms (offspring) are produced

BASIC LIFE FUNCTIONS RESPONSE How organisms react to changes in their surroundings

BASIC LIFE FUNCTIONS EXCRETION The process by which the body gets rid of liquid waste The lungs, kidneys, and skin function to excrete waste produces created by the body

BASIC LIFE FUNCTIONS GROWTH The repair and production of new and larger cells within a living organism

TO BE LIVING An organism must perform all life functions to be considered living However, these life functions may be carried out in different ways

BACTERIA Prokaryotic organisms Single-celled organisms that lack a nucleus Identified by shape, type of cell wall, movement, and the ways in which they obtain energy Most reproduce by binary fission, creating two identical cells May participate in conjugation Genes move from one cell to another

ARE VIRUSES ALIVE? Not considered alive by many biologists Not composed of cells Not able to reproduce independently; must use host cell Infect living cells Can make copies of themselves Made of a DNA or RNA core surrounded by protein coat HIV Virus

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