IB Biology SL Year 1: Exam Review Questions with Answers. Updated to the latest Edition

Enzyme - AnsGlobular proteins that act as catalysts of chemical reactions Active Site - AnsRegion on the surface of an enzyme to which substrates bind and which catalyzes a chemical reaction involving substrates Enzyme-substrate specificity - AnsThe active sites of enzymes are specific to their substrates because it has a very specific shape, which means enzymes can catalyze only certain reactions as only a small number of substrates fit in the active site Effect of temperature on enzyme activity - AnsRises in temperature cause a rise in enzyme activity, but too high a temperature results in denaturation and loss of enzyme function Effect of pH on enzyme activity - AnsEnzymes work most effectively at their optimum pH, and diversions from this optimum result in a decrease of enzyme activity Effect of substrate concentration on enzyme activity - AnsAn increase in substrate concentration results in an increase in enzyme activity because of the increase in random collisions between the substrate and the active site Denaturation - Anschanging the structure of an enzyme (or other protein) so it can no longer carry out its function Use of lactase in production of lactose-free milk - AnsLactase breaks down the lactose in milk in order to create lactose-free milk Photosynthesis - Ansthe conversion of light energy into chemical energy Chlorophyll - Ansmain photosynthetic pigment Differences in absorption of red, blue and green light by chlorophyll - AnsChlorophyll can absorb more blue and red light than green light, which it instead reflects, resulting in the green color of plants Uses for light energy - Anslight energy is used to produce ATP, and to split water molecules (photolysis) to form oxygen and hydrogen. Use of ATP and hydrogen - AnsATP and hydrogen (derived from photolysis of water) are used to fix carbon dioxide to make organic molecules Means of measuring rate of photosynthesis - AnsThe rate of photosynthesis can be measured directly by the production of oxygen or the uptake of carbon dioxide, or indirectly by an increase in biomass. Effect of temperature on the rate of photosynthesis - AnsAn increase in temperature results in an increase in the rate of photosynthesis until the optimum is reached, after which photosynthesis will begin to decrease rapidly Effect of carbon dioxide concentration on the rate of photosynthesis - AnsAs the carbon dioxide concentration increases so does the rate of photosynthesis. There is no photosynthesis at very low levels of carbon dioxide and at high levels the rate reaches a plateau. Effect of light intensity on the rate of photosynthesis - AnsLight intensity results in an increase in photosynthesis until a certain point, after which it plateaus Species - AnsA group of organisms that can interbreed and produce fertile offspring Habitat - Ansthe environment in which a species normally lives or the location of a living organism Population - AnsA group of species who live in the same area at the same time Community - AnsA group of populations living and interacting with each other in an area Ecosystem - Ansa community and its abiotic environment Ecology - Ansthe study of relationships between living organisms and their abiotic environment Autotroph - Ansan organism that synthesizes its organic molecules from simple inorganic substances Heterotroph - AnsAn organism that obtains organic molecules from other organisms Consumers - Ansorganisms that ingest other organic matte