4.2 Energy Flow Flashcards
most ecosystems rely on a supply of energy from…
sunlight
three groups of autotroph carry out photosynthesis:
plants, eukaryotic algae(including seaweeds that grow on rocky shores), and cyanobacteria.
groups of heterotroph
consumers, saprotrophs, detritivores
how do heterotroph get their energy?
they use carbon compounds in their foods as a source of energy.
how do producers release energy from their carbon compounds?
By cell respiration. (energy released in this way is eventually lost to the environment as waste heat. However, only some of the carbon compounds in producers are used in this way and the largest part remains in the cells and tissues of producers. The energy in these carbon compounds is available to heterotrophs).
what do living organisms need energy for?
- to synthesize large molecules like DNA, RNA, and proteins.
- to pump molecules or ions across membranes by active transport.
- to move things around inside the cell, such as chromosomes or vesicles, or in muscle cells the protein fibres that cause muscle contraction.
all cells can produce ATP by cell respiration. in this process, carbon compounds such as carbohydrates and lipids are oxidized. these oxidation reactions are exothermic and the energy released is used in endothermic reactions to make ATP.
every cell produces its own ATP supply
what is the second law of thermodynamics?
it states that energy transformations are never 100% efficient. Not all of the energy from the oxidation of carbon compounds in cell respiration is transferred to ATP. the remainder is converted to heat.
energy conversions of living organisms:
- light energy to chemical energy in photosynthesis
- chemical energy to kinetic energy in muscle contraction
- chemical energy to electrical energy in nerve cells
- chemical energy to heat energy in heat-generating adipose tissue
- they cannot convert heat energy into any other form of energy.
what is biomass?
biomass is the total mass of a group of organisms. it consists of the cells and tissues of those organisms, including the carbohydrates and other carbon compounds that they can contain. Because carbon compounds have chemical energy, biomass has energy.
